In possible neuroprotective effect of 20(S) ginsenoside RG3 in experimental model of diabetes in rats

Ginseng is an herbal agent that has an antidiabetic, anti-inflammatory, antioxidant, and antiapoptotic activities. 20(S)-ginsenoside Rg3 (20(S)-Rg3), an active ingredient of ginseng saponins, has been reported to enhance insulin secretion in pancreatic beta cells and to have protective effects on diabetic renal damage. This study aims to evaluate the neuroprotective effects of 20(S)-Rg3 in experimental diabetic neuropathy. Adult male Wistar rats (n=18) were randomly assigned for control, untreated diabetic and 20(S)-Rg3 treated diabetic groups. Diabetes was induced by a single intraperitoneal injection of STZ (50 mg/kg), and 3 days after the STZ injection diabetes was assigned by the presence of hyperglycemia (>250 mg/dl). Rats in 20(S)-Rg3 treated group received a 5mg/kg/day dose of 20(S)-Rg3 by oral gavage for 5 weeks. Body weights of the rats in the study groups were monitored daily. Tail flick and hot plate tests were conducted to record nociceptive changes at 3rd and 4th week of treatment. Nerve conduction velocities (NCV) and distal latencies were determined in both sciatic nerves. STZ-induced diabetes caused a decrease in body weight while 20(S)-Rg3 treatment restored this decrement. Moreover, ginsenoside treatment significantly reduced plasma glucose levels compared to pretreatment states (p<0.05). Also 20(S)-Rg3 decreased both tail flick and hot plate latencies significantly in diabetic rats revealing its protection against nociceptive behavior. Diabetic rats showed a significant decrease (p<0.001) in NCV and distal latencies as compared to the control rats. However, NCVs and distal latencies were improved by the treatment of 20(S)-Rg3. In conclusion, these findings highlighted the possible neuroprotective effects of 20(S)-Rg3 treatment on diabetic neuropathy.