The gut metabolite 3-hydroxyphenylacetic acid ameliorates the aging-related spermatogenic dysfunction in mice

Age-related fertility decline is a prevalent concern globally. Male reproductive system aging is mainly characterized by a decrease in sexual hormones levels, sperm quality and fertility. While it is known that intestinal physiology changes with age and that microbiota is shaped by physiology,the underlying molecular mechanism is still largely unexplored. Here, we utilized fecal microbiota transplantation (FMT) to exchange the fecal microbiota between young and old mice. In order to identify differences in gut microbiota composition and metabolic regulation during aging, we conducted cecal shotgun metagenomics of young and old mice, and analyzed the cecal, plasma and testicular metabolomics of FMT mice. Our results demonstrate that FMT from young to old mice alleviated aging-associated spermatogenic dysfunction through an unexpected mechanism mediated by a gut bacteria-derived metabolite, 3-hydroxyphenylacetic acid (3-HPAA). Administration of 3-HPAA treatment resulted in a significant improvement of spermatogenesis in old mice. RNA sequencing analysis, qRT-PCR and Western blot from testis tissues revealed that 3-HPAA induced GPX4 expression to restrain ferroptosis and restore spermatogenesis, which was confirmed by induction of ferroptosis and inhibition of GPX4 expression in vitro. Our results demonstrate the microbiome-derived metabolite, such as 3-HPAA, can facilitate spermatogenesis in old mice through a ferroptosis-mediated mechanism.