Decreased autophagy was implicated in the decreased apoptosis during decidualization in early pregnant mice.

Folate deficiency is a major risk factor of birth defects. Mechanistic studies on folate deficiency resulting in birth defects have mainly focused on fetal development. There have been few studies on folate deficiency from the point of view of the mother's uterus. In our previous study, we demonstrated that folate deficiency inhibits apoptosis of decidual cells, thereby restraining decidualization of the endometrium and impairing pregnancy. In this study, we further investigated the potential mechanism by which folate deficiency decreases endometrial apoptosis during decidualization. To investigate whether endometrium autophagy was inhibited under folate deficiency during decidualization, we performed real-time PCR for endometrial LC3 and P62 on day 6 (D6) to D8 of pregnancy in mice, and both were significantly changed compared to non-folate-deficient mice. Western blots showed that LC3-II and P62 were also changed in folate-deficient mice. Compared with control mice, a few punctuate LC3-II structures were detected in the folate deficiency group by immunofluorescence. Transmission electron micrographs of decidual cells on D8 showed that there were no evident autophagosomes in the folate deficiency group. In addition, apoptosis-related protein analysis by western blotting, TUNEL staining and flow cytometry showed that decreased endometrial apoptosis on D8 of pregnancy under folate deficiency was reversed after treatment with rapamycin, an autophagy inducer. ROS measurement showed that the endometrium ROS level was reduced by folate deficiency and that rapamycin reversed this effect on day 8 of pregnancy. All the results suggest that inhibiting endometrial autophagy may be implicated in the decreased endometrial apoptosis under folate deficiency during decidualization.