Expression of connexin 43 protein in testes, epididymides and prostates of stallions

Connexin 43 (Cx43) is a ubiquitously distributed gap junction protein in testes and other reproductive tissues. Adjacent cells share ions and small metabolites through intercellular channels, which are present in gap junctions. Previously, Cx43 has not been reported in testes, epididymides and prostates either in healthy stallions or cryptorchid horses.

To demonstrate the expression pattern of Cx43 in the reproductive tissues of stallions and examine whether naturally occurring bilateral cryptorchidism has any influence on distribution and expression of Cx43.

The expression and the presence of Cx43 protein were detected by means of immunohistochemistry and Western blot analysis using a polyclonal rabbit anti-Cx43 antibody.

In stallions, gap junctions appeared as structures localised to cell-cell contacts between adjacent cells. In testes, Cx43 expression was detected in the interstitial tissue and seminiferous tubules, between Leydig and Sertoli, as well as Sertoli and germ cells. In epididymides, Cx43 was localised between epithelial cells, whereas in prostates, between secretory cells of the glandular epithelium. In the cryptorchid, a clear reduction of Cx43 signal was observed in all reproductive tissues.

Coupling of Leydig cells via gap junctions may suggest that steroidogenic function of the testis is under the influence of these intercellular channels. Within seminiferous tubules, the expression was found to be stage-specific, pointing to its role in coordinating spermatogenesis. Differential distribution of Cx43 protein in the reproductive tract of normal and cryptorchid stallions indicates that expression is clearly dependent on the physiological status of the horse.

Detection of Cx43 expression in equine testicular, epididymal, and prostatic cells is important for a better understanding of the role of intercellular membrane channels in direct cell communication within the reproductive tract of stallions.