Background and Objective: Heat stress is one of the most important environmental pressures which can reduce sexual performance. Garlic has been proposed for increasing resistance against stress. This study dealt with the effects of garlic hydroalcoholic extract on reproductive hormones in male mice under heat stress.

Materials and Methods: Fifty male mice were studied in five groups (n=10). The experiment consisted of a control group (normal situation without receiving extract) and four treatment groups that were kept under heat stress (36±3C) four hours a day (on site) and received 0, 200, 400, and 800 mg/kg of body weight garlic extract in drinking water for thirty days. Blood samples were taken at the end of the experiment and testosterone, FSH and LH hormones were measured. After dissection and removal of the testicles, changes in spermatocytes were evaluated. The obtained data were analyzed using SPSS software.

Results: Heat stress reduced all sexual hormones significantly (p<0.05) in group Zero but testosterone and LH levels increased in groups receiving 400 and 800 mg/kg doses of garlic extract. FSH levels increased significantly in groups receiving doses of 200, 400, and 800 mg/kg, which were similar to the control group. The number of primary spermatocytes in groups Zero reduced compared to the control, but significantly increased at 200, 400 and 800 doses. 

Conclusion: Heat stress can reduce reproductive hormones and spermatogenic cells in male mice and garlic extract can compensate for this loss and play a moderating role on the reproductive potential under heat stress.