165 EXPRESSION OF CALCIUM TRANSPORTER 1 GENE IN THE UTERUS OF RATS DURING PREGNANCY

Abstract

Calcium Transporter 1 (CaT1), which is highly expressed in calcium-absorption organs, i.e. duodenum and kidney, is a critical mediator for calcium uptake during transcellular calcium transport. It has been shown that CaT1 gene is also expressed in the placenta and uterine smooth muscle in female reproductive organs. We previously demonstrated that uterine CaT1 mRNA is highly expressed at diestrus and tightly regulated by progesterone (P4) related to calcium homeostasis for uterine functions during the estrous cycle in rats. Thus, in the recent study, we further examined the expression of CaT1 mRNA in the uterus and placenta of rats to elucidate its role during pregnancy in these tissues. Female Sprague Dawley rats (n = 2) were employed and their pregnancy days (PD) were determined by a vaginal plug every morning; the rats were euthanized daily (PD 0 to 21). The expression of CaT1 mRNA decreased from PD 0 to 4 and highly increased on PD 5 to 10. Its increased transcripts gradually decreased at the end of pregnancy. Taken together, these results indicate that the expression level of CaT1 mRNA is regulated in the uterus of rats during pregnancy, probably via sex steroid hormones and their receptors through a complex pathway. A further study is warranted to verify relevant factors which regulate CaT1 gene and to provide further insight into its role(s) in the female reproductive tissues.