0 Seth SD Srinivasan BP Siddiqui HH Sivam SP 1983 Indian Journal of Pharmacology 15 3 165-170 L-dopa, amantadine, tremorine, serotonin, biogenic amines, behavioural The effect of L-dopa, alone and in combination, on brain dopamine, norepinephrine, serotonin, 5-hydroxyindole acetic acid and monoamine oxidase activity was investigated in tremorine induced tremor syndrome in rats. L-dopa, alone and in combination with amantadine, produced a remarkable rise in dopamine and 5-hydroxyindole acetic acid and a reduction in serotonin content.Tremorine failed to influence any of the parameters. The findings suggest that L-dopa and amantadine have pro-found effects on brain biogenic amines which may account for the therapeutic effects as well as behavioural side-effects frequently encountered in clinical practice