Vasoactive intestinal peptide regulates angiotensin II catabolism in the rabbit

Although vasoactive intestinal peptide (VIP) is natriuretic it stimulates renin and aldosterone secretion. Therefore, to effect a natriuresis, VIP may need to modulate the sodium conserving actions of the renin angiotensin system (RAS) by another means. One possibility is that it alters the rate of disappearance from the circulation of one or more components of the RAS. We sought to determine whether VIP regulates the rate of catabolism of angiotensin II (Ang II). Steady state metabolic clearance studies of Ang II were undertaken with and without simultaneous VIP infusion. These studies were performed in rabbits on low, normal and high sodium diets, as dietary sodium has been shown to affect the metabolism of both VIP and Ang 11. The effects of VIP on plasma Ang 11 concentration and secretion were also studied. VIP decreased Ang II catabolism in rabbits on low (P < 0.05) and normal sodium diets (P < 0.05). Plasma levels of Ang II increased significantly in response to VIP in rabbits on these diets (low, P < 0.04; normal, P < 0.05). In contrast, in rabbits on a high sodium diet VIP increased the rate of catabolism of Ang II (P < 0.001). Thus we conclude that the effect of VIP on sodium excretion may be modulated by its effects on Ang II metabolism. The decrease in Ang II catabolism seen in rabbit on low and normal sodium diets may prevent or ameliorate any natriuresis while the more rapid degradation of Ang II which occurs in dietary sodium excess may enhance the natriuretic effect of VIP.     

Vasoactive intestinal peptide receptor localization in rat forebrain by autoradiography

Vasoactive intestinal peptide (VIP) receptors were localized in rat forebrain by in vitro labeling light microscopic autoradiography with 125I-labeled VIP. Binding sites for VIP were found in discrete areas of rat forebrain including lamina I of the neocortex and pyriform cortex, caudate-putamen, the hippocampus and molecular layer of the dentate gyrus, basolateral nucleus of the amygdala, several thalamic nuclei and the magnocellular paraventricular and supraoptic nuclei of the hypothalamus. These results are consistent with earlier findings on the immunohistochemical distribution and proposed sites of action of VIP, and reinforce the concept that endogenous VIP may function as a neuromodulator in brain.     

局灶性脑缺血后侧脑室室下区神经发生及其与血管内皮生长因子关系的研究

为了研究成年大鼠局灶性脑缺血后侧脑室室下区(SVZ)神经发生的情况及其与血管内皮生长因子(VEGF)的关系,探讨脑缺血后神经发生及其调控机制,本研究通过大脑中动脉阻断法(MCAO)建立大鼠局灶性脑缺血模型,5-溴-2-脱氧尿核苷(BrdU)标记增殖的神经前体细胞,用免疫荧光双标记法动态检测BrdU、TuJ1、MAP-2、GFAP的表达,同时观察增殖细胞表达VEGF及其受体情况。结果显示:与对照组相比,大鼠SVZ的BrdU阳性细胞数在脑缺血后4 d组明显增加,14 d组达到高峰;Br-dU/TuJ1、BrdU/MAP-2阳性双标细胞数在脑缺血后14 d组开始增加,28 d组达到高峰;但BrdU/GFAP阳性双标细胞数则无明显变化;增殖的BrdU阳性细胞同时表达VEGF及其受体FLK-1。以上结果提示:大鼠局灶性脑缺血可激活SVZ自体神经前体细胞原位增殖、分化,且增殖的细胞同时表达VEGF及其受体可能是脑缺血后神经发生增强的调节机制之一。     

The evolving concept of physiological ischemia training vs. ischemia preconditioning

Ischemic heart diseases are the leading cause of death with increasing numbers of patients worldwide. Despite advances in revascularization techniques, angiogenic therapies remain highly attractive. Physiological ischemia training, which is first proposed in our laboratory, refers to reversible ischemia training of normal skeletal muscles by using a tourniquet or isometric contraction to cause physiologic ischemia for about 4 weeks for the sake of triggering molecular and cellular mechanisms to promote angiogenesis and formation of collateral vessels and protect remote ischemia areas. Physiological ischemia training therapy augments angiogenesis in the ischemic myocardium by inducing differential expression of proteins involved in energy metabolism, cell migration, protein folding, and generation. It upregulates the expressions of vascular endothelial growth factor, and induces angiogenesis, protects the myocardium when infarction occurs by increasing circulating endothelial progenitor cells and enhancing their migration, which is in accordance with physical training in heart disease rehabilitation. These findings may lead to a new approach of therapeutic angiogenesis for patients with ischemic heart diseases. On the basis of the promising results in animal studies, studies were also conducted in patients with coronary artery disease without any adverse effect in vivo, indicating that physiological ischemia training therapy is a safe, effective and non-invasive angiogenic approach for cardiovascular rehabilitation. Preconditioning is considered to be the most protective intervention against myocardial ischemia-reperfusion injury to date. Physiological ischemia training is different from preconditioning. This review summarizes the preclinical and clinical data of physiological ischemia training and its difference from preconditioning.     

脑缺血新模型:大鼠胡须体觉皮层局灶性缺血模型的建立

目的:建立一个简单、可靠的、可以直接研究单一功能变化和组织形态变化之间联系的大鼠胡须体觉皮层局灶性脑缺血模型。方法:大鼠经10%水合氯醛麻醉后,经右侧顶叶皮层处开颅,在显微镜下结扎大脑中动脉的2～3个分支。应用激光多普勒血流仪检测结扎前、后局部脑血流情况,细胞色素氧化酶染色确定胡须体觉皮层和梗死部位的关系,2,3,5-氧化三苯基四氮唑(TTC)染色检测梗死面积大小。胡须依赖实验检测胡须功能。结果:大脑中动脉主要侧支结扎后,梗死中心及周围局部脑血流明显下降。细胞色素氧化酶染色及TTC染色均示梗死区域位于胡须体觉皮层。局灶性缺血3d,测定梗死面积约占全脑面积的15%。梗死形成后大鼠胡须分辨物体纹理的能力下降。结论:选择性的将大鼠具有单一功能的胡须体觉皮层制作成局灶性脑缺血模型,提供了一个较好的研究功能变化和组织形态变化之间联系的脑缺血动物模型。     

Vasoactive intestinal peptide stimulates immunoglobulin production and growth of human B cells.

The effect of vasoactive intestinal peptide (VIP) on human lymphoblastoid B cell lines and tonsil B cells was studied. VIP increased immunoglobulin production and proliferation by lymphoblastoid B cell line, GM-1056, in a dose-dependent manner. As little as 10(-12) M of VIP was effective, and higher concentrations of VIP induced an approximately five-fold increase in IgA production. Moreover, this enhancement was blocked by VIP antagonist. Similarly, VIP enhanced IgM and IgG production by other lymphoblastoid B cell lines, CBL and IM-9, respectively. In contrast to VIP, another neuropeptide substance P (SP) or somatostatin failed to enhance immunoglobulin production and thymidine uptake. VIP also enhanced IgA production and thymidine uptake by purified tonsil B cells. However, in contrast to B cell lines, VIP failed to enhance IgM and IgG production by tonsil B cells. SP or somatostatin failed to enhance immunoglobulin production or thymidine uptake by tonsil B cells. These results indicate that VIP acts as B cell stimulatory factor and that VIP may also have preferential effect on IgA production on tonsil B cells.     

慢性脑缺血大鼠大脑皮质中的神经生长因子表达

目的：研究慢性脑缺血时大鼠大脑皮质中神经生长因子（NGF）的表达变化,探讨缺血性脑损伤及修复机制。方法：永久性结扎Wistar大鼠双侧颈总动脉,取慢性脑缺血30、120d组。行为学测试,免疫组化ABC法染色,计数大鼠大脑皮质中的NGF阳性神经元数及测量平均灰度值。结果：大鼠慢性脑缺血时,大脑皮质中NGF的表达,第120d比第30d及对照组显著增强,而30d与对照组无显著性差异,同时伴有学习和记忆力下降。结论：慢性脑缺血时,NGF在大脑皮质中的表达将随时间逐渐增强,对坏死神经元起保护作用。     

脑的不对称性影响大鼠局灶性脑缺血的结局

为评价左右侧大脑中动脉闭塞(MCAO)对右利大鼠神经行为功能和脑梗死体积的影响,本研究应用四足动物觅食实验筛选右利爪雄性SD大鼠24只,随机分为经左、右侧插线组各12只,8%水合氯醛腹腔注射(300mg/kg)麻醉,线栓法经左、右侧颈外-内动脉插入头端涂有多聚赖氨酸的4-0尼龙线,建立大鼠MCAO缺血2h模型,再灌注72h后评价动物的神经行为功能,测量脑梗死体积。结果表明,所有动物在脑缺血2h神经功能缺损评分最高,再灌注1、24、48和72h经左侧MCAO大鼠显著高于经右侧MCAO大鼠(P<0.05),后者功能明显优于前者,脑梗死体积经左侧插线的大鼠显著大于经右侧插线的大鼠(P<0.05)。研究结果提示,大鼠主侧半球大脑中动脉缺血后,神经功能缺损和脑梗死体积较对侧严重,脑的不对称性影响大鼠局灶性脑缺血的最终结局。     

大鼠局灶性脑缺血模型的改进

本研究旨在改进SD大鼠的局灶性脑缺血模型的制作方法。 1%的戊巴比妥钠腹腔内注射麻醉动物 ,采用线栓法制作大鼠大脑中动脉栓塞模型。采用 3种不同的手术方法完成手术 ,1组不分离迷走神经节 ,不结扎翼腭动脉 ;2组分离保护迷走神经节、结扎翼腭动脉 ;3组分离并保护迷走神经节 ,但暂时阻断翼腭动脉。 1、2和 3组的手术死亡率分别为 33%、7%和 10 % (P <0 0 5 ) ,成功率分别是 6 0 %、80 %和 85 % ;与 1、2组相比 ,3组的手术费时短 (P<0 0 1)、创伤小。因而分离并保护迷走神经节是降低局灶性脑缺血模型手术死亡率的重要手段 ,从而成功制作大鼠的局灶性脑缺血模型。     

Effect of mild hypothermia on angiogenesis in rats with focal cerebral ischemia

In the present study, we investigated the effect of mild hypothermia on infarct volume, angiogenesis and brain-derived neurotrophic factor (BDNF) level after stroke. After permanent middle cerebral artery occlusion, mild hypothermia was induced immediately and maintained for 24h. 2,3,5-Triphenyltetrazolium chloride (TTC) staining, laser scanning confocal microscopy (LSCM) and ELISA were performed to assay infarct volume, angiogenesis and BDNF level in the ischemic boundary zone (IBZ), respectively. Compared with normothermic group, mild hypothermia reduced total infarct volume and increased endogenous BDNF level. And the microvessel diameter, the number of vascular branch points and the vessel surface area were significantly increased in the mild hypothermia group. These findings suggest that mild hypothermia enhances angiogenesis in ischemic brain, which might be enhanced in part via BDNF.     

大鼠脑缺血后突触超微结构的变化

目的：探讨脑缺血损伤对突触的影响。方法：采用大鼠，制成脑缺血模型，应用透射电镜观察大脑顶叶皮质突触的变化。结果：随着缺血时间的延长，神经毡内突触数目逐渐减少；突触结构中突触小泡、线粒体也发生改变。缺血48h，突触小泡减少，甚至消失；线粒体变性、减少乃至消失，嵴减少或消失呈空泡状。突触前后膜被破坏，典型的突触结构已不存在。结论：脑缺血后，随缺血时间延长，突触结构异常，突触密度下降。     

Peptidergic (vasoactive intestinal peptide) nerves in the genito-urinary tract

The feline genito-urinary tract receives a rich supply of nerve fibers displaying immuno-reactivity like that of vasoactive intestinal peptide. Nerves containing vasoactive intestinal peptide are particularly numerous in the trigonum area of the bladder, around the ureteral openings and in the upper part of the urethra in both sexes, in the epididymis, prostate and vas deferens, and in the uterine cervix. Ganglia located close to or within the wall of the trigonum area and of the upper urethra contain numerous immunoreactive nerve cell bodies, which may be the origin of the fibers containing vasoactive intestinal peptide that innervate these regions.     

Vasoactive intestinal peptide impairs leucocyte migration but fails to modify experimental murine colitis

Inflammatory bowel diseases are chronic inflammatory disorders of the gastrointestinal tract. Vasoactive intestinal peptide (VIP) is a neuropeptide with known anti-inflammatory activity. We have demonstrated previously that administration of VIP inhibits leucocyte migration in a murine model of delayed-type hypersensitivity, and anti-inflammatory efficacy is supported by other studies. The aim of this study was to investigate the VIP effects in a murine model of intestinal inflammation. Colitis was induced in BALB/c mice by a 2.5 mg enema of 2,4,6-trinitrobenzenesulphonic acid (TNBS) and the mice were killed on day 7. Mice were administered either a 3-day (therapeutic) or 7-day (prophylactic) constant infusion of VIP by subcutaneously implanted mini-osmotic pumps, or intraperitoneal (i.p.) injection of VIP on alternate days over 7 days. Clinical disease scores, weight changes, histopathology of colon tissues, plasma VIP levels, cytokine levels and chemotaxis of peripheral blood mononuclear cells were evaluated. After administration of TNBS, mice quickly developed severe colitis accompanied by dramatic body weight loss (20% by day 6) and high mortality (30%). Prophylactic treatment using high-dose VIP abrogated leucocyte chemotaxis; however, it failed to ameliorate the weight loss and mortality. Moreover, VIP delivered either by constant infusion or i.p. failed to modify the clinical, histological or cytokine markers of disease. Our studies show that, despite an ability to inhibit chemokine-induced chemotaxis of mononuclear cells, VIP was unable to modulate TNBS-induced colitis. This contrasts with the efficacy of VIP in models of mild inflammatory disease and suggests that VIP is unlikely to provide a useful model for novel anti-IBD therapy.     

Vasoactive intestinal peptide-like immunoreactivity in nerves associated with the cardiovascular system of guinea-pigs

The distribution of nerves with vasoactive intestinal peptide (VIP)-like immunoreactivity has been examined in the heart and vascular system of guinea-pigs. There was a very sparse supply of fibres to the heart. No immunoreactive cell bodies were found in the intrinsic cardiac ganglia; however, positive nerve cell bodies were seen along the superior vena cava near the right atrium. There were immunoreactive fibres with most arteries; these fibres were located at the media-adventitia junction. The supply to major distributing arteries, such as the aorta, subclavian, carotid and femoral arteries as well as to the pulmonary arteries, was sparse. Of the individual vascular beds, the most densely supplied arteries were the mesenteric and uterine (or in the male deferential) arteries. Arteries running to other organs or tissues, such as skeletal muscle, kidney, pancreas, spleen and heart were less densely supplied. There were clear differences in the innervation of different cerebral vessels. The greatest density was associated with the anterior and middle cerebral arteries. Fewer nerves accompanied the posterior cerebral, cerebellar and meningeal arteries. There was a sparse innervation of the rostral part of the basilar artery. Throughout the body, veins were sparsely supplied. The distribution of nerves with VIP-like immunoreactivity was not changed when noradrenergic nerves were degenerated by 6-hydroxydopamine or when substance P nerves were disrupted by capsaicin. It is concluded that VIP containing nerves innervating the heart and blood vessels form a population distinct from the substance P-containing and the noradrenergic nerves. It is suggested that the VIP fibres might be efferent vasodilator nerves to the blood vessels.     

Interaction of cholecystokinin with vasoactive intestinal peptide in body shaking response to ice-water immersion in rats

Interaction of cholecystokinin (CCK) with vasoactive intestinal peptide (VIP) in body shaking response to ice-water immersion was observed in pentobarbital-anesthetized rats. Although CCK itself had no influence on the response, VIP suppressed it and this effect of VIP was antagonized by simultaneous administration of sulfated octapeptide of CCK, but not by non-sulfated CCK.     

Intranasally delivered bFGF enhances neurogenesis in adult rats following cerebral ischemia

Basic fibroblast growth factor (bFGF) is a very important mitogenic factor with proved neurogenesis effects in the central nervous system. Intranasal administration can bypass blood-brain barrier and deliver drugs into the brain directly. We investigated whether intranasal administration of bFGF at later time points after ischemia could promote adult neurogenesis and improve neurologic functions. Rats received bFGF or saline intranasally once daily for 6 consecutive days, starting at 1 day after transient middle cerebral artery occlusion (MCAO). Bromodeoxyuridine (BrdU) was injected at 5 and 6 days after MCAO. Rats were killed at 7 or 28 days after MCAO. Neurogenesis was assessed by immunostaining for BrdU and cell type-specific markers. Neurological functions were evaluated by the modified Neurological Severity Scores. Compared with the control animals, intranasal administration of bFGF improved behavioral recovery without affecting infarct size, and enhanced proliferation of progenitor cells in the subventricular zone and the subgranular zone of the dentate gyrus (DG). Furthermore, the new proliferated cells could differentiate into neurons (BrdU+NeuN+ cells) in the striatum and DG at 28 days after MCAO. Intranasal administration of bFGF offers a non-invasive alternative for the treatment of stroke.     

Atorvastatin and whisker stimulation synergistically enhance angiogenesis in the barrel cortex of rats following focal ischemia

Physical therapy can promote neurovascular plasticity and functional recovery after CNS disorders such as ischemic stroke. We have previously demonstrated that whisker stimulation promotes angiogenesis in the penumbra of the ischemic barrel cortex. The aim of this study was to examine whether atorvastatin and whisker stimulation can act synergistically in enhancing angiogenesis in the barrel cortex following ischemia. Rats were divided into sham-operation, control, atorvastatin-treatment, whisker stimulation and combination therapy groups. And they were trained continuously for 10 trials per half day until the rat fulfilled 80% correct choices for continuous thirty trials, which were considered to reach the criteria. The number was significantly less in the combination therapy group than that in the whisker stimulation group (P<0.01). Immunofluorescence was used to detect angiogenesis 14d following focal ischemia. These data showed that the combination therapy was more effective in enhancing VEGF and BDNF expression than whisker stimulation (P<0.01). Our study indicated that atorvastatin can improve the discrimination ability of whisker stimulation in rats and amplify post-ischemic angiogenesis induced by whisker stimulation, potentially via enhanced expression of VEGF and BDNF in the peri-infarct region.     

Vasoactive intestinal polypeptide-immunoreactive neurons in rat visual cortex

An antibody to vasoactive intestinal polypeptide (VIP) was used to examine the forms of VIP-positive neurons and the synapses made by VIP-positive axon terminals. Vasoactive intestinal polypeptide-positive cells are most common in layers II and III and the majority of them are typical bipolar neurons, with two primary dendrites which emanate from the upper and lower poles of the cell body. Their somata, which have only a few symmetric and asymmetric synapses, generally have a fusiform or "tear-drop" shape and contain nuclei with a vertically oriented cleft. The dendritic trees are arranged vertically and often extend through five cortical layers. The axons are thin and extend either from the soma or from one of the primary dendrites. The axons also follow a vertical trajectory. Other VIP-positive neurons are modified bipolar cells and a few of them are multipolar cells. The synapses formed by the VIP-positive axon terminals in the neuropil are symmetric in form, and although the synaptic clefts are narrow, the junctions are usually long and continuous, rather like those described for asymmetric synapses. Most of the VIP-positive axon terminals synpase with small dendritic shafts, but a few synapse with neuronal cell bodies. Since the majority of the VIP-positive neurons are bipolar cells it is concluded that these are the source of most of the VIP-positive axon terminals. If this is so, then the VIP-positive bipolar cells form symmetric synapses. This is in contrast to the observations of Peters and Kimerer (1981. J. Neurocytol. 10, 921-946) for the bipolar cells they examined in a Golgi-electron microscopic study had axon terminals forming asymmetric synapses. It is suggested that this disparity can be reconciled if it is assumed that the bipolar cell population consists of subgroups which have different biochemical characteristics and different synaptic relationships.     

MnTBAP对大鼠局灶性脑缺血损伤的保护作用

目的探讨锰卟啉(MnTBAP)对大鼠局灶性脑缺血损伤的保护作用及其可能机制。方法采用线拴法建立大鼠大脑中动脉栓塞(MCAO)模型,分为假手术组、缺血组、MnTBAP治疗组。缺血组和治疗组术后立即腹腔注射生理盐水和MnTBAP(10mg/kg体重),缺血24h后处死,用原位末端标记技术(TUNEL)和免疫组织化学方法对缺血侧脑组织神经细胞凋亡和凋亡调控蛋白Caspase-3表达进行检测。结果与假手术组相比,缺血组脑组织神经细胞凋亡及Caspase-3蛋白表达水平明显增加(P<0.01);与缺血组相比,MnTBAP治疗组神经细胞凋亡及Caspase-3蛋白表达水平显著减少。结论 MnTBAP能下调Caspase-3蛋白表达,抑制脑组织神经细胞凋亡,对缺血性脑损伤具有保护作用。