REVERSAL LEARNING ENHANCED BY LYSERGIC ACID DIETHYLAMIDE (LSD): CONCOMITANT RISE IN BRAIN 5‐HYDROXYTRYPTAMINE LEVELS

Low doses of LSD (12.5–50 μg/kg) consistently made rats faster at learning a brightness discrimination reversal task. A similar compound, BOL-148, which has the same anti-serotonin effects outside the brain but lacks LSD's hallucinogenic properties, had no effect on learning at a comparable dose (25 μg/kg). LSD, but not BOL-148, slightly raised serotonin levels in the brain, while neither drug changed brain catecholamine levels at 25 μg/kg. These results suggest that LSD's effect on learning is tied to its specific psychoactive properties, not just its peripheral anti-serotonin activity.

Study at a glance

Abstract

Small doses of lysergic acid diethylamide (LSD) (12.5–50 μg/kg) consistently facilitated learning of a brightness discrimination reversal. 2‐Bromo‐lysergic acid diethylamide (BOL‐148), a structural analogue of LSD, with similar peripheral anti‐5‐hydroxytrypamine activity but no psychotomimetic properties, had no effect in this learning situation at a similar dose (25 μg/kg). LSD, but not BOL‐148, caused a small but significant increase in brain 5‐hydroxytryptamine levels, but had no effect on the levels of catecholamines in the brain at 25 μg/kg.