Search

Sertoli cells play crucial roles in spermatogenesis and are impaired by aging. Icariin, a flavonoid from Epimedium , has been reported to exhibit anti-aging effects and improve testicular dysfunction in the clinical setting. However, whether icariin improves age-related degeneration of testicular function via protection from Sertoli cell injury remains unclear. In the present study, we evaluated the protective effect of icariin on Sertoli cell injury and explored the possible mechanism(s) in vivo and in vitro. Dietary administration of icariin for 4 months significantly ameliorated the age-related decline in testicular function by increasing testicular and epididymal weights and indices, sperm count and sperm viability, testicular testosterone and estradiol concentrations, and seminiferous tubule diameters and heights. In addition, icariin protected age-related Sertoli cells from injury as evidenced by an analysis of Sertoli cell number, ultrastructure, and function. Such changes were accompanied by upregulation of ER α and Nrf2 signaling in Sertoli cells. Parallel in vitro studies also demonstrated that icariin inhibited untoward effects on the TM4 mouse Sertoli cell line with concomitant upregulation of ER α and Nrf2 signaling. Conversely, ER α siRNA reversed icariin-mediated protection of Sertoli cell injury. Our data suggest that icariin effectively ameliorates age-related degeneration of testicular function by alleviating Sertoli cell injury via the ER α /Nrf2 signal-transduction pathway. Thus, mitigating Sertoli cell damage via the ER α /Nrf2 signaling pathway likely represents a promising strategy for the prevention of age-related testicular dysfunction. [ABSTRACT FROM AUTHOR]

Objective To establish a model of decline in secretion of senescent TM4 cells in vitro induced by D-galactose (D-gal). Methods Different concentrations of D-Gal (25, 50, 100, 150, 200 and 250 mmol/L) were used to induce TM4 cell senescence. The viability of TM4 cells was detected by MTT assay. The cell cycle was analyzed by flow cytometry. The cell morphology was observed by light microscopy and the percentage of senescent cells was observed by senescence-associated β-galactosidase (SA-β-Gal) staining. The mRNA expression levels of P21, P16, glial-derived neurotrophic factor (GDNF) and stem cell factor (SCF) were detected by reverse transcription PCR. The protein expression levels of GDNF, SCF, nuclear factor erythroid 2 like 2 (NRF2), NAD(P)H dehydrogenase [quinone] 1 (NQO-1) and heme oxygenase-1 (HO-1) were detected by Western blot analysis. Results Compared with normal control group, D-Gal stimulation significantly decreased the cell viability in a concentration-dependent manner. The arrest of D-Gal-treated cells in G1 phase of cell cycle significantly increased, while it significantly decreased in S phase, and D-Gal induced cell cycle arrest at G0/G1 phase in TM4 cells. The percentages of SA-β-Gal positive cells increased significantly. The expression levels of P21 and P16 mRNAs were significantly up-regulated. The mRNA and protein levels of GDNF and SCF-1 were significantly down-regulated. Furthermore, the expression levels of oxidative stress-related protein NRF2, HO-1 and NQO-1 were significantly reduced. Conclusion The model of declined secretion function of senescent TM4 cells induced by D-Gal we established is stable and reliable. Its mechanism may be related to the down-regulation of NRF2 signaling pathway.