EFFECTS OF BEFLOXATONE, A NEW POTENT REVERSIBLE MAO-A INHIBITOR, ON CORTEX AND STRIATUM MONOAMINES IN FREELY MOVING RATS

Single administration of befloxatone (0.75 mg/kg, i.p.) in the rat inc reased extracellular levels of DA (+300%) in striatum. In frontal cort ex, befloxatone (0.75 mg/kg, i.p.) and nialamide (100 mg/kg, i.p.) inc reased NA by +100% but did not modify 5HT, whereas pargyline (100 mg/k g i.p.) increased extracellular NA and 5HT by 400 and 600%, respective ly. At these doses, befloxatone inhibited totally and selectively MAO- A, pargyline inhibited totally MAO-A and MAO-B. Increases of tissue an d extracellular concentrations of NA and 5HT were highest after Pargyl ine suggesting that both monoamines may be metabolized by MAO-A and MA O-B. Befloxatone and nialamide potentiated the effects of idazoxan (20 mg/kg, i.p.) on extracellular NA in frontal cortex, which increased f rom 350% to 2,000 and 1,500% respectively. These results suggest that alpha(2)-adrenoceptors play a major role in the regulation of extracel lular NA in frontal cortex.