Endocrine Abstracts

Introduction: Calbindin-D_9k is a 9 kDa polypeptide expressed in the mammalian intestine, uterus, and pituitary gland. Calbindin-D_9k increase Ca²⁺ absorption by buffering intracellular Ca²⁺. The intracellular concentration of calcium is regulated by calcium related proteins such as calbindin-D_9k, TRPV1 and PMCA1. The regulatory effect of steroid hormones and glucocorticoids on calbindin-D_9k, TRPV1 and PMCA1 expressions in the cerebellum are currently unknown. In this study, we investigate the expressions of calbindin-D_9k, TRPV1 and PMCA1 by sex steroid hormones and glucocorticoids in rat cerebellum.

Methods: To investigate the effect of sex steroid hormones and glucocorticoids to the cerebellum calbindin-D_9k, TRPV1 and PMCA1 expressions, 14 days old rat were administered 40 ug/kg of E2, 20 mg/kg of P4, 10 mg/kg of ICI 182,780 and 13 weeks old rat were administered 10 mg/kg of Dexamethasone (Dex), 50 mg/kg of RU486.

Results: Transcriptional level and localization of Calbindin-D_9k, TRPV1, PMCA1 were examined in the cerebellum. mRNA and protein level of Calbindin-D_9k was increased by Dex, but not by E2 nor P4. Immunofluorescence shows that calbindin-D_9k were mainly localized in the purkinje cell. Like the expression of calbindin-D_9k, mRNA levels of TRPV1 and PMCA1 only increased in response to Dex treatment.

Conclusion: These results are correlated with calbindin-D_9k, TRPV1 and PMCA1 expressions were regulated by glucocorticoids in cerebellum. Especially, the localization and regulation of calbindin-D9k in purkinje cell could indicate that glucocorticoids can bring functional changes in the purkinje cell.