An investigation of the relationship between the dopaminergic and electroencephalographic effects of gamma-butyrolactone.

An investigation was made into the relationship between dopaminergic and EEG effects of gamma-butyrolactone (GBL) by comparing time-course and dose-response studies of these two actions of gamma-butyrolactone in rats implanted with permanent cortical electrodes. Dopaminergic effects were assessed by the changes induced by gamma-butyrolactone in the concentration of dopamine and dihydroxyphenylacetic acid (DOPAC) in the striatum and cortex. In addition, the effects of anticonvulsant drugs, known to overcome the EEG effects of gamma-butyrolactone, were assessed against the dopaminergic actions of this drug. The EEG changes induced by gamma-butyrolactone occurred with smaller doses, had an earlier onset and lasted longer than the elevation in striatal dopamine and DOPAC concentration induced by gamma-butyrolactone. There were marked sequential changes in EEG and behavior in the face of normal dopamine and DOPAC concentrations in animals given 200 mg/kg of gamma-butyrolactone. The anticonvulsants, ethosuximide and trimethadione, which abolish or attenuate seizure activity induced by gamma-butyrolactone, were effective in aborting or decreasing the rise in striatal dopamine concentration produced by gamma-butyrolactone. However, sodium valproate, also known to abolish or attenuate the EEG effects of gamma-butyrolactone exacerbated the dopamine effects of this compound. The elevation in dopamine produced by gamma-butyrolactone does not seem to be responsible for the EEG or behavioral effects seen with this substance.