THE RESPONSE OF ASTROCYTES IN SPINAL CORD IN STREPOZOTOCIN-INDUCED DIABETIC RAT MODEL WITH PAINFUL DIABETIC NEUROPATHY

Objective: To evaluate the astroglial response in spinal cord in the streptozotocin (STZ)-induced diabetic rat model with painful diabetic neuropathy. Methods: Painful diabetic neuropathy was induced by intraperitoneal injection of STZ in 10 Sprague-Dawley rats (group Ⅱ),10 age-matched healthy rats were served as control group (group I). The blood samples were collected from vena caudalis to assess the blood glucose level before STZ injection and 2d,7d,14d,21d,28d after STZ injection. Body weights were measured at the same time points. Responses to the mechanical stimulus were measured with von Frey filament,and 50% paw withdraw threshold (PWT)was recorded before STZ injection and 7 d,14 d,21d,28d after STZ injection. At 28d after STZ injection,the animals were sacrificed and lumbar segments of spinal cord were collected for analysis of glial fibrillary acidic protein (GFAP) in the astrocytes in spinal cord by immuno-histochemical assay. Results: The level of blood glucose increased dramatically after STZ injection in group Ⅱ while the body weight decreased. The PWT in group Ⅱ decreased significantly comparing to group I at 21～28 d after STZ injection. Immuno-histochemical assay demonstrated that GFAP positive astrocytes in the dorsal horn significantly increased at 4W after STZ injection. Conclusion: Astrocytes activation may be involved in the pathogenesis of painful diabetic neuropathy.