NOS2 and diabetic neuropathy: Represents the effect of berbamine (BBM), bergapten (BRG), carveol (CAR), and pregabalin (PBN) on streptozotocin (STZ)-induced diabetic neuropathy and expression of glutathione (GSH), glutathione s-transferase (GST), inducible nitric oxide (iNOS), and lipid peroxidase (LPO) in the sciatic nerve and spinal cord.