Generalization of morphine and lysergic acid diethylamide (LSD) stimulus properties to narcotic analgesics
Psychopharmacology January 1, 1976 I. D. Hirschhorn, J. A. Rosecrans 30 citations
In rats trained to distinguish morphine from saline or LSD from saline using a two-lever discrimination task, the stimulus properties of morphine generalized fully to methadone and meperidine, and partially to pentazocine—drugs known to produce morphine-like subjective effects in humans. Morphine's stimulus properties did not generalize to nalorphine or cyclazocine, which produce dissimilar subjective effects. The stimulus properties of LSD generalized partially to cyclazocine but not to nalorphine. In humans, cyclazocine and nalorphine produce a high incidence of psychotomimetic effects, but cyclazocine's subjective effects are differentiable from those of LSD.