Capsaicin-evoked release of pituitary adenylate cyclase activating peptide (PACAP) and calcitonin gene-related peptide (CGRP) from rat spinal cord in vivo.
Capsaicin-evoked release of pituitary adenylate cyclase activating peptide (PACAP)-like immunoreactivity (LI) from rat spinal cord was examined in vivo. In anaesthetized rats, a catheter was inserted through the atlanto-occipital membrane into the subarachnoid space at the level of the sacral spinal cord for infusion of artificial cerebrospinal fluid. Another catheter was placed in the cisternal opening for outflow. Blood pressure was monitored and kept stable during the experiment. Perfusion samples were analyzed for PACAP and calcitonin gene-related peptide (CGRP) by radioimmunoassay. The addition of capsaicin (10 microM) to the perfusate elevated the concentrations of PACAP-27-LI in the artificial cerebrospinal fluid by 177%, PACAP-38-LI by 93% and CGRP-LI by 692%. In view of the presence of PACAP-immunoreactive nerve fibres in the superficial layers of the dorsal horn and the expression of PACAP in the small sized neurons in the dorsal root ganglia, the findings suggest that PACAP is released into the artificial cerebrospinal fluid from C-fibres in the spinal cord. PACAP conceivably plays a modulating role in nociception.
Zhang
Y
Y
Department of Anesthesiology, University of California, San Diego, La Jolla, USA. Yanzhen.Zhang@expmas.lu.se
Malmberg
A B
AB
Yaksh
T L
TL
Sjölund
B
B
Sundler
F
F
Håkanson
R
R
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002211:Capsaicin / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D008297:Male; D009479:Neuropeptides / Q000378:metabolism*; D010477:Perfusion; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism
C495403:Adcyap1 protein, rat; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin