EFFECTS OF CHRONIC TREATMENT WITH ETHANOL AND WITHDRAWAL ON LEVELS OFMONOAMINES IN RAT CEREBRAL-CORTEX AND STRIATUM - INFLUENCE OF MIDAZOLAM, THIOPENTHAL AND SOMATOSTATIN

It is accepted that ethanol affects the central neurotransmission, Thi s paper deals with the effects of chronic ethanol treatment and withdr awal on cortical and striatal levels of several neurotransmitters, The influence of barbiturate, benzodiazepine and somatostatin has been st udied in order to establish possible cross-interactions. Serotonin, 5- hydroxyindoleacetic acid, dopamine and norepinephrine levels from rat cerebral cortex and striatum were determined by high performance Liqui d chromatography (HPLC) with electrochemical detection, Rats were chro nically treated with ethanol (11-12 g/kg/day) for 6 weeks. The chronic ethanol treatment decreased the cortical serotonin (P < 0.01) and 5-h ydroxyindoleacetic acid (P < 0.01) concentrations, while ethanol withd rawal decreased them in cortex and striatum, A single dose of differen t drugs produced an increase of serotonin and 5-hydroxyindoleacetic ac id striatal-but not cortical-levels. The chronic ethanol treatment or 48 hr of ethanol-withdrawal produced a depletion of striatal serotoner gic system when barbiturate thiopenthal was administered. The benzodia zepine midazolam elicited a decrease of striatal serotonin (P < 0.01) and 5-hydroxyindoleacetic acid (P < 0.05) levels in 48 hr ethanol-with drawn and chronically ethanol-treated rats, respectively, Somatostatin injected to chronically ethanol-exposed rats resulted in decreased (P < 0.05) striatal serotonin concentrations, Cortical norepinephrine le vels decreased after 24 and 48 hr of ethanol-withdrawal (P < 0.05 and P < 0.01, respectively), The depletion of striatal and cortical seroto nergic systems after both chronic ethanol treatment and withdrawal, co uld be explained as an environment-dependent tolerance response, It ca n be concluded that ethanol and/or psychotropic drugs interact with ne urotransmission systems in specific ways in different regions of the b rain.