Background: Dexamethasone is used to treat inflammatory and autoimmune conditions. Its prescription has been increased during the recent years. The aim was to investigate the protective effect of N-acetyl cysteine (NAC), as an antioxidant, on the spermatogenic cells population and daily sperm production in mice treated with dexamethasone. Methods: 24 NMRI mice were divided into 4 groups (n=6) and treated for 7 days: NAC (100 mg/kg), Dexamethasone (7mg/kg), Dexamethasone + NAC (100 mg/kg) and Control. one day after the last injection,body and left testis were weighed and the left testis was fixed, stained and studied using stereological methods and the right testis was used to calculate the daily sperm production (DSP).finally total number of spermatocyte, round and long spermatid, leydig ,Sertoli cells and DSP were analyzed. Results: male mice treated with Dex for 7 days significantly decreased in DSP (p<0.05), spermatocyte (p<0.05), leydig(p<0.05), round and long spermatid(p<0.05)(Table 1). It also There was no significant decrease in body and testis weight compared to the control group(Table 2). Co-administration of NAC and Dex compensated for the adverse effects of Dex on the above parameters. Conclusion: This study showed that Co-administration of NAC with Dex could prevent the adverse effects of Dex on the testicular cells and tissue in male mice.
