The action of psychotropic drugs on DOPA induced behavioural responses in mice

The "DOPA potentiation" test in mice was investigated for its usefulness in the detection of compounds with antidepressant properties. It was found that the anti-depressant drugs imipramine, amitriptyline, 5-methylamino-acetyl-6-methyl-5,6-dihydro-phenanthridine-HCl (Org OI77) and 1,2,3,4,10,14b-hexahydro-2-methyl-dibenzo[c,f]pyrazino[1,2-a]azepine-HCl (mianserin, Org GB 94) potentiated the behavioural effect of DOPA in groups of mice which had been treated 17 h previously with the monoamine oxidase inhibitor (MAOI) iproniazid. However, the DOPA response was also potentiated by a variety of centrally acting drugs which do not have antidepressant properties (atropine, methysergide, chlordiazepoxide, apomorphine). The peptide hormones ACTH4-10 and desglycinamide lysine vasopressin had equivocal effects while melanocyte stimulating hormone release-inhibiting factor (MIF) had no effect on the DOPA response. The DOPA response was inhibited by the neuroleptics chlorpromazine and haloperidol. There appeared to be no correlation between the effects of the drugs on the behavioural responses elicited by DOPA and the changes found in the brain concentration of noradrenaline, dopamine, serotonin, gamma-aminobutyric acid, tryptophan and tyrosine. It is concluded that the "DOPA potentiation" test cannot be considered as a reliable test in the detection of anti-depressant compounds.