Alterations in P urkinje cell GABA A receptor pharmacology following oxygen and glucose deprivation and cerebral ischemia reveal novel contribution of β 1 ‐subunit‐containing receptors

Cerebellar P urkinje cells ( PC s) are particularly sensitive to cerebral ischemia, and decreased GABA A receptor function following injury is thought to contribute to PC sensitivity to ischemia‐induced excitotoxicity. Here we examined the functional properties of the GABA A receptors that are spared following ischemia in cultured Purkinje cells from rat and in vivo ischemia in mouse. Using subunit‐specific positive modulators of GABA A receptors, we observed that oxygen and glucose deprivation ( OGD ) and cardiac arrest‐induced cerebral ischemia cause a decrease in sensitivity to the β 2/3 ‐subunit‐preferring compound, etomidate. However, sensitivity to propofol, a β‐subunit‐acting compound that modulates β 1–3 ‐subunits, was not affected by OGD . The α/γ‐subunit‐acting compounds, diazepam and zolpidem, were also unaffected by OGD . We performed single‐cell reverse transcription–polymerase chain reaction on isolated PC s from acutely dissociated cerebellar tissue and observed that PC s expressed the β 1 ‐subunit, contrary to previous reports examining GABA A receptor subunit expression in PC s. GABA A receptor β 1 ‐subunit protein was also detected in cultured PC s by western blot and by immunohistochemistry in the adult mouse cerebellum and levels remained unaffected by ischemia. High concentrations of loreclezole (30 μ m ) inhibited PC GABA ‐mediated currents, as previously demonstrated with β 1 ‐subunit‐containing GABA A receptors expressed in heterologous systems. From our data we conclude that PC s express the β 1 ‐subunit and that there is a greater contribution of β 1 ‐subunit‐containing GABA A receptors following OGD .