Injections of nociceptin into nucleus accumbens shell or ventromedial hypothalamic nucleus increase food intake

THE novel opioid receptor ORL1 is widely distributed throughout the CNS of the rat, and is present in high densities in several brain regions known to participate in the control of food intake. We injected a recently identified endogenous agonist of this receptor, nociceptin, into two of these feeding-related areas. Microinjections of nociceptin (2.5–25 nmol) into either the ventromedial hypothalamic nucleus or the nucleus accumbens shell significantly increased food intake in rats. We believe this to be the first report of a specific effect of nociceptin on a motivated behavior.