EFFECTS OF 2-SUBSTITUTED HYDRAZINE MONOAMINE-OXIDASE (MAO) INHIBITORSON NEUROTRANSMITTER AMINES, GAMMA-AMINOBUTYRIC-ACID, AND ALANINE IN RAT-BRAIN

Time- and dose-response analyses were undertaken to investigate the ef fects of the substituted hydrazine monoamine oxidase (MAO) inhibitors iproniazid and nialamide on the following: MAO-A and -B activity; leve ls of gamma-aminobutyric acid (GABA), alanine (ALA), and the neurotran smitter amines dopamine, noradrenaline, and 5-hydroxytryptaimine (sero tonin) and their acid metabolites; and the activity of GABA-transamina se and ALA-transaminase. The results showed that these drugs are relat ively potent MAO inhibitors but, unlike the unsubstituted hydrazine MA O inhibitor phenelzine, they do not produce increased GABA and ALA lev els in brain. These experiments suggest that a free hydrazine group is necessary for MAO inhibitors to also have marked effects on GABA and ALA.