P38MAPK和PI3K/Akt信号通路在大鼠糖尿病神经病理性疼痛中的交互作用

The interaction of p38MAPK and PI3K/Akt signal pathway in rats with diabetic neuropathic pain

目的观察p38MAPK和PI3K/Akt信号通路在大鼠糖尿病神经病理性疼痛中的交互作用。方法 Wistar大鼠腹腔单次注射链脲菌素65mg/kg制作糖尿病神经病理痛模型。4周后用vonfrey纤维测双后足机械痛阈,痛阈明显下降为糖尿病神经病理性疼痛造模成功。将96只成模大鼠随机均分为三组:糖尿病神经病理痛组(D组),PI3K抑制药组(E组)和p38MAPK抑制药组(F组)。另取同窝大鼠32只作为对照组(C组)。成模后的每周周一,E组和F组大鼠分别静脉注射PI3K抑制药Wortmannin0.5mg/kg和p38MAPK抑制药SB2035801mg/kg,直至处死大鼠。于给药前(T1)和给药后第2周末(T2)、第4周末(T3)、第6周末(T4)分别随机取8只大鼠,检测机械缩足反应阈值(MWT)、神经传导速度(NCV)、脊髓和背根神经节(DRG)磷酸化Akt(p-Akt)水平和磷酸化p38MAPK(p-p38MAPK)水平。结果与C组比较,D、E和F组在T1～T4时MWT下降,NCV减慢,p-Akt和p-p38MAPK水平升高(P<0.05);与D组比较,E和F组在T2～T4时MWT升高,NCV增快,E和F组p-Akt明显下降,F组p-p38MAPK水平明显下降(P<0.05)。结论 P38MAPK通过激活其下游的PI3K/Akt信号通路参与了糖尿病大鼠神经病理痛的形成和维持。

Objective To investigate the interaction of p38MAPK and PI3K/Akt signal pathway in rats with diabetic neuropathic pain. Methods Diabetic neuropathic pain animal model was established in Wistar rats via single intraperitoneal injection of streptozocin 65 mg/kg. Mechanical withdrawl threshold（NWT） of bilateral hind foot was measured by von frey fibers after 4 weeks. Diabetic neuropathic pain model was confirmed when pain threshold decreased significantly. Ninetysix rats with diabetic neuropathic pain were equally randomized into 3 groups of diabetic neuropathic pain（D）, PI3K inhibitor（E）, and p38MAPK inhibitor（F）. Another 32 rats were taken from the same litter served as the controls（group C）. PI3K inhibitor Wortmannin 0. 5 mg/kg was intravenously administrated in group E and p38MAPK inhibitor SB203580 1 mg/kg in group F on every monday until the rats were sacrificed. Eight rats were randomly taken for the determinations of MWT, nerve conduction velocity（NCV）, and levels of p-Akt and p-p38MAPK in spinal cord and dorsal root gangtion（DRG） before administration and on the 2nd, 4th, 6th weekend following administration, respectively. Results Compared with group C, MWT and NCV were lower, while p-Akt and p- p38MAPK levels were higher,in groups of D, E,and F at T1-4 （P〈0. 05）. Compared with group D, MWT and NCV increased at T2-4 and p-Akt decreased in groups of E and F, while p-p38MAPKD decreased in group F （P〈0.05 ）. Conclusion P38MAPK is involved in the development and maintenance of diabetic neuropathic pain by the activation of downstream signal transduction pathway of PI3K/Akt in rats.