Does increasing stress change the behavioral action of mescaline from disruption to facilitation?

Effects of hallucinogenic agents mescaline and phencyclidine on zebrafish behavior and physiology

Mescaline and phencyclidine (PCP) are potent hallucinogenic agents affecting human and animal behavior. As their psychotropic effects remain poorly understood, further research is necessary to characterize phenotypes they evoke in various animal models. Zebrafish (Danio rerio) are rapidly emerging as a new model organism for neuroscience research. Here, we examine the effects of mescaline (5-20mg/l) and PCP (0.5-3mg/l) in several zebrafish paradigms, including the novel tank, open field and shoaling tests. Mescaline and PCP dose-dependently increased top activity in the novel tank test, also reducing immobility and disrupting the patterning of zebrafish swimming, as assessed by ethograms. PCP, but not mescaline, evoked circling behavior in the open field test. At the highest doses tested, mescaline markedly increased, while PCP did not affect, zebrafish shoaling behavior. Finally, 20mg/l mescaline did not alter, and 3mg/l PCP elevated, whole-body cortisol levels. Overall, our studies indicate high sensitivity of zebrafish models to hallucinogenic compounds with complex behavioral and physiological effects.

Inescapable shock alters mescaline's disruption of active avoidance acquisition

Rats were tested on a two-way avoidance acquisition with or without inescapable shock given 24 h prior to training. Mescaline given to nonshock rats disrupted acquisition in a dose-dependent fashion and tolerance developed to this disruption. Mescaline given to shock rats had no effect on acquisition even though levels of acquisition were the same for both shock and nonshock rats without drug. Moreover, subchronic treatment (5 days facilitated acquisition. These experiments demonstrate an interaction between shock, which presumably is a stressor, and mescaline. The data are consistent with the observation that when animals are exposed to presumptive stressors (e.g., shock, handling) hallucinogens can facilitate behavior, while in other situations, hallucinogens disrupt behavior.

Facilitation and disruption by mescaline and 3,4-dimethoxyphenylethylamine of shock avoidance in rats

The effects of mescaline hydrochloride (4.95-79.2 mg/kg i.p.) and its non-hallucinogenic analogue 3,4-dimethoxyphenylethylamine hydrochloride (DMPEA) (12.5-100 mg/kg i.p.) on shock avoidance in a shuttlebox were studied in male Long-Evans rats trained to high (above 88%, good performers) or low (below 6%, poor performers) stable base-line avoidance rates. In good performers, mescaline and DMPEA caused a dose-dependent decrease in avoidance rate (ED 50's 44.6 and 39.2 mg/kg, respectively) without affecting presession (5-min adaptation period) or intertrial shuttlebox crossings. In poor performers, mescaline caused a dose-dependent increase in avoidance rate (ED 50 = 24.8 mg/kg) and intertrial crossings, without affecting presession crossings. The results suggest that mescaline, but not DMPEA, has dual facilitative and disruptive effects on avoidance behavior at similar dose ranges. The facilitative, but not the disruptive, effect may be related to changes in motor activity.