FFAR4 Mediates High-Altitude Hypoxia-Induced Asthenozoospermia through Oxidative Stress and Mitochondrial Dysfunction: An Integrative Bioinformatics and Experimental Study.

High-altitude hypoxia is a significant environmental factor contributing to male infertility, particularly asthenozoospermia, yet the underlying molecular mechanisms remain elusive. To address this, we performed an integrated bioinformatics analysis of transcriptome datasets (SRP418387 and SRP418442) to identify candidate genes, followed by the establishment of a high-altitude hypoxia mouse model (simulated 5000 m, 12.5% O₂) for validation. Functional mechanisms were elucidated using AAV-mediated FFAR4 knockdown and pharmacological modulation, alongside comprehensive assessments of sperm motility, oxidative stress, and mitochondrial function. Bioinformatics screening identified 142 commonly upregulated differentially expressed genes, with FFAR4, OR7D2, and CALHM6 highlighted as key candidates. Hypoxia exposure significantly impaired sperm motility and upregulated FFAR4 expression in testicular tissue. Notably, FFAR4 knockdown significantly restored progressive sperm motility and ATP production while reducing intracellular and mitochondrial reactive oxygen species (ROS) levels, whereas pharmacological activation of FFAR4 exacerbated hypoxia-induced motility defects. Mechanistically, genetic knockdown of FFAR4 restored antioxidant enzyme activities and mitochondrial respiratory chain complex functions without disrupting reproductive hormone levels. These findings suggest that FFAR4 mediates high-altitude hypoxia-induced asthenozoospermia by exacerbating oxidative stress and mitochondrial dysfunction, positioning FFAR4 as a promising therapeutic target for preserving sperm quality and motility in hypoxic environments.