Effects of gamma-butyrolactone, amphetamine, and haloperidol in mice differing in sensitivity to alcohol.

Gamma-butyrolactone (GBL) induced longer loss of righting reflex in mice (LS-line) selectively bred for greater sensitivity to ethanol than in less sensitive SS-line mice. GBL also induced a three-fold greater increase of brain dopamine levels in LS than in SS mice. Among three inbred strains, GBL-induced loss of righting reflex was greater in BALB/c, and greater in DBA/2 than in C57BL/6 mice. A low dose of GBL produced biphasic effects on locomotor activity. Both an initial depressant action and a later increase in activity were greater in LS than in SS mice. These GBL effects on activity were modified in a genotype-dependent fashion by amphetamine. Results of these experiments as well as greater catalepsy-inducing properties of haloperidol in SS mice suggest that genotypic influences on motor reactivity to ethanol may be modeled by GBL effects on brain dopamine systems.