Influence of gamma-butyrolactone on behavior due to dopaminergic drugs.

Gamma-butyrolactone (GBL) is well known to reduce dopamine neuronal impulse flow, but the effects of the drug on dopamine-dependent behavioral states is not well studied. Qualitative and quantitative data are presented, detailing the influence of GBL on stereotypy when this drug is given after administration of the indirectly-acting dopamine mimetics amphetamine and methylphenidate, and the direct dopamine agonist apomorphine. GBL reversed the stereotypy produced by all three drugs, given at moderate doses producing comparable intensities of stereotypy. GBL unexpectedly proved effective in reversing stereotypy after higher-dose apomorphine while producing a rather weak influence on that of higher-dose amphetamine and methylphenidate. The results are discussed in terms of the dopamine impulse flow, and possible GABA-potentiating, effects of GBL, and the sedative effects of apomorphine.