Pituitary adenylate cyclase activating polypeptide and vasoactive intestinal peptide inhibit feeding in the chick brain by different mechanisms.
Intracerebroventricular (ICV) injections of pituitary adenylate cyclase-activating polypeptide-38 (PACAP) and vasoactive intestinal peptide (VIP) inhibit feeding in chicks. However, the precise anorexigenic mechanisms have not been investigated, since both peptides activate the VPAC receptor in mammals. We investigated which receptor mediates the anorexigenic effects of these peptides in chicks. ICV co-injection of PACAP (6-38), a PAC1 receptor antagonist, attenuated the anorexigenic effect of PACAP but not VIP. On the other hand, ICV co-injection of [D-p-Cl-Phe6, Leu17]-VIP, a VPAC receptor antagonist, did not affect the effects of both peptides. Although these results imply that the effect of VIP was not specific, a subsequent experiment demonstrated that ICV injection of anti-chicken VIP antiserum stimulated feeding and suggested that endogenous VIP inhibits feeding in the chick brain. Collectively, the data suggest that the anorexigenic mechanism of PACAP is different from that of VIP and that an undiscovered VIP receptor may be present in the chicken brain.
Tachibana
Tetsuya
T
Laboratory of Advanced Animal and Marine Bioresources, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka 812-8581, Japan. tetsu@brs.kyushu-u.ac.jp
Tomonaga
Shozo
S
Oikawa
Daichi
D
Saito
Shin
S
Takagi
Tomo
T
Saito
Ei-Suke
ES
Boswell
Tim
T
Furuse
Mitsuhiro
M
D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D001923:Brain Chemistry; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004435:Eating / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects*; D005765:Gastrointestinal Agents / Q000494:pharmacology*; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D007276:Injections, Intraventricular / Q000379:methods; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D013997:Time Factors; D014660:Vasoactive Intestinal Peptide / Q000276:immunology / Q000494:pharmacology*
C495401:ADCYAP1 protein, human; D004338:Drug Combinations; D005765:Gastrointestinal Agents; D007106:Immune Sera; D009479:Neuropeptides; D010446:Peptide Fragments; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D014660:Vasoactive Intestinal Peptide