Pub Date : 2026-05-01Epub Date: 2026-02-03DOI: 10.1016/j.physbeh.2026.115249
Ailyn Luna-Hernández , Raymundo Domínguez-Ordóñez , Marcos García-Juárez , José Luis Encarnación Sánchez , José Luis Tlachi-López , James G. Pfaus , Oscar González-Flores
The present study aimed to determine whether apelin-13 facilitates lordosis behavior through the activation of specific hypothalamic kinases and to identify which signaling pathways mediate this response. Because lordosis is a well-established neuroendocrine indicator of female sexual receptivity, it served as an appropriate behavioral model to detect peptide-induced facilitation. Thus, we examined the role of protein kinase A (PKA), protein kinase C (PKC), mitogen activated protein kinase (MAPK), or Src kinase (Src), in the facilitation of lordosis behavior following bilateral intrahypothalamic injection of 0.75 μg of apelin-13 to ovariectomized-estradiol benzoate (OVX-EB) primed rats. Apelin-13 consistently induced lordosis at 30, 120, and 240 minutes post-infusion. To explore the role of these kinases, various inhibitors or their vehicles were administered bilaterally into the ventromedial hypothalamus (VMH) of OVX-EB-primed rats 30 min before the infusion of apelin-13. The inhibitors used were Rp-cAMPS for PKA, bisindolilmaleimide (BIS) for PKC, PD98059 for MAPK, and PP2 for Src. The VMH injection of Rp-cAMPS failed to reverse the facilitation of lordosis at the different times tested, while BIS or PP2 decreased the lordosis quotient (LQ) significantly only at 240 min without any statistical effect on the lordosis score (LS). However, PD98059 significantly reduced both the LQ and LS at 120 and 240 min. These data indicate that apelin-13 exerts its facilitatory effects on lordosis through MAPK, PKC, and/or Src, but not PKA pathways.
{"title":"Apelin-13 induces lordosis behavior in estradiol-primed ovariectomized rats via the activation of multiple protein kinases in the ventromedial hypothalamus","authors":"Ailyn Luna-Hernández , Raymundo Domínguez-Ordóñez , Marcos García-Juárez , José Luis Encarnación Sánchez , José Luis Tlachi-López , James G. Pfaus , Oscar González-Flores","doi":"10.1016/j.physbeh.2026.115249","DOIUrl":"10.1016/j.physbeh.2026.115249","url":null,"abstract":"<div><div>The present study aimed to determine whether apelin-13 facilitates lordosis behavior through the activation of specific hypothalamic kinases and to identify which signaling pathways mediate this response. Because lordosis is a well-established neuroendocrine indicator of female sexual receptivity, it served as an appropriate behavioral model to detect peptide-induced facilitation. Thus, we examined the role of protein kinase A (PKA), protein kinase C (PKC), mitogen activated protein kinase (MAPK), or Src kinase (Src), in the facilitation of lordosis behavior following bilateral intrahypothalamic injection of 0.75 μg of apelin-13 to ovariectomized-estradiol benzoate (OVX-EB) primed rats. Apelin-13 consistently induced lordosis at 30, 120, and 240 minutes post-infusion. To explore the role of these kinases, various inhibitors or their vehicles were administered bilaterally into the ventromedial hypothalamus (VMH) of OVX-EB-primed rats 30 min before the infusion of apelin-13. The inhibitors used were Rp-cAMPS for PKA, bisindolilmaleimide (BIS) for PKC, PD98059 for MAPK, and PP2 for Src. The VMH injection of Rp-cAMPS failed to reverse the facilitation of lordosis at the different times tested, while BIS or PP2 decreased the lordosis quotient (LQ) significantly only at 240 min without any statistical effect on the lordosis score (LS). However, PD98059 significantly reduced both the LQ and LS at 120 and 240 min. These data indicate that apelin-13 exerts its facilitatory effects on lordosis through MAPK, PKC, and/or Src, but not PKA pathways.</div></div>","PeriodicalId":20201,"journal":{"name":"Physiology & Behavior","volume":"308 ","pages":"Article 115249"},"PeriodicalIF":2.5,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146126200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-11DOI: 10.1016/j.physbeh.2025.115203
Diego Fernández-Lázaro , Manuel Garrosa , Gema Santamaría , Enrique Roche , José María Izquierdo , Jesús Seco-Calvo , Juan Mielgo-Ayuso
Background
The influence of sexual activity prior to exercise on athletic performance remains controversial. While pre-competition abstinence is commonly advised, scientific evidence on its physiological impact is limited and inconsistent.
Methods
A randomized crossover study was conducted in 21 well-trained male athletes (age 22 ± 1 y) to compare the acute effects of masturbation-induced orgasm versus sexual abstinence performed 30 min before testing. Each participant completed an incremental cycling test and an isometric handgrip strength test under both conditions. Blood samples were analyzed for muscle damage (CK, LDH, Mb), inflammatory (CRP, IL-6), and hormonal (testosterone, cortisol, LH) markers.
Results
Compared with abstinence, the post-masturbation condition resulted in a longer exercise duration (+3.2%, p< 0.01) and higher heart rate (p< 0.001), accompanied by a small increase in mean handgrip strength (p< 0.05). Lower plasma LDH levels (p< 0.001) indicated reduced muscle stress. Testosterone and cortisol concentrations were significantly higher (both p< 0.001), whereas inflammatory markers (CRP, IL-6) showed no significant change.
Conclusions
Masturbation 30 min before exercise elicited mild sympathetic and hormonal activation without detrimental effects on performance or muscle damage. These findings suggest that pre-exercise sexual activity does not impair athletic capacity in trained men, challenging the long-standing myth of mandatory abstinence before competition.
{"title":"Sexual activity before exercise influences physiological response and sports performance in high-level trained men athletes","authors":"Diego Fernández-Lázaro , Manuel Garrosa , Gema Santamaría , Enrique Roche , José María Izquierdo , Jesús Seco-Calvo , Juan Mielgo-Ayuso","doi":"10.1016/j.physbeh.2025.115203","DOIUrl":"10.1016/j.physbeh.2025.115203","url":null,"abstract":"<div><h3>Background</h3><div>The influence of sexual activity prior to exercise on athletic performance remains controversial. While pre-competition abstinence is commonly advised, scientific evidence on its physiological impact is limited and inconsistent.</div></div><div><h3>Methods</h3><div>A randomized crossover study was conducted in 21 well-trained male athletes (age 22 ± 1 y) to compare the acute effects of masturbation-induced orgasm versus sexual abstinence performed 30 min before testing. Each participant completed an incremental cycling test and an isometric handgrip strength test under both conditions. Blood samples were analyzed for muscle damage (CK, LDH, Mb), inflammatory (CRP, IL-6), and hormonal (testosterone, cortisol, LH) markers.</div></div><div><h3>Results</h3><div>Compared with abstinence, the post-masturbation condition resulted in a longer exercise duration (+3.2%, <em>p</em>< 0.01) and higher heart rate (<em>p</em>< 0.001), accompanied by a small increase in mean handgrip strength (<em>p</em>< 0.05). Lower plasma LDH levels (<em>p</em>< 0.001) indicated reduced muscle stress. Testosterone and cortisol concentrations were significantly higher (both <em>p</em>< 0.001), whereas inflammatory markers (CRP, IL-6) showed no significant change.</div></div><div><h3>Conclusions</h3><div>Masturbation 30 min before exercise elicited mild sympathetic and hormonal activation without detrimental effects on performance or muscle damage. These findings suggest that pre-exercise sexual activity does not impair athletic capacity in trained men, challenging the long-standing myth of mandatory abstinence before competition.</div></div>","PeriodicalId":20201,"journal":{"name":"Physiology & Behavior","volume":"307 ","pages":"Article 115203"},"PeriodicalIF":2.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145752085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-14DOI: 10.1016/j.physbeh.2026.115228
Zequn Li , Kairi Hayashi , Gen Tanabe , Hiroshi Churei , Toshiaki Ueno , Kenji Fueki
Hyposalivation affects cognitive function. However, its impact on hippocampus-dependent memory remains unclear. Saliva contains brain-derived neurotrophic factor (BDNF), which is also synthesized in the hippocampus and can pass through the blood-brain barrier (BBB) to influence hippocampal plasticity. Therefore, we hypothesized that hyposalivation reduces peripheral BDNF availability, leading to decreased hippocampal BDNF levels and cognitive impairment. In this study, this relationship was investigated using an in vivo model of sialadenectomy-induced hyposalivation. A total of 24 8-week-old male ddY mice were divided into control and extraction (EXT) groups. The EXT group underwent submandibular and sublingual salivary gland extractions, whereas the control group underwent a sham operation. Saliva was collected at baseline (0 weeks) and at 2- and 3-weeks postoperatively. Cognitive function was assessed using the Y-maze, fear conditioning (FC), novel object recognition (NOR), and object location tests (OLT). Anxiety-like behavior was evaluated using the open field test (OFT) and elevated plus-maze (EPM) tests. Hippocampi were collected at 3 weeks post-operation for BDNF quantification using enzyme-linked immunosorbent assay, and its concentration in subregions of the hippocampus was determined by semi-quantitative analysis. Hyposalivation significantly impaired spatial working memory in the Y-maze test and contextual fear memory in the FC, both of which are hippocampus-dependent. NOR showed only a transient deficit at 24 h during the 2-week period (no significant difference in 3-week post-operation), whereas long-term spatial memory measured by the OLT exhibited a persistent 24-h impairment at both 2 and 3 weeks, indicating reduced long-term spatial memory rather than accelerated decay. No significant differences were observed in anxiety-like behavior. Although sialoadenectomy significantly reduced salivary secretion and total salivary BDNF output, the concentration of BDNF in saliva in both groups remained unchanged at 2- and 3-weeks post-operation. However, hippocampal BDNF levels were significantly lower in the EXT group than in the control group. These findings suggest that hyposalivation may selectively impair hippocampus-related spatial memory without affecting recognition memory or anxiety-related behaviors.
{"title":"Hyposalivation induced by salivary gland extraction impairs cognitive function in mice","authors":"Zequn Li , Kairi Hayashi , Gen Tanabe , Hiroshi Churei , Toshiaki Ueno , Kenji Fueki","doi":"10.1016/j.physbeh.2026.115228","DOIUrl":"10.1016/j.physbeh.2026.115228","url":null,"abstract":"<div><div>Hyposalivation affects cognitive function. However, its impact on hippocampus-dependent memory remains unclear. Saliva contains brain-derived neurotrophic factor (BDNF), which is also synthesized in the hippocampus and can pass through the blood-brain barrier (BBB) to influence hippocampal plasticity. Therefore, we hypothesized that hyposalivation reduces peripheral BDNF availability, leading to decreased hippocampal BDNF levels and cognitive impairment. In this study, this relationship was investigated using an in vivo model of sialadenectomy-induced hyposalivation. A total of 24 8-week-old male ddY mice were divided into control and extraction (EXT) groups. The EXT group underwent submandibular and sublingual salivary gland extractions, whereas the control group underwent a sham operation. Saliva was collected at baseline (0 weeks) and at 2- and 3-weeks postoperatively. Cognitive function was assessed using the Y-maze, fear conditioning (FC), novel object recognition (NOR), and object location tests (OLT). Anxiety-like behavior was evaluated using the open field test (OFT) and elevated plus-maze (EPM) tests. Hippocampi were collected at 3 weeks post-operation for BDNF quantification using enzyme-linked immunosorbent assay, and its concentration in subregions of the hippocampus was determined by semi-quantitative analysis. Hyposalivation significantly impaired spatial working memory in the Y-maze test and contextual fear memory in the FC, both of which are hippocampus-dependent. NOR showed only a transient deficit at 24 h during the 2-week period (no significant difference in 3-week post-operation), whereas long-term spatial memory measured by the OLT exhibited a persistent 24-h impairment at both 2 and 3 weeks, indicating reduced long-term spatial memory rather than accelerated decay. No significant differences were observed in anxiety-like behavior. Although sialoadenectomy significantly reduced salivary secretion and total salivary BDNF output, the concentration of BDNF in saliva in both groups remained unchanged at 2- and 3-weeks post-operation. However, hippocampal BDNF levels were significantly lower in the EXT group than in the control group. These findings suggest that hyposalivation may selectively impair hippocampus-related spatial memory without affecting recognition memory or anxiety-related behaviors.</div></div>","PeriodicalId":20201,"journal":{"name":"Physiology & Behavior","volume":"307 ","pages":"Article 115228"},"PeriodicalIF":2.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145990305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fascin 1 is an actin-bundling protein with limited expression in normal tissues, such as the brain and spleen. Fascin knockout mice exhibit enlarged lateral ventricles and impaired neuronal extension in the posterior region of the anterior commissure. Despite these observations, the effect of fascin loss on animal behavior and cognitive function has not been previously assessed. In the present study, fascin knockout (fascin−/−) and wild-type (fascin+/+) female mice were compared on a number of standard behavioral tests, including open-field, object recognition, elevated plus maze, light–dark transition, sociability, and Morris water maze tests. Fascin-/- mice exhibited reduced locomotor activity during the open-field test and spent more time in the dark zone during the light–dark transition tests. Furthermore, fascin-/- mice showed comparable social interactions and exhibited altered early exploratory behavior during Morris water maze tests. This study concluded that whole-body fascin loss modestly affects animal behavior, particularly locomotor and exploratory activities. The whole-body knockout experimental findings highlight the regulatory role of fascin on these behavioral domains and emphasize the importance of considering these effects in future studies using this animal model.
{"title":"Effect of fascin loss on animal behavior using a knockout mouse model","authors":"Sarah Farooq , Angela Inglis , Falah Almohanna , Jennifer Thiam , Samiyah Al-Khaldi , Rayanah Barnawi , Hazem Ghebeh , Monther Al-Alwan","doi":"10.1016/j.physbeh.2026.115243","DOIUrl":"10.1016/j.physbeh.2026.115243","url":null,"abstract":"<div><div>Fascin 1 is an actin-bundling protein with limited expression in normal tissues, such as the brain and spleen. Fascin knockout mice exhibit enlarged lateral ventricles and impaired neuronal extension in the posterior region of the anterior commissure. Despite these observations, the effect of fascin loss on animal behavior and cognitive function has not been previously assessed. In the present study, fascin knockout (fascin<sup>−/−</sup>) and wild-type (fascin<sup>+/+</sup>) female mice were compared on a number of standard behavioral tests, including open-field, object recognition, elevated plus maze, light–dark transition, sociability, and Morris water maze tests. Fascin<sup>-/-</sup> mice exhibited reduced locomotor activity during the open-field test and spent more time in the dark zone during the light–dark transition tests. Furthermore, fascin<sup>-/-</sup> mice showed comparable social interactions and exhibited altered early exploratory behavior during Morris water maze tests. This study concluded that whole-body fascin loss modestly affects animal behavior, particularly locomotor and exploratory activities. The whole-body knockout experimental findings highlight the regulatory role of fascin on these behavioral domains and emphasize the importance of considering these effects in future studies using this animal model.</div></div>","PeriodicalId":20201,"journal":{"name":"Physiology & Behavior","volume":"307 ","pages":"Article 115243"},"PeriodicalIF":2.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146096925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-08DOI: 10.1016/j.physbeh.2026.115226
Ivanka Rainer , Leah Hershberger , Megan Pedicini , Madison Davis , Yvonne M. Ulrich-Lai
Many individuals eat highly palatable foods to cope with stress, and this so-called ‘comfort’ feeding occurs to a greater extent in people who are overweight and obese. To study this relationship, we previously characterized a limited sucrose intake (LSI) paradigm that reduces hypothalamic-pituitary-adrenocortical (HPA) axis stress responses in normal weight rats, but not in those with Western diet-induced obesity (DIO). The present work tests the hypothesis that a larger volume of sucrose drink recovers effective HPA blunting during obesity. Time-limited sucrose access, in which sucrose was offered in an unlimited volume for 30 min twice-daily to chow-fed lean and Western DIO rats for 2 weeks, resulted in greater sucrose drink intake than that allowed in the LSI paradigm (4 ml/twice-daily session) and reduced post-stress plasma corticosterone relative to water controls in both lean and DIO rats. Likewise, when given volume-limited access to a larger sucrose volume (6 ml vs. the standard 4 ml per twice-daily session) the 6 ml volume reduced post-stress plasma corticosterone relative to water controls, in both lean and DIO rats, whereas the 4 ml volume was only effective in lean rats. These data replicate that the typical LSI sucrose volume does not produce effective stress-blunting during Western DIO, and extend this to show that larger sucrose volumes, given via either time- or volume-limited access paradigms, recovers this effect. This suggests that stress-related eaters with obesity may require larger amounts of palatable foods to maintain adequate stress relief.
{"title":"A larger amount of palatable food is needed to provide stress relief during Western diet-induced obesity","authors":"Ivanka Rainer , Leah Hershberger , Megan Pedicini , Madison Davis , Yvonne M. Ulrich-Lai","doi":"10.1016/j.physbeh.2026.115226","DOIUrl":"10.1016/j.physbeh.2026.115226","url":null,"abstract":"<div><div>Many individuals eat highly palatable foods to cope with stress, and this so-called ‘comfort’ feeding occurs to a greater extent in people who are overweight and obese. To study this relationship, we previously characterized a limited sucrose intake (LSI) paradigm that reduces hypothalamic-pituitary-adrenocortical (HPA) axis stress responses in normal weight rats, but not in those with Western diet-induced obesity (DIO). The present work tests the hypothesis that a larger volume of sucrose drink recovers effective HPA blunting during obesity. Time-limited sucrose access, in which sucrose was offered in an unlimited volume for 30 min twice-daily to chow-fed lean and Western DIO rats for 2 weeks, resulted in greater sucrose drink intake than that allowed in the LSI paradigm (4 ml/twice-daily session) and reduced post-stress plasma corticosterone relative to water controls in both lean and DIO rats. Likewise, when given volume-limited access to a larger sucrose volume (6 ml vs. the standard 4 ml per twice-daily session) the 6 ml volume reduced post-stress plasma corticosterone relative to water controls, in both lean and DIO rats, whereas the 4 ml volume was only effective in lean rats. These data replicate that the typical LSI sucrose volume does not produce effective stress-blunting during Western DIO, and extend this to show that larger sucrose volumes, given via either time- or volume-limited access paradigms, recovers this effect. This suggests that stress-related eaters with obesity may require larger amounts of palatable foods to maintain adequate stress relief.</div></div>","PeriodicalId":20201,"journal":{"name":"Physiology & Behavior","volume":"307 ","pages":"Article 115226"},"PeriodicalIF":2.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145949100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-15DOI: 10.1016/j.physbeh.2026.115231
Spencer E. Fields , Arul Elango , Elif Ece Akgun , Adrianna M. Sweeney , Eileen Carry , Ariane Vasilatis , Emma Bernstein , James E. Simon , Qingli Wu , Nicholas T. Bello
Kratom (Mitragyna speciosa) has been marketed and used for a variety of health-promoting applications. Kratom contains an expansive bioactive alkaloid profile with mitragynine (MTG) as the most abundant. Individual responses to kratom have been reported, but the role of obesity as a factor influencing the effects of kratom has not been studied. First, we used a standardized kratom extract (KE) to determine the cardiopulmonary differences with KE (290, 500 mg/kg) and matched MTG (18 mg/kg) in high-fat diet (HFD; 45% Fat) induced obese male C57Bl/6 J mice. As measured by whole-body plethysmography, acute oral dosing revealed an approximate 15% reduction in the respiratory rate with all doses of KE and MTG. Unlike a well-known respiratory depressant, alprazolam, KE and MTG did not reduce minute ventilation (MvB; ml/min). As measured by volume-pressure recordings, KE 500 mg/kg produced an approximate 12% reduction in heart rate in normal weight mice. Second, we determined whether daily oral dosing KE (50, 150 mg/kg) prevented HFD-induced weight gain. Daily 150 mg/kg resulted in an increase in body weight gain (∼1 g) in the last week after 21 days of dosing. After 4 days following kratom cessation, there was reduced distance traveled in the KE 150 mg/kg compared with the KE 50 mg/kg group in an elevated plus maze test. These findings demonstrate a dose-dependent-increase in weight gain with KE, suggesting further investigation is needed to delineate kratom alkaloid effects on metabolism and body weight control.
{"title":"Kratom (Mitragyna speciosa) alkaloids influence on cardiopulmonary measures and high-fat diet-induced weight gain in mice","authors":"Spencer E. Fields , Arul Elango , Elif Ece Akgun , Adrianna M. Sweeney , Eileen Carry , Ariane Vasilatis , Emma Bernstein , James E. Simon , Qingli Wu , Nicholas T. Bello","doi":"10.1016/j.physbeh.2026.115231","DOIUrl":"10.1016/j.physbeh.2026.115231","url":null,"abstract":"<div><div>Kratom (<em>Mitragyna speciosa</em>) has been marketed and used for a variety of health-promoting applications. Kratom contains an expansive bioactive alkaloid profile with mitragynine (MTG) as the most abundant. Individual responses to kratom have been reported, but the role of obesity as a factor influencing the effects of kratom has not been studied. First, we used a standardized kratom extract (KE) to determine the cardiopulmonary differences with KE (290, 500 mg/kg) and matched MTG (18 mg/kg) in high-fat diet (HFD; 45% Fat) induced obese male C57Bl/6 J mice. As measured by whole-body plethysmography, acute oral dosing revealed an approximate 15% reduction in the respiratory rate with all doses of KE and MTG. Unlike a well-known respiratory depressant, alprazolam, KE and MTG did not reduce minute ventilation (MvB; ml/min). As measured by volume-pressure recordings, KE 500 mg/kg produced an approximate 12% reduction in heart rate in normal weight mice. Second, we determined whether daily oral dosing KE (50, 150 mg/kg) prevented HFD-induced weight gain. Daily 150 mg/kg resulted in an increase in body weight gain (∼1 g) in the last week after 21 days of dosing. After 4 days following kratom cessation, there was reduced distance traveled in the KE 150 mg/kg compared with the KE 50 mg/kg group in an elevated plus maze test. These findings demonstrate a dose-dependent-increase in weight gain with KE, suggesting further investigation is needed to delineate kratom alkaloid effects on metabolism and body weight control.</div></div>","PeriodicalId":20201,"journal":{"name":"Physiology & Behavior","volume":"307 ","pages":"Article 115231"},"PeriodicalIF":2.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145994466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-23DOI: 10.1016/j.physbeh.2026.115240
Samantha M. Stead , Phoebe Edwards , Rudy Boonstra , Rupert Palme , Edward Mujjuzi , Julie A. Teichroeb
Glucocorticoids (GCs) are hormones that are secreted in response to energetic demands, allowing animals to cope with internal and external challenges. We investigated the factors impacting fecal GC metabolite (FGM) concentrations (a proxy of blood GC concentrations) in a population of Rwenzori Angolan colobus monkeys (Colobus angolensis ruwenzorii) in Uganda. These monkeys live in a multi-level society with three tiers of non-random association: the core unit (individuals that feed, rest, and travel together), the clan (core units that associate preferentially), and the band (core units that share a home range). We used linear mixed-effect models to assess the impact of reproductive state, fruit availability, and core unit composition on FGM concentrations of reproductive females. We found that FGM concentrations increased over the course of pregnancy and decreased over the course of lactation. There was a quadratic relationship between FGM concentrations and core unit size, with FGM concentrations being lower for mothers living in intermediate-sized core units compared to those living in smaller and larger core units. This aligns with previous work on this population showing that individuals living in intermediate-sized core units expend the least energy travelling. Future work should investigate the impact of FGM concentrations on infant growth and development in this subspecies.
{"title":"Impacts of reproductive state and social environment on glucocorticoid concentrations in female Rwenzori Angolan colobus monkeys (Colobus angolensis ruwenzorii)","authors":"Samantha M. Stead , Phoebe Edwards , Rudy Boonstra , Rupert Palme , Edward Mujjuzi , Julie A. Teichroeb","doi":"10.1016/j.physbeh.2026.115240","DOIUrl":"10.1016/j.physbeh.2026.115240","url":null,"abstract":"<div><div>Glucocorticoids (GCs) are hormones that are secreted in response to energetic demands, allowing animals to cope with internal and external challenges. We investigated the factors impacting fecal GC metabolite (FGM) concentrations (a proxy of blood GC concentrations) in a population of Rwenzori Angolan colobus monkeys (<em>Colobus angolensis ruwenzorii</em>) in Uganda. These monkeys live in a multi-level society with three tiers of non-random association: the core unit (individuals that feed, rest, and travel together), the clan (core units that associate preferentially), and the band (core units that share a home range). We used linear mixed-effect models to assess the impact of reproductive state, fruit availability, and core unit composition on FGM concentrations of reproductive females. We found that FGM concentrations increased over the course of pregnancy and decreased over the course of lactation. There was a quadratic relationship between FGM concentrations and core unit size, with FGM concentrations being lower for mothers living in intermediate-sized core units compared to those living in smaller and larger core units. This aligns with previous work on this population showing that individuals living in intermediate-sized core units expend the least energy travelling. Future work should investigate the impact of FGM concentrations on infant growth and development in this subspecies.</div></div>","PeriodicalId":20201,"journal":{"name":"Physiology & Behavior","volume":"307 ","pages":"Article 115240"},"PeriodicalIF":2.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146047159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The co-consumption of alcohol (ethanol) and caffeine, commonly found in alcoholic beverages mixed with energy drinks (AmED), has been linked to increased alcohol intake and heightened risk-taking behaviors. However, the effects of this combination under voluntary drinking conditions in animal models remain poorly understood. The present study investigated whether caffeine modulates ethanol intake in Swiss male mice, an outbred strain with inherent low ethanol preference. Mice were exposed to a two-bottle choice Intermittent Overnight Drinking (IOD) protocol for 12 sessions. Each mouse had access to water and either ethanol (10%), caffeine (0.75 mg/mL), or a combination of both. Using lickometer devices, we analyzed drinking microstructure, including total intake, latency to first lick and bout, and temporal licking patterns. Caffeine and water were consumed in similar amounts and followed comparable circadian patterns, whereas both ethanol and ethanol + caffeine solutions were consistently avoided. Thus, in Swiss male mice, caffeine did not modify ethanol intake. These findings emphasize the importance of strain-specific studies for a better understanding of the behavioral interaction between alcohol and caffeine.
{"title":"Does caffeine alter preference or patterns of voluntary ethanol consumption in Swiss male mice?","authors":"Beatriz Nunes Petribu, Karina Possa Abrahao , Maria Lucia Oliveira Souza-Formigoni","doi":"10.1016/j.physbeh.2026.115241","DOIUrl":"10.1016/j.physbeh.2026.115241","url":null,"abstract":"<div><div>The co-consumption of alcohol (ethanol) and caffeine, commonly found in alcoholic beverages mixed with energy drinks (AmED), has been linked to increased alcohol intake and heightened risk-taking behaviors. However, the effects of this combination under voluntary drinking conditions in animal models remain poorly understood. The present study investigated whether caffeine modulates ethanol intake in Swiss male mice, an outbred strain with inherent low ethanol preference. Mice were exposed to a two-bottle choice Intermittent Overnight Drinking (IOD) protocol for 12 sessions. Each mouse had access to water and either ethanol (10%), caffeine (0.75 mg/mL), or a combination of both. Using lickometer devices, we analyzed drinking microstructure, including total intake, latency to first lick and bout, and temporal licking patterns. Caffeine and water were consumed in similar amounts and followed comparable circadian patterns, whereas both ethanol and ethanol + caffeine solutions were consistently avoided. Thus, in Swiss male mice, caffeine did not modify ethanol intake. These findings emphasize the importance of strain-specific studies for a better understanding of the behavioral interaction between alcohol and caffeine.</div></div>","PeriodicalId":20201,"journal":{"name":"Physiology & Behavior","volume":"307 ","pages":"Article 115241"},"PeriodicalIF":2.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146047108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-27DOI: 10.1016/j.physbeh.2026.115242
Alexey Sarapultsev , Maria Komelkova , Evgenii Gusev , Desheng Hu , Vladimir Naumenko
Background
Social context modulates stress physiology and resilience, yet preclinical rat paradigms vary widely in stressor type, timing of social exposure, contact modality, and endpoint definitions. We synthesized rat studies to quantify directional and, where feasible, standardized effect-size evidence for social buffering and to outline translational implications.
Methods
PubMed, Scopus, and Web of Science were searched (2008–2025) for in vivo rat studies comparing conspecific (pair/group housing or conspecific presence) versus solitary conditions across validated stress and PTSD-like paradigms (e.g., fear conditioning/extinction, CUS/CMS, social defeat, predator threat). Data extraction and reporting followed PRISMA 2020 and SYRCLE guidance. Synthesis followed a two-tier approach: (i) all eligible contrasts were direction-coded as beneficial, neutral/mixed, or detrimental under conspecific conditions based strictly on reported statistical contrasts; and (ii) for domains with sufficient coded contrasts, the proportion of beneficial comparisons was estimated with exact binomial tests and 95% confidence intervals. Standardized mean-difference meta-analysis (Hedges’ g; random-effects REML) was conducted only for predefined outcomes with adequate numerical reporting.
Results
Forty studies met inclusion criteria, yielding 89 extracted comparisons. Overall, 69/89 comparisons (≈78%) favored conspecific conditions. Domain-level directional syntheses supported predominance of beneficial outcomes for hormonal (0.72; 95% CI 0.50–1.00; p = 0.048) and neurotrophic/plasticity markers (0.89; 95% CI 0.57–1.00; p = 0.020), whereas inflammatory/oxidative outcomes were more variable (0.71; 95% CI 0.39–0.94; p = 0.227). For predefined behavioral endpoints with sufficient data, effect-size pooling showed a large reduction in conditioned fear (Hedges’ g = -1.22 [-1.53; -0.91], p < 0.0001).
Conclusions
Social buffering is robust at behavioral and neuroendocrine levels and often aligns with neurotrophic/plasticity markers, while peripheral immune/redox readouts are more context-dependent.
背景：社会环境调节应激生理和恢复力，然而临床前大鼠范式在应激源类型、社会暴露时间、接触方式和终点定义方面差异很大。我们综合了大鼠研究，以量化定向的，在可行的情况下，标准化的社会缓冲效应证据，并概述翻译意义。方法：检索PubMed、Scopus和Web of Science（2008-2025）的体内大鼠研究，比较同种（配对/群体居住或同种存在）与孤独条件下的有效应激和类ptsd范式（如恐惧条件反射/灭绝、CUS/CMS、社会失败、捕食者威胁）。数据提取和报告遵循PRISMA 2020和cycle指南。综合采用两层方法：(i)严格根据报告的统计对比，在相同条件下，所有符合条件的对比被方向编码为有益、中性/混合或有害；（ii）对于具有足够编码对比的域，使用精确的二项检验和95%置信区间估计有益比较的比例。标准化均差荟萃分析（Hedges' g；随机效应REML）仅对预定义结果进行了充分的数值报告。结果：40项研究符合纳入标准，产生89项提取比较。总体而言，69/89比较（≈78%）倾向于同特定条件。领域水平的定向合成支持激素（0.72;95% CI 0.50-1.00; p=0.048）和神经营养/可塑性标志物（0.89;95% CI 0.57-1.00; p=0.020）的有利结果占主导地位，而炎症/氧化结果则更为可变（0.71;95% CI 0.39-0.94; p=0.227）。对于具有足够数据的预定义行为终点，效应大小池显示条件恐惧的大幅减少（Hedges' g=-1.22[-1.53; -0.91]）。结论：社会缓冲在行为和神经内分泌水平上是强大的，并且通常与神经营养/可塑性标记一致，而外周免疫/氧化还原读数更多地依赖于环境。
{"title":"Social buffering of stress in rats: a multisystem meta-analysis and translational framework for stress resilience","authors":"Alexey Sarapultsev , Maria Komelkova , Evgenii Gusev , Desheng Hu , Vladimir Naumenko","doi":"10.1016/j.physbeh.2026.115242","DOIUrl":"10.1016/j.physbeh.2026.115242","url":null,"abstract":"<div><h3>Background</h3><div>Social context modulates stress physiology and resilience, yet preclinical rat paradigms vary widely in stressor type, timing of social exposure, contact modality, and endpoint definitions. We synthesized rat studies to quantify directional and, where feasible, standardized effect-size evidence for social buffering and to outline translational implications.</div></div><div><h3>Methods</h3><div>PubMed, Scopus, and Web of Science were searched (2008–2025) for in vivo rat studies comparing conspecific (pair/group housing or conspecific presence) versus solitary conditions across validated stress and PTSD-like paradigms (e.g., fear conditioning/extinction, CUS/CMS, social defeat, predator threat). Data extraction and reporting followed PRISMA 2020 and SYRCLE guidance. Synthesis followed a two-tier approach: (i) all eligible contrasts were direction-coded as beneficial, neutral/mixed, or detrimental under conspecific conditions based strictly on reported statistical contrasts; and (ii) for domains with sufficient coded contrasts, the proportion of beneficial comparisons was estimated with exact binomial tests and 95% confidence intervals. Standardized mean-difference meta-analysis (Hedges’ g; random-effects REML) was conducted only for predefined outcomes with adequate numerical reporting.</div></div><div><h3>Results</h3><div>Forty studies met inclusion criteria, yielding 89 extracted comparisons. Overall, 69/89 comparisons (≈78%) favored conspecific conditions. Domain-level directional syntheses supported predominance of beneficial outcomes for hormonal (0.72; 95% CI 0.50–1.00; <em>p</em> = 0.048) and neurotrophic/plasticity markers (0.89; 95% CI 0.57–1.00; <em>p</em> = 0.020), whereas inflammatory/oxidative outcomes were more variable (0.71; 95% CI 0.39–0.94; <em>p</em> = 0.227). For predefined behavioral endpoints with sufficient data, effect-size pooling showed a large reduction in conditioned fear (Hedges’ <em>g</em> = -1.22 [-1.53; -0.91], <em>p</em> < 0.0001).</div></div><div><h3>Conclusions</h3><div>Social buffering is robust at behavioral and neuroendocrine levels and often aligns with neurotrophic/plasticity markers, while peripheral immune/redox readouts are more context-dependent.</div></div>","PeriodicalId":20201,"journal":{"name":"Physiology & Behavior","volume":"307 ","pages":"Article 115242"},"PeriodicalIF":2.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146087078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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