Effects and mechanisms of blueberry extract on improving age-related sperm motility in mice by alleviating inflammatory responses

Aging leads to progressive decline in male fertility, characterized by structural degeneration of the seminiferous epithelium and oxidative imbalance. Objective: This study aimed to evaluate the efficacy of Blueberry Extract (BBE) in ameliorating reproductive aging and to elucidate the underlying molecular mechanisms involving cell fate determination. Methods: Aging male ICR mice (8 months old) were treated with varying doses of BBE. Testicular histology, sperm quality, and expression of key germ cell markers were analyzed. Results: BBE administration significantly alleviated body weight loss, reduced seminiferous tubule vacuolization, and improved sperm motility parameters in aging mice. Immunofluorescence and Western Blot analyses revealed that BBE successfully reconstituted the germline population, as evidenced by the upregulation of DDX4. Notably, a dose-dependent divergence in cellular fate was observed: high-dose BBE significantly promoted the self-renewal of PLZF+ spermatogonial stem cells (SSCs), whereas low/medium doses preferentially upregulated STRA8 to drive meiotic differentiation. This cell fate remodeling was associated with a "U-shaped" regulation of the cell cycle regulator CCND1 and enhanced SIRT1 expression. Conclusion: BBE mitigates age-related spermatogenic failure by orchestrating a delicate balance between SSC self-renewal and differentiation via the SIRT1 pathway. These results position BBE as a promising functional food ingredient for preserving male reproductive health.