Adiponectin affects uterine steroidogenesis during early pregnancy and the oestrous cycle: An in vitro study.

Reproduction in females is an energetically demanding process. We assumed that adiponectin (ADPN), known for its role in energy balance maintenance, is also engaged in the regulation of uterine steroidogenesis in the pig. We determined the impact of ADPN alone or in combination with insulin (INS) on testosterone (T), estrone (E) and estradiol (E) secretion by porcine endometrium and myometrium, uterine expression of CYP17A1 and CYP19A3 genes, and endometrial abundance of P450 and P450 proteins during the peri-implantation period and the oestrous cycle, using radioimmunoassay, qPCR, and Western Blot, respectively. During pregnancy, in the endometrial explants from days 10-11, ADPN decreased CYP17A1 gene expression, P450 protein abundance and T secretion, whereas increased E secretion. On days 12-13 of pregnancy, ADPN decreased CYP17A1 and CYP19A3 expression, P450 and P450 protein abundance and E secretion, but stimulated T secretion. On days 15-16 of pregnancy, ADPN decreased P450 protein accumulation but enhanced CYP19A3 expression and E secretion. On days 27-28 of pregnancy, ADPN increased CYP17A1 and CYP19A3 mRNA content and T secretion in this tissue and decreased P450 content. ADPN effect on myometrial explants was dependent on stage of gestation or oestrous cycle. Moreover, INS treatment modulated basal and ADPN-affected steroidogenic enzymes gene and protein expression and steroids secretion. The results obtained indicate that ADPN may affect processes required for successful implantation such as steroidogenesis. ADPN and INS were also shown to modulate each other action, which indicates that the proper course of uterine steroidogenesis may be dependent on both hormones' interaction.