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目的观察损毁炎症大鼠下丘脑弓状核(ARC)对炎症大鼠痛觉过敏的影响。方法用完全弗氏佐剂(CFA)建立大鼠外周组织炎症模型;采用新生期大鼠注射谷氨酸单钠(MSG)破坏ARC神经元或电解损毁成年大鼠的ARC;用辐射热-缩腿法测定炎症大鼠热痛阈的变化,用von Frey法测定机械痛阈的变化。结果 (1)大鼠在注射CFA后热痛阈和机械痛阈均明显降低,出现痛觉过敏,3h达到高峰,到第3天有所恢复并且稳定维持痛觉过敏状态,一直维持到本实验观察的第14天;(2)新生期注射MSG的大鼠在注射CFA后3h,热痛阈和机械痛阈也明显降低,出现痛觉过敏,但其痛阈降低的幅度明显小于注射高渗盐水对照的CFA组;(3)CFA炎症大鼠在电解损毁ARC之后,其热痛阈和机械痛阈与假损毀组相比,均明显上升,即痛觉过敏减轻。结论在外周存在炎症条件下,两种方法损毁ARC都能减轻痛觉过敏。提示ARC参与外周组织炎症引起的痛觉过敏,对痛觉过敏的发生有下行易化作用。
Objective To observe the effect of hypothalamic arcuate nucleus (ARC) on inflammatory hyperalgesia in inflammatory rats. Methods Peroxisome proliferator-activated protein kinase (CFA) was used to establish the peritoneal inflammation model in rats. ARC was used to injurinate ARC neurons in neonatal rats injected with monosodium glutamate (MSG) or electrolyzed to destroy ARC in adult rats. The leg pain method was used to measure the change of thermal pain threshold in vomiting rats, and the von Frey method was used to measure the changes of mechanical pain threshold. Results (1) The thermal pain threshold and mechanical pain threshold of rats after CFA injection were significantly decreased, hyperalgesia occurred, reached the peak at 3h, recovered to the third day and maintained the hyperalgesia state continuously until the experimental observation On the 14th day, (2) In the neonatal rats injected with MSG, the pain thresholds and mechanical pain thresholds were significantly decreased at 3h after injection of CFA. Hyperalgesia was observed but the extent of decrease in pain threshold was significantly less than that of the rats injected with hypertonic saline CFA group. (3) Compared with sham-operated group, the thermal pain threshold and mechanical pain threshold of CFA-inflamed rats after electrolytic destruction of ARC were significantly increased, that is, the relief of hyperalgesia. Conclusion Under the circumstance of inflammatory condition, both methods can reduce the hyperalgesia by damaging ARC. It is suggested that ARC participates in hyperalgesia caused by inflammation in peripheral tissues and has a downward easing effect on the occurrence of hyperalgesia.