Change in microglia activation in spinal cord in a rat model of diabetic neuropathic pain

Objective To investigate the change in microglia activation in the spinal cord in a rat,model of diabetic neuropathie pain. Methods Twenty 2-month old SD rats of both sexes weighing 180-200g were divided into 2 groups（ n = 10 each）： group Ⅰ normal control （NC） and group Ⅱ diabetes mellitus （DM）. Diabetes mellitus was induced by intraperitoneal （IP） streptozotocin （STZ） 60 mg/kg and confirmed by blood glucos level〉 16.7 mmol/L. Body weight and blood glucose were measured before （T1） and at 2, 7, 14, 21, 28 day after STZ IP injection （T2-6）. Paw withdrawal threshold to van Frey filament stimulation was measured at T1 and T3-6 . The animals were killed and lumbar segments of the spinal cord were removed for determination of expression of complement receptor 3 （CR3） in mieroglia in the spinal cord by immuno-histoehemieal assay. Results The blood glucose level was significantly increased While body weight was significantly decreased after IP STZ injection as compared with the baseline before STZ injection in group DM. The blood glucose level was significantly higher and body weight significantly lower after STZ injection in group DM than in group NC. The Paw withdrawal threshold was significantly decreased after STZ at T4-6 as compared with the baseline at T1 in group DM and was significantly lower than in group NC. Immuno-histoehemistry demonstrated that the expression of CR3 in mieroglia in the dorsal horn was significantly up-regulated after STZ injection in group DM. Conclusion Mieroglia activation is involved in the pathogenesis of diabetie neuropathie pain. Key words: Diabetic neuropathy ;  Neuralgia;  Spinal cord ;  Mieroglia