OBJECTIVETo observe the change of neuronal nitric oxide synthase (nNOS) expression in the spinal cord of diabetic rats with painful diabetic neuropathy.

METHODSSixty SD rats were randomized equally into painful diabetic neuropathy group (DM group) and control group. Painful diabetic neuropathy was induced by intraperitoneal injection with STZ (60 mg/kg) in DM group, and the rats in the control group received a solvent injection. Blood glucose levels were measured before and at 2, 7, 14, 21, and 28 days after STZ injection (T1-6 respectively). Responses to the mechanical stimulus were measured with von Frey filament, and 50% paw withdraw threshold (PWT) and body weight were recorded at T1 and T3-6. At T1 and T3-6, 6 rats from each group were sacrificed to examine the expression of nNOS in the lumbar segments of the spinal cord using Western blotting.

RESULTSThe level of blood glucose increased while the body weight decreased significantly after STZ injection in DM group (P<0.05). Comparing to those in the control group, PWT decreased while spinal nNOS expression increased significantly in DM group at T4-6 (P<0.05) showing an inverse correlation between them (P<0.01).

CONCLUSIONThe enhanced expression of spinal nNOS might be involved in the pathogenesis of painful diabetic neuropathy in rats.