Changes in autophagy in spinal neurons of rats with diabetic neuropathic pain

Objective To evaluate the changes in autophagy in spinal neurons of rats with diabetic neuropathic pain (DNP).Methods Forty-eight male Sprague-Dawley rats,weighing 220-250 g,were randomly divided into control group (group C,n =8) and group DNP (n =40) using a random number table.Diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin (STZ) 60 mg/kg.Before STZ injection and at 1,2,4,and 8 weeks after STZ injection,8 rats randomly chosen from each group were used to measure mechanical pain threshold.The animals were sacrificed after measurement of mechanical pain threshold and the spinal cords were removed for determination of the expression of LC3-Ⅰ,LC3-Ⅱ,Beclin-1 and p62 protein.LC3-Ⅱ/LC3-Ⅰ ratio was calculated.Results Compared with group C,mechanical pain threshold was significantly decreased at 2,4,and 8 weeks after STZ injection in group DNP.The expression of LC3-Ⅱ and Beclin-1 in the spinal cord was significantly up-regulated,p62 protein expression was down-regulated,and LC3-Ⅱ/LC3-Ⅰ ratio was increased at 2,4,and 8 weeks after STZ injection as compared with the baseline value before STZ injection in group DNP.Conclusion Enhanced autophagy in spinal neurons may be involved in the development and maintenance of DNP in rats. Key words: Diabetes mellitus ;  Neuralgia;  Autophagy ;  Spinal cord ;  Neurons