多巴胺、肾上腺素及胆碱能神经在实验性溃疡病中的相互作用

本文通过多巴胺能，α及β肾上腺素能和乙酰胆碱能拮抗剂及激动剂，检测了实验动物MPTP溃疡时上述三种神经可能的相互作用，发现溴隐亭能减轻，面吗丁啉能加重MPTP溃疡；心得安对MPTP溃疡无明显影响，但它能显著减少胃液的分泌；哌唑嗪和育亨平能明显保护十二指肠溃疡，对胃溃疡影响不大；阿托品亦仅能保护十二指肠溃疡。提示MPTP溃疡发生过程中尤其十二指肠溃疡发生过程中多巴胺起了先导作用，肾上腺素能和乙酰胆碱能神经亦参与了作用。     

免疫大鼠血清中抗β1、β3肾上腺素受体及M2乙酰胆碱受体抗体IgG亚类的分布

目的明确免疫大鼠血清中抗β1、β3肾上腺素受体及M2乙酰胆碱受体抗体的IgG亚类,为进一步研究此类抗体的作用机制提供实验依据。方法以合成的大鼠β1、β3肾上腺素受体和M2乙酰胆碱受体细胞外第二环肽段为抗原分别主动免疫Wistar大鼠,应用免疫球蛋白纯化技术特异性提纯其血清中IgG类抗体,应用BCA进行蛋白定量,调整血清中蛋白量一致,用SA—ELISA法检测抗β1、β3肾上腺素受体和M2乙酰胆碱受体抗体的IgG亚类。结果免疫组中属于IgG2a亚类的抗β1肾上腺素受体抗体的A值为（0．45±0．01）,明显高于对照组（0．08±0．003,P〈0．05）;免疫组中属于IgG2b亚类的抗艮肾上腺素受体抗体的A值为（0．59±0．02）,显著高于对照组（0．2±0．02,P〈0．05）;免疫组中属于IgG2a亚类的抗M2乙酰胆碱受体抗体的A值为（0．56±0．04）,显著高于对照组（0．12±0．01,P〈0．05）。结论免疫大鼠血清中抗β1肾上腺素受体抗体和抗M2乙酰胆碱受体抗体主要属于IgG2a亚类,抗β3肾上腺素受体抗体主要属于IgG2b亚类。     

大鼠门静脉α肾上腺素受体亚型的分布及功能

目的:探讨门静脉α肾上腺素受体及亚型的分布及其对门脉循环的调控机制。方法:采用药理受体分析方法,结合离体和整体实验,测定α肾上腺素受体拮抗剂和激动剂应用前后;ｐＡ２,ｐＤ２,ＥＣ５０,Ｒｍａｘ和门静脉压力（ＰＶＰ）。结果:①ＮＥ浓度－收缩曲线均右移,程度为哌唑嗪（Ｐｒａ）４０倍,硝苯吡啶（Ｎｉｆ）２３１．８倍,育亨宾（Ｙｏｈ）４．２倍。②对Ｒｍａｘ的抑制率:Ｎｉｆ８９．１％,Ｐｒａ７１．２％,Ｙｏｈ４１．９％。③与门静脉α受体亲和力（ｐＡ２）:Ｐｒａ８．１９,Ｙｏｈ６．０９,Ｎｉｆ６．０２。④对ＰＶＰ影响:苯福林（Ｐｈｅ）显著升高ＰＶＰ（Ｐ＜０．０５）,Ｐｒａ和Ｎｉｆ显著降低ＰＶＰ（Ｐ＜０．０１）。结论:大鼠静脉α受体亚型分布α１亚型,而α１受体亚型构成中主要以α１ａ为主。它们介导门静脉的收缩效应,调节门脉循环。     

肾上腺素能受体与心肌细胞凋亡

心肌细胞凋亡参与了慢性心衰的病理生理机制。而交感神经过度激活肾上腺素能受体是慢性心衰的一个明显特征，因此，研究肾上腺素能受体在心肌细胞凋亡中的调节作用对理解β-受体阻滞剂的治疗慢性心衰中的药理作用具有重要的意义。     

慢性充血性心力衰竭患者循环血细胞α_2、β肾上腺素能受体功能

本文分别用血小板α_2受体和淋巴细胞β受体研究中枢神经和交感末梢突触前α_2受体和心肌β受体的功能状态。结果提示:中枢神经和交感末梢突触前α_2受体功能降低是心衰交感张力增高的原因之一;心肌β受体由于交感张力增高而向下调节,导致功能降低。     

肾上腺素受体在心肌细胞肥大中的作用

目的 :观察 α受体阻滞剂酚妥拉明和 β受体阻滞剂心得安对肾上腺素诱导的心肌细胞肥大的作用。方法 :用培养的新生大鼠心肌细胞 ,测量其表面积和 [3H]-亮氨酸 （[3H]- L eu）的掺入量来判断心肌细胞肥大。结果 :肾上腺素可明显增加心肌细胞表面积和 [3H]- L eu的掺入量 ,α,β受体阻滞剂能阻断肾上腺素增加心肌细胞表面积和 [3H]-L eu掺入量。结论 :α,β受体阻滞剂有减轻肾上腺素诱导心肌细胞肥大的作用。     

胆碱能受体拮抗剂、拟肾上腺素药物及哌替啶对兔离体Oddi括约肌功能的影响

目的 探讨胆碱能受体拮抗剂、拟肾上腺素药物及阿片受体激动剂哌替啶对Oddi括约肌舒缩功能的不同效果.方法 将60只健康家兔的离体Oddi括约肌环随机分为6组,每组10只,分别置入正常Krebs液(即正常功能记录组)和按非累积加药法,以浓度递增方式加入阿托品、山莨菪碱、肾上腺素、去甲肾上腺素、哌替啶的Krebs液中,观察和比较不同浓度的上述药物对Oddi括约肌的舒缩频率和收缩幅度的影响.结果 与对照组相比,5种药物在其浓度为10-6mol/L～10-2mol/L时,均可明显降低Oddi括约肌的收缩幅度(P＜0.05),而对Oddi括约肌收缩频率的影响则不明显.抑制效应的顺序是去甲肾上腺素＞肾上腺素＞阿托品＞山莨菪碱≈哌替啶.结论 除阿托品和山茛菪碱外,去甲肾上腺素、肾上腺素和哌替啶也同样可以通过降低Oddi括约肌的收缩幅度而松弛Oddi括约肌;肾上腺素和去甲肾上腺素对Oddi括约肌收缩幅度的降低作用强于阿托品和山莨菪碱.     

毒蕈碱胆碱受体3在肺癌的研究进展

毒蕈碱胆碱受体3(M3受体)在多种肿瘤组织均有表达,并与多种细胞重要信号通路相关联,在肿瘤的增殖、侵袭、转移等方面起到重要作用;同时,M3受体参与多种肺部疾病如COPD 的病理生理过程。近年来,M3受体在肺癌中的研究受到较大的重视,M3受体有可能成为肺癌预防治疗的新靶点。     

毒蕈碱胆碱受体与肿瘤关系的研究进展

非神经元性胆碱能信号通路与肿瘤关系密切，许多肿瘤细胞表达胆碱能自分泌环。肿瘤细胞自分泌及旁分泌乙酰胆碱，作用于自身或邻近细胞的烟碱胆碱受体及毒蕈碱胆碱受体，调节肿瘤细胞的增殖、血管发生及凋亡。毒蕈碱胆碱受体是 G 蛋白耦联受体，主要有 M1R-M5R 共5个亚型。研究发现毒蕈碱胆碱受体在肺癌、结肠癌、黑色素瘤、乳腺癌、卵巢癌、前列腺癌、胃癌和脑星形细胞瘤等多种恶性肿瘤中均有表达，与肿瘤细胞的增殖、迁移、血管发生、凋亡有密切关系，其中尤以毒蕈碱胆碱受体3最为重要，这为肿瘤的治疗提供了一个新的研究方向。     

The effect of cholinergic agonists on coronary flow rate and oxygen consumption in isolated perfused rat heart

The metabolic and circulatory consequences of activation of the muscarinic receptor(s) were investigated by local administration of acetylcholine and its three analogues (bethanechol, carbachol and methacholine) into beating and KCl-arrested perfused rat hearts. Acetylcholine and the three other choline esters caused vasoconstriction in both types of preparations and this vasoconstriction was accompanied by a decrease in oxygen consumption. In most cases the dose-response curves were biphasic and changes in coronary flow paralleled those in oxygen consumption. Both phenomena were abolished by administration of atropine and either removal of calcium or infusion of verapamil but were unaffected by addition of the adrenergic alpha-blocker, prazosin, and the adrenergic beta-blocker, propranolol. Infusions of low concentrations of the cholinergic agonists were accompanied by increases in the myocardial phosphorylation state ratio [( ATP]free/[ADP]free[Pi]) which correlated with the simultaneous decreases in oxygen consumption and coronary flow. It is suggested that muscarinic receptors responsible for vasoconstriction in perfused rat heart are located not only on coronary vessels but also on the cardiac muscle cells. Activation of the former receptors induces vasoconstriction by direct action on the vascular smooth muscle while activation of the latter receptors induces vasoconstriction indirectly by decreasing cardiac work and increasing the myocardial [ATP]free/[ADP]free[Pi] ratio. The results also show that stimulation of muscarinic receptor(s) and the consequent metabolic and vasoregulatory responses are coupled to calcium movements.     

Voltage regulates adrenergic receptor function

The present study demonstrates that agonist-mediated activation of α2A adrenergic receptors (α_2AAR) is voltage-dependent. By resolving the kinetics of conformational changes of α_2AAR at defined membrane potentials, we show that negative membrane potentials in the physiological range promote agonist-mediated activation of α_2AAR. We discovered that the conformational change of α_2AAR by voltage is independent from receptor-G protein docking and regulates receptor signaling, including β-arrestin binding, activation of G proteins, and G protein-activated inwardly rectifying K⁺ currents. Comparison of the dynamics of voltage-dependence of clonidine- vs. norepinephrine-activated receptors uncovers interesting mechanistic insights. For norepinephrine, the time course of voltage-dependent deactivation reflected the deactivation kinetics of the receptor after agonist withdrawal and was strongly attenuated at saturating concentrations. In contrast, clonidine-activated α_2AAR were switched by voltage even under fully saturating concentrations, and the kinetics of this switch was notably faster than dissociation of clonidine from α_2AAR, indicating voltage-dependent regulation of the efficacy. We conclude that adrenergic receptors exhibit a unique, agonist-dependent mechanism of voltage-sensitivity that modulates downstream receptor signaling.     

Distribution of hypothalamic cholinergic and adrenergic system controlling hypophyseal-adrenal system function

It has been shown on rat experimental models that the cholinergic systems, participating in hypothalamic regulation of the hypophyseal adrenocortical function, are localized in the posterior hypothalamus whereas alpha-adrenergic systems in the posterior and anterior hypothalamus, and beta-adrenergic systems in the ventromedial hypothalamus.     

Changes in muscarinic acetylcholine receptors in guinea-pig lung: Effects of aging,inhalation of an allergen,administration of drugs,and vagotomy

This study was undertaken to investigate the effects of aging; inhalation of Konjak-Maiko, a typical Japanese allergen; administration of various drugs; and unilateral cervical vagotomy on muscarinic acetylcholine receptors (MAchR) in guinea-pig lung. We assessed the characteristics of MAchR by determining the affinity and the density of MAchR using [³H]quinuclidinyl benzilate, a potent muscarinic antagonist. A significant decrease in the density of MAchR was observed at 6 months of age and this decrease became more prominent until 2 years of age. No significant change in the affinity of MAchR was noted through the experimental period. Inhalation of Konjak-Maiko (60 min/day, for 10 days) did not affect either the affinity or the density of the receptors. Administration of ipratropium bromide (0.1 mg/kg/day, for 10 days) or prednisolone acetate (2 mg/kg/day, for 7 days) did not affect the characteristics of the receptors. In contrast to these drugs, diisopropyl fluorophosphate, an irreversible acetylcholinesterase inhibitor, produced a 26% reduction in the density without affecting the affinity of the receptors. The right cervical vagotomy increased the density of MAchR in the right lung by 17% without affecting the affinity of MAchR. These results suggest that the density of MAchR in lung may be controlled by changes in the activity of the receptors.     

Multiple roles for cholinergic signaling in pancreatic diseases

Cholinergic nerves are widely distributed throughout the human body and participate in various physiological activities, including sensory, motor, and visceral activities, through cholinergic signaling. Cholinergic signaling plays an important role in pancreatic exocrine secretion. A large number of studies have found that cholinergic signaling overstimulates pancreatic acinar cells through muscarinic receptors, participates in the onset of pancreatic diseases such as acute pancreatitis and chronic pancreatitis, and can also inhibit the progression of pancreatic cancer. However, cholinergic signaling plays a role in reducing pain and inflammation through nicotinic receptors, but enhances the proliferation and invasion of pancreatic tumor cells. This review focuses on the progression of cholinergic signaling and pancreatic diseases in recent years and reveals the role of cholinergic signaling in pancreatic diseases.     

Transfection with 5-HT1A receptor gene and antisense directed against muscarinic M2 receptors reveal a mutual influence between Gi/o-coupled receptors in rat atrial myocytes

A recently described reduction in sensitivity of G protein-activated inward-rectifying K(+) (GIRK) channels to stimulation of muscarinic M(2) receptors (M(2)AChR) in atrial myocytes overexpressing purinergic A(1) receptors (A(1)AdoR) was further investigated by heterologous expression of a 5-HT(1A) receptor (5-HT(1A)R) and by reducing the expression level of endogenous M(2)AChR receptors using antisense. In 5-HT(1A)R-expressing myocytes, in line with previous studies, sizable GIRK currents could be activated by 5-HT. In these cells, the mean current density and activation rate of M(2)AChR-activated current were significantly reduced, supporting the notion that signalling via this receptor is negatively regulated by other G protein-coupled receptors (GPCR) coupling to the same class (G(i/o)) of G proteins. To study if reducing M(2)AChR expression affects sensitivity of GIRK current to stimulation of A(1)AdoR, antisense oligodinucleotides (AsODN) against the M(2)AChR were used. Incubation of myocytes with M(2)AChR-specific AsODN resulted in a significant reduction in mean amplitude and activation rate of ACh-induced currents. This was paralleled by an increase in mean amplitude and activation rate of current activated by stimulation of A(1)AdoR. Plotting amplitudes of 5-HT- or Ado-induced currents from individual manipulated cells against the amplitude of ACh-induced current yielded a positive correlation between these data. Although difficult to interpret in mechanistic terms, this argues against a competition of receptors for a common pool of G(i/o). The mutual interaction between G(i/o)-coupled receptors depends on manipulation of the expression level, since long-term desensitization or down regulation of M(2)AChR by treatment with carbachol did not affect sensitivity of GIRK current to A(1)AdoR stimulation, despite a substantial reduction in amplitude and activation rate of M(2)AChR-activated currents. These data suggest a novel crosstalk between parallel receptors converging on the same class of G proteins.     

奥美沙坦对心力衰竭大鼠肺脏肾上腺素能受体表达的影响

目的:研究奥美沙坦对心力衰竭大鼠肺脏α1A-肾上腺素受体(α1A-AR)和β1、β2肾上腺素受体(β-AR)表达水平及对血浆肾素活性(plasma rennin activity,PRA)和血管紧张素Ⅱ(angiotensinⅡ,AngⅡ)水平的影响。方法:45只Wistar大鼠随机分为正常对照组(A组)、假手术组(B组)、心力衰竭模型对照组(C组)和奥美沙坦组(D组),采用灌胃法给药。超声心动图检测用药前后大鼠心脏功能,灌胃治疗8 w后,腹主动脉取血,采用放射免疫法测定各组大鼠PRA、AngⅡ水平,取大鼠肺组织,采用蛋白质免疫印迹法(Western Blot)测定各组的α1A-AR、β1-AR和β2-AR的蛋白表达水平。超声心动图检测用药前后大鼠心脏功能。治疗8 w后,腹主动脉取血,采用放射免疫法测定各组大鼠PRA、AngⅡ水平,取大鼠肺组织,采用蛋白质免疫印迹法(Western Blot)测定各组的α1A-AR、β1-AR和β2-AR的蛋白表达水平。结果 :用药前A组与B组比较,大鼠左心室射血分数(LVEF)组间差异无统计学意义(P>0.05);与B组比较,C组、D组大鼠LVEF明显降低(均P<0.05)。用药后,与C组比较,D组LVEF显著改善(P<0.05)。用药后,A组与B组大鼠PRA、AngⅡ水平差异无统计学意义(P>0.05);与B组比较,C组大鼠PRA、AngⅡ水平明显升高(P<0.01);与C组比较,D组大鼠血浆PRA、AngⅡ水平明显降低(P<0.05);在蛋白质表达水平,A组与B组用药后比较,各受体水平差异无统计学意义(P>0.05)。与B组比较,C组大鼠α1A-AR、β1-AR表达水平显著下调(P<0.05),β2-AR表达水平明显上调(P<0.01);与C组相比,D组α1A-AR、β1-AR及β2-AR水平均显著升高(均P<0.05)。结论:奥美沙坦能够改善心肌梗死后心力衰竭大鼠的心脏功能,提高LVEF,同时能够降低心力衰竭时血浆中升高的PRA和AngⅡ,并使心力衰竭大鼠肺脏下调的α1A-AR、β1-AR上调,表达增加的β2-AR进一步上调。奥美沙坦对慢性心力衰竭(chronic heart failure,CHF)时交感-肾上腺素系统激活后肾上腺素受体表达的调节作用和对PRA、AngⅡ的抑制作用,有利于维持心力衰竭时肺脏的通气/血流比值,减轻肺水肿,改善心力衰竭时的肺循环淤血,对CHF的肺脏起到了有益的保护作用。