Pub Date : 2023-05-01DOI: 10.1152/physiol.2023.38.s1.5732862
Bethany G Beekly, Katherine Furman, C. Burgess, C. Elias
Levels of circulating gonadal hormones, including estrogens, affect both subjective and objective measures of sleep quality. However, the mechanisms linking sex variables to sleep architecture are incompletely understood. One brain region known to be potently regulated by circulating levels of estradiol is the arcuate nucleus of the hypothalamus (ARH). In particular, ARH neurons containing the trio of neuropeptides kisspeptin, neurokinin B (NKB), and dynorphin (“KNDy neurons”) express ERα and are well-known to respond to estradiol. We sought to determine whether ARH KNDy neurons are implicated in estrogenic effects on sleep.Melanin-concentrating hormone (MCH) neurons of the lateral hypothalamus are established regulators of sleep. A subset of MCH neurons also express the NKB receptor, NK3R, and are innervated by NKB immunoreactive fibers. Thus, we hypothesized that ARH KNDy neurons modulate sleep architecture in an estradiol-dependent manner via NKB signaling to NK3R-expressing MCH neurons. To test this hypothesis, we employed optogenetic stimulation in the LHA of female Kiss1-Cre;ChR2-eYFP transgenic mice, which express channelrhodopsin in kisspeptin-expressing neurons, to activate KNDy neuron terminals apposing MCH-expressing cells.We recorded sleep via electroencephalogram (EEG) with and without optogenetic stimulation in a randomized-crossover design. Adult ovariectomized female mice with and without estradiol replacement were used (“OVX and OVX+E2 mice”). Each mouse was recorded under both conditions to minimize the effects of individual variation, with the first condition (i.e., with vs without estradiol implant) randomly assigned. EEG data were first evaluated using a semiautomated scoring algorithm and then manually checked. These steps were performed by at least two different researchers to ensure accurate, reproducible scoring.During the light phase, when sleep pressure is highest for mice, stimulation of KNDy terminals in the LHA caused OVX females to spend more time awake, primarily at the expense of rapid-eye movement (REM) sleep. Conversely, OVX+E2 females exhibited reduced wakefulness when KNDy neuron terminals were stimulated. This corresponded to increases to both REM and non-REM sleep. During the dark phase, the reverse phenotype was observed. Optogenetic stimulation caused OVX females to spend less time awake and more time in both REM and non-REM sleep during the dark phase, while it resulted in OVX+E2 females spending more time awake at the expense of both REM and non-REM sleep. Taken together, these data suggest that the activation of KNDy neuron terminals in the LHA affects sleep in manner determined by both circulating estrogens and circadian rhythms. (NIH) Grants R01HD069702, R01HD096324; T32HD079342, F31HD102160; 1R01DK129366-01, the Michigan Diabetes Research Center Pilot and Feasibility Award, and the Whitehall Foundation New Investigator Grant #2018-08-50 This is the full abstract presented at the American Physiology S
包括雌激素在内的循环性腺激素水平会影响睡眠质量的主观和客观指标。然而，将性别变量与睡眠结构联系起来的机制尚不完全清楚。下丘脑弓状核(ARH)是已知受循环雌二醇水平有效调节的一个大脑区域。特别是，ARH神经元含有kisspeptin、neurokinin B (NKB)和dynorphin(“KNDy神经元”)这三种神经肽，它们表达ERα，并对雌二醇有反应。我们试图确定ARH KNDy神经元是否与雌激素对睡眠的影响有关。下丘脑外侧的黑色素集中激素(MCH)神经元是公认的睡眠调节因子。MCH神经元的一个子集也表达NKB受体NK3R，并由NKB免疫反应纤维支配。因此，我们假设ARH KNDy神经元通过向表达nk3r的MCH神经元发送NKB信号，以雌二醇依赖的方式调节睡眠结构。为了验证这一假设，我们在kisspeptin表达通道视紫红质的雌性Kiss1-Cre;ChR2-eYFP转基因小鼠的LHA中采用光遗传刺激，激活与mch表达细胞相对应的KNDy神经元末端。在随机交叉设计中，我们通过脑电图(EEG)记录了有和没有光遗传刺激的睡眠情况。使用切除卵巢的成年雌性小鼠(“OVX和OVX+E2小鼠”)进行雌二醇替代和不替代。在两种情况下记录每只小鼠，以尽量减少个体差异的影响，并随机分配第一种情况(即，植入雌二醇与未植入雌二醇)。EEG数据首先使用半自动评分算法进行评估，然后进行人工检查。这些步骤至少由两名不同的研究人员执行，以确保准确、可重复的评分。在光照阶段，当小鼠的睡眠压力最高时，刺激LHA中的KNDy终端导致OVX雌性花更多的时间清醒，主要是以牺牲快速眼动(REM)睡眠为代价的。相反，当KNDy神经元末梢受到刺激时，OVX+E2雌性小鼠的清醒程度降低。这与快速眼动和非快速眼动睡眠的增加相对应。在暗期，观察到相反的表型。光遗传刺激导致OVX雌性在黑暗期的快速眼动和非快速眼动睡眠中清醒时间减少，而在快速眼动和非快速眼动睡眠中清醒时间增加，而OVX+E2雌性在快速眼动和非快速眼动睡眠中清醒时间增加。综上所述，这些数据表明，LHA中KNDy神经元末梢的激活以循环雌激素和昼夜节律决定的方式影响睡眠。(NIH)资助R01HD069702, R01HD096324;T32HD079342 F31HD102160;1R01DK129366-01，密歇根糖尿病研究中心试点和可行性奖，白厅基金会新研究者资助#2018-08-50这是2023年美国生理学峰会会议上发表的全文摘要，仅以HTML格式提供。此摘要没有附加版本或附加内容。生理学没有参与同行评议过程。
{"title":"KNDy innervation of MCH neurons modulates sleep in an estradiol-dependent manner","authors":"Bethany G Beekly, Katherine Furman, C. Burgess, C. Elias","doi":"10.1152/physiol.2023.38.s1.5732862","DOIUrl":"https://doi.org/10.1152/physiol.2023.38.s1.5732862","url":null,"abstract":"Levels of circulating gonadal hormones, including estrogens, affect both subjective and objective measures of sleep quality. However, the mechanisms linking sex variables to sleep architecture are incompletely understood. One brain region known to be potently regulated by circulating levels of estradiol is the arcuate nucleus of the hypothalamus (ARH). In particular, ARH neurons containing the trio of neuropeptides kisspeptin, neurokinin B (NKB), and dynorphin (“KNDy neurons”) express ERα and are well-known to respond to estradiol. We sought to determine whether ARH KNDy neurons are implicated in estrogenic effects on sleep.Melanin-concentrating hormone (MCH) neurons of the lateral hypothalamus are established regulators of sleep. A subset of MCH neurons also express the NKB receptor, NK3R, and are innervated by NKB immunoreactive fibers. Thus, we hypothesized that ARH KNDy neurons modulate sleep architecture in an estradiol-dependent manner via NKB signaling to NK3R-expressing MCH neurons. To test this hypothesis, we employed optogenetic stimulation in the LHA of female Kiss1-Cre;ChR2-eYFP transgenic mice, which express channelrhodopsin in kisspeptin-expressing neurons, to activate KNDy neuron terminals apposing MCH-expressing cells.We recorded sleep via electroencephalogram (EEG) with and without optogenetic stimulation in a randomized-crossover design. Adult ovariectomized female mice with and without estradiol replacement were used (“OVX and OVX+E2 mice”). Each mouse was recorded under both conditions to minimize the effects of individual variation, with the first condition (i.e., with vs without estradiol implant) randomly assigned. EEG data were first evaluated using a semiautomated scoring algorithm and then manually checked. These steps were performed by at least two different researchers to ensure accurate, reproducible scoring.During the light phase, when sleep pressure is highest for mice, stimulation of KNDy terminals in the LHA caused OVX females to spend more time awake, primarily at the expense of rapid-eye movement (REM) sleep. Conversely, OVX+E2 females exhibited reduced wakefulness when KNDy neuron terminals were stimulated. This corresponded to increases to both REM and non-REM sleep. During the dark phase, the reverse phenotype was observed. Optogenetic stimulation caused OVX females to spend less time awake and more time in both REM and non-REM sleep during the dark phase, while it resulted in OVX+E2 females spending more time awake at the expense of both REM and non-REM sleep. Taken together, these data suggest that the activation of KNDy neuron terminals in the LHA affects sleep in manner determined by both circulating estrogens and circadian rhythms. (NIH) Grants R01HD069702, R01HD096324; T32HD079342, F31HD102160; 1R01DK129366-01, the Michigan Diabetes Research Center Pilot and Feasibility Award, and the Whitehall Foundation New Investigator Grant #2018-08-50 This is the full abstract presented at the American Physiology S","PeriodicalId":49694,"journal":{"name":"Physiology","volume":"57 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90883904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1152/physiol.2023.38.s1.5731276
A. Miller, Erik A. Ovrom, J. Senefeld, C. Wiggins, P. Dominelli, Michael J. Joyner, B. Welch, A. Ramsook
Background: Interstitial lung disease (ILD) encompasses several pulmonary disorders associated with scarring and fibrosis of pulmonary tissue. People with idiopathic pulmonary fibrosis, a subset of ILD, have greater central airway luminal area compared to age- and sex-matched healthy controls when evaluated using microcomputed tomography, a process examining the luminal area of ex-vivo lung tissue. In this study we aimed to confirm these findings using a different method of airway assessment, three-dimensional (3D) reconstruction of computed tomography (CT) scans. Moreover, in health, males have larger central airways than height-matched females, but it remains unknown if there are sex differences in airway area among people with ILD. We hypothesized that sex differences observed in healthy people would persist among people with ILD. Methods: A cohort of 399 patients with lung CT scans were screened, of which 19 people (7 females) with ILD were included in analyses after exclusions. People with ILD were matched based on sex, age, and height to 19 healthy controls. We assessed cross-sectional luminal area at the midpoint of seven conducting airways (trachea, left and right main bronchus, intermediate bronchus, left and right upper lobe, and left lower lobe). Results from pulmonary function tests were also abstracted, as available. To examine sex differences, we compared airway luminal area, normalized to participant height, between males and females with ILD. Sex differences were analyzed using a univariate ANOVA test. Results: People with ILD had a preserved ratio of forced expiratory volume in the first second to forced vital capacity (101 ±12%predicted) and decreased diffusing capacity for carbon monoxide (55 ±23%predicted). People with ILD had airways that were between 19.6%-45.0% larger than controls (p<0.05). Composite physiologic index, a marker of ILD severity, was not different between sexes (p=0.07). Males with ILD had significantly larger, luminal areas than females in two central airways - right main bronchus (1.46±0.41 vs. 1.07±0.22 mm2/cm, p=0.04) and left upper lobe (0.54±0.10 vs. 0.43±0.08 mm2/cm, p=0.02). However, luminal area of other central airways, including: trachea (2.15±0.57 vs. 1.65±0.32 mm2/cm, p=0.051), bronchus intermediate (0.77±0.23 vs. 0.61±0.13 mm2/cm, p=0.12), right upper lobe (0.47±0.15 vs. 0.40±0.06 mm2/cm, p=0.26), left main bronchus (0.93±0.33 vs. 0.69±0.16 mm2/cm, p=0.09), and left lower lobe (0.41±0.13 vs. 0.40±0.08 mm2 /cm, p=0.79) were not different between sexes in people with ILD. Conclusion: Sex differences observed in healthy people are potentially preserved in ILD, but a more robust sample is required to fully elucidate these findings. Illuminating any sex differences in ILD pathophysiology may provide knowledge to treat and improve clinical outcomes in ILD. Funding: National Heart, Lung, and Blood Institute (F32HL154320 to JWS; 5R35HL139854 to MJJ). This is the full abstract presented at the American
{"title":"Sex differences in central airway luminal area among people with interstitial lung disease","authors":"A. Miller, Erik A. Ovrom, J. Senefeld, C. Wiggins, P. Dominelli, Michael J. Joyner, B. Welch, A. Ramsook","doi":"10.1152/physiol.2023.38.s1.5731276","DOIUrl":"https://doi.org/10.1152/physiol.2023.38.s1.5731276","url":null,"abstract":"Background: Interstitial lung disease (ILD) encompasses several pulmonary disorders associated with scarring and fibrosis of pulmonary tissue. People with idiopathic pulmonary fibrosis, a subset of ILD, have greater central airway luminal area compared to age- and sex-matched healthy controls when evaluated using microcomputed tomography, a process examining the luminal area of ex-vivo lung tissue. In this study we aimed to confirm these findings using a different method of airway assessment, three-dimensional (3D) reconstruction of computed tomography (CT) scans. Moreover, in health, males have larger central airways than height-matched females, but it remains unknown if there are sex differences in airway area among people with ILD. We hypothesized that sex differences observed in healthy people would persist among people with ILD. Methods: A cohort of 399 patients with lung CT scans were screened, of which 19 people (7 females) with ILD were included in analyses after exclusions. People with ILD were matched based on sex, age, and height to 19 healthy controls. We assessed cross-sectional luminal area at the midpoint of seven conducting airways (trachea, left and right main bronchus, intermediate bronchus, left and right upper lobe, and left lower lobe). Results from pulmonary function tests were also abstracted, as available. To examine sex differences, we compared airway luminal area, normalized to participant height, between males and females with ILD. Sex differences were analyzed using a univariate ANOVA test. Results: People with ILD had a preserved ratio of forced expiratory volume in the first second to forced vital capacity (101 ±12%predicted) and decreased diffusing capacity for carbon monoxide (55 ±23%predicted). People with ILD had airways that were between 19.6%-45.0% larger than controls (p<0.05). Composite physiologic index, a marker of ILD severity, was not different between sexes (p=0.07). Males with ILD had significantly larger, luminal areas than females in two central airways - right main bronchus (1.46±0.41 vs. 1.07±0.22 mm2/cm, p=0.04) and left upper lobe (0.54±0.10 vs. 0.43±0.08 mm2/cm, p=0.02). However, luminal area of other central airways, including: trachea (2.15±0.57 vs. 1.65±0.32 mm2/cm, p=0.051), bronchus intermediate (0.77±0.23 vs. 0.61±0.13 mm2/cm, p=0.12), right upper lobe (0.47±0.15 vs. 0.40±0.06 mm2/cm, p=0.26), left main bronchus (0.93±0.33 vs. 0.69±0.16 mm2/cm, p=0.09), and left lower lobe (0.41±0.13 vs. 0.40±0.08 mm2 /cm, p=0.79) were not different between sexes in people with ILD. Conclusion: Sex differences observed in healthy people are potentially preserved in ILD, but a more robust sample is required to fully elucidate these findings. Illuminating any sex differences in ILD pathophysiology may provide knowledge to treat and improve clinical outcomes in ILD. Funding: National Heart, Lung, and Blood Institute (F32HL154320 to JWS; 5R35HL139854 to MJJ). This is the full abstract presented at the American ","PeriodicalId":49694,"journal":{"name":"Physiology","volume":"82 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90884049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1152/physiol.2023.38.s1.5731132
Wenxiong Li, Fei-Fei Chen, Kuaiqiang Zhang, Zhiping Sun, Yan Zhang, Feng Yang
Objective: Vitamin D deficiency is associated with a range of skeleton and muscle disorders, including osteoporosis and sarcopenia, but its functional role and the underlying mechanism in skeleton and muscle physiology remain unclear. We investigated the effect of vitamin D receptor (VDR) deletion on skeleton and muscle using a mice model with dexamethasone-induced osteo-sarcopenia (OS). Methods: The wildtype and VDR(-/-) mice were treated with vehicle and dexamethasone (i.p., once daily) for 14 consecutive days. The murine myoblast cell line C2C12 and bone mesenchymal stem cells (BMSCs) were used as an in vitro model in this study. Results: After challenging to dexamethasone, VDR-null mice exhibited more severe amyotrophy and bone rarefaction compared with wildtype counterparts, manifested by marked weight loss and significant decrease in muscle wet weight coefficient of the tibialis anterior muscle and gastrocnemius, accompanying with a decrease in bone mineral density (BMD). In addition, the limb grip and weight-loading swimming time were also fall off. Similarly, dystrophin fluorescence staining and haematoxylin eosin staining showed the decrease in cross-sectional area of skeletal muscle in the VDR-null mice. Alizarin red staining and TRAP staining showed that the differentiation of osteoblasts was significantly decreased, while the activity of osteoclasts was significantly increased in the VDR-null mice. VDR knockout mice significantly accelerated protein degradation and bone destructions, but inhibited protein synthesis and bone construction in skeleton and muscle tissue. In addition, we further assessed whether increased Fe2+ level and decreased GPX4 in VDR knockout muscle accelerated the muscle injury, since the deletion of VDR activated ferroptosis, giving rise to the accumulated of Fe2+ in mice and Depleting GSH and inhibiting GPX4 expression. Treatment with the inhibitor of ferroptosis Ferrostatin-1 eliminated dexamethasone-induced atrophy and osteoporosis of myotube cells and BMSCs, reflected by alleviating myotube cell atrophy and BMSCs bone rarefaction via MHC fluorescent staining, Alizarin red staining and TRAP staining. It is suggested that ferroptosis may be one of the pathogenesis of OS. Conclusion: These results provided evidence that VDR attenuated dexamethasone-induced OS at least in part by suppressing the ferroptosis. This work was sponsored by the Program of Natural Science Foundation of China (81973889), the Program of Shaanxi Education Department (19JC013 to FY & 22JK0346 to WL), Youth Innovation Team in Shaanxi universities, and the Program of Health Commission of Shaanxi Province (2022B002). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
{"title":"Vitamin D Receptor Attenuates Osteo-sarcopenia by Suppressing the Ferroptosis","authors":"Wenxiong Li, Fei-Fei Chen, Kuaiqiang Zhang, Zhiping Sun, Yan Zhang, Feng Yang","doi":"10.1152/physiol.2023.38.s1.5731132","DOIUrl":"https://doi.org/10.1152/physiol.2023.38.s1.5731132","url":null,"abstract":"Objective: Vitamin D deficiency is associated with a range of skeleton and muscle disorders, including osteoporosis and sarcopenia, but its functional role and the underlying mechanism in skeleton and muscle physiology remain unclear. We investigated the effect of vitamin D receptor (VDR) deletion on skeleton and muscle using a mice model with dexamethasone-induced osteo-sarcopenia (OS). Methods: The wildtype and VDR(-/-) mice were treated with vehicle and dexamethasone (i.p., once daily) for 14 consecutive days. The murine myoblast cell line C2C12 and bone mesenchymal stem cells (BMSCs) were used as an in vitro model in this study. Results: After challenging to dexamethasone, VDR-null mice exhibited more severe amyotrophy and bone rarefaction compared with wildtype counterparts, manifested by marked weight loss and significant decrease in muscle wet weight coefficient of the tibialis anterior muscle and gastrocnemius, accompanying with a decrease in bone mineral density (BMD). In addition, the limb grip and weight-loading swimming time were also fall off. Similarly, dystrophin fluorescence staining and haematoxylin eosin staining showed the decrease in cross-sectional area of skeletal muscle in the VDR-null mice. Alizarin red staining and TRAP staining showed that the differentiation of osteoblasts was significantly decreased, while the activity of osteoclasts was significantly increased in the VDR-null mice. VDR knockout mice significantly accelerated protein degradation and bone destructions, but inhibited protein synthesis and bone construction in skeleton and muscle tissue. In addition, we further assessed whether increased Fe2+ level and decreased GPX4 in VDR knockout muscle accelerated the muscle injury, since the deletion of VDR activated ferroptosis, giving rise to the accumulated of Fe2+ in mice and Depleting GSH and inhibiting GPX4 expression. Treatment with the inhibitor of ferroptosis Ferrostatin-1 eliminated dexamethasone-induced atrophy and osteoporosis of myotube cells and BMSCs, reflected by alleviating myotube cell atrophy and BMSCs bone rarefaction via MHC fluorescent staining, Alizarin red staining and TRAP staining. It is suggested that ferroptosis may be one of the pathogenesis of OS. Conclusion: These results provided evidence that VDR attenuated dexamethasone-induced OS at least in part by suppressing the ferroptosis. This work was sponsored by the Program of Natural Science Foundation of China (81973889), the Program of Shaanxi Education Department (19JC013 to FY & 22JK0346 to WL), Youth Innovation Team in Shaanxi universities, and the Program of Health Commission of Shaanxi Province (2022B002). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.","PeriodicalId":49694,"journal":{"name":"Physiology","volume":"111 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91004508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1152/physiol.2023.38.s1.5735207
K. Deruisseau, Silas Derfel, J. MacDonald, L. DeRuisseau
Down syndrome is the most common developmental and intellectual disability that leads to co-morbidities including lower heart rate and blood pressure. We previously showed that Ts65Dn mice also display reduced heart rate and blood pressure compared to wild-type (WT) colony controls. Lower serum Vitamin D (VitD) levels have been reported among individuals with Ds. In other populations, VitD is a regulator of nitric oxide synthase and a known modulator of cardiovascular outcomes. VitD effects on cardiovascular physiology in Ds is unknown. In this preliminary study, we hypothesized that Ts65Dn mice supplemented with VitD would display improved heart rate compared to Ts65Dn mice on a control diet. Two-month old male Ts65Dn mice were placed onto a control diet (1IU VitD/g; n=4) or VitD supplemented diet (50IU/g; n=5) for two weeks and subsequently tested for resting heart rate. Mice were fitted with a MouseOx neck collar to monitor heart rate while freely moving within the cage. After habituation to the collar, heart rate was recorded for 30 minutes in the light cycle. Heart rate in Ts65Dn on the control diet was 510±67 bpm vs. 636±78 on the VitD diet (p=.038; t-test). As expected, WT (n=5; control diet) displayed a higher heart rate of 729±62 bpm. These preliminary data reveal a partial rescue of resting heart rate in Ts65Dn following VitD supplementation. Future studies can evaluate serum VitD levels, nitric oxide synthase, and cardiovascular metrics including blood pressure, heart rate, and pulse wave velocity in Ts65Dn and WT mice supplemented with dietary VitD. This work was supported by NIH R21HD099573 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
{"title":"Dietary vitamin D supplementation partially rescues heart rate in Ts65Dn mice, a model of Down syndrome","authors":"K. Deruisseau, Silas Derfel, J. MacDonald, L. DeRuisseau","doi":"10.1152/physiol.2023.38.s1.5735207","DOIUrl":"https://doi.org/10.1152/physiol.2023.38.s1.5735207","url":null,"abstract":"Down syndrome is the most common developmental and intellectual disability that leads to co-morbidities including lower heart rate and blood pressure. We previously showed that Ts65Dn mice also display reduced heart rate and blood pressure compared to wild-type (WT) colony controls. Lower serum Vitamin D (VitD) levels have been reported among individuals with Ds. In other populations, VitD is a regulator of nitric oxide synthase and a known modulator of cardiovascular outcomes. VitD effects on cardiovascular physiology in Ds is unknown. In this preliminary study, we hypothesized that Ts65Dn mice supplemented with VitD would display improved heart rate compared to Ts65Dn mice on a control diet. Two-month old male Ts65Dn mice were placed onto a control diet (1IU VitD/g; n=4) or VitD supplemented diet (50IU/g; n=5) for two weeks and subsequently tested for resting heart rate. Mice were fitted with a MouseOx neck collar to monitor heart rate while freely moving within the cage. After habituation to the collar, heart rate was recorded for 30 minutes in the light cycle. Heart rate in Ts65Dn on the control diet was 510±67 bpm vs. 636±78 on the VitD diet (p=.038; t-test). As expected, WT (n=5; control diet) displayed a higher heart rate of 729±62 bpm. These preliminary data reveal a partial rescue of resting heart rate in Ts65Dn following VitD supplementation. Future studies can evaluate serum VitD levels, nitric oxide synthase, and cardiovascular metrics including blood pressure, heart rate, and pulse wave velocity in Ts65Dn and WT mice supplemented with dietary VitD. This work was supported by NIH R21HD099573 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.","PeriodicalId":49694,"journal":{"name":"Physiology","volume":"1 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91036295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1152/physiol.2023.38.s1.5732497
Ranjan K. Roy, Yifan Yao, R. Silver, J. Stern
By transporting products directly from the capillary bed of one region to the capillary bed of another region, vascular portal pathways enable minute amounts of important secretions to reach their specialized targets in high concentrations, without dilution in the systemic circulatory system. For decades there has been only one known portal system in the mammalian brain - that of the pituitary gland, first identified in 1933 (Popa and Fielding, J. Anatomy 1933). This year, we described a second portal pathway in the mouse linking the capillary vessels of the brain's clock suprachiasmatic nucleus (SCN) to those of the organum vasculosum of the lamina terminalis (OVLT), a circumventricular organ (Yao et al., Nat. Comm. 2021). A caveat in this initial work was that the direction of blood flow was unknown. To determine whether the SCN signaled the OVLT or vice-versa, we performed in vivo 2-photon imaging in anesthetized eGFP-vasopressin (VP) rats using a recently developed approach (Roy et al., Cell Report 2021) to study blood flow in this portal system. To delineate the SCN microvasculature in vivo, we intravenously infused fluorescent dextrans in anesthetized rats. The SCN-OVLT portal system was identified as Alexa 633 (an artery/arteriole specific dye)-negative vessels originating from a dense SCN capillary network that run rostrally towards the OVLT. These vessels displayed a mean diameter of ~20 μm. Blood flow in the portal vessels was measured by monitoring red blood cell (RBC) movement after intravenous injections with Rho70 kDa. Using kymographs, we found that in all cases, RBCs flowed rostrally, from the SCN towards the OVLT. Importantly, we found than blood flow was significantly higher at night (ZT17-19) compared to daylight (ZT5-7) (p< 0.001), while directionality remained the same (SCN→OVLT). Taken together, our results support the presence of a functional SCN-OVLT portal system in the rat in which blood flows unidirectionally from the SCN towards the OVLT. Moreover, our studies support the notion that blood flow in this system can be regulated. This clock portal system points to entirely new routes and targets for secreted signals from the SCN, restructuring our understanding of its output pathways. Support: NIH HLBI R01HL162575 to JES, AHA916907 to RKR and NSF 1749500 to RS. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
{"title":"In vivo determination of direction of blood flow in the newly discovered SCN-OVLT vascular portal system in rat","authors":"Ranjan K. Roy, Yifan Yao, R. Silver, J. Stern","doi":"10.1152/physiol.2023.38.s1.5732497","DOIUrl":"https://doi.org/10.1152/physiol.2023.38.s1.5732497","url":null,"abstract":"By transporting products directly from the capillary bed of one region to the capillary bed of another region, vascular portal pathways enable minute amounts of important secretions to reach their specialized targets in high concentrations, without dilution in the systemic circulatory system. For decades there has been only one known portal system in the mammalian brain - that of the pituitary gland, first identified in 1933 (Popa and Fielding, J. Anatomy 1933). This year, we described a second portal pathway in the mouse linking the capillary vessels of the brain's clock suprachiasmatic nucleus (SCN) to those of the organum vasculosum of the lamina terminalis (OVLT), a circumventricular organ (Yao et al., Nat. Comm. 2021). A caveat in this initial work was that the direction of blood flow was unknown. To determine whether the SCN signaled the OVLT or vice-versa, we performed in vivo 2-photon imaging in anesthetized eGFP-vasopressin (VP) rats using a recently developed approach (Roy et al., Cell Report 2021) to study blood flow in this portal system. To delineate the SCN microvasculature in vivo, we intravenously infused fluorescent dextrans in anesthetized rats. The SCN-OVLT portal system was identified as Alexa 633 (an artery/arteriole specific dye)-negative vessels originating from a dense SCN capillary network that run rostrally towards the OVLT. These vessels displayed a mean diameter of ~20 μm. Blood flow in the portal vessels was measured by monitoring red blood cell (RBC) movement after intravenous injections with Rho70 kDa. Using kymographs, we found that in all cases, RBCs flowed rostrally, from the SCN towards the OVLT. Importantly, we found than blood flow was significantly higher at night (ZT17-19) compared to daylight (ZT5-7) (p< 0.001), while directionality remained the same (SCN→OVLT). Taken together, our results support the presence of a functional SCN-OVLT portal system in the rat in which blood flows unidirectionally from the SCN towards the OVLT. Moreover, our studies support the notion that blood flow in this system can be regulated. This clock portal system points to entirely new routes and targets for secreted signals from the SCN, restructuring our understanding of its output pathways. Support: NIH HLBI R01HL162575 to JES, AHA916907 to RKR and NSF 1749500 to RS. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.","PeriodicalId":49694,"journal":{"name":"Physiology","volume":"6 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91064585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1152/physiol.2023.38.s1.5731414
H. Hemingway, Amy E. Bazzoni, Daniel H. Craighead, Hannah L Rosenberg, Kathy H Nguyen, Kaitlin A. Freeberg, Emily C. Adam, Abigail G Longtine, M. Chonchol, C. Minson, D. Seals, Vienna E. Brunt
Fluid cognitive function (the domain of cognition most impaired in Alzheimer’s Disease) declines with aging, predisposing older adults to Alzheimer’s Disease and related dementias. Age-related cerebrovascular dysfunction contributes to cognitive decline by impairing brain blood flow such that there is chronic cerebral hypoperfusion, which has been linked to cognitive impairment. Increased oxidative stress and the resultant loss of nitric oxide (NO) bioavailability likely play mechanistic roles in age-related cerebrovascular dysfunction. Passive heat therapy (i.e., regular heat exposure) improves peripheral vascular outcomes and reduces oxidative stress and, therefore, may also improve cognitive and cerebrovascular function. Purpose: To test the hypotheses that heat therapy would 1) improve fluid cognitive function, 2) increase total cerebral blood flow (tCBF), and 3) reduce cerebrovascular reactive oxygen species (ROS) production and increase NO bioavailability. Methods and results: Midlife and older (ML/O) adults (50+ years) were randomized to 8-10 weeks of passive heat therapy (via hot [40 °C] water immersion; 30 x 60-min sessions) or sham control (via thermoneutral [36 °C] water immersion; NCT03264508). The following preliminary results were collected at baseline (pre) and at the end (post) of the heat therapy or sham intervention (n=6-10/group). Fluid Cognition Composite scores, assessed using the NIH Toolbox Cognition Battery, increased from 97± 3 (mean ± SEM) at baseline to 100± 3 at end-intervention (p=0.03) in subjects who underwent heat therapy, an improvement from the 42nd to 50th percentile of all U.S. adults, but there was no consistent change in sham subjects (p=0.16). tCBF, assessed via duplex ultrasonography of the vertebral and internal carotid arteries, increased from 766± 99 mL/min at baseline to 841± 123 mL/min after heat therapy (p=0.03), whereas there was no change following sham (pre: 723± 20 vs. post: 729± 26 mL/min; p=0.89). Cerebrovascular ROS production and NO bioavailability were assessed with fluorescent probes in vitro using human brain endothelial cells (HBECs; technical replicates n=24-29) cultured in hot (39 °C; to match in vivo body core temperature during heat therapy sessions) and standard (37 °C) conditions. HBECs cultured in hot conditions had lower basal ROS production (hot: 860± 7 AU vs. standard: 907± 5 AU; p<0.01) and higher acetylcholine-stimulated NO production (hot: 1.5± 0.06 vs. standard: 1.3± 0.04 fold change in NO production; p=0.03). Conclusions: These results suggest that heat therapy can improve fluid cognition and brain blood flow in ML/O adults, possibly by reducing brain endothelial cell ROS production and increasing NO bioavailability. Heat therapy shows potential to protect cognitive performance in the domain most affected by Alzheimer’s Disease and improve cerebrovascular function in ML/O adults. NIH/NCATS UL1 TR002535; T32 AG000279; R01 AG073117 This is the full abstract presented at the Am
{"title":"Passive heat therapy improves cognitive and cerebrovascular function in healthy midlife and older adults","authors":"H. Hemingway, Amy E. Bazzoni, Daniel H. Craighead, Hannah L Rosenberg, Kathy H Nguyen, Kaitlin A. Freeberg, Emily C. Adam, Abigail G Longtine, M. Chonchol, C. Minson, D. Seals, Vienna E. Brunt","doi":"10.1152/physiol.2023.38.s1.5731414","DOIUrl":"https://doi.org/10.1152/physiol.2023.38.s1.5731414","url":null,"abstract":"Fluid cognitive function (the domain of cognition most impaired in Alzheimer’s Disease) declines with aging, predisposing older adults to Alzheimer’s Disease and related dementias. Age-related cerebrovascular dysfunction contributes to cognitive decline by impairing brain blood flow such that there is chronic cerebral hypoperfusion, which has been linked to cognitive impairment. Increased oxidative stress and the resultant loss of nitric oxide (NO) bioavailability likely play mechanistic roles in age-related cerebrovascular dysfunction. Passive heat therapy (i.e., regular heat exposure) improves peripheral vascular outcomes and reduces oxidative stress and, therefore, may also improve cognitive and cerebrovascular function. Purpose: To test the hypotheses that heat therapy would 1) improve fluid cognitive function, 2) increase total cerebral blood flow (tCBF), and 3) reduce cerebrovascular reactive oxygen species (ROS) production and increase NO bioavailability. Methods and results: Midlife and older (ML/O) adults (50+ years) were randomized to 8-10 weeks of passive heat therapy (via hot [40 °C] water immersion; 30 x 60-min sessions) or sham control (via thermoneutral [36 °C] water immersion; NCT03264508). The following preliminary results were collected at baseline (pre) and at the end (post) of the heat therapy or sham intervention (n=6-10/group). Fluid Cognition Composite scores, assessed using the NIH Toolbox Cognition Battery, increased from 97± 3 (mean ± SEM) at baseline to 100± 3 at end-intervention (p=0.03) in subjects who underwent heat therapy, an improvement from the 42nd to 50th percentile of all U.S. adults, but there was no consistent change in sham subjects (p=0.16). tCBF, assessed via duplex ultrasonography of the vertebral and internal carotid arteries, increased from 766± 99 mL/min at baseline to 841± 123 mL/min after heat therapy (p=0.03), whereas there was no change following sham (pre: 723± 20 vs. post: 729± 26 mL/min; p=0.89). Cerebrovascular ROS production and NO bioavailability were assessed with fluorescent probes in vitro using human brain endothelial cells (HBECs; technical replicates n=24-29) cultured in hot (39 °C; to match in vivo body core temperature during heat therapy sessions) and standard (37 °C) conditions. HBECs cultured in hot conditions had lower basal ROS production (hot: 860± 7 AU vs. standard: 907± 5 AU; p<0.01) and higher acetylcholine-stimulated NO production (hot: 1.5± 0.06 vs. standard: 1.3± 0.04 fold change in NO production; p=0.03). Conclusions: These results suggest that heat therapy can improve fluid cognition and brain blood flow in ML/O adults, possibly by reducing brain endothelial cell ROS production and increasing NO bioavailability. Heat therapy shows potential to protect cognitive performance in the domain most affected by Alzheimer’s Disease and improve cerebrovascular function in ML/O adults. NIH/NCATS UL1 TR002535; T32 AG000279; R01 AG073117 This is the full abstract presented at the Am","PeriodicalId":49694,"journal":{"name":"Physiology","volume":"26 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91144964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1152/physiol.2023.38.s1.5729417
JH Hill, Mitchell Harberson, Erin Semple
Female sexual dysfunction affects approximately 40% of women in the United States, yet few therapeutic options exist for these patients. The melanocortin system is a new treatment target for Hypoactive Sexual Desire Disorder (HSDD), but the neuronal pathways involved are unclear. In this study, female MC4R knockout mice lacking melanocortin 4 receptors (MC4Rs) paired with males were found to approach males less and have reduced receptivity to copulation, as indicated by a low lordosis quotient. The mice were then bred to express MC4Rs exclusively on Sim1 neurons (tbMC4RSim1 mice) or on oxytocin neurons (tbMC4ROxt mice). Lordosis behavior was normalized in tbMC4RSim1 mice and improved in tbMC4ROxt mice. In contrast, approach behavior was unchanged in tbMC4RSim1 mice but greatly increased in tbMC4ROxt animals. The changes were independent of melanocortin-driven metabolic effects. These results implicate MC4R signaling in Oxt neurons in appetitive behaviors and MC4R signaling in Sim1 neurons in female sexual receptivity, while suggesting melanocortin-driven sexual function does not rely on metabolic neural circuits. R01HD081792 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
{"title":"Melanocortin 4 receptor signaling in Sim-1 neurons permits sexual receptivity in female mice","authors":"JH Hill, Mitchell Harberson, Erin Semple","doi":"10.1152/physiol.2023.38.s1.5729417","DOIUrl":"https://doi.org/10.1152/physiol.2023.38.s1.5729417","url":null,"abstract":"Female sexual dysfunction affects approximately 40% of women in the United States, yet few therapeutic options exist for these patients. The melanocortin system is a new treatment target for Hypoactive Sexual Desire Disorder (HSDD), but the neuronal pathways involved are unclear. In this study, female MC4R knockout mice lacking melanocortin 4 receptors (MC4Rs) paired with males were found to approach males less and have reduced receptivity to copulation, as indicated by a low lordosis quotient. The mice were then bred to express MC4Rs exclusively on Sim1 neurons (tbMC4RSim1 mice) or on oxytocin neurons (tbMC4ROxt mice). Lordosis behavior was normalized in tbMC4RSim1 mice and improved in tbMC4ROxt mice. In contrast, approach behavior was unchanged in tbMC4RSim1 mice but greatly increased in tbMC4ROxt animals. The changes were independent of melanocortin-driven metabolic effects. These results implicate MC4R signaling in Oxt neurons in appetitive behaviors and MC4R signaling in Sim1 neurons in female sexual receptivity, while suggesting melanocortin-driven sexual function does not rely on metabolic neural circuits. R01HD081792 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.","PeriodicalId":49694,"journal":{"name":"Physiology","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134903838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Frailty in aging is driven by the dysregulation of multiple biological pathways. Protectin DX (PDX) is a docosahexaenoic acid (DHA)-derived molecule that alleviates many chronic inflammatory disorders, but its potential effects on frailty remain unknown. Our goal is to identify age-related impairments in metabolic systems and to evaluate the therapeutic potential of PDX on frailty, physical performance, and health parameters. A set of 22-month-old C57BL/6 male and female mice were assigned to vehicle (Old) or PDX daily gavage treatment for 8 weeks, whereas 6-month-old (Adult) mice received only vehicle. Forelimb and hindlimb strength, endurance, voluntary wheel activity and walking speed determined physical performance and were combined with a frailty index score and body weight loss to determine frailty status. Our data shows that old vehicle-treated mice from both sexes had body weight loss paralleling visceromegaly, and old females also had impaired insulin clearance as compared to the Adult group. Aging was associated with physical performance decline together with higher odds of frailty development. There was also age-driven mesangial expansion and glomerular hypertrophy as well as bone mineral density loss. All of the in vivo and in vitro impairments observed with aging co-occurred with upregulation of inflammatory pathways and Myc signaling as well as downregulation of genes related to adipogenesis and oxidative phosphorylation in liver. PDX attenuated the age-driven physical performance (strength, exhaustion, walking speed) decline, promoted robustness, prevented bone losses and partially reversed changes in hepatic expression of Myc targets and metabolic genes. In conclusion, our data provides evidence of the beneficial therapeutic effect of PDX against features of frailty in mice. Further studies are warranted to investigate the mechanisms of action and the potential for human translation. The authors declare no conflict of interest. Funding: μCT analysis was performed by the Center for Skeletal Research Imaging and Biomechanical Testing Core at Massachusetts General Hospital (NIH P30 AR075042). We acknowledge the Boston University Microarray and Sequencing Resource Core Facility and the Clinical and Translational Science Institute (NIH UL1TR001430) for the RNA sequencing analysis. This work is supported, in part, by the Travis Roy Endowed Professorship (to L.V. Thompson) and the National Institute on Aging (R56 AG-067724 to L.V. Thompson and H. Brown-Borg, K07 AG-072124 to L.V. Thompson). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
{"title":"Protectin DX as a therapeutic strategy against frailty in mice","authors":"Lais Perazza, Adam Gower, Holly Brown-Borg, Paola Divieti Pajevic, LaDora Thompson","doi":"10.1152/physiol.2023.38.s1.5764188","DOIUrl":"https://doi.org/10.1152/physiol.2023.38.s1.5764188","url":null,"abstract":"Frailty in aging is driven by the dysregulation of multiple biological pathways. Protectin DX (PDX) is a docosahexaenoic acid (DHA)-derived molecule that alleviates many chronic inflammatory disorders, but its potential effects on frailty remain unknown. Our goal is to identify age-related impairments in metabolic systems and to evaluate the therapeutic potential of PDX on frailty, physical performance, and health parameters. A set of 22-month-old C57BL/6 male and female mice were assigned to vehicle (Old) or PDX daily gavage treatment for 8 weeks, whereas 6-month-old (Adult) mice received only vehicle. Forelimb and hindlimb strength, endurance, voluntary wheel activity and walking speed determined physical performance and were combined with a frailty index score and body weight loss to determine frailty status. Our data shows that old vehicle-treated mice from both sexes had body weight loss paralleling visceromegaly, and old females also had impaired insulin clearance as compared to the Adult group. Aging was associated with physical performance decline together with higher odds of frailty development. There was also age-driven mesangial expansion and glomerular hypertrophy as well as bone mineral density loss. All of the in vivo and in vitro impairments observed with aging co-occurred with upregulation of inflammatory pathways and Myc signaling as well as downregulation of genes related to adipogenesis and oxidative phosphorylation in liver. PDX attenuated the age-driven physical performance (strength, exhaustion, walking speed) decline, promoted robustness, prevented bone losses and partially reversed changes in hepatic expression of Myc targets and metabolic genes. In conclusion, our data provides evidence of the beneficial therapeutic effect of PDX against features of frailty in mice. Further studies are warranted to investigate the mechanisms of action and the potential for human translation. The authors declare no conflict of interest. Funding: μCT analysis was performed by the Center for Skeletal Research Imaging and Biomechanical Testing Core at Massachusetts General Hospital (NIH P30 AR075042). We acknowledge the Boston University Microarray and Sequencing Resource Core Facility and the Clinical and Translational Science Institute (NIH UL1TR001430) for the RNA sequencing analysis. This work is supported, in part, by the Travis Roy Endowed Professorship (to L.V. Thompson) and the National Institute on Aging (R56 AG-067724 to L.V. Thompson and H. Brown-Borg, K07 AG-072124 to L.V. Thompson). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.","PeriodicalId":49694,"journal":{"name":"Physiology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134903841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1152/physiol.2023.38.s1.5729560
Anna Stavniichuk, Kyrylo Pyrshev, Oleg Zaika, Viktor Tomilin, Oleh Pochynyuk
Distal segments of the renal tubule have a major role in controlling whole body K + homeostasis by performing flow-induced K + secretion (FIKS) during K + load and K+ reabsorption in response to systemic K + deficiency. The transient receptor potential vanilloid type 4 (TRPV4) Ca2 + -permeable channel serves as the sensor of tubular flow thus being well-suited to govern K + transport in the distal renal tubule. In the current manuscript, we directly tested whether TRPV4 function in the renal tubule is significant in affecting K + balance. For this, we employed balance metabolic cage studies and systemic measurements with different K+ feeding regimens: high (5% K + ), regular (0.9% K + ), and low (<0.01% K + ) in newly created transgenic mice with selective TRPV4 deletion in the renal tubule (TRPV4fl/fl-Pax8Cre) and their littermate genetic controls (TRPV4fl/fl). Successful deletion was verified by the absence of TRPV4 protein expression in renal homogenates and the lack of TRPV4-mediated Ca2 + influx in freshly-isolated split-opened collecting ducts. There were no differences in plasma electrolytes, baseline urinary volume, and K + levels when both strains were fed regular K + intake. In contrast, plasma K+ levels were significantly elevated in TRPV4fl/fl-Pax8Cre mice on both high and low K + intake. This was associated with a marked decrease in 24 h urinary K+ levels in the knockout, whereas urinary volume and aldosterone levels were indistinguishable from the control TRPV4fl/fl littermates suggesting a direct decrease in the distal tubule K + transport. Interestingly, we also detected significant differences in urinary pH levels indicative of the altered K + reabsorption via H + -K + ATPase in the collecting duct. Indeed, we detected a significantly faster pHi recovery after intracellular acidification with ammonium pulse in both acid secreting A- and base-secreting B-types of intercalated cells and to a lesser degree in principal cells in split-opened collecting ducts from TRPV4fl/fl-Pax8Cre mice on low but not regular K + intake, which is consistent with augmented H + -K + ATPase activity and K + reabsorption in the knockouts. In summary, our results demonstrate an indispensable pro-kaliuretic role of TRPV4 in the renal tubule in controlling K + balance and urinary K + excretion during variations in dietary K + intake This research was supported by NIH-NIDDK DK117865, DK119170, AHA EIA35260097 (to O. Pochynyuk) and AHA-19CDA34660148 (to V. N. Tomilin). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
{"title":"TRPV4 expression in the renal tubule is necessary for maintaining whole body K+ homeostasis","authors":"Anna Stavniichuk, Kyrylo Pyrshev, Oleg Zaika, Viktor Tomilin, Oleh Pochynyuk","doi":"10.1152/physiol.2023.38.s1.5729560","DOIUrl":"https://doi.org/10.1152/physiol.2023.38.s1.5729560","url":null,"abstract":"Distal segments of the renal tubule have a major role in controlling whole body K + homeostasis by performing flow-induced K + secretion (FIKS) during K + load and K+ reabsorption in response to systemic K + deficiency. The transient receptor potential vanilloid type 4 (TRPV4) Ca2 + -permeable channel serves as the sensor of tubular flow thus being well-suited to govern K + transport in the distal renal tubule. In the current manuscript, we directly tested whether TRPV4 function in the renal tubule is significant in affecting K + balance. For this, we employed balance metabolic cage studies and systemic measurements with different K+ feeding regimens: high (5% K + ), regular (0.9% K + ), and low (<0.01% K + ) in newly created transgenic mice with selective TRPV4 deletion in the renal tubule (TRPV4fl/fl-Pax8Cre) and their littermate genetic controls (TRPV4fl/fl). Successful deletion was verified by the absence of TRPV4 protein expression in renal homogenates and the lack of TRPV4-mediated Ca2 + influx in freshly-isolated split-opened collecting ducts. There were no differences in plasma electrolytes, baseline urinary volume, and K + levels when both strains were fed regular K + intake. In contrast, plasma K+ levels were significantly elevated in TRPV4fl/fl-Pax8Cre mice on both high and low K + intake. This was associated with a marked decrease in 24 h urinary K+ levels in the knockout, whereas urinary volume and aldosterone levels were indistinguishable from the control TRPV4fl/fl littermates suggesting a direct decrease in the distal tubule K + transport. Interestingly, we also detected significant differences in urinary pH levels indicative of the altered K + reabsorption via H + -K + ATPase in the collecting duct. Indeed, we detected a significantly faster pHi recovery after intracellular acidification with ammonium pulse in both acid secreting A- and base-secreting B-types of intercalated cells and to a lesser degree in principal cells in split-opened collecting ducts from TRPV4fl/fl-Pax8Cre mice on low but not regular K + intake, which is consistent with augmented H + -K + ATPase activity and K + reabsorption in the knockouts. In summary, our results demonstrate an indispensable pro-kaliuretic role of TRPV4 in the renal tubule in controlling K + balance and urinary K + excretion during variations in dietary K + intake This research was supported by NIH-NIDDK DK117865, DK119170, AHA EIA35260097 (to O. Pochynyuk) and AHA-19CDA34660148 (to V. N. Tomilin). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.","PeriodicalId":49694,"journal":{"name":"Physiology","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134903842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-01DOI: 10.1152/physiol.2023.38.s1.5733912
Melissa Eilbes, Anna Manis, Vladislav Levchenko, Hubert Forster, Oleg Palygin, Alexander Staruschenko, Matthew Hodges
Epilepsy is a common neurological disorder in which 1/3rd of patients experience repeated seizures, putting them at greater risk for Sudden Unexpected Death in Epilepsy (SUDEP). A leading hypothesis based on human data suggests severe post-ictal cardiorespiratory suppression precedes a SUDEP event. However, the pathophysiological consequences of repeated seizures on cardiorespiratory control/function remain unclear. Our lab has previously established a rat model harboring an 18 bp-mutation in the Kcnj16 gene (encoding Kir5.1 channel; SSKcnj16-/- rats), which is susceptible to sound-induced (audiogenic) seizures. In this model, repeated seizures (1/day for 10 days) lead to ictal apnea, post-ictal respiratory suppression, blunted chemoreflexes, and spontaneous mortality. While the respiratory effects of repeated seizures in our rat model have been established, the cardiorespiratory sequence of events leading to a SUDEP-like event remain unknown. Here we test the hypothesis that repeated seizures in SSKcnj16-/- rats result in cardiorespiratory dysfunction and lead to a sequence of pathological events accompanying human SUDEP. Male and female SSKcnj16-/- rats (n=5,6) were surgically implanted with radiotelemetry pressure devices and allowed >3 days to recover. The rats were then housed in a custom-made plethysmograph for long-term housing to measure breathing, blood pressure (BP), heart rate (HR), and behavior continuously for 10 days (d). The rats were exposed to a sound stimulus (2 min) to elicit a seizure once/d for 10d. As reported previously, audiogenic seizures caused ictal apneas and transient post-ictal respiratory frequency depression. However, for the first time, we also found ictal asystole and dramatic decreases in HR but increases in BP for ~20 min after seizures. These acute effects of seizures on breathing and HR/BP appear to be exaggerated with increasing numbers of seizures throughout the 10d protocol. In addition, we captured during the 10d protocol SUDEP-like events in six out of eleven SSKcnj16-/- rats studied. Unlike most experiments that showed recovery of cardiorespiratory measures within ~30 min, SSKcnj16-/- rats with a terminal event had reduced ventilation due to a reduced tidal volume, and BP steadily declined with minimal effects on HR in the 2-5 hours preceding death (n=4). Our preliminary data suggest repeated seizures induce acute cardiorespiratory disruptions which in some cases can lead to a SUDEP-like event in SSKcnj16-/- rats characterized by suppressed tidal volume, hypopnea and time-dependent hypotension. Funded by NIH HL122358 (MRH), DK126720 (OP), and HL135749 (AS). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
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