Effect of honey and insulin treatment on oxidative stress and nerve conduction in an experimental model of diabetic neuropathy Wistar rats

Abstract

Diabetic neuropathy is the most common complication affecting more than 50% of patients with longstanding diabetes. Till date, there are no reports to explain the scientific basis of alternative medicine as an adjunct therapy for treating diabetic neuropathy. Hence, we studied the effect of honey and insulin treatment on hyperglycemia, dyslipidemia, oxidant and anti-oxidant status and nerve conduction in experimental diabetic neuropathy Wistar rats. In this experimental study, forty healthy male Wistar albino rats of 10-12 weeks age, weighing between 150 to 200g were obtained from our institute central animal house. After acclimatization, the rats were divided into control (n = 8) and experimental (n = 32) groups randomly. In the experimental group, type 2 diabetic neuropathy was induced with high fat and high sugar diet for 8 weeks followed by streptozotocin at a dose of 35 mg/kg body weight. Three days after streptozotocin injection, blood glucose levels of rats were measured from fasting samples to confirm diabetes. After the development of diabetes, rats were given standard rodent chow and allowed four more weeks to remain diabetic and to develop neuropathy. Every second week, nerve conduction study was done to confirm neuropathy. All the diabetic rats of experimental group developed neuropathy after 4 weeks of developing diabetes, which was confirmed by significant reduction in conduction velocity of sensory and motor nerve when compared to non-diabetic control group. After the development of neuropathy, these rats were randomly divided into diabetic neuropathy with no treatment group (n = 8) and three treatment groups (n = 8, each). The rats of treatment group were administered with either honey or insulin or honey+insulin for six weeks. After six-weeks of intervention, there was significant decrease in blood glucose and lipids in honey, insulin and honey+insulin treated neuropathy rats, when compared with no treatment group. Malondialdehyde was reduced and total anti-oxidant status improved in all the three treatment groups. There was no significant increase in conduction velocity of sciatic tibial motor nerve in treatment groups when compared with no treatment group. However, the sensory nerve conduction velocity improved significantly in honey+insulin treated neuropathy rats. In conclusion, six-week honey treatment helped in reducing dyslipidemia and oxidative stress. Honey given along with insulin for six-weeks improved sensory nerve conduction velocity in experimental diabetic neuropathy Wistar rats.

Fig 1. Schematic representation of the experimental design.

Fig 2. Percentage change in TBW and FBG before and after six weeks of intervention in all the groups.

TBW: total body weight; FBG: Fasting blood glucose P value less than 0.05 were considered statistically significant. *Comparison with normal control group: *(P<0.05); **(P<0.01); ***(P<0.001), #Comparison with diabetic neuropathy control group:# (P<0.05); ## (P<0.01); ### (P<0.001), †Comparison with honey treated group: † (P<0.05); †† (P<0.01); ††† (P<0.001).

Fig 3. Percentage change in lipid profile before and after six weeks of intervention in all the groups.

TC: Total cholesterol; TG: Triglycerides; HDL: High density lipoprotein cholesterol; AIP: Atherogenic index of plasma; P value less than 0.05 were considered statistically significant. *Comparison with normal control group: *(P<0.05); **(P<0.01); ***(P<0.001), #Comparison with diabetic neuropathy control group:# (P<0.05); ## (P<0.01); ### (P<0.001), †Comparison with honey treated group: † (P<0.05); †† (P<0.01); ††† (P<0.001).

Fig 4. Percentage change in MDA and TAS before and after six weeks of intervention in all the groups.

MDA: Malondialdehyde; TAS: Total antioxidant status; P value less than 0.05 were considered statistically significant. *Comparison with normal control group: *(P<0.05); **(P<0.01); ***(P<0.001), #Comparison with diabetic neuropathy control group:# (P<0.05); ## (P<0.01); ### (P<0.001), †Comparison with honey treated group: † (P<0.05); †† (P<0.01); ††† (P<0.001).

Fig 5. Percentage change in Neuron specific enolase (NSE) before and after six weeks of intervention in all the groups.

P value less than 0.05 were considered statistically significant. *Comparison with normal control group: *(P<0.05); **(P<0.01); ***(P<0.001), #Comparison with diabetic neuropathy control group:# (P<0.05); ## (P<0.01); ### (P<0.001).