Protective effect of ethanolic extract of Shorea robusta resin in streptozotocin induced diabetic rat model of neuropathy

Abstract

Chronic pain such as peripheral neuropathy is the major complication in long term hyperglycemia. The present context was conducted to explore the protective effect of ethanolic extract of S. robusta resin (SRE) in diabetes associated pain in rats as resin has phenolic components, hypoglycemic and anti-oxidative properties. Pure resin was extracted with 70% ethanol using a Soxhlet apparatus and evaporated under rotary vacuum evaporator. Diabetic peripheral neuropathy rat model was generated by single intraperitoneal injection of streptozotocin (STZ). Rats were treated for 8 week as follows: normal control with vehicle, normal with SRE (300 mg/kg), Diabetic control with vehicle and Diabetic with SRE (30,100 and 300 mg/kg). To evaluate the effects various parameters, including nociceptive response (tail flick and formalin test), oxidative status [super oxide dismutase (SOD), catalase, lipid peroxidation (MDA) and nitric oxide (NO)] and histopathology (H&E) were assessed. Behavioral assessment showed significant hyperalgesia in diabetic rats but long term administration of SRE caused a concentration dependent increase in pain threshold, restored the activity of SOD and catalase activity, as well as reduced the MDA and NO level significantly (p<0.05). Furthermore diabetic rats exhibited loss of myelin sheath, loose and disorganized sciatic nerve fibers these changes were also ameliorated in treatment groups. In conclusion the results suggest that S. robusta resin can limit neurodegenerative changes in sciatic nerve by suppression of STZ-induced hyperglycemia associated oxidative stress may represent promising agents to improve peripheral nervous system functioning.