Delta(9)-tetrahydrocannabinol stimulates palatable food intake in Lewis rats: Effects of peripheral and central administration

To further study effects of delta(9)-tetrahydrocannabinol (THC) on food intake, male Lewis rats were maintained on rat chow and, on testing days, presented with chocolate cake batter (CCB) for 4 h in addition to chow. Chow intake was not affected by THC administration in either experiment. In experiment 1 (n = 13) THC was administered intraperitoneally, and low doses produced increases in CCB intake for up to 1 h while the highest dose significantly decreased CCB intake over this same time period. In experiment 2 (n = 10) THC was injected intracerebroventricularly. Doses of 2.5, 10 and 25 mug significantly increased CCB intake for up to 1 h while stimulatory effects following 5 mug lasted up to 2 h. Overall THC produced short-term increases in palatable food intake following both peripheral and central administration. Intraperitoneal administration resulted in an inverted U dose-response curve at all time points, while all central doses resulted in increased intake early in the time course and the hyperphagic effects were of greater duration than those following peripheral administration.