Neuroprotective effects of Gymnema sylvestre on streptozotocin-induced diabetic neuropathy in rats

Abstract

Abstract. The application of traditional medicine for diabetes and associated complications, such as diabetic neuropathy (DN), has received increasing attention. The aim of the present study was to investigate the potential ameliorative effect of Gymnema sylvestre (Gs) in a rat model of DN. Diabetes was induced via a single intraperitoneal injection of streptozotocin (STZ; 60 mg/kg). Treatment with Gs extract (50 or 100 mg/kg/day) began two weeks following the administration of STZ and was continued for five weeks. Pain threshold behavior tests were performed subsequent to the five-week Gs treatment period. In addition, the serum levels of glucose, insulin and proinflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, were determined. Furthermore, the sciatic tissue levels of nitric oxide, thiobarbituric acid reactive substances and reduced glutathione were determined, as well as the activity levels of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. Levels of insulin-like growth factor (IGF), nerve growth factor (NGF), TNF-α, IL-1β and IL-6 were also assessed in the sciatic tissue. In addition, the sciatic nerve tissue samples were analyzed for histopathological alterations. The diabetic rats exhibited apparent reductions in the paw-withdrawal (31%; P<0.01) and tail-flick latencies (38%; P<0.05). Furthermore, the diabetic rats demonstrated an evident elevation in serum and sciatic levels of proinflammatory cytokines. Measured oxidative stress biomarkers were significantly altered in the sciatic nerve tissue of the diabetic rats. Treatment with Gs attenuated diabetes-induced modifications with regard to the levels of serum glucose, insulin and proinflammatory cytokines. In the sciatic nerve tissue, the diabetes-induced alterations in IL levels and oxidative stress biomarkers were significantly improved in the Gs-treated rats. Furthermore, the reduction in the sciatic tissue expression levels of IGF and NGF was also ameliorated by Gs treatment. Histological analysis indicated that Gs corrected the sciatic tissue in the diabetic rats. Therefore, the results demonstrated that the neuroprotective effect of Gs may be associated with the inhibitory effect on the excessive activation of inflammatory molecules and oxidative stress mediators.

Exploring the Potential of Traditional Herbs in the Management of Diabetic Retinopathy: An Overview

“…Several studies have proven this fact that the gymnemic acids present in the plant are effective in reducing glucose level. Hence it has been speculated that this effect could be utilized for the treatment of diabetic retinopathy [70,71].…”

Phytochemicals, Management of Diabetic Peripheral Neuropathy, Experimental Evidences

“…GS at 100 mg/kg body weight was observed to induce attenuation in diabetes-induced biochemical and histopathological alterations in the sciatic nerves of rats [39].…”

Exogenous neuregulin-1 attenuates STZ-induced diabetic peripheral neuropathic pain in rats

“…Nerve growth factor (NGF), normally synthesized in neuronal target tissues and retrogradely transported to the neuronal cell body to exert its trophic functions, is essential for the survival and maintenance of sympathetic and sensory nerves 21,22 . It can stimulate the growth of axon, maintain the diameter of axon, prevent the death of adult neurons after injury, regulate the plasticity of synaptic and the transmission of neurotransmitter.…”