Effect of Drugs on Amino Acid Levels in Brain: Excitants and Depressants

Eighteen chemical agents and electroshock were tested for their effects on ten amino acid and related compounds in rat brains. Convulsant agents (pentylenetetrazole, semicarbazide, strychnine, picrotoxin) and excitants (pheniprazine, amphetamine, mescaline) consistently increased free alanine levels. Semicarbazide uniquely lowered GABA levels to 60% of control values, while other convulsants did not. The tranquilizers chlorpromazine and methoxypromazine raised brain glutamine levels. These findings link specific neurochemical changes to the convulsant or tranquilizing actions of the drugs.

Study at a glance

Abstract

1. Effect of electroshock and 18 chemical agents (pentylenetetrazole, semicarbazide, strychnine, picrotoxin, caffeine, pheniprazine, amphetamine, mescaline, LSD, phenobarbital, chloral hydrate, acetazolamide, diphenylhydantoin, meprobamate, chlorpromazine, methoxypromazine, reserpine and morphine) was determined on the level of 10 ninhydrin-reacting compounds in the rat brain (glutathione, phosphoethanolamine, aspartic acid, glutamic acid, GABA, glutamine, glycine + serine, alanine, taurine and ethanolamine). 2. The convulsant agents, pentylenetetrazole, semicarbazide, strychnine, picrotoxin and electroshock as well as the excitants, pheniprazine, amphetamine and mescaline, brought about significant rises in free alanine in the brain. Lowering of the GABA levels to 60% of that of the controls was brought about by semicarbazide but not by any of the other convulsant agents. 3. Two phenothiazine tranquilizers chlorpromazine and methoxypromazine, brought about a significant rise in level of brain glutamine.