The Impact of the Antipsychotic Medication Chlorpromazine on Cytotoxicity through Ca2+ Signaling Pathway in Glial Cell Models.

Chlorpromazine, an antipsychotic medication, is conventionally applied to cope with the psychotic disorder such as schizophrenia. In cellular studies, chlorpromazine exerts many different actions through calcium ion (Ca2+) signaling, but the underlying pathways are elusive. This study explored the effect of chlorpromazine on viability, Ca2+ signaling pathway and their relationship in glial cell models (GBM 8401 human glioblastoma cell line and Gibco® Human Astrocyte (GHA)). First, chlorpromazine between 10 and 40 μM induced cytotoxicity in GBM 8401 cells but not in GHA cells. Second, in terms of Ca2+ homeostasis, chlorpromazine (10-30 μM) increased intracellular Ca2+ concentrations ([Ca2+]i) rises in GBM 8401 cells but not in GHA cells. Ca2+ removal reduced the signal by approximately 55%. Furthermore, chelation of cytosolic Ca2+ with BAPTA-AM reduced chlorpromazine (10-40 μM)-induced cytotoxicity in GBM 8401 cells. Third, in Ca2+-containing medium of GBM 8401 cells, chlorpromazine-induced Ca2+ entry was inhibited by the modulators of store-operated Ca2+ channel (2-APB and SKF96365). Lastly, in Ca2+-free medium of GBM 8401 cells, treatment with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin completely inhibited chlorpromazine-increased [Ca2+]i rises. Conversely, treatment with chlorpromazine abolished thapsigargin-increased [Ca2+]i rises. Inhibition of phospholipase C (PLC) with U73122 abolished chlorpromazine-increased [Ca2+]i rises. Together, in GBM 8401 cells but not in GHA cells, chlorpromazine increased [Ca2+]i rises by Ca2+ influx via store-operated Ca2+ entry and PLC-dependent Ca2+ release from the endoplasmic reticulum. Moreover, the Ca2+ chelator BAPTA-AM inhibited cytotoxicity in chlorpromazine-treated GBM 8401 cells. Therefore, Ca2+ signaling was involved in chlorpromazine-induced cytotoxicity in GBM 8401 cells.