Yohimbine protects against endotoxin-induced acute lung injury by blockade of alpha 2A adrenergic receptor in rats
Yohimbine protects against endotoxin-induced acute lung injury by blockade of alpha 2A adrenergic receptor in rats
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DOI：
10.3760/cma.j.issn.0366-6999.2011.07.022
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发表时间：
2011-04-05
影响因子：
6.1
通讯作者：
Chen Li
中科院分区：
文献类型：
--
作者：
Lin Ying;Zhu Xi;Chen Li
α 2A肾上腺素能受体（Alpha 2A adrenergic receptor， AR）是α 2 AR的亚型，属于G蛋白偶联受体，具有多种生物学作用。近年来的研究表明，α 2A AR的激活与炎症反应密切相关。本研究旨在探讨α 2A AR拮抗剂育亨宾对内毒素诱导的大鼠急性肺损伤严重程度的影响。方法雄性sd大鼠72只，随机分为对照组、脂多糖（LPS）组和脂多糖+育亨宾组。大鼠气管内灌胃生理盐水或LPS (300 μ g)， LPS +育亨宾组大鼠在给药后立即加用育亨宾（2 mg/kg, i.p）。治疗后6、24、48 h行动脉血气分析，光学显微镜观察肺病理变化，并进行肺损伤评分。测定支气管肺泡灌洗液（BALF）白细胞计数。采用酶联免疫吸附法测定BALF中去甲肾上腺素、肿瘤坏死因子(TNF)- α、白细胞介素(IL)-1 β和IL-6的水平。免疫细胞化学检测BALF炎症细胞α 2A AR。结果与对照组比较，LPS组大鼠肺氧合指数显著降低，白细胞计数、肺组织病理学评分、去甲肾上腺素、IL-6水平及BALF炎症细胞α 2A AR表达均显著升高，除LPS给药后48 h外，tnf - α和IL-1 β浓度均升高。LPS +育亨宾组肺氧合指数降低，BALF白细胞计数和肺组织病理学评分明显升高。LPS +育亨宾组BALF中去甲肾上腺素水平在每个时间间隔均升高，LPS给药后6和48 h tnf - α、IL-1 β和IL-6水平也升高。与LPS组比较，LPS +育himine组各时间间隔的氧合指数、白细胞计数、肺组织病理学评分和IL-6水平均显著提高，LPS给药24 h时tnf - α和IL-1 β浓度均降低（P < 0.05）。相关分析表明去甲肾上腺素水平是tnf水平相关,il - 1β和BALF中il - 6和肺组织病理学评分(r = 0.703, r = 0.595, r = 0.487和r = 0.688, P < 0.001)和免疫反应性的强度得分上α2 AR炎症细胞也与tnf水平相关,il - 1β和il - 6以及肺histopathologial分数(r = 0.803, r = 0.978, r = 0.716和r = 0.808, P < 0.001)。结论育亨宾可抑制tnf - α、IL-1 β和IL-6的过量产生，减轻内毒素所致肺部炎症的严重程度，其机制可能是通过阻断炎性细胞的α 2A AR介导的。中华医学杂志2011；124 (7): 1069 - 1074
Background Alpha 2A adrenergic receptor (AR) is a subtype of alpha 2 AR belonging to G protein-coupled receptors, and exerts a variety of biological effects. Recent studies have demonstrated that the alpha 2A AR activation was closely related with inflammatory reaction. The present study aimed to investigate the influence of alpha 2A AR antagonist, yohimbine, on the severity of endotoxin-induced acute lung injury in rats.Methods A total of 72 male Sprague-Dawley rats were randomly divided into three groups: control group, lipopolysaccharide (LPS) group and LPS + yohimbine group. Rats were intratracheally administrated with normal saline or LPS (300 mu g), and the rats in the LPS + yohimbine group were treated with additional yohimbine (2 mg/kg, i.p) soon after LPS administration. Six, 24 and 48 hours after treatment, arterial blood gas analysis was carried out, and optical microscopy was performed to evaluate pathological changes in the lung, and lung injury score was assessed. The count of white blood cells in bronchoalveolar lavage fluid (BALF) was determined. The levels of norepinephrine, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta and IL-6 in BALF were measured with enzyme-linked immunosorbent assay. Immunocytochemistry was performed for the detection of alpha 2A AR on inflammatory cells in BALF.Results When compared with the control group, the oxygenation index in the LPS group was significantly decreased, and white blood cell count, the lung histopathological scores, levels of norepinephrine and IL-6 as well as alpha 2A AR expression on inflammatory cells in the BALF were dramatically increased at different time points, and the concentrations of TNF-alpha and IL-1 beta were also increased except at 48 hours after LPS administration. The oxygenation index decreased while white blood cell count in BALF and the lung histopathological scores were obviously increased in the LPS + yohimbine group. The level of norepinephrine in BALF was increased at each time interval in the LPS + yohimbine group, and so did the levels of TNF-alpha, IL-1 beta and IL-6 at 6 and 48 hours after LPS administration respectively. When compared with the LPS group, the oxygenation index, white blood cell count, the lung histopathological scores and the level of IL-6 in the LPS + yohimbine group were significantly improved at each time interval, and the concentrations of TNF-alpha and IL-1 beta were also lower at 24 hours of LPS administration (all P < 0.05). Correlation analysis indicated the level of norepinephrine was related to the levels of TNF-alpha, IL-1 beta and IL-6 in the BALF and the lung histopathological scores (r=0.703, r=0.595, r=0.487 and r=0.688, respectively, P < 0.001) and the intensity scores of immunoreactivity to alpha 2A AR on inflammatory cells were also associated with the levels of TNF-alpha, IL-1 beta and IL-6 as well as the lung histopathologial scores (r=0.803, r=0.978, r=0.716 and r=0.808, respectively, P < 0.001).Conclusions Yohimbine can inhibit TNF-alpha, IL-1 beta and IL-6 overproduction and relieve the severity of pulmonary inflammation induced by endotoxin, which is maybe mediated by blockade of alpha 2A AR on inflammatory cells. Chin Med J 2011;124(7):1069-1074