{"title":"Reassessment of capsaicin desensitization in the rodent spinal dorsal horn","authors":"","doi":"10.1016/j.neuint.2024.105887","DOIUrl":null,"url":null,"abstract":"<div><div>Capsaicin activates primary afferent transient receptor potential vanilloid 1 (TRPV1) in the spinal dorsal horn and induces exaggerated glutamate release. This capsaicin action is followed by a lasting refractory state referred to as “capsaicin desensitization”, which is considered a presynaptic event. In this study, using whole-cell recordings and holographic photostimulation, we reassessed this notion by investigating presynaptic glutamate release and the postsynaptic glutamate response during capsaicin administration. We found that both presynaptic synchronous glutamate release and the postsynaptic glutamate response were largely attenuated in this refractory state; in contrast, asynchronous release was exaggerated. Further behavioral studies revealed a quick increase in the mechanical pain threshold with intrathecal capsaicin administration. Taken together, both presynaptic synchronous glutamate release and the postsynaptic response are downregulated during capsaicin desensitization, and this desensitization may transiently increase the pain threshold. Since both presynaptic synchronous release and postsynaptic glutamate responses are attenuated, the traditional electrophysiological evidence supporting capsaicin desensitization as a presynaptic event should be reassessed.</div></div>","PeriodicalId":398,"journal":{"name":"Neurochemistry international","volume":null,"pages":null},"PeriodicalIF":4.4000,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Neurochemistry international","FirstCategoryId":"3","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0197018624002146","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Capsaicin activates primary afferent transient receptor potential vanilloid 1 (TRPV1) in the spinal dorsal horn and induces exaggerated glutamate release. This capsaicin action is followed by a lasting refractory state referred to as “capsaicin desensitization”, which is considered a presynaptic event. In this study, using whole-cell recordings and holographic photostimulation, we reassessed this notion by investigating presynaptic glutamate release and the postsynaptic glutamate response during capsaicin administration. We found that both presynaptic synchronous glutamate release and the postsynaptic glutamate response were largely attenuated in this refractory state; in contrast, asynchronous release was exaggerated. Further behavioral studies revealed a quick increase in the mechanical pain threshold with intrathecal capsaicin administration. Taken together, both presynaptic synchronous glutamate release and the postsynaptic response are downregulated during capsaicin desensitization, and this desensitization may transiently increase the pain threshold. Since both presynaptic synchronous release and postsynaptic glutamate responses are attenuated, the traditional electrophysiological evidence supporting capsaicin desensitization as a presynaptic event should be reassessed.
期刊介绍:
Neurochemistry International is devoted to the rapid publication of outstanding original articles and timely reviews in neurochemistry. Manuscripts on a broad range of topics will be considered, including molecular and cellular neurochemistry, neuropharmacology and genetic aspects of CNS function, neuroimmunology, metabolism as well as the neurochemistry of neurological and psychiatric disorders of the CNS.