In vitro neurotoxicity by ropivacaine is reduced by silencing Cav3.3 T-type calcium subunits in neonatal rat sensory neurons

Abstract

Neurotoxicity of local anaesthetics has been alerted by more and more peoples. Cav3.1 and Cav3.2 T-type calcium channels were closely related with local anaesthetics toxicity. However, the role of Cav3.3, another subtype of the T-type calcium channel, on the neurotoxicity induced by local anaesthetics remains unclear. CaMKIIγ is a kind of multifunctional kinase and associated with a variety of physiological and pathological process. T-type calcium channel is closely related with CaMKIIγ. Up-regulation CaMKIIγ can increase T-type currents at the dorsal root ganglia (DRG). On the contrary, down-regulation results in the T-type currents decrease. Is the relation between Cav3.3 T-type channel calcium and CaMKIIγ involved with the ropivacaine hydrochloride neurotoxicity? In this study, we generated pAd-Cav3.3 and pAd-shRNA adenovirus vector to up-regulate and down-regulate Cav3.3 mRNA expression of the DRG. The cells treated or untreated with ropivacaine hydrochloride (3 mM) for 4 h were used to evaluate the neurotoxicity. Cell viability, cell death rate and apoptosis rate, Cav3.3 and CaMKIIγ expression were detected with MTT method, Hoechst–PI, flow cytometry, qRT-PCR and western blotting. Results showed that the cell viability of the DRG treated with ropivacaine hydrochloride markedly decreased, death rate and apoptosis rate, Cav3.3 and CaMKIIγ mRNA and protein expression significantly increased. Cav3.3 overexpression aggravated DRG injury induced by ropivacaine hydrochloride and inhibition of Cav3.3 expression improved the cell damages. Cav3.3 can regulate CaMKIIγ mRNA and protein expression. In conclusion, Cav3.3 regulated CaMKIIγ in DRG, which was involved with the cell injury induced by ropivacaine hydrochloride.