EFFECTS OF L-THREO-3,4-DIHYDROXYPHENYLSERINE AND ERYTHRO-3,4-DIHYDROXYPHENYLSERINE ON LEARNING-PERFORMANCE AND CONCENTRATIONS OF BRAIN NORADRENALINE AND ITS METABOLITES IN RATS

Effects of L-threo and L-erythro-3,4-dihydroxyphenylserine [DOPS, precursor amino acids for noradrenaline (NA)] on the learning performance in a maze paradigm designed to model on the water maze paradigm using a multicomputerized behavioral analysis system were studied. A marked facilitation of learning performance was observed in rats after an intraventricular injection of 5-mu-g L-threo-DOPS (the s-NA precursor), and this effect was inhibited by a simultaneous administration of 1 or 2-mu-g propranolol (a beta-adrenergic antagonist). As concentrations of brain NA, 3-methoxy-4-hydroxyphenylglycol, and normethanephrine were increased by the injection of 5-mu-g L-threo-DOPS, the effect seemed to be derived from activation of beta-adrenoceptors in the CNS by the formed s-NA. On the other hand, an intraventricular injection of 5-mu-g L-erythro-DOPS (the r-NA precursor) attenuated the learning performance, and this effect was probably caused by the formed r-NA from L-erythro-DOPS.