Effects of macromerine, normacromerine, and bisnormacromerine on a bar-press appetitional and a shuttle-aversive task

Abstract

Mescaline (ME) is one of the best known and most studied hallucinogenic compounds. On the other hand, macromerine (MA), normacromerine (NMA), and bisnormacromerine (BNMA) are all relatively unstudied compounds which may possess hallucinogenic properties. All of these compounds are structurally similar, and are, or are closely associated with, naturally-occurring cactus alkaloids. These chemicals were administered to rats in a shuttle-avoidance and a free-operant appetitional task. Four concentrations each of ME (8, 9, 10, and 11 mg/kg), NMA (20, 40, 60, and 100 mg/kg), and BNMA (20, 30, 40, and 60 mg/kg) were tested in the appetitional task. Three concentrations each of ME (10, 35, 65 mg/kg), MA (30, 50, and 80 mg/kg), and NMA and BNMA (20, 60, and 100 mg/kg) were tested in the shuttle-avoidance task. In both tasks, 8 Ss were administered the same concentration. Mescaline, but not MA, NMA, or BNMA, affected the performance of untrained Ss in the CAR task. Concentrations of 35 and 65 mg/kg of body weight inhibited group mean response latencies to the CS-UCS. Mescaline, NMA and BNMA all produced a drug effect (suppression of bar-pressing behavior for a minimum of five consecutive min.) in the appetitional task, food-rewarded bar-pressing on a VI 30-sec. reinforcement schedule. Probit analyses indicated that BNMA was approximately twice as potent as NMA in the appetitional task. The potencies of BNMA and NMA relative to ME could not be meaningfully determined and it was proposed that these compounds suppressed bar-pressing behavior by different mechanisms. Dose-response curves, estimates of the ED50 values, were also obtained for the appetitional data. The implications of the data obtained from both the shuttle-avoidance and free-operant appetitional tasks were discussed in relation to S-A-R factors, a biological model of psychosis hypothesis, and the potential usefulness of the behavioral techniques in the study of potential hallucinogenic compounds.