Fertility-enhancing potential of ethanol extract of Cuscuta chinensis seeds in a rat model of unilateral cryptorchidism

Abstract

Purpose: To investigate the fertility-enhancing potential of the ethanol extract of Cuscuta chinensis seeds in a rat model of unilateral cryptorchidism (ULC), and the mechanism(s) of action. Methods: Healthy male Sprague Dawley rats (n = 48; mean weight = 220 ± 10 g) were randomly assigned to 4 groups (12 rats/group): control, ULC, 100 mg extract/kg and 200 mg extract/kg groups. Unilateral cryptorchidism of right testis was induced via standard method using an operating microscope. Rats in the treatment groups received 100 and 200 mg of ethanol extract of Cuscuta chinensis/kg orally once a day for 60 days. Sperm count and sperm motility were determined in seminal vesicular fluid (SVF) suspension. Oxidative stress markers and histological changes in rat testis were evaluated. The levels of caspase-3 and caspase-9 in testicular tissue were assessed by enzyme-linked immunosorbent assay (ELISA), while the protein expressions of Nrf2 and heme oxygenase 1 (HO-1) were determined using Western blotting. Results: Body and reproductive organ weights, sperm count, sperm motility, and activities of glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD) were significantly reduced in ULC group, relative to control group, but these parameters were significantly and dose-dependently increased following extract treatment (p < 0.05). Malondialdehyde (MDA), 8-hydroxy-2’-deoxyguanosine (8-OHdG), caspase-3 and caspase-9 levels were significantly higher in ULC group than in control group, but they were reduced significantly and dose-dependently after extract treatment (p < 0.05). Moreover, the protein expressions of Nrf2 and HO-1 were significantly downregulated in ULC group, when compared with control group, but they were significantly and dose-dependently upregulated by the extract (p < 0.05). Cross sections of testicular tissues of rats in ULC group revealed narrowed and thickened seminiferous tubules (disrupted spermatogonia) characterized by increased apoptotic bodies (increased number of necrotic Sertoli and Leydig cells). However, there were few damaged or necrotic Sertoli and Leydig cells, and complete absence of thickening of seminiferous tubules in testicular tissues of rats treated with the extract. Conclusion: The ethanol extract of Cuscuta chinensis seeds effectively mitigates cryptorchidism in rats via mechanisms involving the regulation of Nrf2/HO-1 signaling pathway, and inhibition of apoptosis and oxidative stress. Thus, the plant extract has potentials for further development for the management of male infertility