Cholecystokinin activates both A- and C-type vagal afferent neurons.
Patch-clamp electrophysiological methods were used on dissociated rat nodose neurons maintained in culture to determine whether responses to cholecystokinin (CCK) were associated with capsaicin-resistant (A type) or capsaicin-sensitive (C type) neurons. Nodose neurons were classified as A or C type on the basis of the characteristics of the Na+ current, a hyperpolarization-activated current, and sensitivity to a low concentration of capsaicin to ascertain the presence of vanilloid receptor 1 that has been associated with C-type neurons in sensory ganglia. It was expected that only capsaicin-sensitive C-type neurons would respond to CCK, because most vagally mediated actions of CCK are blocked by capsaicin treatment. However, we found that subpopulations of both A- and C-type neurons responded to CCK (24 and 38%, respectively). Thus some vagally mediated actions of CCK may be mediated by capsaicin insensitive A-type neurons.
Simasko
Steven M
SM
Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, College of Veterinary Medicine, Washington State University, Pullman, Washington 99164-6520, USA. simasko@vetmed.wsu.edu
Ritter
Robert C
RC
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004553:Electric Conductivity; D008297:Male; D009475:Neurons, Afferent / Q000145:classification / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012844:Sincalide / Q000494:pharmacology*; D015222:Sodium Channels / Q000502:physiology; D014630:Vagus Nerve / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*
D015222:Sodium Channels; D012844:Sincalide; D002211:Capsaicin