Melatonin Rescues Heat Stress-Induced Suppression of TCA Cycle and Mitochondrial Damage in Goat Sertoli Cells

Global climate change exacerbates heat stress, a major threat to male fertility in livestock. As Sertoli cells (SCs) are essential for spermatogenesis but are highly vulnerable to heat, understanding the underlying metabolic dysfunction is critical. This study investigated heat-induced metabolic dysregulation in goat SCs and evaluated the protective effects of melatonin. Through integrated transcriptomics and stable isotope-assisted metabolic flux analysis (MFA), we mapped alterations in gene expression and central carbon metabolism. Heat stress provoked mitochondrial dysfunction and oxidative damage. Metabolic flux analysis revealed suppressed mitochondrial oxidative metabolism, evidenced by reduced glucose-derived carbon incorporation into TCA cycle intermediates. Transcriptomics identified key perturbations in energy metabolism and sphingolipid signaling. Melatonin pretreatment restored mitochondrial function and redox homeostasis, and triggered a protective metabolic reprogramming that enhanced cell viability. Our findings demonstrate that melatonin mitigates heat stress by preserving mitochondrial integrity and redox homeostasis, providing mechanistic insights into male infertility and suggesting melatonin as a promising therapeutic for enhancing livestock reproductive resilience under climate stress.