ORAL AND HYPOTHALAMIC INJECTIONS OF BARBITURATES, BENZODIAZEPINES AND CANNABINOIDS AND FOOD-INTAKE IN RATS

To evaluate and compare CNS sites of action of chemicals which stimulate feeding, intakes were measured after ventromedial hypothalamic (VMH) and lateral hypothalamic (LH) administration of pentobarbital sodium (PBS), diazepam (D) and the d- and l-isomers of Δ9-tetrahydrocannabinol (THC); and intragastric administration of D and d- and 1-THC. In rats fed ad lib PBS (8 and 16 μg) increased intake tenfold (p<0.05) 0.5 hr after injection in the VMH, but not the LH. Intragastric administration of 2.5 and 5 mg/kg D increased intake twofold (p<0.01) at 0.5 and 2 hr but did not affect 24 hr intake. VMH injections of D (10 and 20 μg) caused a 15-fold increase (p<0.05) at 0.5 but not 24 hr, but LH injection of D did not affect 0.5 or 24 hr intake. Intragastric administration of 4 mg/kg 1-THC increased (p<0.01) food intake at 1 and 2 hr, but 24 hr intake was not affected; d-THC had no effect. VMH, but not LH, injection of 1-THC (0.25 μg) caused a 24-hr increase in intake. d-THC (0.25 μg) caused a decrease (p<0.05) in feeding at 0.5 hr, but not 24 hr when administered in the VMH, and increased (p<0.05) feeding at 24 hr when injected in the LH. The VMH appears to mediate the action of both PBS and D, but the increased feeding caused by systemic 1-THC is not duplicated by VMH administration, thereby suggesting an alternate site of action. © 1979.