Protective effect of herbal medicine on murine spermatogenesis under heat stress and other injury models: Evidence from meta-analyses

The incidence of male infertility has increased dramatically in recent decades, and herbal medicine is a potential complementary treatment. Animal studies are essential to gain insights into the mechanisms involved and refine the development of herbal medicine in human trials. This study aimed to systematically review the protective effects of herbal medicines on murine spermatogenesis. A literature search was conducted using databases such as EMBASE, PubMed, and Google Scholar, as well as scientific journals indexed in the Web of Science, until October 21, 2024. The studies included in the analysis focused on the effects of herbal medicines on murine models, specifically examining physical and organ weights, reproductive parameters, metabolic and biochemical markers, oxidative stress, and antioxidant markers. The analysis included 48 studies from 44 articles involving 1597 murine subjects, 27 plant species, and seven formulations. Herbal medicine significantly increased male murine reproductive organ weights, including body weight (SMD = 1.83; 95% CI: 1.24, 2.42), testis weight (SMD = 1.94; 95% CI: 1.42, 2.46), relative testis weight (SMD = 2.01; 95% CI: 1.27, 2.75), epididymis weight (SMD = 1.22; 95% CI: 0.79, 1.65), relative epididymal weight (SMD = 1.93; 95% CI: 0.93, 2.93), seminal vesicle weight (SMD = 1.25; 95% CI: 0.75, 1.75), and relative seminal vesicle weight (SMD = 1.67; 95% CI: 0.81, 2.54). Additionally, treatment increased the seminiferous tubule diameter (SMD = 9.10; 95% CI: 4.93, 13.28) and Johnson's score (SMD = 6.40; 95% CI: 3.73, 9.06). In the injury models, the semen parameters, including sperm count (SMD = 3.47; 95% CI: 2.72, 4.21), motility (SMD = 3.57; 95% CI: 2.70, 4.44), viability (SMD = 2.04; 95% CI: 1.21, 2.87), and abnormal sperm morphology (SMD = -2.28; 95% CI: -3.65, -1.72), improved. Although no significant changes were observed in FSH and LH levels, the serum testosterone levels increased favorably. Moreover, blood serum biochemical parameters and oxidative stress markers in the injured mouse model were improved following herbal treatment. Herbal medicines have been shown to enhance spermatogenesis in murine models. These in-depth findings provide a foundation for optimizing future human studies.