Differential expression of taste receptors T1R1 and T1R3 in different regions of epididymis in Congjiang Xiang pigs

【Objective】To clarify the location and expression of taste receptors T1R1 and T1R3 in different regions of the epididymis of Congjiang Xiang pigs, and to provide reference for revealing the mechanism of the formation of unique microenvironment in different segment of the epididymis to ensure sperm maturation. 【Method】The epididymis tissue samples at the puberty(30 d) and sexual maturity(180 d) were collected, and real-time fluorescence quantitative PCR, immunohistochemistry, and Western blotting were used to detect the location and expression of taste receptors T1R1 and T1R3 in different regions of epididymis of Congjiang Xiang pigs. 【Result】The expression level of TAS1R1/TAS1R3 coding gene of taste receptor T1R1/T1R3 was significantly higher in epididymis IV region than in other regions(P<0.05, the same below), while the relative expression level of epididymis I region was significantly lower than that of other regions, and the rank was IV>V>II>III>I region. Immunohistochemical localization analysis showed that T1R1/T1R3 immunopositive signals at different extents were detected in different parts of the epididymis of Congjiang Xiang pigs. Among them, T1R1 was mainly located in myoid cell layer and basal nucleus in epididymis region I. In epididymis II region, it mainly located in epididymal epithelial cells, myoid cells and sperm cells. In epididymis III region, it was strongly localized in epididymis lumen and microvilli root. Epididymis IV region was the most strongly expressed part among the five regions, which was located in the epididymis lumen sperm, lumen inner margin and narrow cell membrane. The V region of the epididymis was mainly located on the epididymis interstitial tissue and narrow cell membrane of the epididymis. T1R3was localized in vascular endothelial cells, exfoliated spermatogenic cells and epididymal epithelial cells(especially basal cells) in epididymal region I. It was strongly expressed on sperm, halo cells and narrow cells in epididymis II region. In areas III and IV of the epididymis, it was mainly located in the vacuolated epididymal epithelial cells. The expression intensity of epididymal epithelial cells located in irregularity and vacuolated epididymal duct in epididymal region V was second only to that in region III. Western blotting test results showed that the expression level of T1R1/T1R3 in epididymis region IV of Congjiang Xiang pigs was the highest, followed by that in epididymis region II, which was significantly higher than that other regions. 【Conclusion】The expression of T1R1 and T1R3 from the epididymis of Congjiang Xiang pigs during at puberty is region-specific and cell-specific, with the highest expression level in region IV, which is mainly located in the apex of epididymal epithelial cells, narrow cells and microvilli roots, suggesting that T1R1/T1R3 plays an important role in establishing a unique intracellular microenvironment that promotes maturation and storage of porine epididymal sperm.