Neuroprotective mechanism of (+)SKF 10,047 in vitro and in gerbil global brain ischemia.

BACKGROUND AND PURPOSE The N-methyl-D-aspartate receptor is believed to mediate part of the ischemic neuronal damage caused by the excitatory amino acid glutamate. (+)SKF 10,047, the prototypic sigma-agonist, interacts with the N-methyl-D-aspartate receptor. Therefore, we studied the neuroprotective effect of (+)SKF 10,047 on cultured rat cerebellar neurons and on CA1 hippocampal neurons of gerbils exposed to brain ischemia. METHODS Mechanisms of neuroprotection were studied in vitro by measuring calcium influx into cultured rat cerebellar granule cells loaded with fura 2-AM. In vivo neuroprotection of gerbil CA1 hippocampal neurons was studied in a posttreatment regimen following 5 minutes of bilateral carotid artery occlusion and 7 days of reperfusion. RESULTS In primary cultured rat cerebellar granule cell neurons, (+)SKF 10,047 in a dose-dependent manner diminished intracellular calcium levels of N-methyl-D-aspartate-stimulated neurons by a maximum of 87% (n = 8), with a 50% inhibitory concentration of 0.8 microM. (+)SKF 10,047 did not prevent subsequent calcium influx stimulated by kainic acid or KCl, nor did it interfere with modulation of the kainate response by quisqualic acid. Neuroprotection of 64% (p = 0.006, n = 15) of gerbil CA1 hippocampal neurons was achieved by posttreatment injection followed by minipump infusion. CONCLUSIONS Neuroprotection by (+)SKF 10,047 most likely involves interaction at the N-methyl-D-aspartate receptor. These results suggest that the benzomorphan class of sigma-agonists may provide neuroprotection in cerebral ischemia and stroke.