Protective effects of a selective L-type voltage-sensitive calcium channel blocker, S-312-d, on neuronal cell death

Amyloid beta protein (Abeta)- and human group IIA secretory phospholipase A(2) (sPLA(2)-IIA)-induced neuronal cell death have been established as in vitro models for Alzheimer's disease (AD) and stroke. Both sPLA(2)-IIA and Abeta causes neuronal apoptosis by increasing the influx of Ca(2+) through L-type voltage-sensitive Ca(2+) channel (L-VSCC). In the present study, we evaluated effects of a selective L-VSCC blocker, S-(+)-methyl 4,7-dihydro-3-isobutyl-6-methyl-4-(3-nitro-phenyl)thieno[2,3-b]pyridine-5-carboxylate (S-312-d), on Abeta- and sPLA(2)-IIA-induced neuronal apoptosis in primary cultures of rat cortical neurons. S-312-d significantly rescued cortical neurons from Abeta- and sPLA(2)-IIA-induced cell death. Both cell death stimuli caused the appearance of apoptotic features such as plasma membrane blebs, chromatin condensation, and DNA fragmentation. S-312-d completely suppressed these apoptotic features. Before apoptosis, the two death ligands markedly enhanced an influx of Ca(2+) into neurons. S-312-d significantly prevented neurons from sPLA(2)-IIA- and Abeta-induced Ca(2+) influx. Furthermore, the neuroprotective effect of S-312-d was more potent than that of another L-VSCC blocker, nimodipine. On the other hand, blockers of other VSCCs such as the N-type and P/Q-type calcium channels had no effect on the neuronal cell death, apoptotic features and Ca(2+) influx. In conclusion, we demonstrated that S-312-d rescues cortical neurons from Abeta- and sPLA(2)-IIA-induced apoptosis.