This study explored the expression of connexin 43 (Cx43) in the testes of prepubertal Sprague-Dawley (SD) rats following in utero flutamide (Flu) exposure. Connexins constitute the major protein type in gap junctions. Connexin 43, the most prominent connexin family member expressed by testes, is localized at the base of seminiferous tubules in humans and rodents, and may be involved in fertility. Flutamide was injected subcutaneously into pregnant SD rats on gestational days 12-21 (25 mg/kg/day). Immunohistochemistry, Western blotting, and real-time PCR was used to investigate the distribution and the expression of Cx43 protein and mRNA in the testis on postnatal day 20 (PD20). Following Flu-exposure, Cx43 was observed between Sertoli cells in the seminiferous tubules. On PD20, no Cx43 protein was expressed by the spermatogonial cell layer of the seminiferous tubules in the controls, but was observed in the Flu-exposed group. Western blotting showed that Cx43 was expressed at significantly lower levels in Flu-exposed testes than controls on PD20 (p < 0.001). On PD20, levels of Cx43 mRNA in undescended Flu-exposed testes were significantly lower than in controls (p < 0.05) and descended Flu-exposed testes (p < 0.01). After Flu-exposure in the rat embryonic period, Cx43 mRNA and protein expression were downregulated, and its distribution in the seminiferous tubules was abnormal.
Keywords: Connexin 43; Sprague-Dawley rat; flutamide; testicular descent; testis.