Abstract: PD08-08
Sources of Funding: This work was supported in part by the Urology Care Foundation Research Scholar Award Program to RR_x000D_

Introduction

Nitrosative stress is regulated by S-nitrosylation of cysteine thiols. Mice lacking S-nitrosoglutathione reductase (GSNOR KO mice), a denitrosylase that regulates S-nitrosylation, show increased levels of S-nitroslyated proteins and exhibit nitrosative stress.  Nitrosative stress, similar to oxidative stress, can affect spermatogenesis. We hypothesized that GSNOR KO male mice will exhibit impaired fertility and spermatogenesis.

Methods

Male wild-type (WT) and GSNOR KO mice (N=6 each) were studied after postnatal day 42, at a stage where they have completed the first wave of spermatogenesis.  Testes were either fixed and/or frozen for further analysis.  Histology of testes was quantified using Johnsen score, epididymal sperm counts was determined using an automated counter, serum testosterone levels was determined using ELISA and GSNOR protein within the testis was evaluated using immunofluorescence and Western blot analysis.

Results

GSNOR KO males exhibited significantly smaller testes as compared to WT (0.1± 0.0 grams vs. 0.07± 0.0 grams, p<0.05).  Furthermore, serum testosterone levels was significantly lower in the GSNOR KO as compared to WT mice (370.18 ± 0.0ng/mL vs. 42.55 ± 21.7 ng/mL, p<0.05).  Histological analyses using Johnsen score of GSNOR KO testes showed evidence of degeneration of seminiferous tubules, overall reduction in post-meiotic cells and disrupted spermatogenesis (9.5 vs. 6.5, p<0.05). We observed a ~2-fold reduction in epididymal sperm count in GSNOR KO males compared to WT males, indicating that spermatogenesis was impaired, but not globally arrested (2054 ± 35.35 sperms vs. 1236 ± 86.26 sperms, p<0.05). Wild type testis showed extremely high levels of GSNOR protein expressed in the germ cells as well as Leydig cells.

Conclusions

This is the first study demonstrating the association between GSNOR and male fertility. GSNOR KO males exhibit small testes with impaired spermatogenesis and reduced fertility. Attempts to decrease nitrosative stress can reverse impaired spermatogenesis.

Funding

This work was supported in part by the Urology Care Foundation Research Scholar Award Program to RR_x000D_