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Sequential changes in androgen receptor (AR) distribution were investigated in rat ovarian follicles during their physiological development. Mature female Wistar rats, exhibiting a regular 4-day oestrous cycle, were killed in succession on the day of oestrus, metoestrus, dioestrus, and pro-oestrus. Excised ovaries were submitted to immunohistochemical procedure in which polyclonal androgen receptor antibody, avidin-biotin-peroxidase complex, and DAB were used. Strong AR immunostaining was located predominantly in the nuclei of the granulosa layer of preantral and very early antral follicles, present in the ovaries at all stages of the oestrous cycle. At early oestrus a decline in AR was noted in the mural granulosa cells of presumably recruited early antral follicles. The decline involved the area of appearing pseudostratification. During metoestrus and dioestrus AR decline proceeded towards the antrum, but the antral regions connected with COC by strings of granulosa cells or lying in close proximity to COC were always strongly AR-positive. It was only on the day of pro-oestrus that AR was confined to COCs and a few antral cells bordering the antrum. These findings indicate that during the oestrous cycle AR decline starts in the mural granulosa cells of oestrous antral follicles beginning to differentiate and is completed at pro-oestrus, but even before ovulation it does not extend to COC. The persistence of AR immunostaining in the latter region suggests that androgens can play here a paracrine role especially before ovulation. Atretic follicles showed a different pattern of AR distribution, dependent on their stage of development and the advancement of this process.

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Evidence is mounting that the foetal and neonatal period of reproductive tract development is highly sensitive to hormonal disruption induced by various endocrine active compounds. Thus, we asked whether androgen withdrawal caused by prenatal (GD20, GD80) or neonatal (PD2) exposure to an anti-androgen flutamide alters Cx43 gene expression and may induce delayed effects on morphology and function of adult pig testes. Flutamide was given in five doses (50 mg/kg bw). Our histological analysis and TUNEL staining revealed varying degrees of seminiferous tubules abnormalities in all experimental pigs. Testes of pigs exposed to flutamide in utero exhibited moderate alterations of the spermatogenic process, whereas those of exposed neonatally were severely impaired. The most striking effects were spermatogenic arrest, germ cell detachment and a statistically significant increase in the frequency of germ cell apoptosis (p<0.01). Moreover, all pigs exposed to flutamide displayed Leydig cell hyperplasia. Because the network of cell-cell communication provided by gap junction channels plays an essential role in the regulation and maintenance of spermatogenesis, the physiological significance of Cx43-based gap junctions with regards to the gonadal impairment was evaluated by analysis of its expression using immunohistochemical, Western blot and qRT-PCR approaches. Significantly, lower Cx43 expression was found when flutamide was administered neonatally, which has coincided with severe disruption of spermatogenesis. Our data suggest that neonatal exposure to flutamide induces long-term effects on the spermatogenic capacity of the pig testis through alterations of Cx43-mediated intercellular communication and permanent alteration of both Sertoli and Leydig cell functions.

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