Ca(2+)signaling as a mechanism of haloperidol-induced cytotoxicity in human astrocytes and assessing the protective role of a Ca(2+)chelator

摘要

Haloperidol, a typical antipsychotic medication, has been shown to possess various biological effects in different brain models. However, the impact of haloperidol on Ca(2+)signaling in astrocytes is elusive. This study explored the effect of haloperidol on cytosolic free Ca(2+)levels ([Ca2+](i)) and viability, and established these two connections in Gibco (R) Human Astrocytes (GHAs) and DI TNC1 rat astrocytes. Haloperidol (5-20 mu M) caused [Ca2+](i)rises in a concentration-dependent manner in GHAs but not in DI TNC1 cells. Furthermore, removal of extracellular Ca(2+)reduced haloperidol's effect by approximately 30% in GHAs. Haloperidol (20-40 mu M) evoked concentration-dependent cytotoxicity in GHAs and DI TNC1 cells. However, chelating cytosolic Ca(2+)with the Ca(2+)chelator BAPTA/AM significantly reversed haloperidol's cytotoxicity only in GHAs. In GHAs, haloperidol-induced Ca(2+)entry was inhibited by store-operated Ca(2+)modulators (2-APB and SKF96365) and the protein kinase C (PKC) inhibitor GF109203X. This Ca(2+)entry induced by haloperidol was confirmed by Mn(2+)entry-induced quench of fura-2 fluorescence. In Ca2+-free medium, treatment with the endoplasmic reticulum Ca(2+)pump inhibitor 2,5-di-tert-butylhydroquinone (BHQ) abolished haloperidol-induced [Ca2+](i)rises. Conversely, treatment with haloperidol inhibited 45% of BHQ-evoked [Ca2+](i)rises. Moreover, haloperidol-induced Ca(2+)release from the endoplasmic reticulum was abolished by inhibition of phospholipase C (PLC) by U73122. Together, in GHAs but not in DI TNC1 cells, haloperidol caused Ca2+-associated cell death, induced Ca(2+)entry via PKC-sensitive store-operated Ca(2+)channels, and evoked PLC-dependent Ca(2+)release from the endoplasmic reticulum. The protective effect of Ca(2+)chelating on haloperidol-induced cytotoxicity in human astrocytes was also demonstrated.