Rapid Elevation of Calcium Concentration in Cultured Dorsal Spinal Cord Astrocytes by Corticosterone
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In addition to the classic genomic effects, increasing evidence suggests that GC can generate multiple rapid effects on many tissues and cells through nongenomic pathway. In the present study, the effects of corticosterone (CORT) on the intracellular calcium concentration ([Ca2+]i) in cultured dorsal spinal cord astrocytes were detected with confocal laser scanning microscopy using fluo-4/AM as a calcium fluorescent indicator that could monitor real-time alterations of [Ca2+]i. CORT (0.01–10 μM) caused a rapid increase in [Ca2+]i with a dose-dependent manner in cultured dorsal spinal cord astrocytes. The action of CORT on astrocytic [Ca2+]i was blocked by pertussis toxin (a blocker of G protein activation, 100 ng/ml), but was unaffected by RU38486 (glucocorticoid receptor antagonist, 10 μM). In addition, cycloheximide (protein-synthesis inhibitor, 10 μg/ml) pretreatment could not impair the CORT-evoked [Ca2+]i elevation. Furthermore, Ca2+ mobilization induced by CORT was abolished by chelerythrine chloride (protein kinase C inhibitor, 10 μM), but was not impaired by H89 (protein kinase A inhibitor, 10 μM). These observations suggest that a nongenomic pathways might be involved in the effect of CORT on [Ca2+]i in cultured dorsal spinal cord astrocytes. In addition, our results also raise a possibility that a putative pertussis toxin-sensitive mGCR (G-protein-coupled membrane-bound glucocorticoid receptor) and the downstream activation of protein kinase C may be responsible for CORT-induced Ca2+ mobilization in cultured dorsal spinal cord astrocytes.
KeywordsCorticosterone Spinal cord Astrocytes Calcium
This work is supported by the National Natural Science Foundation of China (No.30960126 and 31000497). We are very grateful to the other staff of Department of Physiology. We also thank Guo Luo and Jing-yu Xu (Central Laboratory, Zunyi Medical College) for their technique assistance in laser scanning confocal microscopy.
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