Alterations in the γ-Aminobutyric Acid-Gated Chloride Channel Following Transient Forebrain Ischemia in the Gerbil

The role of inhibitory neurotransmission in selective neuronal degeneration after transient forebrain ischemia was studied by binding of t-35S]butylbicyclophosphorothionate (35S]TBPS) to the gamma-aminobutyric acid (GABA)-gated chloride channel and measurement of GABAA receptor function in Mongolian gerbil brain. 35S]TBPS binding to the hippocampus, striatum, and cortex quantified by autoradiography and muscimol-stimulated 36Cl- uptake in synaptoneurosomes of the same regions were examined 1, 4, and 29 days after a 5-min bilateral carotid occlusion. 35S]TBPS binding was decreased in the pyramidal cell dendritic layers, stratum oriens, and stratum lacunosum-moleculare of the CA1 hippocampus, 4 and 29 days after occlusion, and in the stratum radiatum 29 days after occlusion. 35S]TBPS binding sites in the lateral striatum decreased 47% 4 days after occlusion. At the same time, there was a corresponding decrease in muscimol-stimulated 36Cl- uptake in the striatal synaptoneurosomes. Muscimol-stimulated 36Cl- uptake in the hippocampus decreased slightly 4 days after occlusion and more so after 29 days, although these decreases were not significant. No changes were observed in somatosensory cortex at any time point. These data suggest that a portion of GABAA receptors in areas sensitive to ischemic insult are associated with degenerating neurons, whereas other GABAA) receptors are spared.