[Drug-induced influence of the GABA-fluorescence in rat brain structures with some comments on the chemistry of the reaction (author's transl)].

1. GABA was demonstrated in rat brain in fluorescence histochemistry. The alteration by application of submaximal doses of drugs of the distribution and intensity of the transmitter fluorescence was studied in hippocampus and cerebellum. 2. Isonicotinic acid hydrazide and Penicillamine leads to a distinct grain formation and diminishing of the fluorescence product, normally appearing homogenous. These effects are considered to reflect an enzyme (GAD) inhibition. 3. By Cycloserine a distinct increase of the GABA fluorescence is effected, presumably by inhibiting GABA-transaminase-activity. 4. Chloropromazine causes diminishing, grain formation and dislocation as well of the fluorescent product, supposedly due to an affection of the membrane binding properties of GABA. 5. Hypotheses concerning the chemical events of the GABA-reaction are worded.