HIGH EXTRACELLULAR GABA LEVELS IN HIPPOCAMPUS - AS A MECHANISM OF NEURONAL PROTECTION IN CEREBRAL-ISCHEMIA IN ADRENALECTOMIZED GERBILS

Adrenalectomy protects the brain from delayed neuronal damage that occ urs following transient forebrain ischemia in gerbils. Gamma-amino but yric acid (GABA) and GABA-mimetic drugs also have a neuro-protective e ffect. In this study we estimated the extracellular glutamate and GABA levels in the hippocampus during transient forebrain ischemia in adre nelectomized gerbils (n = 8) compared to controls (n = 6). Duration of ischemia was 10 min, and glutamate and GABA levels were measured with in vivo microdialysis. Microdialysis was started 2 h after the placem ent of a probe (to stabilise baseline) and samples were collected at I O-min intervals. The pattern of glutamate release did not show any dif ference between adrenelectomized animals and controls. Adrenelectomize d animals showed marked increase in GABA levels during ischemia and up to 30 min after ischemia (P = 0.0287, 2-way ANOVA for repeated measure ments). The enhanced GABA release may be one of the possible mechanism s of neuronal protection against ischemia in adrenelectomized gerbils.