不同电针频率刺激对胃扩张疼痛大鼠下丘脑内P物质、β-内啡肽表达的影响

摘要

Objective To observe the effect of different frequency electroacupuncture (EA) on hippocampal substance P (SP) and p-endorphin ((β-EP) in rats with gastralgia so as tp explore its underlying mechanism in preventing and relieving vis-ceral pain. Method Fifty rats were randomly divided into control, sham operation, model, low- frequency-EA and high frequen-cy-EA groups. Gastralgia model was duplicated by gastric distension (a pressure of 40 mmHg) with a latex balloon. Low (2 Hz) and high (100 Hz) frequency EA was applied to bilateral "Zusanli (ST 36)" for 30 min. Pain score was given by using Al-Chaer's method (abdominal withdrawal reflex) and the expression of hypothalamic p-EP and SP was detected by immunohistochemistry. Results Both low- and high-frequency EA of ST 36 could significantly lower the pain score (P<0. 01), and the effect of high-frequency EA was markedly superior to that of low-frequency ( P<0. 01). Compared with control and sham-operation groups, both SP immuno-reaction (IR) and P-EP IR positive cells in the hypothalamus in model group increased significantly in the number (P<0. 01), suggesting an upregulation of SP and p-EP expression after occurrence of gastralgia. In comparison with model group, the number of SP IR and P-EP IR positive cells in the hypothalamus in low frequency and high frequency EA groups in-creased further (P<0. 01) particularly in low frequency EA group. Conclusion Both low-frequency and high-frequency EA of "ZusanlKST 36)" can effectively relieve gastric distension-induced gastralgia in the rat, and the effect of high-frequency EA is bet-ter, which may be closely related to its actions in promoting the release and synthesis of hypothalamic p-EP and SP.%目的:通过比较不同电针频率刺激"足三里"对胃扩张疼痛大鼠的拟痛行为学评分和下丘脑内疼痛信息物质P物质(SP)、β-内啡肽(β-EP)的影响,阐明电针防治胃扩张疼痛可能的物质基础,探讨不同电针频率的效应差异.方法:50只大鼠完全随机分成空白组、假手术组、模型组、低频电针组和高频电针组,除空白组外采用胃内植入气囊并充气40 mmHg压力造成胃扩张疼痛模型,低频(2 Hz)和高频(100 Hz)电针刺激"足三里"为施治因素,观察大鼠拟痛行为学评分,用免疫组化法检测下丘脑组织中SP、β-EP的表达.结果:低、高频电针均能明显降低胃扩张疼痛大鼠的拟疼痛行为学评分,与针前比较差异有统计学意义(P<0.01);且高频电针组优于低频电针组(P<0.01).与空白组和假手术组比较,模型组下丘脑组织中SP、β-EP阳性细胞数明显增加(P<0.01),低、高频电针可使下丘脑组织中SP、β-EP阳性细胞数继续增加(P<0.01),且低频电针组的SP、β-EP阳性细胞数增加更明显(P<0.01).结论:不同电针频率刺激"足三里"均可减轻胃扩张疼痛大鼠的应激反应,这可能是通过促进了下丘脑内疼痛信息物质SP、 β-EP的合成与释放,从而发挥镇痛作用,且高频电针的镇痛效应优于低频针.