Anorexia and hyperphagia produced by five pharmacologic classes of hallucinogens

The acute actions of five prototype hallucinogens administered SC on food consumption in 23 hr food deprived dogs were compared with the anorexic effect of d-amphetamine and the hyperphagic effect of sodium pentobarbital. Comparisons were made on the basis of dose-response relationships. Among the hallucinogens decreasing food intake, both LSD and atropine produced substantial anorexia, but the slopes of their dose-response curves were clearly different from d-amphetamine. Phencyclidine and the opioid SKF 10,047 suppressed food intake also; their individual dose-effect curves were parallel to the amphetamine curve, although both were less potent. Of the hallucinogens tested, only delta-9-tetrahydrocannabinol (delta 9-THC) stimulated food consumption, and though it was less potent, it resembled pentobarbital both qualitatively and by having a parallel dose-response curve. The appetitive responses are discussed in relation to other pharmacologic actions of these hallucinogens in the dog, and consideration is given to the possible modes of action for phencyclidine- and SKF 10,047-induced anorexia.