LSD and other related hallucinogens elicit myoclonic jumping behavior in the guinea pig

1. We evaluated the behavioral response of guinea pigs to hallucinogenic agents in order to characterize the response of this species to a variety of known hallucinogenic drugs. 2. The systemic injection of LSD in the guinea pig elicited a "myoclonic-like" response the frequency of which was dose-dependent. This behavior exhibited rapid tolerance which was more prominent at higher doses. 3. Subacute mescaline pretreatment reduced the myoclonic response to LSD suggesting cross-tolerance. 4. Mescaline, DOM, TMA, DMA and 5 Me-ODMT also elicited myoclonus in a dose-dependent manner and in potency ratios which approximate the human experience for hallucinogenic activity. 5. Brom-LSD failed to induce myoclonus. 6. Since the myoclonic response of the guinea pig shares a number of pharmacologic characteristics with the human hallucinogenic event, this species may be useful in the study of hallucinogenic compounds.