Evidence for a nerve impulse-dependent GABA accumulation in the substantia nigra after treatment with gamma-glutamylhydrazide.

GABA accumulation was studied in the substantia nigra after treatment with L-glutamic acid-gamma-hydrazide (GAH) in rats 3 h following hemisection at the posterior hypothalamic level. GAH-induced GABA accumulation was significantly reduced on the hemisectioned side (P < 0.05, Wilcoxon's test). Two or three weeks after hemisection, glutamic acid decarboxylase activity was reduced in the substantia nigra of the hemisectioned side by 80%, showing that the descending GABA pathway to the substantia nigra had been transected. It is concluded that GAH-induced GABA accumulation might be nerve impulse-dependent.