Facilitory effect of delta 9-tetrahydrocannabinol on hypothalamically induced feeding.

Six male Lewis rats were tested for the effect of delta 9-tetrahydrocannabinol (delta 9-THC) on feeding evoked by electrical stimulation of the lateral hypothalamus. Treatment with delta 9-THC (0.4 mg/kg IP) decreased frequency threshold for feeding by 20.5% (+/- 4.3), causing a leftward shift in the function relating stimulation frequency to the latency to begin eating 45-mg food pellets upon stimulation onset; there was no change in the asymptotic performance that was approached with sufficiently high stimulation frequencies. Naloxone (1 and 2 mg/kg) reduced the facilitory effect of delta 9-THC, but did so at doses that can inhibit feeding in the no-drug condition. These data are consistent with evidence implicating endogenous opioids in feeding, and suggest (but do not confirm) that the facilitation of feeding by delta 9-THC may be mediated by endogenous opioids. The facilitation of stimulation-induced feeding by doses of delta 9-THC that have been found to facilitate brain stimulation reward is consistent with evidence suggesting common elements in the brain mechanisms of these two behavioral effects of medial forebrain bundle stimulation.