DOPAMINE RELEASE IN THE RAT CEREBELLUM AND HIPPOCAMPUS - A TISSUE 3-METHOXYTYRAMINE STUDY

Multiple lines of evidence indicate dopamine is a neurotransmitter or neuromodulator in the cerebellum and hippocampus. In this study, we ex plored the utility of 3-methoxytyramine as an index of dopamine releas e in these regions. We found that: (1) cerebellar and hippocampal 3-me thoxytyramine levels can be measured by combined gas chromatography-ma ss fragmentography with negative chemical ionization; (2) basal 3-meth oxytyramine accumulation rates following monoamine oxidase inhibition, but not the steady-state tissue levels, are several times lower in th ese regions than in the frontal cortex; (3) accumulation of 3-methoxyt yramine in the hippocampus and cerebellum can be enhanced following el ectroconvulsive shock, but not acute haloperidol (0.4 mg/kg) treatment . We conclude that 3-methoxytyramine accumulation may be a useful inde x of dopamine release in the cerebellum and hippocampus, but dopamine release is regulated differently in these regions than in the frontal cortex and striatum.