Akhigbe_2026_Steroids_228_109748

BACKGROUND: Type 2 diabetes mellitus (T2DM) induces testicular damage through xanthine oxidase (XO)/uric acid (UA)/caspase-3-driven oxidative stress and apoptosis. Although metformin is effective in managing diabetes, combined therapy is more effective. Though donepezil protects against neuronal and retinal damage in diabetic rats, its role in diabetes-induced testicular damage is yet to be reported. AIM: This study investigated the protective effects of combined metformin and donepezil treatment on testicular dysfunction in a high-fat diet/streptozotocin-induced T2DM rat model. Also, the involvement of XO/UA and Bax/Bcl-2/caspase signaling was examined. METHODS: Forty-eight 8-week-old male Wistar rats were randomly assigned into six equal groups: control, diabetes (DM), DM+metformin, donepezil, DM+donepezil, and DM+metformin+donepezil groups. RESULTS: T2DM caused testicular inflammation and oxidative stress, evidenced by elevated pro-inflammatory cytokines (IL-1beta, IL-6, TNF-alpha), activation of NF-kappaB signaling, increased oxidative markers (MDA), and reduced antioxidant enzymes. T2DM also led to testicular apoptosis (increased Bax and caspase-3 and reduced Bcl-2). More so, T2DM repressed serum testosterone, FSH, and LH, and caused morphological disorganization of the testes, including germ cell loss and Leydig cell degeneration. Treatment with metformin and donepezil, singly or in combination, significantly mitigated these adverse effects, with the combined therapy demonstrating superior efficacy. The intervention suppressed XO/uric acid signaling, oxidative stress, and inflammatory responses via downregulation of NF-kappaB and apoptotic cascades. These results imply that donepezil and metformin work in concert to provide a potentially effective treatment strategy for reducing testicular damage caused by diabetes through modulation of oxidative, inflammatory, and apoptotic pathways, ultimately restoring testicular structure and function.