On the specificity of a cat behavior model for the study of hallucinogens.

LSD is the prototype for a cat behavior model for the study of hallucinogens. The model's specificity was tested with the nonhallucinogen methysergide, a d-lysergic acid amide derivative structurally similar to LSD. The frequencies of occurrence of the model behaviors limb flicking, grooming, and head plus body shaking show statistically significant dose dependency after i.p. methysergide (62.5-1000 micrograms/kg), and the maximum frequencies of the methysergide-elicited behaviors occur between 1-3 h post-dose. Methysergide produces statistically significant tolerance to limb flicking and grooming 24 h following an acute dose, and there is statistically significant methysergide-LSD and LSD-methysergide cross tolerance to limb flicking at 24 h. In addition, pretreatment with methysergide 15 min before LSD or lisuride antagonizes their elicitation of model behaviors. The dose-response, time course, and tolerance results with methysergide are analogous to those observed after LSD, showing that methysergide has all of the key properties of the model's prototype and, therefore, that the cat behavior model is not specific for hallucinogens.