脊髓星形胶质细胞在创伤后应激障碍诱发痛觉过敏中的作用

Role of spinal astrocytes in posttraumatic stress disorder-induced hyperalgesia in rats

目的 评价脊髓星形胶质细胞在创伤后应激障碍诱发痛觉过敏中的作用.方法 清洁级健康雄性SD大鼠40只,6～8周龄,体重200～250 g,采用随机数字表法分为4组（n=10）：对照组（C组）、创伤后应激障碍组（PTSD组）、生理盐水组（NS组）和氟代柠檬酸组（FC组）.PTSD组、NS组和FC组采用单次延长应激法建立创伤后应激障碍模型.分别于造模前30 min和造模后1～7 d,NS组鞘内注射生理盐水10 μl,FC组鞘内注射1 nmol∕10 μl星形胶质细胞活化抑制剂氟代柠檬酸10 μl.分别于造模前24 h、造模后1、2、3、5和7 d时测定机械缩足反应阈（MWT）.分别于造模后1和7 d痛阈测定结束后取4只大鼠,取L3-5节段脊髓,采用Western blot法测定星形胶质细胞标记物胶质纤维酸性蛋白（GFAP）表达水平.结果 与C组比较,PTSD组、NS组和FC组造模后各时点MWT降低,造模后1和7 d时脊髓GFAP表达上调（P〈0.05）;与PTSD组比较,NS组各时点MWT差异无统计学意义（P〉0.05）,FC组造模后各时点MWT升高,造模后1和7 d时脊髓GFAP 表达下调（P〈0.05）.结论 脊髓星形胶质细胞活化参与了创伤后应激障碍诱发大鼠痛觉过敏的过程.

Objective To evaluate the role of spinal astrocytes in posttraumatic stress disorder （PTSD）-induced hyperalgesia in rats. Methods Forty pathogen-free healthy male Sprague-Dawley rats, aged 6-8 weeks,weighing 200-250 g, were divided into 4 groups（n=10 each）using a random number table：control group（group C）, group PTSD, normal saline group（group NS）and fluorocitrate group （group FC）.The rats were exposed to single prolonged stress for establishment of the PTSD model in PTSD, NS and FC groups. At 30 min before establishment of the model and 1-7 days after establishment of the model,normal saline 10 μl was intraperitoneally injected in group NS, and 1 nmol∕10 μl fluorocitrate 10 μl, an inhibitor of astrocyte activation, was intraperitoneally injected in group FC. The mechanical paw withdrawal threshold（MWT）was measured at 24 h before establishment of the model and on 1, 2, 3, 5 and 7 days after establishment of the model. Four rats were sacrificed after measurement of pain threshold on 1 and 7 days after establishment of the model, and the lumbar segment（L3-5）of the spinal cord was re-moved for determination of the expression of glial fibrillary acidic protein（GFAP, an astrocyte marker）u-sing Western blot. Results Compared with group C, the MWT was significantly decreased at each time point after establishment of the model,and the expression of spinal GFAP was up-regulated on 1 and 7 days after establishment of the model in PTSD,NS and FC groups（P〈0.05）. Compared with group PTSD, no significant change was found in the MWT at each time point in group NS（P〉0.05）,and the MWT was sig-nificantly increased at each time point after establishment of the model,and the expression of spinal GFAP was down-regulated on 1 and 7 days after establishment of the model in group FC（P〈0.05）.Conclusion Activation of spinal astrocytes is involved in PTSD-induced hyperalgesia in rats.