Ratio-dependent effects of quinestrol and levonorgestrel compounds (EP-1) on reproductive parameters of adult male Swiss mice.

Fertility control is considered as the second-generation pest rodent management strategy. Most previous studies have focused on the dosage-dependent effects of quinestrol and levonorgestrel compounds (EP-1) at a ratio of 1:2, but the ratio-dependent effects of EP-1 have not been fully investigated, especially in male rodents. To test the ratio-dependent antifertility effects of EP-1 with different ratios (1:2, 1:1, and 2:1) on male Swiss outbred strain of laboratory mice, forty male mice were randomly assigned into four groups (n = 10). Mice in the three treatment groups were provided one of the three EP-1 mixture compounds for 3 successive days via gavage at a dosage of 50 mg/kg(body weight), and then all mice were sacrificed 15 days after the gavage treatment. Reproductive organ weights, sperm density and motility, levels of testosterone (T), estradiol (E2), luteinizing hormone (LH), and follicle stimulating hormone (FSH) in serum and/or testis, and androgen receptor (AR), estrogen receptor α (ERα), estrogen receptor β (ERβ), luteinizing hormone receptor (LHR), and aromatase in testis were determined. Each of the ratios of quinestrol and levonorgestrel significantly decreased the density and motility of sperm and induced atrophy of the epididymis and seminal vesicle. The combination of compounds also significantly reduced serum T and LH levels, increased testicular T levels and decreased testicular estradiol ERβ and aromatase levels. EP-1 delivered at a ratio of 1:1 induced the most significant effects on the reproductive parameters assessed and shows the potential for use in fertility control of male rodents.