β淀粉样肽前体蛋白N端319～335肽段APP17肽对糖尿病大鼠外周神经损伤的防治作用

目的　研究β淀粉样肽前体蛋白中的319～335肽段(APP17肽)对糖尿病大鼠神经病变的保护作用。方法　链脲佐菌素诱发大鼠糖尿病，皮下注射APP17肽4周，测定痛阈及大鼠坐骨神经肌电图，并取脊髓组织冰冻切片做NT3和NF免疫组化染色。结果　用APP17肽的糖尿病大鼠组的潜伏期及传导速度较糖尿病组显著加快，其痛阈较糖尿病组有提高(P<0.05)。免疫组化染色脊髓前角区大多角细胞神经元NT3和NF表达接近正常大鼠，阳性细胞计数及色素数值(反应染色强度)与糖尿病组比较P<0.05。结论　糖尿病大鼠坐骨神经的传导速度减慢,潜伏期延长,痛阈降低，其脊髓前角区运动神经元NT3与NF的表达明显减少。而给予APP17肽的大鼠组，在所观察的指标均接近正常组，提示APP17肽具有防治糖尿病神经元病变的功效。

Effect of APP17 peptide on peripheral nerve injury of diabetic rat

Objectives To study the protective action of APP17 peptide on neurons changes of diabetic rat. Methods After the creation of the STZ induced rat diabetic model,APP17 peptide was injected subcutaneously for 4 weeks,pain threshold and conduction velocity along sciatic nerve in EMG were measured,cryostat section of the spinal cord were prepared and stained for NT3 and NF immunohistochemically.Results On EMG of the sciatic nerve,the latent period was shorter and the neural conduction velocity was faster in the diabetic rats treated with APP17 peptide than the untreated.The pain threshold was also higher among the treated than in the untreated ( P <0.05).In the treated group immunohistochemical staining of the anterior horn neurons for NT3 and NF was the same as that in normal rats; the number of positively stained cells was much more, and the pigment value were much higher,that of than untreated diabetic rats ( P <0.05).Conclusion In diabetic rats,the sciatic nerve shows a longer latent period, a slower conduction velocity, a lowered pain threshold and diminished expression of NT3 and NF in the motor neurons in the anterior horn.The above mentioned changes were almost normalized in diabetic rats given APP17 peptide,indicating that APP17 peptide is active in preventing and treating neural pathology due to diabetes.