Central injection of endomorphin-2, but not endomorphin-1, increases food intake in chicks via mu1-opioid receptors
2007
Bungo, T.(Hiroshima Univ., Higashi-hiroshima (Japan)) | Dodo, K. | Izumi, T.
The endogenous tetrapeptides endomorphin-1 and -2 are potent, selective micro-opioid receptor agonists in mammals. The present study was done to elucidate whether central injection of endomorphins enhances feeding behavior in chicks, and to investigate the interaction with the microsub(1)-opioid receptor. We found that the intracerebroventricular injection of endomorphin-2 (10-30 nmol) significantly stimulated food intake in neonatal chicks during the 60-min period postinjection. However, the same doses of endomorphin-1 injected with ICV had no significant effects on feeding behavior. The orexigenic effect of endomorphin-2 was significantly attenuated by the microsub(1)-opioid receptor antagonist naloxonazine. These results indicate that the administration of endomorphin-2, but not endomorphin-1, into the chick brain produces the orexigenic effect through the microsub(1)-opioid receptor.
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