Neuroprotection by JM-1232(-) against oxygen-glucose deprivation-induced injury in rat hippocampal slice culture.

Abstract JM-1232(−) (JM) is a novel isoindoline derivative with sedative and hypnotic activities that are mediated by binding to the benzodiazepine site of the Gamma-aminobutyric acid type A (GABA A ) receptor. Although the neuroprotective effects of other GABA A receptor agonists are well known, there is no published report regarding JM. Thus, we examined the effects of JM on neurons exposed to oxygen-glucose deprivation (OGD) using rat hippocampal slice cultures. Hippocampal slices were assigned to either control or JM-administered groups. To assess the neuroprotective effects of JM from necrotic changes, we measured the fluorescence of propidium iodide and compared the cell mortality 24 h following OGD between the control and JM-administered groups. We also verified that the effects of JM were mediated by GABA A receptors by adding flumazenil, a benzodiazepine receptor antagonist, in the same experimental settings. JM, at concentrations of 250 and 500 µM, significantly reduced cell mortality in pyramidal neurons after OGD; however, flumazenil did not inhibit this effect. To analyze more immediate effects of JM, we next measured the fluorescence of Oregon Green 488 BAPTA-1 during the OGD and re-oxygenation periods, and evaluated changes in intracellular Ca 2+ in single CA1 pyramidal neurons. JM reduced the elevation of intracellular Ca 2+ concentration during OGD, and this effect was antagonized by flumazenil. These findings indicate that JM suppressed the elevation of intracellular Ca 2+ concentration during OGD through GABA A receptors, but its neuroprotective effects from necrotic changes also involve other unknown mechanisms.