Gut microbiota supports male reproduction via nutrition, immunity, and signaling

Abstract

Gut microbiota (GM) is a major component of the gastrointestinal tract. Growing evidence suggests that it has various effects on many distal organs including the male reproductive system in mammals. GM and testis form the gut-testis axis involving the production of key molecules through microbial metabolism or de novo synthesis. These molecules have nutrition, immunity, and hormone-related functions and promote the male reproductive system via the circulatory system. GM helps maintain the integral structure of testes and regulates testicular immunity to protect the spermatogenic environment. Factors damaging GM negatively impact male reproductive function, however, the related mechanism is unknown. Also, the correlation between GM and testis remains to be yet investigated. This review discusses the complex influence of GM on the male reproductive system highlighting the impact on male fertility.

Characterization of the semen, gut, and urine microbiota in patients with different semen abnormalities

“…Supplementation with Bifidobacterium can improve sperm motility ( Valcarce et al, 2017 ). It has been shown that cultured gut Bifidobacterium produces γ-aminobutyric acid (GABA) ( Cai et al, 2022 ), which is important for fertilization. GABA not only promotes the acrosome reaction ( Kurata et al, 2019 ) but also facilitates sperm capacitation by promoting tyrosine phosphorylation of the sperm proteins ( Cai et al, 2022 ).…”

“…It has been shown that cultured gut Bifidobacterium produces γ-aminobutyric acid (GABA) ( Cai et al, 2022 ), which is important for fertilization. GABA not only promotes the acrosome reaction ( Kurata et al, 2019 ) but also facilitates sperm capacitation by promoting tyrosine phosphorylation of the sperm proteins ( Cai et al, 2022 ). Blautia can also inhibit pathogenic bacterial colonization in the gut by producing bacteriocins, which inhibit the proliferation of Clostridium perfringens and vancomycin-resistant enterococci ( Liu et al, 2021 ).…”

“…Gut flora can also influence the permeability of the blood–brain barrier (BBB) ( Braniste et al, 2014 ; Hoyles et al, 2021 ). The bidirectional regulation of the microbiome-gut-brain axis plays an important role in regulating immune and metabolic processes ( Zhang et al, 2015 ), promoting androgen production, and regulating gonadal development and testicular immunity ( Cai et al, 2022 ). Gut microbiota dysbiosis can lead to increased permeability of the blood-testis barrier (BTB) and affect serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone levels in mice ( Al-Asmakh et al, 2014 ).…”

Selenized glucose improves rat semen quality by improving the gut microbiota and serum metabolome

“…Then, Sertoli cells and their intercellular junctions deliver nutrients to the testicular mesenchyme. 22 Therefore, changes in blood metabolites' concentration may impact spermatogenic function. A good GM can also contribute to maintaining a stable testicular immune microenvironment and promoting the release of anti-inflammatory cytokines.…”

“…A good GM can also contribute to maintaining a stable testicular immune microenvironment and promoting the release of anti-inflammatory cytokines. 23 Finally, GM-secreted signaling molecules can influence the development and function of the male reproductive system via signaling pathways such as 5-HT, which can balance androgen production and inhibit ejaculation. 24 The GM plays a critical role in maintaining testicular health through the gut-testis axis which is closely associated with male reproductive function.…”