SKF-96365 attenuates toxin-induced neuronal injury through opposite regulatory effects on Homer1a and Homer1b/c in cultured rat mesencephalic cells

Disturbances in Ca2+ homeostasis have been implicated in a variety of neuro-pathological conditions including Parkinson's disease (PD). In the present study, we investigated the potential protective effect of SKF-96365, an originally identified blocker of receptor-mediated calcium entry, on MPP+ induced neuronal injury in cultured rat mesencephalic cells. We found that pretreatment with SKF-96365 30 min before injury significantly reduced nuclear damage, decreased LDH release and inhibited apoptotic neuronal death. The results of calcium image also showed that SKF-96365 inhibited the increase of intracellular calcium induced by MPP+, which was not dependent on the expression and function of TRPC1. In addition, SKF-96365 increased the expression of Homer1a, but decreased the expression of Homer1b/c in the presence or absence of MPP+. Furthermore, overexpression of Homer1a by using recombinant lentivirus and knockdown of Homer1b/c by short interfering RNA (siRNA) further enhanced protective effects of SKF-96365 against MPP+ injury. Taken together, these data suggest that SKF-96365 protects cultured rat mesencephalic cells against MPP+ induced cytotoxicity, and this protection may be at least in part dependent on attenuating intracellular calcium overload, opposite regulatory effects on Homer1a and Homer1b/c expressions.