The impact of exogenous testosterone supplementation on spermatogenesis in a rat model of oligoasthenospermia

Oligoasthenospermia is one of the main causes of infertility in reproductive-age men. This study aimed to explore the feasibility of exogenous testosterone supplemental therapy (TST) for adult male rats with oligoasthenospermia model. The rats (n=40) were randomized equally into 4 groups: control group, model group, low-dose and high-dose groups (n=10, respectively). After establishment of an oligoasthenospermia model that was treated with glucosides of tripterygium wilfordii (GTWs), the low-dose and high-dose groups were treated with 2 testosterone undecanoate (TU) injections at doses of 7.5 mg and 15 mg for 8-week period (4-week intervals). Body weights, serum reproductive hormone levels, sperm measurements in the epididymis, and testis histology were monitored. The TU injections increased serum testosterone levels steadily. The epididymis sperm concentration and motility increased slowly in high dose group at 4-weeks whereas sperm measurements increased significantly in the TST groups at 8 weeks. In addition, exogenous TST increased the intra-testicular testosterone concentration somewhat and alleviated the testicular oxidative stress markers of Malondialdehyde (MDA) and level of GSH-PX (Glutathione Peroxidase) after 8 weeks treatment. The improvement of sperm and testicular function acted mainly by curbing mitochondrial apoptosis in the testis by modulation of Bcl-2, Bax, Caspase-3, and Caspase-9 expression. However, the results of immunohistochemistry and western blotting in the low-dose group were still lower than control values. TST at an appropriate dose within a period of 8 weeks was effective to stimulate spermatogenesis and alleviate inflammation, oxidative stress, and apoptosis through suppression of testis damage in this rat model of oligoasthenospermia.