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

In male Long-Evans rats trained to either high (above 88%) or low (below 6%) stable baseline shock-avoidance rates, mescaline hydrochloride (4.95–79.2 mg/kg i.p.) and its non-hallucinogenic analogue DMPEA (12.5–100 mg/kg i.p.) produced opposite effects depending on performance level. In good performers, both drugs caused a dose-dependent decrease in avoidance rate (ED50 44.6 and 39.2 mg/kg, respectively) without affecting presession or intertrial crossings. In poor performers, mescaline caused a dose-dependent increase in avoidance rate (ED50 24.8 mg/kg) and intertrial crossings, while DMPEA did not. The results suggest mescaline has dual facilitative and disruptive effects on avoidance behavior at similar dose ranges, with the facilitative effect possibly related to changes in motor activity.

Study at a glance

Abstract

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.