Effect of a nonsteroidal antiandrogen, flutamide on intraluminal acidification in rat testis and epididymis

The MAPK/ERK signaling pathway regulates the expression and localization of Cx43 in mouse proximal epididymis†

This study aimed to clarify the functional role of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK1/2)-signaling pathway in the expression and localization of connexin 43 (Cx43). Mice were treated with the mitogen-activated protein kinase kinase (MEK1/2) inhibitor, PD325901, which induced a progressive decrease in ERK1/2 phosphorylation (pERK) in the proximal epididymis of the mice, without affecting total ERK level. Cx43 staining with punctuated reactive sites was observed in the basolateral membranes in the initial segment (IS) of mouse epididymis. However, PD325901 induced a significant decrease in Cx43 labeling in the basolateral membranes. Interestingly, Cx43, which was undetectable in the apical region of epididymis under control conditions, showed a significant increase in the apical region after PD 325901 treatment. To confirm whether Cx43 was present in tight junctions (TJs) after PD 325901 treatment, PD325901-treated epididymis samples were double-labeled with Cx43 and zonula occludens (ZO)-1 (a TJ protein marker). Thereafter, confocal microscopy showed the colocalization of Cx43 and ZO-1 in the epididymis after PD325901 treatment. Collectively, our results indicated that PD325901 treatment induced a significant increase in Cx43 localization on TJs, where it was colocalized with ZO-1. Therefore, the study suggested that ERK phosphorylation is essential for the proper expression and localization of the gap junction (GJ) protein, and that the relationship between GJs and TJs could play an important role in establishing and maintaining microenvironmental homeostasis for sperm maturation in the IS of mouse epididymis.

Androgens are essential for epithelial cell recovery after efferent duct ligation in the initial segment of the mouse epididymis†

Efferent duct ligation (EDL) induces epithelial cell degeneration followed by regeneration in the epididymal initial segment. We tested here the role of androgens in the recovery phase. EDL was performed at post-natal weeks (PNW) 3, 4, 5, 6, and 7, and apoptotic and proliferating epithelial cells were quantified 24 h, and at days 2 and 2.5 post-EDL, respectively. A progressive increase in the number of apoptotic basal cells (BCs) and principal cells (PCs) was detected from PNW3 to 6, 24 h after EDL. Two days after EDL, no increase in proliferating BCs and PCs was observed at PNW3 and 4, despite the induction of apoptosis by EDL. A progressive increase in the number of proliferating BCs was then observed from PNW5 to 6, while the number of proliferating PCs remained low. 2.5 days after EDL, the number of proliferating BCs and PCs remained low at PNW3, 4, and 5, but a marked increase in the number of proliferating PCs was observed at PNW6. Flutamide pretreatment for 3 weeks followed by EDL at PNW7 dramatically decreased the number of proliferating BCs on EDL day 2, and the number of proliferating PCs on EDL day 2.5, compared to controls. We conclude that (1) BCs are the first to show recovery after EDL, followed by PCs; (2) androgens are essential for BC and PC repair after injury in the postpubertal epididymis; and (3) the prepubertal epididymis lacks repair ability following injury.

Pigment epithelium derived factor (PEDF) expression in the male tract of Wistar rats

Pigment epithelium derived factor (PEDF) expression has been described in many organs as showing neurotrophic, anti-angiogenic, anti-apoptotic, anti-inflammatory, anti-oxidant and pro-cell survival properties. However, references to its activity in the male reproductive system are scarce. We aimed to characterize the expression of PEDF in the male reproductive tract of Wistar rats by using RT-PCR, western blot and immunostaining and also evaluate the effect of flutamide in PEDF expression. We found that PEDF is expressed in the epididymis, prostate and seminal vesicles in Wistar rats, but notably not in the testes. Under the effect of flutamide PEDF expression decreased, recovering by suppressing the antiandrogen. The epididymis is an essential organ in sperm maturation-storages. The role of PEDF in this physiological process has not been fully elucidated yet, but considering that in other systems PEDF has anti-apoptotic, anti-oxidants and pro-cell survival properties, its expression along the epididymis could play a role in the protection of spermatozoa while they are stored.

Role of testicular luminal factors on Basal cell elongation and proliferation in the mouse epididymis

A subset of basal cells (BCs) in the initial segment (IS) of the mouse epididymis has a slender body projection between adjacent epithelial cells. We show here that these projections occasionally cross the apical tight junctions and are in contact with the luminal environment. Luminal testicular factors are critical for the establishment of the IS epithelium, and we investigated their role in the regulation of this luminal sensing property. Efferent duct ligation (EDL) was performed to block luminal flow from the testis without affecting blood flow. Cytokeratin 5 (KRT5) labeling showed a time-dependent reduction of the percentage of BCs with intercellular projections from 1 to 5 days after EDL, compared to controls. Double labeling for caspase-3 and KRT5 showed that a subset of BCs undergoes apoptosis 1 day after EDL. Ki67/KRT5 double labeling showed a low rate of BC proliferation under basal conditions. However, EDL induced a marked increase in the proliferation rate of a subset of BCs 2 days after EDL. A 2-wk treatment with the androgen receptor antagonist flutamide did not affect the number of BCs with intercellular projections, but reduced BC proliferation. Flutamide treatment also reduced the increase in BC proliferation induced 2 days after EDL. We conclude that, in the adult mouse IS, 1) luminal testicular factors play an important role in the ability of BCs to extend their body projection towards the lumen, and are essential for the survival of a subset of BCs; 2) androgens play an important role in the proliferation of some of the BCs that survive the initial insult induced by EDL; and 3) the formation and elongation of BC intercellular projections do not depend on androgens.