Further evidence for a relationship between changes in GABA concentration in rat brain and enhanced monoamine-mediated behavioural responses following repeated electroconvulsive shock.

Administration of bicuculline (3.5 mg/kg i.p.) or pentylenetetrazol (30 mg/kg i.p.) 3 min before each of a series of 5 electroconvulsive shocks (ECS), given over 10 days (1, 3, 5, 8 and 10), prevented the enhanced behavioural responses to the dopamine agonist apomorphine and the 5-hydroxytryptamine agonist quipazine 24 hr after the last application of ECS. Pretreatment with these antagonists of gamma-aminobutyric acid (GABA) also abolished the rise in the concentration of GABA in the corpus striatum, normally seen after repeated ECS. Taken with data showing that the change in GABA concentration occurred at times when enhanced monoamine-mediated behavioural responses were seen, these results suggest that the enhanced behavioural responses following repeated ECS might be associated with changes in GABA function. Daily injection for 8 days with pentylenetetrazol (30 mg/kg) resulted in enhanced apomorphine-mediated behaviour. However, there was no change in the concentration of striatal GABA at this time.