β-Endorphin Is Associated with Overeating in Genetically Obese Mice ( <i>ob</i> / <i>ob</i> ) and Rats ( <i>fa</i> / <i>fa</i> )

Abstract

Small doses of the opiate antagonist naloxone selectively abolished overeating in genetically obese mice (ob/ob) and rats (fa/fa). Elevated concentrations of the naturally occurring opiate beta-endorphin were found in the pituitaries of both obese species and in the blood plasma of the obese rats. Brain levels of beta-endorphin and Leu-enkephalin were unchanged. These data suggest that excess pituitary beta-endorphin may play a role in the development of the overeating and obesity syndrome.