Enhancement of the Neuroprotective Effect of Curcumin in Combination with Piperine in Nicotinamide-Streptozotocin Induced Diabetic Rats.

Introduction: Curcumin (CUR) is a hydrophobic molecule with poor bioavailability.Piperine is reported to enhance the bioavailability of drugs by increasing absorption in the small intestine and decreasing glucuronidation in the liver.Objective:The objective of the present investigation was to evaluate the neuroprotectiveeffect of curcuminincombinationwith piperine innicotinamide- streptozotocin (NIC-STZ) induced diabetic rats.Methods:MaleWistar rats were divided into groups viz.vehicle control, disease control,glibenclamide (1), glibenclamide+ piperine(1+50), curcumin (50) and curcumin (50) with piperine10, 30 and 50.All the groups except vehicle control were induced diabetes by injecting NIC-STz. The animals received treatment daily for six weeks after the confirmation of diabetic status.Behavioural, biochemical and histological parameters were evaluated to access the neuroprotective effect.Results: Oral administration of curcumin + piperine (50+50 mg/kg) caused a significant fall in blood glucose level. Disease control showed increased paw withdrawal latency and nociceptive threshold compared with vehicle control. Curcumin + piperine treated animals showed decreased paw withdrawal latency. Combination of curcumin + piperine (50+50 mg/kg, p.o.) showed significant antioxidant property by increasing tissue GSH and SOD and lowering lipid content (MDA) compared to the disease control group. The histopathological study showed reduced damage to the sciatic nerve in curcumin + piperine (50+50 mg/kg, p.o.) treated group.Conclusion: Itis concluded that the curcumin-piperine combination reducedthe degeneration of sciatic nerve by reduction of lipid peroxidation and lowering oxidative stress indicating the neuroprotective effect in diabetic neuropathy