Anti-nociceptive effects of calcitonin gene-related peptide in nucleus raphe magnus of rats: an effect attenuated by naloxone.
The present study investigated the role of calcitonin gene-related peptide (CGRP) on nociception in nucleus raphe magnus (NRM) and the interaction between CGRP and opioid peptides in NRM of rats. CGRP-like immunoreactivity was found at a concentration of 6.0+/-0. 77 pmol/g in NRM tissue of ten samples of rats, suggesting that it may contribute to physiological responses orchestrated by the NRM. The hindpaw withdrawal latency (HWL) to thermal and mechanical stimulation increased significantly after intra-NRM administration of 0.5 or 1 nmol of CGRP in rats, but not 0.25 nmol. The anti-nociceptive effect induced by CGRP was antagonized by following intra-NRM injection of 1 nmol of the CGRP receptor antagonist CGRP8-37. Furthermore, the CGRP-induced anti-nociceptive effect was attenuated by following intra-NRM administration of 6 nmol of naloxone. The results indicate that CGRP and its receptors play an important role in anti-nociception, and there is a possible interaction between CGRP and opioid peptides in NRM of rats.
Huang
Y
Y
Department of Physiology, College of Life Sciences, Peking University, Beijing, People's Republic of China.
Brodda-Jansen
G
G
Lundeberg
T
T
Yu
L C
LC
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism / Q000494:pharmacology*; D006614:Hindlimb / Q000502:physiology; D006358:Hot Temperature; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects*; D010446:Peptide Fragments / Q000494:pharmacology; D010812:Physical Stimulation; D011903:Raphe Nuclei / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects
D009292:Narcotic Antagonists; D010446:Peptide Fragments; C058636:calcitonin gene-related peptide (8-37); D009270:Naloxone; D015740:Calcitonin Gene-Related Peptide