The effects of dexamethasone administered during pregnancy on the postpartum spiny mouse ovary

Excessive exposure to glucocorticoids can alter ovarian function by modulating oogenesis, folliculogenesis and steroidogenesis. The aim of the present study was to examine the effects of dexamethasone (DEX) administered during pregnancy on folliculogenesis and corpus luteum development in the postpartum spiny mouse ovary. DEX (125 μg kg-1 body weight per day) was applied to pregnant spiny mouse from day 20 of gestation to parturition. The obtained ovaries were fixed and used for immunohistochemistry and TEM analysis. The expression of proteins related to apoptosis (caspase-3, Bax, Bcl-2) and autophagy (Beclin1, Lamp1) as well as PCNA and GR receptors were evaluated by western-blot. In comparison with DEX-treated group a higher percentage of TUNEL positive granulosa and luteal cells was observed in the control group. These data were consistent with changes in caspase-3 and Bax expression, which increased in the control and decreased after DEX exposure. In turn, the proliferation index and PCNA expression were higher in the DEX-treated group. Moreover, the higher level of Beclin1, Lamp1, anti-apoptotic Bcl-2 protein and GR was observed in the DEX-treated females than in the control group. Beclin1 and Lamp1 were strongly expressed in luteal cells which exhibited an autophagic ultrastructure. Surprisingly, DEX augmented the number of ovarian follicles and corpora lutea, which resulted in a significant increase in ovarian weight. These findings suggest that DEX exerts anti-apoptotic action on granulosa layer and stimulates follicular maturation. Moreover, DEX induces autophagy in luteal cells promoting cell survival rather than cell death, which can prolong the corpus luteum life span.