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高脂血症大鼠肠系膜上动脉NPY免疫反应性神经纤维的变化
http://www.100md.com 《解剖学报》 1998年第3期
     作者:郭国庆* 魏 洪 邝国璧

    单位:中山医科大学解剖学教研室,广州510089;*暨南大学医学院解剖学教研室,广州

    关键词:高脂血症;肠系膜上动脉;神经肽Y;免疫组织化学;大鼠

    解剖学报980309 摘 要 为探讨神经肽Y与动脉粥样硬化的关系,用ABC免疫组织化学及体视学方法观察高脂血症大鼠肠系膜上动脉神经肽Y免疫反应性神经纤维的变化。(1)定性观察:对照组各时期神经肽Y免疫反应性神经纤维呈网状攀附于血管周围,分布均匀,并见串珠状膨体;高脂组纤维呈密集网状分布,在纤维网孔中出现大量较纤细的新增生纤维,其排列较紊乱,膨体清晰可见,这种变化见于各期实验组。(2)定量结果:对照组各时期纤维密度无明显改变;高脂组纤维密度逐渐增多,30d、90d与7d比较差异显著(P<0.01),且分别较对照组增多(P<0.01)。结果提示,血脂升高可促使肠系膜上动脉壁神经肽Y免疫反应性神经纤维增生,这种变化可能与动脉粥样硬化的发生、发展有关。
, 百拇医药
    神经肽(neuropeptide Y, NPY)是交感神经末梢分泌的神经递质之一,不仅调节心血管系统的正常生理功能,而且与心血管系统疾病有密切关系。交感神经在动脉粥样硬化(atherosclerosis,AS)发生,发展中的作用一直存有争议,故许多有关AS病因学的文献很少提及交感神经系统的作用[1]。近年来,学者们[2~5]发现NPY能促进平滑肌细胞增殖,而且高脂血症时血管对NPY的收缩反应明显增强,且随年龄而递增。但目前尚缺乏有关高脂血症时NPY能神经纤维变化的形态学资料。鉴于此,本实验对雄性SD大鼠进行高脂血症造型,用ABC免疫组织化学方法观察肠系膜上动脉NPY免疫反应性神经纤维,并进行动态定量分析,初步探讨NPY与AS的关系。

    材料和方法

    1.实验动物

    雄性SD大鼠(中山医科大学实验动物中心提供)48只,随机分2组:(1)高脂组:高脂饮食,饲料配方[6]:胆固醇2%,猪油10%,白糖5%,牛胆盐0.5%,他巴唑0.2%,基础饲料81.3%,合计100%;20g/d/只。(2)对照组:普通饮食;分别于7d、30d、90d 3时期处死动物进行观察;各时期动物均为8只。
, 百拇医药
    2.试剂

    胆固醇(进口分装,Holland产品),兔抗NPY血清(香港中文大学医学院姚大卫教授馈赠),生物素标记羊抗兔IgG及ABC复合物(Vector产品),DAB(Sigma产品)。

    3.血脂测定

    处死前禁食12h,经下腔静脉采用1~1.5ml;离心分离血清;分离抽提-乙酰丙酮显色法测甘油三酯,醋酐硫酸单一试剂直接显示法测总胆固醇[7]

    4.免疫组织化学染色

    4%多聚甲醛灌(4℃)注固定1h,先快后慢;取肠系膜上动脉第一级分支;入相同固定液(4℃)5h;20%蔗糖(4℃)保存;O1ympus体视显微镜下去除血管外结缔组织,进行免疫组织化学染色,简要过程如下:(1)0.3%H2O2,室温,5min;(2)正常羊血清,室温,1h(不冲洗);(3)1∶1 500兔抗NPY血清,4℃,湿盒,60h;(4)1∶200生物素化羊抗兔IgG抗体,4℃,湿盒,24h;(5)1∶100ABC复合物,4℃,湿盒,12h;(6)0.05%DAB/0.01%H2O2显色7min;以上各步骤前后均用0.01mol/L PBS漂洗3×10min;铺片,自然干燥,常规脱水、透明、封片。染色结果用Olympus BH-2显微镜观察并摄片。
, http://www.100md.com
    本实验用0.01mol/L PBS或正常羊血清替代第一抗体作为阴性对照。

    5.NPY免疫反应性神经纤维体视学分析方法

    按Dhital等[8]的神经纤维定量程序,每条动脉(n=8)取近、中、远3段3个视野,于40×物镜和10×目镜(内装方格测微尺)下计数0.25mm长血管神经纤维与方格线的交叉点数,取3个值的平均数表示该血管NPY免疫反应性神经纤维的密度(交叉点数/0.25mm2),用SPSS/PC统计软件进行组内及组间t检验。

    结 果

    1.血脂变化

    对照组血总胆固醇为3.45±0.42mmol/L;高脂组7d即明显升高,达12.08±1.15mmol/L,30d、90d皆维持于此水平;各组动物血甘油三酯实验前后无明显变化,维持在3.15±0.65mmol/L。
, 百拇医药
    附表 高脂血症大鼠各时期肠系膜上动脉NPY免疫反应性神经

    纤维的密度比较(±s,交叉点数/0.25mm2)

    Table Changes of NPY-containing innervation on the wallof the superior mesenteric

    arteries in hyperlipidemic rats (±s, crossing dots/0.25mm2) 组别

    groups

    时期(period)
, 百拇医药
    7d

    30d

    90d

    对照组

    control group

    146.2±2.5

    143.5±3.8

    146.2±1.6

    高脂组

    hyperilipidemic group

    148.0±3.0

    172.7±4.0△▲
, http://www.100md.com
    190.1±2.6△▲

    注:高脂组30d、90d与7d比较:△(P<0.01);各时期与对照组比较:▲(P<0.01)Note:density of innervation at 30d or 90d was compared with that at 7d in hyperlipidemic group:△(P<0.01); density of innervation in three periods was compared with that in control group:▲(P<0.01)

    2.肠系膜上动脉NPY免疫反应性神经纤维定性观察

    对照组各时期神经肽Y免疫反应性神经纤维呈网状攀附于血管周围,分布均匀,纤维粗大,并见串珠状膨体(图1~3);高脂组纤维呈密集网状分布,在较粗纤维形成的网孔中出现大量较纤细的新增生纤维,其排列紊乱,膨体清晰可见(图4~6),这种变化持续整个实验周期。
, 百拇医药
    3.肠系膜上动脉NPY免疫反应性神经纤维密度定量结果

    见附表。

    讨 论

    AS发生主要是血液和血管壁,血管壁各细胞间相互作用的结果。Ross[1]指出,血管内皮细胞发生功能性(如前列环素分泌增多)或结构性损伤(如内皮细胞剥脱)是AS发生的始动因素,中膜平滑肌细胞增殖、迁移进入内膜,并蓄积脂质形成泡沫细胞则进一步形成典型AS病变。高血脂作为诱发AS的危险因素之一已被公认,但交感神经特别是NPY在AS发生、发展中的作用仍知之甚少。

    Jaganthan[9]观察到即使血脂正常,反复注射肾上腺素后猴主动脉仍出现脂质沉着等AS病变,认为肾上腺素等缩血管因子可通过对血管内皮细胞的毒性作用或影响血流动力学因素而加速AS病变形成。交感神经末梢释放去甲肾上腺素(norepinephrine, NE)和NPY两种缩血管神经递质,和NE一样,NPY也具有强烈的缩血管作用。应用肾上腺素拮抗剂育亨宾(yohimbine)或用利血平(reserpine)耗竭NE,仅使交感神经的缩血管效应降低50%[10],说明还有非肾上腺素能血管收缩因素。大鼠肠系膜上动脉有大量的NPY免疫反应性神经纤维[11];免疫电镜观察显示[12],豚鼠肠系膜上动脉NPY免疫反应性神经纤维进入血管中膜,其终末与平滑肌细胞贴近;Edvinsson等[13]发现,与NE相比,NPY引起血管收缩所需的浓度较低,且持续时间较长。大鼠肠系膜上动脉NPY受体的发现[14],说明NPY免疫反应性神经纤维释放NPY,可能作用于血管NPY受体引起血管收缩。另一方面,高血脂不仅为AS病变形成提供脂质来源,而且还可改变血管对NPY等缩血管因子的反应性。Stewart-Lee[4]报道遗传性高脂血症兔(watanabe heritable hyperlipidemic rabbit,WHHL)基底动脉对NPY反应增强;Corr[5]进一步证实这种增强的缩血管反应随年龄增加而呈递增趋势。本实验发现肠系膜上动脉有大量增生的NPY免疫反应性神经纤维,而且可见清晰的串珠状膨体,说明纤维已与血管中膜平滑肌细胞形成了某种非突触联系,平滑肌细胞对NPY的敏感性增高则可导致血管持续性的剧烈收缩以致损伤血管内皮。
, 百拇医药
    近年来,人们注意到NPY与细胞增殖的关系。有学者报道[2,3],和NE一样,NPY能增加平滑肌细胞Ca2+内流,NPY还能促进平滑肌细胞对3H-亮氨酸的摄入,说明NPY具有促进平滑肌细胞增殖的作用,而AS病变产生的主要原因之一即血管平滑肌细胞增殖。本实验观察到:高脂组NPY免疫反应性神经纤维密度逐渐增多,30d、90d与7d比较差异显著,且较对照组增多。由于NPY有较强的缩血管及促进平滑肌细胞增殖的作用,故纤维增多可能引起血管持续强烈的收缩,损伤血管内皮,并且促进血管内皮细胞及平滑肌细胞增殖,增殖的平滑肌细胞吞噬脂质,并迁移至内膜形成泡沫细胞,从而诱发AS病变形成。我室对高脂血症大鼠肠系膜上动脉透射电镜的观察显示[15],高脂组大鼠血管壁增厚,平滑肌细胞数量增多,胞体增大;并见平滑肌细胞形成“斑块”样结构突入管腔,结果支持上述观点。

    因此,高血脂可促使大鼠动脉壁NPY能神经纤维增生,这种变化可能与AS的发生、发展有关。
, http://www.100md.com
    承蒙香港中文大学医学院解剖学系姚大卫教授馈赠兔抗NPY血清,特此致谢。

    收稿 1997-06 修回 1997-11

    参考文献

    [1]Ross R. The pathogenesis of atherosclerosis-an update. New Eng J Med, 1986, 314(8):488

    [2]Erdbrugger W, Vischer P, Bauch HJ, et al. Norepinephrine and neuropeptide Y increase intercellar Ca2+ in cultured porcine aortic smoothmuscle cells. J Cardiovasc Pharmacol, 1993, 22(1):97
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    [3]王 涛,韩启德,陈明哲.神经肽Y对血管平滑肌3H-亮氨酸参入有促进作用.北京医科大学学报,1990,22(3):164

    [4]Stewart-Lee AL, Burnstock G. Changes in vasoconstrictor and vasodilator responses of the basilar artery during maturation in the Watanabe heritable hyperlipidemic rabbit differ from these in the New Zealand white rabbit. Arterioscler Thromb, 1991, 11(5):1147

    [5]Corr L, Gleeson M, Wilson G. Effects of age and hyperlipidemic on rabbit coronary responses to neuropeptide Y and the interaction with norepinephrine. Peptide, 1993, 14(2):359
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    [6]Nakatake J, Wasano K, Yamamoto T. Three-dimensional architecture of elastic tissue in early atherosclerotic lesions of the rat aorta. Atherosclerosis, 1985, 57(2,3):199

    [7]李影林主编.临床医学检验手册.长春:吉林人民卫生出版社,1987: 279, 310

    [8]Dhital KK, Gerli R, Lincoln J, et al. Increased density of perivascular nerves to the major cerebral vessels of the spontaneously hypertensive rat: defferential changes in noradrenaline and neuropeptide Y during development. Brain Res, 1988, 444(1):33
, 百拇医药
    [9]Jaganathan SN, Madhavan TV, Gopalan C. Effect of adreneline on aortic structure and serum cholesterol on Macaca radiata. J Atheroscler Res, 1964, 64(4):335

    [10]Edvinsson L, Emson P, McCulloch J, et al. Neuropeptide Y: cerebrovascular innervation and vasomotor effects in the cat. Neurosci Lett. 1983, 43(1):79

    [11]张成岗,苏慧慈,黄威权.大鼠肠系膜上动脉和静脉各级分支中NPY免疫反应神经纤维密度的相关分析.解剖学报,1995,26(3):274

    [12]Edvinsson L, Gulbenkian J, Jansen I, et al. Comparison of peptidergic mechanisms in different parts of the guinea pig supe rior mesenteric artery: immunocytochemistry at the light and the ultrastructural levels and responses in vitro of large and small arteries. J Auton Nerv Syst, 1989, 28(2):141
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    [13]Edvinsson L, Emson P, McCulloch J, et al. Neuropeptide Y: immunocytochemical localization to and effect upon feline pial arteries and vien in vitro and in situ. Acta Physiol Scan, 1984, 122(2):155

    [14]McAuley NA, Westflat TC. Possible location and function of neuropeptide Y receptor subtypes in the rat mesenteric arteral bed. J Pharmacal Exp Ther, 1992, 26(3):863

    [15]郭国庆,魏 洪,邝国璧.高脂血症大鼠肠系膜上动脉超微结构观察.广东解剖学通报,(待发表)
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    CHANGES OF NPY-CONTAINING INNERVATION ON THE

    WALL OF THE SUPERIOR MESENTERIC ARTERIES

    IN HYPERLIPIDEMIC RATS

    WALL OF THE SUPERIOR MESENTERIC ARTERIES

    IN HYPERLIPIDEMIC RATS

    Guo Guoqing*, Wei Hong, Kuang Guobi

    (Department of Anatomy, Sun Yat Sen University of Medical Sciences, Guangzhou;
, 百拇医药
    *Department of Anatomy,Medical College, Jinan University, Guangzhou)

    For studying the relationship between neuropeptide Y and atherosclerosis, the NPY containing innervation on the wall of the superior mesenteric arteries in hyperlipidemic rats was examined by ABC immunohistochemical and morphometric technique. The results were as follows: (1)qualitative observation: on the wall of the mesenteric arteries there were a number of reticular innervations with strings of varicosities, which distribution was regular, in the control group; The distribution of NPY-containing innervations in hyperlipidemic group were denser reticular pattern, and the newborn NPY-containing innervations, which also had varicosities, appeared in the reticular innervations; Their distributions were irregular. These changes could be observed in all periods in experimental groups. (2)quantitative results: in the control group, the density between two of them was not significantly different, but in the hyperlipidemic group, the density of NPY-containing innervations increased significantly at 30d and 90d, compared with that at 7d(P<0.01) or with that in the control group (P<0.01). The results suggested that hyperlipidemia should result in the increase of the NPY-containing innervation, which might be associated with the development of atherosclerosis.

    KEY WORDS Hyperlipidemia; Superior mesenteric artery; Neuropeptide Y; Immunohistochemistry; Rat

    △Department of Anatomy, Sun Yat Sen University of Medical Sciences, Guangzhou 510089, 百拇医药(郭国庆* 魏 洪 邝国璧)