[Relationship between decreased expression of inhibin B and spermatogenesis dysfunction in rats testis].

Objective

To explore the effects of varicocele on the expressions of inhibin B in rat testes and the relationship between expression of inhibin B and spermatogenesis dysfunction.

Methods

Twenty specific-pathogen-free Sprague-Dawley (SD) male rats were randomly divided into two groups with random number table: 4-week control group (C4) and 4-week experimental group(V4). Experimental varicocele was created by partial ligation of left renal vein in the V4 group; vein isolation without ligation was performed in the C4 group.Spermatogenetic function in the two groups were assessed. The expression of inhibin B in the rat testis was analyzed by immunohistochemistry, the expressions of inhibin B, Fas and Fas ligand(FasL)mRNA measured by reverse transcription-polymerase chain reaction(RT-PCR), and the inhibin B protein expression by Western blot.

Results

In comparison of spermatogenetic function in left rat testes, the Johnsen scores in the V4 group were significantly lower than those in the C4 group (9.79±0.05 vs 9.97±0.02, P=0.023), the seminiferous epithelium in the V4 group was significantly thinner than that in the C4 group [(48.35±0.99)μm vs (57.58±1.98)μm, P=0.000], and the number of sperms in the left epididymis was significantly lower than in the right one in the V4 group [(933±161)×106/(ml·g) vs(1 552±184)×106/(ml·g), P=0.017]. Both Western blot and immunohistochemical assay showed that the expression of inhibin B in the rat testes was significantly lower in the V4 group than in the C4 group(0.407±0.053 vs 0.608±0.076, P=0.038; 0.161±0.004 vs 0.183±0.005, P=0.008). RT-PCR also detected reduced expression of inhibin B mRNA in the V4 group compared with the C4 group(0.522±0.050 vs 1.106±0.210, P=0.003. Compared to the C4 group, the expression of Fas mRNA in the V4 group was significantly lower, while the expression of FasL mRNA in the V4 group was significantly higher(P=0.019, 0.015).

Conclusions

Varicocele can lead to decreased expressions of inhibin B in rat testes and cause spermatogenesis dysfunction. There may be a close correlation between down-regulation ofinhibin B expression and spermatogenesis dysfunction.Inhibin B may play a significant rolein the mechanisms underlying male infertility due to varicocele.