Mechanism underlying inhibition of the capsaicin receptor-mediated current by pregnenolone sulfate in rat dorsal root ganglion neurons.
The effect of pregnenolone sulfate (PS) on the capsaicin receptor-mediated current was studied in acutely dissociated rat dorsal root ganglion neurons using the whole-cell voltage-clamp technique. PS acted extracellularly to inhibit the capsaicin-induced current in a not competitive but concentration-dependent manner, with an EC50 of 13 microM and a maximal inhibition of 65%. Furthermore, antagonism of the capsaicin response by PS is neither voltage- nor agonist-dependent, indicating that PS did not act as an open-channel blocker. The inhibitory action of PS on the capsaicin-induced current may provide a basis for reducing capsaicin receptor-mediated nociception.
Chen
Shu-Cheng
SC
Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
Wu
Fong-Sen
FS
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005727:Ganglia, Spinal / Q000166:cytology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000379:methods; D011284:Pregnenolone / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000502:physiology*; D013997:Time Factors
D011955:Receptors, Drug; C018370:pregnenolone sulfate; D011284:Pregnenolone; D002211:Capsaicin