Pub Date : 2023-01-01DOI: 10.1177/17448069231203090
Shishu Pal Singh, Josee Guindon, Prapti H Mody, Gabriela Ashworth, Jonathan Kopel, Sai Chilakapati, Owoicho Adogwa, Volker Neugebauer, Michael D Burton
Chronic pain is one of the most common, costly, and potentially debilitating health issues facing older adults, with attributable costs exceeding $600 billion annually. The prevalence of pain in humans increases with advancing age. Yet, the contributions of sex differences, age-related chronic inflammation, and changes in neuroplasticity to the overall experience of pain are less clear, given that opposing processes in aging interact. This review article examines and summarizes pre-clinical research and clinical data on chronic pain among older adults to identify knowledge gaps and provide the base for future research and clinical practice. We provide evidence to suggest that neurodegenerative conditions engender a loss of neural plasticity involved in pain response, whereas low-grade inflammation in aging increases CNS sensitization but decreases PNS sensitivity. Insights from preclinical studies are needed to answer mechanistic questions. However, the selection of appropriate aging models presents a challenge that has resulted in conflicting data regarding pain processing and behavioral outcomes that are difficult to translate to humans.
{"title":"Pain and aging: A unique challenge in neuroinflammation and behavior.","authors":"Shishu Pal Singh, Josee Guindon, Prapti H Mody, Gabriela Ashworth, Jonathan Kopel, Sai Chilakapati, Owoicho Adogwa, Volker Neugebauer, Michael D Burton","doi":"10.1177/17448069231203090","DOIUrl":"10.1177/17448069231203090","url":null,"abstract":"<p><p>Chronic pain is one of the most common, costly, and potentially debilitating health issues facing older adults, with attributable costs exceeding $600 billion annually. The prevalence of pain in humans increases with advancing age. Yet, the contributions of sex differences, age-related chronic inflammation, and changes in neuroplasticity to the overall experience of pain are less clear, given that opposing processes in aging interact. This review article examines and summarizes pre-clinical research and clinical data on chronic pain among older adults to identify knowledge gaps and provide the base for future research and clinical practice. We provide evidence to suggest that neurodegenerative conditions engender a loss of neural plasticity involved in pain response, whereas low-grade inflammation in aging increases CNS sensitization but decreases PNS sensitivity. Insights from preclinical studies are needed to answer mechanistic questions. However, the selection of appropriate aging models presents a challenge that has resulted in conflicting data regarding pain processing and behavioral outcomes that are difficult to translate to humans.</p>","PeriodicalId":19010,"journal":{"name":"Molecular Pain","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/f3/4a/10.1177_17448069231203090.PMC10552461.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10307272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1177/17448069231186592
Justin E LaVigne, Ian M Adams, Marena A Montera, Karin N Westlund, Sascha Ra Alles
Dynorphin A (1-17) (DynA17) has been identified as a key regulator of both sensory and affective dimensions of chronic pain. Following nerve injury, increases in DynA17 have been reported in the spinal and supraspinal areas involved in chronic pain. Blocking these increases provides therapeutic benefits in preclinical chronic pain models. Although heavily characterized at the behavioral level, how DynA17 mediates its effects at the cellular physiological level has not been investigated. In this report, we begin to decipher how DynA17 mediates its direct effects on mouse dorsal root ganglion (DRG) cells and how intrathecal administration modifies a key node in the pain axis, the periaqueductal gray These findings build on the plethora of literature defining DynA17 as a critical neuropeptide in the pathophysiology of chronic pain syndromes.
{"title":"Pain-related behavioral and electrophysiological actions of dynorphin A (1-17).","authors":"Justin E LaVigne, Ian M Adams, Marena A Montera, Karin N Westlund, Sascha Ra Alles","doi":"10.1177/17448069231186592","DOIUrl":"https://doi.org/10.1177/17448069231186592","url":null,"abstract":"<p><p>Dynorphin A (1-17) (DynA17) has been identified as a key regulator of both sensory and affective dimensions of chronic pain. Following nerve injury, increases in DynA17 have been reported in the spinal and supraspinal areas involved in chronic pain. Blocking these increases provides therapeutic benefits in preclinical chronic pain models. Although heavily characterized at the behavioral level, how DynA17 mediates its effects at the cellular physiological level has not been investigated. In this report, we begin to decipher how DynA17 mediates its direct effects on mouse dorsal root ganglion (DRG) cells and how intrathecal administration modifies a key node in the pain axis, the periaqueductal gray These findings build on the plethora of literature defining DynA17 as a critical neuropeptide in the pathophysiology of chronic pain syndromes.</p>","PeriodicalId":19010,"journal":{"name":"Molecular Pain","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/0d/fb/10.1177_17448069231186592.PMC10328155.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9763144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Activation of neurons and glial cells in the dorsal root ganglion is one of the key mechanisms for the development of hyperalgesia. The aim of the present study was to examine the role of neuroglial activity in the development of opioid-induced hyperalgesia. Male rats were treated with morphine daily for 3 days. The resultant phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 in the dorsal root ganglion was analyzed by immunohistochemistry and Western blotting. Pain hypersensitivity was analyzed using behavioral studies. The amount of cytokine expression in the dorsal root ganglion was also analyzed. Repeated morphine treatment induced hyperalgesia and marked induction of phosphorylated ERK1/2 in the neurons and satellite glial cells on day 3. An opioid receptor antagonist, toll like receptor-4 inhibitor, MAP/ERK kinase (MEK) inhibitor and gap junction inhibitor inhibited morphine-induced hyperalgesia and ERK1/2 phosphorylation. Morphine treatment induced alteration of cytokine expression, which was inhibited by the opioid receptor antagonist, toll like receptor-4 inhibitor, MEK inhibitor and gap junction inhibitor. Dexamethasone inhibited morphine-induced hyperalgesia and ERK1/2 phosphorylation after morphine treatment. The peripherally restricted opioid receptor antagonist, methylnaltrexone, inhibited hyperalgesia and ERK1/2 phosphorylation. Morphine activates ERK1/2 in neurons and satellite glial cells in the dorsal root ganglion via the opioid receptor and toll like receptor-4. ERK1/2 phosphorylation is gap junction-dependent and is associated with the alteration of cytokine expression. Inhibition of neuroinflammation by activation of neurons and glia might be a promising target to prevent opioid-induced hyperalgesia.
激活背根神经节中的神经元和神经胶质细胞是产生超痛感的关键机制之一。本研究旨在探讨神经胶质细胞活动在阿片类药物诱导的痛觉减退中的作用。雄性大鼠每天接受吗啡治疗 3 天。通过免疫组织化学和 Western 印迹法分析了背根神经节中细胞外信号调节激酶(ERK)1/2 的磷酸化情况。通过行为研究分析了痛觉过敏性。还分析了背根神经节中细胞因子的表达量。重复吗啡处理可诱导痛觉减退,并在第3天明显诱导神经元和卫星神经胶质细胞磷酸化ERK1/2。阿片受体拮抗剂、类收费受体-4抑制剂、MAP/ERK激酶(MEK)抑制剂和间隙连接抑制剂抑制了吗啡诱导的痛觉减退和ERK1/2磷酸化。阿片受体拮抗剂、收费样受体-4 抑制剂、MEK 抑制剂和间隙连接抑制剂可抑制吗啡诱导的细胞因子表达。地塞米松可抑制吗啡诱导的痛觉减退和吗啡治疗后的ERK1/2磷酸化。外周限制性阿片受体拮抗剂甲纳曲酮抑制了超痛感和ERK1/2磷酸化。吗啡通过阿片受体和类收费受体-4激活背根神经节神经元和卫星胶质细胞中的ERK1/2。ERK1/2 磷酸化依赖于间隙连接,并与细胞因子表达的改变有关。通过激活神经元和神经胶质细胞来抑制神经炎症可能是预防阿片类药物引起的痛觉减退的一个有希望的靶点。
{"title":"Activation of neurons and satellite glial cells in the DRG produces morphine-induced hyperalgesia.","authors":"Shunsuke Yamakita, Daisuke Fujita, Kazuki Sudo, Daiki Ishikawa, Kohsuke Kushimoto, Yasuhiko Horii, Fumimasa Amaya","doi":"10.1177/17448069231181973","DOIUrl":"10.1177/17448069231181973","url":null,"abstract":"<p><p>Activation of neurons and glial cells in the dorsal root ganglion is one of the key mechanisms for the development of hyperalgesia. The aim of the present study was to examine the role of neuroglial activity in the development of opioid-induced hyperalgesia. Male rats were treated with morphine daily for 3 days. The resultant phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 in the dorsal root ganglion was analyzed by immunohistochemistry and Western blotting. Pain hypersensitivity was analyzed using behavioral studies. The amount of cytokine expression in the dorsal root ganglion was also analyzed. Repeated morphine treatment induced hyperalgesia and marked induction of phosphorylated ERK1/2 in the neurons and satellite glial cells on day 3. An opioid receptor antagonist, toll like receptor-4 inhibitor, MAP/ERK kinase (MEK) inhibitor and gap junction inhibitor inhibited morphine-induced hyperalgesia and ERK1/2 phosphorylation. Morphine treatment induced alteration of cytokine expression, which was inhibited by the opioid receptor antagonist, toll like receptor-4 inhibitor, MEK inhibitor and gap junction inhibitor. Dexamethasone inhibited morphine-induced hyperalgesia and ERK1/2 phosphorylation after morphine treatment. The peripherally restricted opioid receptor antagonist, methylnaltrexone, inhibited hyperalgesia and ERK1/2 phosphorylation. Morphine activates ERK1/2 in neurons and satellite glial cells in the dorsal root ganglion via the opioid receptor and toll like receptor-4. ERK1/2 phosphorylation is gap junction-dependent and is associated with the alteration of cytokine expression. Inhibition of neuroinflammation by activation of neurons and glia might be a promising target to prevent opioid-induced hyperalgesia.</p>","PeriodicalId":19010,"journal":{"name":"Molecular Pain","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/17/4c/10.1177_17448069231181973.PMC10291868.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9698902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1177/17448069231152125
Hong-Li Zheng, Shi-Yu Sun, Tong Jin, Ming Zhang, Ying Zeng, Qiaoqiao Liu, Kehui Yang, Runa Wei, Zhiqiang Pan, Fuqing Lin
Nerve injury can induce aberrant changes in ion channels, enzymes, and cytokines/chemokines in the dorsal root ganglia (DRGs); these changes are due to or at least partly governed by transcription factors that contribute to the genesis of neuropathic pain. However, the involvement of transcription factors in neuropathic pain is poorly understood. In this study, we report that transcription factor (TF) ETS proto-oncogene 1 (ETS1) is required for the initiation and development of neuropathic pain. Sciatic nerve chronic constrictive injury (CCI, a clinical neuropathic pain model) increases ETS1 expression in the injured male mouse DRG. Blocking this upregulation alleviated CCI-induced mechanical allodynia and thermal hyperalgesia, with no apparent effect on locomotor function. Mimicking this upregulation results in the genesis of nociception hypersensitivity; mechanistically, nerve injury-induced ETS1 upregulation promotes the expression of histone deacetylase 1 (HDAC1, a key initiator of pain) via enhancing its binding activity to the HDAC1 promotor, leading to the elevation of spinal central sensitization, as evidenced by increased expression of p-ERK1/2 and GFAP in the dorsal spinal horn. It appears that the ETS1/HDAC1 axis in DRG may have a critical role in the development and maintenance of neuropathic pain, and ETS1 is a potential therapeutic target in neuropathic pain.
{"title":"Transcription factor ETS proto-oncogene 1 contributes to neuropathic pain by regulating histone deacetylase 1 in primary afferent neurons.","authors":"Hong-Li Zheng, Shi-Yu Sun, Tong Jin, Ming Zhang, Ying Zeng, Qiaoqiao Liu, Kehui Yang, Runa Wei, Zhiqiang Pan, Fuqing Lin","doi":"10.1177/17448069231152125","DOIUrl":"10.1177/17448069231152125","url":null,"abstract":"<p><p>Nerve injury can induce aberrant changes in ion channels, enzymes, and cytokines/chemokines in the dorsal root ganglia (DRGs); these changes are due to or at least partly governed by transcription factors that contribute to the genesis of neuropathic pain. However, the involvement of transcription factors in neuropathic pain is poorly understood. In this study, we report that transcription factor (TF) ETS proto-oncogene 1 (ETS1) is required for the initiation and development of neuropathic pain. Sciatic nerve chronic constrictive injury (CCI, a clinical neuropathic pain model) increases ETS1 expression in the injured male mouse DRG. Blocking this upregulation alleviated CCI-induced mechanical allodynia and thermal hyperalgesia, with no apparent effect on locomotor function. Mimicking this upregulation results in the genesis of nociception hypersensitivity; mechanistically, nerve injury-induced ETS1 upregulation promotes the expression of histone deacetylase 1 (HDAC1, a key initiator of pain) via enhancing its binding activity to the HDAC1 promotor, leading to the elevation of spinal central sensitization, as evidenced by increased expression of p-ERK1/2 and GFAP in the dorsal spinal horn. It appears that the ETS1/HDAC1 axis in DRG may have a critical role in the development and maintenance of neuropathic pain, and ETS1 is a potential therapeutic target in neuropathic pain.</p>","PeriodicalId":19010,"journal":{"name":"Molecular Pain","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/c3/7a/10.1177_17448069231152125.PMC9909074.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9295119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1177/17448069221148958
Ryan Vaden, Jianguo Gu
The role of Aβ-afferents in somatosensory function is often oversimplified as low threshold mechanoreceptors (LTMRs) with large omission of Aβ-afferent involvement in nociception. Recently, we have characterized Aβ-afferent neurons which have large diameter somas in the trigeminal ganglion (TG) and classified them into non-nociceptive and nociceptive-like TG afferent neurons based on their electrophysiological properties. Here, we extend our previous observations to further characterize electrophysiological properties of trigeminal Aβ-afferent neurons and investigate their mechanical and chemical sensitivity by patch-clamp recordings from large-diameter TG neurons in ex vivo TG preparations of adult male and female rats. Based on cluster analysis of electrophysiological properties, trigeminal Aβ-afferent neurons can be classified into five discrete types (type I, IIa, IIb, IIIa, and IIIb), which responded differentially to mechanical stimulation and sensory mediators including serotonin (5-HT), acetylcholine (ACh) and adenosine triphosphate (ATP). Notably, type I neuron action potential (AP) was small in amplitude, width was narrow in duration, and peak dV/dt repolarization was great with no deflection observed, whereas discretely graded differences were observed for type IIa, IIb, IIIa, and IIIb, as AP increased in amplitude, width broadened in duration, and peak dV/dt repolarization reduced with the emergence of increasing deflection. Type I, IIa, and IIb neurons were mostly mechanically sensitive, displaying robust and rapidly adapting mechanically activated current (IMA) in response to membrane displacement, while IIIa and IIIb, conversely, were almost all mechanically insensitive. Interestingly, mechanical insensitivity coincided with increased sensitivity to 5-HT and ACh. Together, type I, IIa and IIb display features of LTMR Aβ-afferent neurons while type IIIa and type IIIb show properties of nociceptive Aβ-afferent neurons.
a - β传入在体感觉功能中的作用通常被过分简化为低阈值机械感受器(LTMRs),而忽略了a - β传入对伤害感觉的参与。最近,我们对三叉神经节(TG)中具有大直径胞体的a β-传入神经元进行了表征,并根据其电生理特性将其分为非伤害性和类伤害性TG传入神经元。在此,我们扩展了之前的观察结果,进一步表征了三叉神经a β传入神经元的电生理特性,并通过膜片钳记录了成年雄性和雌性大鼠离体TG制剂中大直径TG神经元的机械和化学敏感性。根据电生理特性聚类分析,三叉神经a β传入神经元可分为I型、IIa型、IIb型、IIIa型和IIIb型5种类型,它们对机械刺激和5-羟色胺(5-HT)、乙酰胆碱(ACh)、三磷酸腺苷(ATP)等感觉介质的反应存在差异。其中,I型神经元动作电位(AP)振幅小,宽度窄,持续时间短,dV/dt复极峰明显且无偏转,而IIa、IIb、IIIa和IIIb型神经元动作电位(AP)振幅增大,宽度变宽,且随着偏转的增加,dV/dt复极峰减小。I、IIa和IIb型神经元大多是机械敏感的,在响应膜位移时表现出鲁强和快速适应的机械激活电流(IMA),而IIIa和IIIb型神经元则相反,几乎都是机械不敏感的。有趣的是,机械不敏感与对5-羟色胺和乙酰胆碱的敏感性增加同时发生。I型、IIa型和IIb型表现为LTMR a β-传入神经元的特征,而IIIa型和IIIb型表现为伤害性a β-传入神经元的特征。
{"title":"Non-nociceptive and nociceptive-like trigeminal Aβ-afferent neurons of rats: Distinct electrophysiological properties, mechanical and chemical sensitivity.","authors":"Ryan Vaden, Jianguo Gu","doi":"10.1177/17448069221148958","DOIUrl":"https://doi.org/10.1177/17448069221148958","url":null,"abstract":"<p><p>The role of Aβ-afferents in somatosensory function is often oversimplified as low threshold mechanoreceptors (LTMRs) with large omission of Aβ-afferent involvement in nociception. Recently, we have characterized Aβ-afferent neurons which have large diameter somas in the trigeminal ganglion (TG) and classified them into non-nociceptive and nociceptive-like TG afferent neurons based on their electrophysiological properties. Here, we extend our previous observations to further characterize electrophysiological properties of trigeminal Aβ-afferent neurons and investigate their mechanical and chemical sensitivity by patch-clamp recordings from large-diameter TG neurons in ex vivo TG preparations of adult male and female rats. Based on cluster analysis of electrophysiological properties, trigeminal Aβ-afferent neurons can be classified into five discrete types (type I, IIa, IIb, IIIa, and IIIb), which responded differentially to mechanical stimulation and sensory mediators including serotonin (5-HT), acetylcholine (ACh) and adenosine triphosphate (ATP). Notably, type I neuron action potential (AP) was small in amplitude, width was narrow in duration, and peak dV/dt repolarization was great with no deflection observed, whereas discretely graded differences were observed for type IIa, IIb, IIIa, and IIIb, as AP increased in amplitude, width broadened in duration, and peak dV/dt repolarization reduced with the emergence of increasing deflection. Type I, IIa, and IIb neurons were mostly mechanically sensitive, displaying robust and rapidly adapting mechanically activated current (I<sub>MA</sub>) in response to membrane displacement, while IIIa and IIIb, conversely, were almost all mechanically insensitive. Interestingly, mechanical insensitivity coincided with increased sensitivity to 5-HT and ACh. Together, type I, IIa and IIb display features of LTMR Aβ-afferent neurons while type IIIa and type IIIb show properties of nociceptive Aβ-afferent neurons.</p>","PeriodicalId":19010,"journal":{"name":"Molecular Pain","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/0b/e2/10.1177_17448069221148958.PMC9829874.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9953015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1177/17448069231187366
Sotatsu Tonomura, Jianguo Gu
Large-diameter myelinated fibers in sciatic nerves are composed of both Aα/β-afferent fibers and Aα-efferent fibers to convey sensory and motor impulses, respectively, via saltatory conduction for rapid leg responses. Saltatory conduction and electrophysiological properties at the nodes of Ranvier (NRs) of these sciatic nerve fibers have not been directly studied. We used ex vivo sciatic nerve preparations from rats and applied patch-clamp recordings at the NRs of both Aα/β-afferent fibers and Aα-efferent fibers in the sciatic nerves to characterize their saltatory conduction and intrinsic electrophysiological properties. The velocity and frequency of saltatory conduction in both types of fibers were similar. Resting membrane potentials (RMPs), input resistance, action potential (AP) threshold, and AP rheobase were also not significantly different at the NRs of the two types of fibers in the sciatic nerves. In comparison with Aα/β-afferent fibers, Aα-efferent fibers in the sciatic nerves show higher amplitude and broader width of APs at their NRs. At the NRs of both types of fibers, depolarizing voltages evoked transient inward currents followed by non-inactivating outward currents, and the inward currents and non-inactivating outward currents at the NRs were not significantly different between the two types of fibers. Using AP-clamp, inward currents during AP upstroke were found to be insignificant difference, but amplitudes of non-inactivating outward currents during AP repolarization were significantly lower at the NRs of Aα-efferent fibers than at the NRs of Aα/β-afferent fibers in the sciatic nerves. Collectively, saltatory conduction, ionic currents, and intrinsic electrophysiological properties at the NRs of Aα/β-afferent fibers and Aα-efferent fibers in the sciatic nerves are generally similar, but some differences were also observed.
{"title":"Saltatory conduction and intrinsic electrophysiological properties at the nodes of ranvier of Aα/β-afferent fibers and Aα-efferent fibers in rat sciatic nerves.","authors":"Sotatsu Tonomura, Jianguo Gu","doi":"10.1177/17448069231187366","DOIUrl":"10.1177/17448069231187366","url":null,"abstract":"<p><p>Large-diameter myelinated fibers in sciatic nerves are composed of both Aα/β-afferent fibers and Aα-efferent fibers to convey sensory and motor impulses, respectively, via saltatory conduction for rapid leg responses. Saltatory conduction and electrophysiological properties at the nodes of Ranvier (NRs) of these sciatic nerve fibers have not been directly studied. We used ex vivo sciatic nerve preparations from rats and applied patch-clamp recordings at the NRs of both Aα/β-afferent fibers and Aα-efferent fibers in the sciatic nerves to characterize their saltatory conduction and intrinsic electrophysiological properties. The velocity and frequency of saltatory conduction in both types of fibers were similar. Resting membrane potentials (RMPs), input resistance, action potential (AP) threshold, and AP rheobase were also not significantly different at the NRs of the two types of fibers in the sciatic nerves. In comparison with Aα/β-afferent fibers, Aα-efferent fibers in the sciatic nerves show higher amplitude and broader width of APs at their NRs. At the NRs of both types of fibers, depolarizing voltages evoked transient inward currents followed by non-inactivating outward currents, and the inward currents and non-inactivating outward currents at the NRs were not significantly different between the two types of fibers. Using AP-clamp, inward currents during AP upstroke were found to be insignificant difference, but amplitudes of non-inactivating outward currents during AP repolarization were significantly lower at the NRs of Aα-efferent fibers than at the NRs of Aα/β-afferent fibers in the sciatic nerves. Collectively, saltatory conduction, ionic currents, and intrinsic electrophysiological properties at the NRs of Aα/β-afferent fibers and Aα-efferent fibers in the sciatic nerves are generally similar, but some differences were also observed.</p>","PeriodicalId":19010,"journal":{"name":"Molecular Pain","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/8b/4d/10.1177_17448069231187366.PMC10413906.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9968013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1177/17448069231185696
Fabiana C Dias, Zilong Wang, Garrett Scapellato, Yong Chen
Identification of potential therapeutic targets is needed for temporomandibular disorders (TMD) pain, the most common form of orofacial pain, because current treatments lack efficacy. Considering TMD pain is critically mediated by the trigeminal ganglion (TG) sensory neurons, functional blockade of nociceptive neurons in the TG may provide an effective approach for mitigating pain associated with TMD. We have previously shown that TRPV4, a polymodally-activated ion channel, is expressed in TG nociceptive neurons. Yet, it remains unexplored whether functional silencing of TRPV4-expressing TG neurons attenuates TMD pain. In this study, we demonstrated that co-application of a positively charged, membrane-impermeable lidocaine derivative QX-314 with the TRPV4 selective agonist GSK101 suppressed the excitability of TG neurons. Moreover, co-administration of QX-314 and GSK101 into the TG significantly attenuated pain in mouse models of temporomandibular joint (TMJ) inflammation and masseter muscle injury. Collectively, these results suggest TRPV4-expressing TG neurons represent a potential target for TMD pain.
{"title":"Silencing of TRPV4-expressing sensory neurons attenuates temporomandibular disorders pain.","authors":"Fabiana C Dias, Zilong Wang, Garrett Scapellato, Yong Chen","doi":"10.1177/17448069231185696","DOIUrl":"https://doi.org/10.1177/17448069231185696","url":null,"abstract":"<p><p>Identification of potential therapeutic targets is needed for temporomandibular disorders (TMD) pain, the most common form of orofacial pain, because current treatments lack efficacy. Considering TMD pain is critically mediated by the trigeminal ganglion (TG) sensory neurons, functional blockade of nociceptive neurons in the TG may provide an effective approach for mitigating pain associated with TMD. We have previously shown that TRPV4, a polymodally-activated ion channel, is expressed in TG nociceptive neurons. Yet, it remains unexplored whether functional silencing of TRPV4-expressing TG neurons attenuates TMD pain. In this study, we demonstrated that co-application of a positively charged, membrane-impermeable lidocaine derivative QX-314 with the TRPV4 selective agonist GSK101 suppressed the excitability of TG neurons. Moreover, co-administration of QX-314 and GSK101 into the TG significantly attenuated pain in mouse models of temporomandibular joint (TMJ) inflammation and masseter muscle injury. Collectively, these results suggest TRPV4-expressing TG neurons represent a potential target for TMD pain.</p>","PeriodicalId":19010,"journal":{"name":"Molecular Pain","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/5e/d3/10.1177_17448069231185696.PMC10288408.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10086699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1177/17448069231182501
{"title":"Corrigendum to \"Rac1/PAK1 signaling contributes to bone cancer pain by Regulation dendritic spine remodeling in rats\".","authors":"","doi":"10.1177/17448069231182501","DOIUrl":"10.1177/17448069231182501","url":null,"abstract":"","PeriodicalId":19010,"journal":{"name":"Molecular Pain","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10469238/pdf/10.1177_17448069231182501.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10522497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chemotherapy-induced peripheral neuropathy (CIPN) is the most common side-effect of anti-cancer therapy. To date, there are no clinically effective analgesics that could prevent and treat CIPN. However, the exact pathogenesis of CIPN is still unclear. In the present study, we use the paclitaxel-induced peripheral neuropathy (PIPN) model, aiming to better understand the transcriptomic level of the Dorsal root ganglia (DRG) neurons in rats with PIPN. mRNA from each DRG sample was reverse transcribed to cDNA and sequenced using next-generation high throughput sequencing technology. Quantitative RT-PCR verification was used to confirm the identified Differentially expressed genes (DEGs) in the DRG of PIPN rats. RNAseq results have identified 384 DEGs (adjusted P-value < 0.05; fold change ≥ 2) in the DRG of rats 14 days after paclitaxel injection in total, including 97 up-regulated genes, and 287 down-regulated genes. GO analysis revealed that these DEGs were majorly involved in neuropeptide activity, chemokine receptor activity, defense response, and inflammatory response. Kyoto Encyclopedia of Gene and Genomes analysis showed that neuroactive ligand-receptor interaction and cytokine-cytokine receptor interaction were involved in sensory neurons of rats with PIPN. Besides, comparison analysis identified that 11 DEGs in the PIPN model are shared with either inflammatory pain (Ces1d, Cfd, Retn, and Fam150b) or neuropathic pain (Atf3, Csrp3, Ecel1, Gal, Sprr1a, Tgm1, and Vip). Quantitative RT-PCR results also confirmed the validation of the RNAseq data. These results suggested that neuroactive ligand-receptor interaction and cytokine-cytokine receptor interaction are majorly involved in sensory neurons of rats with PIPN. Immune, inflammatory responses and neuron functional changes are the major pathogenesis of PIPN. Paclitaxel-induced peripheral neuropathy has shared characteristics with both inflammatory pain and neuropathic pain.
{"title":"Transcriptome analysis reveals dysregulation of inflammatory and neuronal function in dorsal root ganglion of paclitaxel-induced peripheral neuropathy rats.","authors":"Wuping Sun, Shaomin Yang, Songbin Wu, Xiyuan Ba, Donglin Xiong, Lizu Xiao, Yue Hao","doi":"10.1177/17448069221106167","DOIUrl":"https://doi.org/10.1177/17448069221106167","url":null,"abstract":"<p><p>Chemotherapy-induced peripheral neuropathy (CIPN) is the most common side-effect of anti-cancer therapy. To date, there are no clinically effective analgesics that could prevent and treat CIPN. However, the exact pathogenesis of CIPN is still unclear. In the present study, we use the paclitaxel-induced peripheral neuropathy (PIPN) model, aiming to better understand the transcriptomic level of the Dorsal root ganglia (DRG) neurons in rats with PIPN. mRNA from each DRG sample was reverse transcribed to cDNA and sequenced using next-generation high throughput sequencing technology. Quantitative RT-PCR verification was used to confirm the identified Differentially expressed genes (DEGs) in the DRG of PIPN rats. RNAseq results have identified 384 DEGs (adjusted <i>P-value</i> < 0.05; fold change ≥ 2) in the DRG of rats 14 days after paclitaxel injection in total, including 97 up-regulated genes, and 287 down-regulated genes. GO analysis revealed that these DEGs were majorly involved in neuropeptide activity, chemokine receptor activity, defense response, and inflammatory response. Kyoto Encyclopedia of Gene and Genomes analysis showed that neuroactive ligand-receptor interaction and cytokine-cytokine receptor interaction were involved in sensory neurons of rats with PIPN. Besides, comparison analysis identified that 11 DEGs in the PIPN model are shared with either inflammatory pain (Ces1d, Cfd, Retn, and Fam150b) or neuropathic pain (Atf3, Csrp3, Ecel1, Gal, Sprr1a, Tgm1, and Vip). Quantitative RT-PCR results also confirmed the validation of the RNAseq data. These results suggested that neuroactive ligand-receptor interaction and cytokine-cytokine receptor interaction are majorly involved in sensory neurons of rats with PIPN. Immune, inflammatory responses and neuron functional changes are the major pathogenesis of PIPN. Paclitaxel-induced peripheral neuropathy has shared characteristics with both inflammatory pain and neuropathic pain.</p>","PeriodicalId":19010,"journal":{"name":"Molecular Pain","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/92/4c/10.1177_17448069221106167.PMC10227877.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9549497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}