Schefflera arboricola Tablets Relieve Diabetic Neuropathic Pain: Involvement of Oxidative Stress and Inflammation

Abstract

Background: Diabetic neuropathic pain (DNP) is a serious chronic complication of diabetes mellitus. Oxidative stress and inflammation are considered the central mechanisms of its pathogenesis. Schefflera arboricola (SA) is a Schefflera plant of the Araliaceae family that has the effect of pain relief. In this study, the effect of SA on DNP was first investigated.Materials and Methods: Diabetic neuropathy in rats was induced by a single injection of streptozotocin (60 mg/kg). Three weeks later, SA (100 mg/kg, 300 mg/kg) or gabapentin (100 mg/kg) was given once a day for a week. Blood glucose, body weight, and thermal withdrawal latency in DNP rats were measured. The morphology of the sciatic nerve was observed by light microscopy and toluidine blue staining. Semiquantitative analysis of myelin basic protein (MBP) of the sciatic nerve was performed by immunohistochemistry. IL-1β, tumor necrosis factor-alpha (TNF-α), and IL-6 were detected by enzyme-linked immunosorbent assay. Commercial reagent kits were used to detect inducible nitric oxide synthase, superoxide dismutase (SOD), and malondialdehyde (MDA). The expression levels of nuclear factor erythroid-2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB) were detected by Western blot.Results: DNP rat model was successfully constructed. SA and gabapentin could alleviate the thermal sting pain of DNP rats, increase the expression of MBP and SOD, and decrease the expression of proinflammatory agents and MDA. Moreover, SA could reverse the upregulation of NF-κB and the downregulation of Nrf2.Conclusion: SA has a significant protective effect on DNP, manifesting in the improvement of allodynia and sciatic nerve pathology, inhibition of neuroinflammation, reduction of oxidative stress, enhancement of Nrf2, and inhibition of NF-κB.

Keywords: Diabetic neuropathic pain; oxidative stress; inflammation; Schefflera arboricola; sciatic nerve