Effects of various mu- and delta-opioid ligands on food intake in the meat-type chick.
The present study was designed to examine the effects of mu- and delta-opioid receptor ligands on feeding behavior in meat-type chicks. Intracerebroventricular (ICV) injection of naltrexone (mu- and delta-antagonist), beta-funaltrexamine (beta-FNA; mu-antagonist), ICI-174,864 (ICI; delta-antagonist), or naloxonazine (NAL; mu1-antagonist) significantly decreased deprivation-induced feeding at 30 min postinjection. Co-injection of beta-FNA, but not NAL, significantly blocked the depressive effect of [D-Ala2, N-MePhe4, Gly5-ol]-enkephalin (mu-opioid agonist) under ad libitum conditions. Central injection of ICI attenuated significant effects of [D-Pen(2,5)]-enkephalin (delta-opioid agonist) on feeding behavior in ad libitum fed chicks. Co-injection of beta-FNA, but not ICI, significantly attenuated the orexigenic effect of [D-Ala2, D-Leu3]-enkephalin (mu- and delta-opioid agonist). These results suggest that the endogenous opioid peptides, which act on the mu- and/or delta-opioid receptor, have an important role in feeding behavior in the central nervous system of meat-type chicks.
Bungo
Takashi
T
Laboratory of Animal Science, Department of Agrobiological Science, Faculty of Agriculture, Ehime University, Matsuyama 790-8566, Japan. bungo@agr.ehime-u.ac.jp
Dodo
Koh-Ichi
K
Kawamura
Kazuya
K
Izumi
Tomofumi
T
Ueda
Hiroshi
H
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D002645:Chickens / Q000502:physiology*; D004435:Eating / Q000187:drug effects*; D007276:Injections, Intraventricular; D008024:Ligands; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*
D008024:Ligands; D009292:Narcotic Antagonists; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu