Protection of T-type calcium channel blocker in spiral ganglion neurons of adult C57BL/6J mice

Abstract

To explore the distribution and expression of three T-type calcium channel receptors (α1G; α1H; α1I) and understand their protective effects in spiral neurons of C57BL/6J mice. The distribution and expression of three T-type calcium channel receptors in spiral ganglion neurons were observed by in situ hybridization and reverse transcription-polymerase chain reaction (RT-PCR) in 6-8-week-old C57BL/6J mice. The mice of 24-26-week-old C57BL/6J were divided into 3 groups of zonisamide, benidipine and saline. And the expression changes of calcium-binding proteins calmodulin and calbindin were observed by immunohistochemistry. Three subunits were expressed in spiral ganglion neurons. The decremented quantities were α1H (24.21 ± 0.10), α1I (14.88 ± 0.04) and α1G (10.42 ± 0.02). The expression level of calmodulin in spiral ganglion neurons was lower in the zonisamide-treated group than that in the saline-treated group (0.336 ± 0.041 vs 0.504 ± 0.020, P < 0.05). The expression level of calbindin in spiral ganglion neurons was lower in the zonisamide (0.482 ± 0.045) and benidipine-treated groups (0.511 ± 0.032) than that in the saline-treated group (0.611 ± 0.035, P < 0.05). The expressions of calcium-binding proteins decrease after 4-week dosing of T-type calcium channel blockers in 24-26-week C57BL/6J mice. It implies a relief of calcium overload. T-type calcium channel blockers may protect the murine spiral ganglion neurons from degeneration.