GABA CONCENTRATIONS IN THE STRIATUM FOLLOWING REPETITIVE CEREBRAL-ISCHEMIA

GABAergic neurons in the striatum are very sensitive to the effects of ischemia. The progressive decline in striatal GABA following transien t forebrain ischemia in gerbils may be secondary to either a decreased production or an increase in reuptake mechanisms or both. The current experiment was designed to evaluate release of GABA by stimulation wi th K+ or inhibition of its uptake with nipecotic acid or their combina tion (K+nipecotic) after repetitive forebrain ischemia in gerbils by i n-vivo microdialysis on Days 1, 3, 5, and 14 following the insult. Inf usion of nipecotic acid or potassium chloride, resulted in a significa nt increase in extracellular GABA. This response was significantly dec reased in the post-ischemic animals. The synergistic effect of increas ed GABA concentrations by the infusion of nipecotic acid + potassium c hloride seen in the controls was not evident in the post-ischemic anim als. In conclusion, though there is a reduction in the extracellular G ABA concentrations in the first week following an ischemic insult, res torative mechanisms are operative in the second week as seen by the in creasing GABA concentrations.