Expression profiles of toll-like receptors 2, 7 and 8 in rat testis and epididymis during postnatal developmental period

Abstract

Toll-like receptors take an essential part in innate immunity in response to invasion of the various harmful pathogens. We aimed to investigate TLR2, 7 and 8 expression in rat testis and epididymis throughout postnatal development. In the prepubertal period, TLR2 and 7 were variably localized to peritubular myoid cells, interstitial cells, blood vessels, epithelial cells, ductal smooth muscle cells in testis and epididymis. In the pubertal period, immunostaining of TLR2 and 7 started to be seen in primary spermatocytes, as well as other cells, in the testis. Narrow cells showed strong intracytoplasmic staining in the epididymis. In the postpubertal period, moderate to strong immunostaining of TLR2 and TLR7 was seen in spermatids at different developmental steps but weak immunoreaction in pachytene spermatocytes. Other cells in testis and epididymis showed variable immunostaining of TLR2 and 7. However, weak to moderate immunoreaction to TLR8 was detected in only interstitial cells in testis. In the mature period, immunostaining of TLR2, 7 and 8 tended to increase in different types of cells in testis and epididymis. Our findings suggest that expression of TLR2, 7 and 8 changed dynamically during postnatal development and increased towards mature period. We consider that TLR2, 7 and 8 might be associated with the regulation of spermatogenesis and the maintenance of innate immunity of testis and epididymis during postnatal development.