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Androgen deficiency during prenatal development may affect the expression of genes involved in the folliculogenesis regulation. In order to study the effect of antiandrogen on fetal ovarian development, pregnant gilts were injected with flutamide (for 7 days, 50 mg/kg body weight per day) or corn oil (control groups) starting on gestation days 43 (GD50), 83 (GD90), or 101 (GD108). The obtained fetal ovaries were fixed for histology and immunohistochemistry or frozen for real-time PCR. Morphological evaluation, TUNEL assay, and expression of selected factors (Ki-67, GATA binding transcription factor 4 (GATA4), E-Cadherin and tumor necrosis factor a (TNFa)) were performed. On GD90 and GD108, ovaries following flutamide administration showed a higher number of egg nests and lower number of follicles than those in respective control groups. An increased mRNA and protein expression of Ki-67 was observed in flutamide-treated groups compared with controls on GD50 and GD108 but decreased expression was found on GD90. In comparison to control groups a higher percentage of TUNEL-positive cells was shown after flutamide exposure on GD50 and GD90 and a lower percentage of apoptotic cells was observed on GD108. These data were consistent with changes in TNF (TNFa) mRNA expression, which increased on GD90 and decreased on GD108. E-cadherin mRNA and protein expression was upregulated on GD50 and downregulated on GD90 and GD108. In conclusion diminished androgen action in porcine fetal ovaries during mid-and late gestation leads to changes in the expression of genes crucial for follicle formation. Consequently, delayed folliculogenesis was observed on GD90 and GD108. It seems however that androgens exhibit diverse biological effects depending on the gestational period.

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Vaspin, visceral-adipose-tissue derived serine protease inhibitor, plays important roles in inflammation, obesity, and glucose metabolism. Our recent research has shown the expression and role of vaspin in the function of ovarian follicles. However, whether vaspin regulates steroidogenesis and luteolysis in the corpus luteum (CL) is still unknown. The aim of this study was first to determine the expression of vaspin and its receptor GRP78 in porcine CL at the early, middle, and late stages of the luteal phase. Next, we investigated the hormonal regulation of vaspin levels in luteal cells in response to luteinizing hormone (LH), progesterone (P4), and prostaglandin PGE2 and PGF2α. Finally, we determined vaspin’s direct impact on luteal cells steroidogenesis, luteolysis and kinases phosphorylation. Our results are the first to show higher vaspin/GRP78 expression in middle and late vs early stages; immunohistochemistry showed cytoplasmic vaspin/GRP78 localization in small and large luteal cells. In vitro, we found that LH, P4, PGE2, and PGF2α significantly decreased vaspin levels. Furthermore, vaspin stimulated steroidogenesis by the activation of the GRP78 receptor and protein kinase A (PKA). Also, vaspin increased the ratio of luteotropic PGE2 to luteolytic PGF2α secretion via GRP78 and mitogen-activated kinase (MAP3/1). Moreover, vaspin, in a dose-dependent manner, decreased GRP78 expression, while it, in a time-dependent manner, increased kinases PKA and MAPK3/1 phosphorylation. Taken together, we found that vaspin/GRP78 expression depends on the luteal phase stage and vaspin affects luteal cells endocrinology, indicating that vaspin is a new regulator of luteal cells steroidogenesis and CL formation.

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