AMPK is required for uterine receptivity and normal responses to steroid hormones

We previously demonstrated that 5'-AMP-activated protein kinase (AMPK) is essential for normal reproductive functions in female mice. Conditional ablation of Prkaa1 and Prkaa2, genes that encode the alpha 1 and alpha 2 catalytic domains of AMPK, resulted in early reproductive senescence, faulty artificial decidualization, uterine inflammation and fibrotic postparturient endometrial regeneration. We also noted a delay in the timing of embryo implantation in Prkaa1/2(d/d) female mice, suggesting a role for AMPK in establishing uterine receptivity. As outlined in new studies here, conditional uterine ablation of Prkaa1/2 led to an increase in ESR1 in the uteri of Prkaa1/2(d/d) mice, resulting in prolonged epithelial cell proliferation and retention of E-2-induced gene expression (e.g. Msx1, Muc1, Ltf) through the implantation window. Within the stromal compartment, stromal cell proliferation was reduced by five-fold in Prkaa1/2(d/d) mice, and this was accompanied by a significant decrease in cell cycle regulatory genes and aberrant expression of decidualization marker genes such as Hand2, Bmp2, Fst and Inhbb. This phenotype is consistent with our prior study, demonstrating a failure of the Prkaa1/2(d/d) uterus to undergo decidualization. Despite these uterine defects, ovarian function seemed to be normal following ablation of Prkaa1/2(d/d) from peri-ovulatory follicles in which ovulation, luteinization and serum progesterone levels were not different on day 5 of pregnancy or pseudopregnancy between Prkaa1/2(fl/fl) and Prkaa1/2(d/d) mice. These cumulative findings demonstrate that AMPK activity plays a prominent role in mediating several steroid hormone-dependent events such as epithelial cell proliferation, uterine receptivity and decidualization as pregnancy is established.