A fluorescent histochemical procedure for gamma-aminobutyric acid

Summary

Gamma aminobutyric acid (GABA) was selectively demonstrated in slide tests by the production of a fluorescent compound with ninhydrin in a non-aqueous medium (octanol). Thirty other related pure compounds either failed to yield a fluorescent product or produced distinguishable fluorescent products. The reaction was tested on sections of several organs of normal mice, mice with experimentally increased GABA levels and mice injected topically with GABA.

In normal mice and in animals injected with AOAA intense GABA fluorescence was found in the brain in groups of cells in the cerebellum, in the hippocampus, and in some mesencephalic and hypothalamic nuclei. In most places flourescent lines surrounded perikarya. Fluorescence of lesser intensity was found around some cortical cells. Intense fluorescence, more marked after AOAA injection, but partly “masked” by autofluorescence, was found in erythrocytes, leptomeninges, choroid plexus and retina.

Outside the brain GABA-fluorescence was found in some cells of the adrenal medulla and in isolated cells of sensory ganglia. After intraperitoneal GABA injection GABA fluorescence was noted in Kupffer cells, in renal tubular cells and in the adrenal.

Topical injections of GABA resulted in non-specific uptake by glial and also neuronal cells of the brain and presumably in the retina.