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目的:本实验旨在研究外周炎症下下丘脑弓状核(hypothalamic arcuate nucleus,ARC)小胶质细胞在其中的作用。方法:雄性SD大鼠采用随机数字法,将其分为4组:假炎症组(S组)、炎症痛组(CFA组)、生理盐水组(NS组)和米诺环素组(M组)。CFA组、NS组和M组采用大鼠左侧后肢足垫皮内注入完全弗氏佐剂(complete Freund’s adjuvant,CFA)0.1 m L/只制备大鼠炎症性痛模型;S组大鼠左侧后肢足垫皮内注入生理盐水(NS)0.1 m L/只。注入后第3天时,NS组和M组分别于下丘脑弓状核内注射生理盐水或米诺环素0.5μL。各组取7只大鼠,分别于注射前1天(T0)、注射后第2天(T1)、第3天给药前30 min(T2)、第3天给药后30 min(T3)、第5天(T4)和第7天(T5)时测定机械痛阈。于T1-5时各处死6只大鼠,取下丘脑弓状核组织,行Western Blot检测小胶质细胞含量。结果:与S组比较,CFA组、NS组和M组T1-5时机械痛阈降低,小胶质细胞表达水平升高(P<0.05);CFA组和NS组各时点机械痛阈和小胶质细胞含量差异无统计学意义(P>0.05);与CFA组和NS组比较,M组T3时机械痛阈升高,小胶质细胞表达水平降低(P<0.05)。结论:下丘脑弓状核小胶质细胞的活化参与了大鼠炎症性痛的形成与维持。
Objective: This study aimed to investigate the role of hypothalamic arcuate nucleus (ARC) microglia in peripheral inflammation. Methods: Male Sprague - Dawley rats were randomly divided into four groups: sham group (S group), inflammatory pain group (CFA group), saline group (NS group) and minocycline group (M group ). CFA group, NS group and M group were infused with complete Freund’s adjuvant (CFA) 0.1 m L / rat in the left hind paw footpad to prepare inflammatory pain model in rats; Hindlimb footpad intradermal injection of saline (NS) 0.1 m L / only. On the 3rd day after injection, NS and M groups were injected with 0.5 μL of normal saline or minocycline into the arcuate nucleus of hypothalamus, respectively. Seven rats in each group were injected intraperitoneally with the rats in each group at the first day before injection (T0), on the second day after injection (T1), 30 min before the third day (T2) and 30 min after the third day (T3) , On day 5 (T4) and on day 7 (T5). Six rats were sacrificed at T1-5, and the arcuate nucleus of the hypothalamus was removed. The content of microglia was detected by Western Blot. Results: Compared with group S, the mechanical pain threshold and the microglia level were increased at T1-5 in CFA group, NS group and M group (P <0.05) Compared with CFA group and NS group, the mechanical pain threshold increased and the microglia expression level decreased in group M at T3 (P <0.05). Conclusion: The activation of hypothalamic arcuate nucleus microglia is involved in the formation and maintenance of inflammatory pain in rats.