Hyperglycemia Impairs the Expression of Mediators of Axonal Regeneration During Diabetic Wound Healing in Rats

Background/Objectives: Diabetic foot ulcers (DFUs) are one of the most debilitating complications of diabetes mellitus, characterized by impaired wound healing, chronic inflammation, and neuropathy. Peripheral nerve degeneration plays a critical role in delayed healing, but the molecular mediators linking hyperglycemia, neurodegeneration, and impaired DFU repair remain incompletely understood. This study aims to characterize the expression of activin A, which is a key regulator of fibroblast activity and neuronal growth, tumor necrosis factor receptor superfamily member 10B (TNFRSF10B), which mediates inflammatory and apoptotic signaling, and synaptophysin, which serves as a marker of axonal sprouting and synaptic remodeling in diabetic tissues. Methods: Skin tissues during wounding and after healing from control and diabetic Sprague-Dawley rats were analyzed using histological staining, immunohistochemistry, and quantitative real-time polymerase chain reactions. Additionally, rat fibroblasts were treated with hyperglycemic medium to evaluate gene and protein expression in vitro. Results: Histological analyses revealed impaired healing in diabetic wounds with reduced collagen deposition, loss of adnexal structures, and disorganized tissue architecture. Gene and protein expression of activin A, TNFRSF10B, and synaptophysin were significantly decreased in diabetic healed tissues compared to controls. In vitro, hyperglycemia induced transient upregulation of activin A and TNFRSF10B at 24 h, followed by a decline at 48 and 72 h. Conclusions: These findings indicate that hyperglycemia disrupts key mediators of axonal regeneration in DFUs, potentially contributing to impaired neuronal regeneration and delayed healing. Targeting these molecular pathways may offer therapeutic opportunities to enhance wound repair in DFUs.