Effects of calcitriol on calbindins gene expression and lipid peroxidation in human placenta

Pregnancy is associated with increased maternal calcitriol levels and placenta is an extrarenal source of this hormone. Calbindin-D9k and calbindin-D28k are vitamin D-dependent. Since calbindin-D28k has been considered as an antioxidant factor, the aim of the present work was to investigate the effects of calcitriol on calbindins gene expression and lipid peroxidation in cultured syncytiotrophoblast cells obtained from healthy human placentas. Gene expression of calbindins was evaluated using RT and real-time PCR techniques. Malondialdehyde (MDA) levels were used as lipid peroxidation marker. The results of the present study showed that cultured syncytiotrophoblast cells expressed the mRNA of calbindin-D9k and calbindin-D28k. In addition, calcitriol stimulated gene expression of both calbindins in a dose-dependent manner. Placental MDA levels were not significantly different at physiological concentrations of calcitriol (10(-11) M and 10(-9) M). However, the use of calcitriol at 10(-7) M resulted in significantly higher MDA levels (P<0.05). In conclusion, the results showed that cultured syncytiotrophoblast cells expressed calbindin-D9k and calbindin-D28k genes, which were stimulated by calcitriol. In addition, the results suggest that calcitriol may be considered as pro-oxidant when used at pharmacological doses.