BDH1 Mediates Aerobic Exercise-Induced Improvement in Skeletal Muscle Metabolic Remodeling in Type 2 Diabetes Mellitus

Background: Type 2 diabetes mellitus (T2DM) is typically characterized by the dysregulation of metabolic remodeling. As a systemic metabolic disease, T2DM can affect the mass and function of skeletal muscle by inducing impaired energy metabolism, mitochondrial dysfunction, and chronic low-grade inflammation. β-Hydroxybutyrate dehydrogenase 1 (BDH1) is a rate-limiting enzyme involved in ketone body metabolism, and its activity is down-regulated in various models of diabetic complications. Aerobic exercise (AE) is recognized as an effective intervention to promote energy homeostasis and alleviate metabolic stress. Whether its protective effect on skeletal muscle in T2DM involves the regulatory control of BDH1 expression remains unclear. Methods: Wild-type (WT) and systemic BDH1 knockout (BDH1−/−) male C57BL/6J mice were used to establish the sedentary control (SED) and AE models of T2DM by providing a high-fat diet combined with streptozotocin injection. The indicators related to metabolic remodeling were detected by hematoxylin and eosin staining, immunofluorescence staining, quantitative real-time PCR, and Western blot assays. Results: After 8 weeks of AE, we found that AE improved glycolipid metabolic disorders and mitochondrial quality control in the gastrocnemius muscle of T2DM mice by up-regulating BDH1, thereby alleviating oxidative stress, inflammation, and fibrosis. Compared with the WT mice, the BDH1−/− T2DM mice in the SED group exhibited more severe phenotypic impairment. The metabolic improvement effect of AE was attenuated in the BDH1−/− mice. Conclusions: BDH1 is a key effector enzyme that may mediate the AE-induced improvement in metabolic remodeling in the gastrocnemius muscle of mice with T2DM.