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延髓头端腹外侧区肾上腺髓质素参与中脑导水管背侧周围灰质电刺激诱发防御性心血管反应的调节

李霞, 樊明欣, 李良, 王锦, 沈霖霖, 曹银祥, 朱大年, 洪震

复旦大学附属华山医院神经内科，上海 200040； 重庆工商大学药物中心，重庆 400067； 南华大学公共卫生学院， 衡阳 421001； 复旦大学上海医学院生理学与病理生理学系，上海 200032

摘要

本文采用原位杂交、免疫组织化学方法检测了接受足底电击结合噪声应激刺激5 天的大鼠延髓、尤其是延髓头端腹外侧区(rostral ventrolateral medulla, rVLM)编码肾上腺髓质素(adrenomedullin, ADM)的肾上腺髓质素前肽原(preproadrenomedullin,ppADM) mRNA表达和ADM 免疫活性(adrenomedullin immunoreactivity, ADM-IR)变化，并通过电刺激中脑导水管背侧周围灰质(dorsal periaquaductal gray of midbrain, dPAG)诱发防御性心血管反应，以及于rVLM微量注射大鼠ADM (rat adrenomedullin,rADM)及其特异性受体拮抗剂——人肾上腺髓质素(22-52) [human adrenomedullin22-52, hADM(22-52)]相结合的手段研究rVLM中ADM 在应激防御性心血管反应中的可能调节作用。结果显示，在闩前1.0~3.0 mm 之间的延髓组织中ppADM mRNA 杂交信号和ADM-IR 阳性细胞在rVLM、面神经核分布最多，中缝核、巨细胞背核、舌下神经核和下橄榄核等处尚有中等量阳性细胞，而孤束核较少；应激第5 天，应激组rVLM 区ppADM mRNA 表达和ADM 免疫阳性细胞均较对照组明显增加(P<0.01)；右侧dPAG电刺激(0.5 ms, 100 Hz)后，正常大鼠动脉压(artery pressure, AP)立即由电刺激前的(116.4±8.9) mmHg 升高到(140.0±9.8) mmHg，心率(heart rate, HR)也从电刺激前的(378.0±7.5) beats/min 明显加快到(413.0±8.2) beats/min。停止电刺激后AP 和HR 快速恢复到正常水平；右侧rVLM 微量注射1 pmol hADM(22-52)后10、20、30 min，再给予dPAG 电刺激，则由电刺激引起的ΔAP、 ΔHR 明显降低(P<0.05, P<0.01)；rVLM微量注射0.1 pmol rADM 后10 min 内引起AP 明显升高，在此基础上再给予中脑dPAG 电刺激，则给药后60 min 内由电刺激dPAG 引起的ΔAP、ΔHR 虽有所增加，但统计学差异无显著性。上述结果提示，大鼠急性足底电击结合噪声刺激引发应激及血压升高伴随rVLM 中ADM 基因表达和免疫活性的明显增加，并且阻断rVLM 中ADM 特异性受体可减弱电刺激dPAG 引起的应激防御心血管反应。因此，rVLM 中ADM 可能作为一种重要的神经递质或神经调质参与了应激防御性心血管反应。

关键词： 延髓头端腹外侧区; 中脑导水管背侧周围灰质; 肾上腺髓质素; 应激; 心率; 血压; 肾上腺髓质素受体拮抗剂; 大鼠

分类号：Q463

Adrenomedullin in the rostral ventrolateral medulla is involved in the regulation of cardiovascular component of defensive responses induced by electrical stimulation of dorsal periaquaductal gray of the midbrain

Li Xia, FAN Ming-Xin, LI Liang, WANG Jin, SHEN Lin-Lin, CAO Yin-Xiang, ZHU Da-Nian, HONG Zhen

Department of Internal Neurology, Huashan Hospital Affiliated to Fudan University, Shanghai 200040, China； The Center of Drug Development, Chongqing Technology and Business University, Chongqing 400067, China； School of Public Health, University of South China, Hengyang 421001, China； Department of Physiology and Pathophysiology, Shanghai Medical College of Fudan University, Shanghai 200032, China

Abstract

In this study, we used techniques of in situ hybridization, immunohistochemistry, electric stimulation of the dorsal periaquaductal gray of the midbrain (dPAG) and microinjection to investigate the changes of preproadrenomedullin (ppADM) gene expression encoding adrenomedullin (ADM) and ADM-like immunoreactivity (ADM-IR) in the medulla oblongata, especially in the rostral ventrolateral medulla (rVLM) of the rats receiving foot-shock and noise stress for 5 d, and the potential role of ADM in cardiovascular component of defense response in the rVLM. The results showed that ppADM mRNA and ADM-IR were widely distributed throughout the medulla oblongata. Highly labeled neurons were found in the ventrolateral reticular nucleus and hypoglossal nucleus. Moderately labeled neurons were seen in the facial, ambiguus, lateral reticular, paragigantocellular reticular, and inferior olivary nuclei. Weak signal was present over neurons of nucleus of the solitary tract. The expression of ppADM mRNA and ADM-IR increased significantly after foot shock and noise stress for 5 d as compared with that in control group (P<0.01). On the other hand, stimulation of the right dPAG raised the artery pressure (AP) rapidly from (116.4±8.9) mmHg to (140.0±9.8) mmHg, and heart rate (HR) from (378.0±7.5) beats/min to (413.0±8.2) beats/min, respectively, in the normotensive rats. After unilaterally microinjection of hADM(22-52) (a specific antagonist of ADM receptor, 1 pmol) into the right rVLM of the normotensive rats for 10 min, the rats received the stimulation of the dPAG again. Then we found that the ΔAP and ΔHR were lowered significantly within 60 min compared with those without hADM(22-52) application (P<0.05). After unilaterally microinjection of 0.1 pmol rat ADM (rADM) into the rVLM, dPAG stimulation caused no significant changes in ΔAP and ΔHR. Our results that foot-shock and noise stress induced significant increases of ppADM mRNA and ADM-IR in the rVLM, and microinjection of ADM receptor antagonist hADM(22-52) into the rVLM partly blocked the cardiovascular component of stress-defensive response induced by stimulation of the dPAG, suggest that ADM in the rVLM might be an important neurotransmitter or neuroregulator in the regulation of cardiovascular function in the stress-related defensive response.

Key words: Rostral ventrolateral medulla; dorsal periaquaductal gray of midbrain; adrenomedullin; stress; heart rate; artery pressure; adrenomedullin receptor antagonist; rat

收稿日期：2009-01-16　　录用日期：2009-05-22

通讯作者：朱大年　　E-mail: dnzhu@shmu.edu.cn

引用本文：

李霞, 樊明欣, 李良, 王锦, 沈霖霖, 曹银祥, 朱大年, 洪震. 延髓头端腹外侧区肾上腺髓质素参与中脑导水管背侧周围灰质电刺激诱发防御性心血管反应的调节[J]. 生理学报 2009; 61 (4): 347-355.

Li Xia, FAN Ming-Xin, LI Liang, WANG Jin, SHEN Lin-Lin, CAO Yin-Xiang, ZHU Da-Nian, HONG Zhen. Adrenomedullin in the rostral ventrolateral medulla is involved in the regulation of cardiovascular component of defensive responses induced by electrical stimulation of dorsal periaquaductal gray of the midbrain. Acta Physiol Sin 2009; 61 (4): 347-355 (in Chinese with English abstract).