• NMN supplementation (500 mg/kg) protects against ionizing radiation-induced testicular injury and spermatogenic dysfunction in adult male mice.
• NMN restores serum testosterone, LH, and FSH levels, as well as testicular NAD+, lactate, and pyruvate levels after 5 Gy γ-ray irradiation.
• NMN downregulates proapoptotic genes (Bax, Caspase-3) and upregulates antiapoptotic Bcl-2, while enhancing Sertoli cell markers and glycolytic enzyme genes (HK2, PKM2, LDHA).
• The protective mechanism likely involves promoting spermatogenic cell proliferation and activating glycolytic pathways, suggesting NMN as a potential radioprotector for male cancer patients.