Rapid inhibitory effects of corticosterone on calcium influx in rat dorsal root ganglion neurons

Corticosterone may nongenomically affect cell functions in addition to its well-characterized effects on gene expression. The purpose of this study is to examine if corticosterone has a rapid nongenomic effect on excitability of dorsal root ganglion neurons by using patch-clamp and single-cell Ca(2+) microfluometry techniques. The results show that corticosterone has a dose-dependent rapid inhibitory effect on the voltage-dependent calcium currents in dorsal root ganglion neurons. Moreover, corticosterone inhibits [Ca(2+)](i) elevation induced by 50 mM high K(+) within just 3 s. The inhibitory effects of corticosterone on the voltage-dependent calcium current and high K(+)-induced calcium influx diminish after adding protein kinase C inhibitor or pretreatment with pertussis toxin for 24 h. Our results demonstrate an nongenomic effect of corticosterone on the excitability of dorsal root ganglion neurons and the effect is mediated through a putative pertussis toxin-sensitive G-protein-coupled receptor and activation of protein kinase C.