Mu-Opioid Receptor is Involved in β-Endorphin-Induced Feeding in the Meat-type Chick

Abstract

β-Endorphin is an endogenous ligand for both mu- and delta-opioid receptors (MOR and DOR), and has an important role in feeding behavior in the central nervous system in mammals. The present study was done to elucidate whether central injection of β-endorphin enhances feeding behavior in neonatal chicks and to investigate the interaction with the MOR and DOR. We found that the intracerebroventricular (ICV) injection of β-endorphin (50pmol) significantly stimulated food intake in neonatal chicks during the 60-min period postinjection. In addition, the orexigenic effect of β-endorphin was significantly attenuated by the MOR, but not by the DOR antagonist. These results indicate that the administration of β-endorphin into the chick brain produces the orexigenic effect through the MOR.