Differential contribution of L-, N-, and P/Q-type calcium channels to [Ca2+]i changes evoked by kainate in hippocampal neurons

The analgesic effect and mechanism of the combination of sodium ferulate and oxymatrine

Sodium ferulate (SF) and Oxymatrine (OMT) were compounds extracted from Chinese herbs, and have been used in clinical treatment of heart and hepatic diseases, respectively, in China for many years. The objective of this study was to examine the analgesic effect and the mechanism of the combined treatment of SF and OMT. Using the animal pain models by applying Acetic Acid Writhing Test and Formalin Test, the combination of SF and OMT showed significant analgesic effect in dose-dependent manner. In vitro, the combined treatment inhibited the increase in intracellular calcium concentration evoked by capsaicin in the dorsal root ganglion neurons. Importantly, a synergistic inhibitory effect of SF and OMT on the capsaicin-induced currents was demonstrated by whole-cell patch-clamp. Our results suggest that SF and OMT cause significant analgesic effect which maybe related to the synergistic inhibition of transient receptor potential vanilloid-1.

Resting intracellular calcium concentration, depolarizing Gamma-Aminobutyric Acid and possible role of local estradiol synthesis in the developing male and female hippocampus

The maturation of the hippocampus is impacted by a multitude of factors, including the regulation of intracellular calcium levels. Depolarizing actions of Gamma-Aminobutyric Acid (GABA) can profoundly alter intracellular calcium in immature hippocampal neurons via influx through voltage-gated calcium channels. We here report fundamental sex differences in properties of depolarizing GABA responses and in resting intracellular calcium in neonatal cultured hippocampal neurons. The effects of the estrogen receptor antagonist, ICI 182,780, and the estradiol-synthesis inhibitor, formestane, indicate the sex differences in depolarizing GABA responses are at least in part due to de novo estradiol synthesis by female neurons, whereas a sex difference in resting calcium is independent of steroids. We postulate that local estradiol synthesis in cultured female hippocampal neurons affects the kinetics of either the GABA(A) receptor or voltage sensitive calcium channels. These data highlight the fact that immature hippocampal neurons exhibit fundamentally different physiological properties in males versus females. Elucidating how and where immature male and female neurons differ is essential for a complete understanding of normal rodent brain development.