Expression profile of Toll‐like receptor 4 in rat testis and epididymis throughout postnatal development

Abstract

Toll‐like receptors (TLRs) belonging to pattern recognition receptors are involved in maintaining testicular and epididymal immune homeostasis. The purpose of the current study was to investigate TLR4 expression in rat testis and epididymis throughout postnatal development. Weak staining was detected in peritubular myoid cells and immature Sertoli cells while no staining was observed in gonocytes during prepubertal period. However, TLR4 expression began to appear in spermatocytes in pubertal period and gradually increased in spermatids. An intense staining was observed in steps 5–19 spermatids in post pubertal and mature periods. Similarly, TLR4 expression in the testes steadily increased from pubertal period to mature period. Puberty also caused a significant increase in TLR4 expression in epididymis. TLR4 expression in cauda epididymis was lower as compared to those of other epididymal segments. The majority of epididymal epithelial cells exhibited apical TLR4 expression, whereas basal cells showed intense intracytoplasmic immunoreaction. We detected an intense staining in epididymal smooth muscle cells. The expression levels of TLR4 showed dynamic changes in both spermatogenic cells, and entire testicular and epididymal tissues during postnatal development. These results suggest that TLR4 expression contributes not only to inflammation but also to the development of spermatogenic cells.

Differential Immune Response to Infection and Acute Inflammation Along the Epididymis

“…To study region-specific immune responses, LPS can be applied systemically to circumvent the temporally different exposures of the epididymal regions to the inflammatory challenge, as seen in models of ascending bacterial infection ( 14 , 34 ). In rodents, TLR4 is expressed in epididymal epithelial cells, smooth muscle cells and interstitial macrophages ( 60 – 63 ). TLR4 and associated signaling molecules [i.e.…”

“…TLR4 and associated signaling molecules [i.e. MYD88, cluster differentiation 14 (CD14), TIR-domain-containing adapter molecule-1 (TICAM1), and LPS-binding protein (LBP)] show a spatial expression pattern in the epididymis, adding further credence to region-specific inflammatory responses in the epididymis ( 14 , 15 , 61 , 63 , 64 ).…”

Expression and Localization of Fas-Associated Factor 1 in Testicular Tissues of Different Ages and Ovaries at Different Reproductive Cycle Phases of Bos grunniens

“…The relative expression of FAF1 mRNA is significantly higher in luteal phase ovaries than in follicular and pregnancy phases, followed by pregnancy phase ovaries, with the lowest being in follicular phase ovaries. In ovarian tissue, apoptosis occurs in atretic follicles and ovarian epithelium at ovulation and during luteal onset [31]. FAF1 mRNA expression increases significantly in luteal phase ovaries due to the formation of the corpus luteum and increased progesterone secretion.…”