Beneficial effects of (−)‐epigallocatechin‐3‐<i>O</i>‐gallate on diabetic peripheral neuropathy in the rat model
Osama M. Abo‐Salem, Tarek M. Ali, Gamaleldin I. Harisa, Osama Mahmoud Mehanna, Ibrahim Younos, Waleed Hassan Almalki
Abstract
Diabetic neuropathic pain is characterized by spontaneous pain with hyperalgesia and allodynia. We investigated whether (-)-epigallocatechin-3-O-gallate could improve diabetic neuropathic pain development through hypoglycemic, hypolipidemic, antioxidant, and anti-inflammatory effects. Diabetes was induced in rats by streptozotocin (55 mg/kg/once) and treated with (-)-epigallocatechin-3-O-gallate (25 mg/kg/orally/once/daily/5 weeks). Diabetic rats showed an increase in serum levels of glucose, nitric oxide, triglyceride, total cholesterol, and low-density lipoprotein-cholesterol with a decrease in high-density lipoprotein-cholesterol and body weight. Also, there was an elevation in brain malondialdehyde with a marked reduction in brain levels of glutathione, superoxide dismutase, catalase, glutathione peroxidase, and glutathione-S-transferase. Furthermore, diabetic rats showed a clear reduction in plasma levels of insulin and an increase in plasma cytokines (interleukin-6 and tumor necrosis factor-α). Moreover, diabetic rats exhibited hyperalgesia as indicated by a hot plate, tail immersion, formalin, and carrageenan-induced edema tests as well as brain histopathological changes (neuron degeneration, gliosis, astrocytosis, congestion and hemorrhage). (-)-Epigallocatechin-3-O-gallate treatment ameliorated alterations in body weight, biochemical parameters, pain sensation, and histopathological changes in brain tissue. (-)-Epigallocatechin-3-O-gallate offers promising hypoglycemic, hypolipidemic, antioxidant and anti-inflammatory effects, which can prevent the development and progression of diabetic neuropathic pain.