Objectives. Adverse effects of obesity, which is caused by an imbalance between the energy intake and expenditure, on the male reproductive system have been reported. Considering the anti-obesity effect of Glycyrrhiza Glabra (GC), we conducted this study to elucidate whether it can ameliorate the sperm parameters.

Methods. In this experimental study, male Wistar rats of 6–8 weeks old were divided into four groups: control, high fat diet (HFD), GC50 (HFD plus 50 mg/kg GC extract), and GC100 (HFD plus 100 mg/kg GC extract). During the 16 weeks of the study course, the rats consumed the extract through gavage, daily. Body mass index (BMI), body weight gain, serum lipid profile, leptin concentration, and sperm parameters were investigated. Data were analyzed by one-way analysis of variance (ANOVA) (post hoc Tukey) to express the significance of mean differences of variables between groups, and linear regression test was used to express the correlation model of variables. Both tests were performed by SPSS software; p≤0.05 was considered significant.

Results. BMI was significantly decreased by the GC50 and GC100 groups compared to HFD group. GC50 group considerably decreased leptin level compared to HFD group. A significant positive correlation between leptin and triglyceride levels was evident. GC50 and GC100 extensively increased the total sperm motility and ameliorated the sperm abnormal morphology and count compared to HFD group.

Conclusion.Glycyrrhiza Glabra extract may exert its ameliorating effects on the sperm parameters through its anti-obesity impact. Both doses of the extract were effective, however, the GC100 was more effective in improving the sperm parameters.