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Intrathoracic injection of anti- ␣ 4 and anti-VCAM-1 antibodies reduces sympathetic innervation of the heart. Cardiac norepinephrine levels ( black bars ) from animals injected with anti- ␣ 4 and anti-VCAM-1 antibodies showed a 33 Ϯ 9% ( n ϭ 23 animals) and 39 Ϯ 5% ( n ϭ 9 animals) reduction compared with controls. Quanti fi cation of the TH- positive fi bers within the ventricles (average number of fi bers per section of the experimental animal divided by the average number of fi bers per section of the control animals; white bars ) revealed a 33 Ϯ 7% ( n ϭ 11 animals) and 30 Ϯ 9% ( n ϭ 3 animals) reduction, respectively. Treatment with the ␣ 4 antagonist ( n ϭ 6 animals) yielded a 43 Ϯ 5% reduction of fi ber density compared with control animals injected with carrier ( n ϭ 7 animals). Error bars represent the SEM. * indicates 95% con fi dence level; ** indicates 99% con fi dence level; Student ’ s two-tailed t test.
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Sympathetic neurons innervate the heart early in postnatal development, an event that is crucial for proper modulation of blood pressure and cardiac function. However, the axon guidance cues that direct sympathetic neurons to the heart, and the neuronal receptors that recognize those cues, are poorly understood. Here we present evidence that intera...
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Context 1
... a double-blind protocol, the numbers of fibers were counted directly in the microscope for animals injected with anti-4, anti-VCAM-1, and control antibodies. Typical sections for anti-4-injected animals and controls are shown in Figure 6. 4 blockade reduced ventricular TH-positive fibers by 33%, and VCAM-1 blockade resulted in a 39% reduction (Fig. 7). The IgG control antibody-injected animals were used to establish a base- line of P6 ventricular innervation. The same results were obtained when digital images were captured and subjected to pixel analysis using the Scion Image software (see Materials and ...
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... a biochemical measure of sympathetic innervation, we as- sayed NE levels in injected hearts using two different NE assay protocols. Blocking 4 integrins reduced cardiac NE by 33%, and blockade of VCAM-1 resulted in a 39% reduction (Fig. 7). These data agree with the fiber quantification above. Immunological blockade significantly reduced the density of sympathetic fibers and NE levels in the heart (95-99% confidence) (Fig. ...
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... in injected hearts using two different NE assay protocols. Blocking 4 integrins reduced cardiac NE by 33%, and blockade of VCAM-1 resulted in a 39% reduction (Fig. 7). These data agree with the fiber quantification above. Immunological blockade significantly reduced the density of sympathetic fibers and NE levels in the heart (95-99% confidence) (Fig. ...
Citations
... The closest homologs of Mys and Scb in mammals are β1 integrin and α4/9 integrin [30], respectively. In mammals, β1 integrin and α4/9 integrin have been shown to be involved in mediating axonal projections [31][32][33][34]. For instance, it is reported that Semaphorin 7A binds to β1 integrin to promote axon growth in the mouse embryo [31], and α4 integrin interacts with VCAM-1 to mediate the innervation of the heart by sympathetic axons in rats [32]. ...
... In mammals, β1 integrin and α4/9 integrin have been shown to be involved in mediating axonal projections [31][32][33][34]. For instance, it is reported that Semaphorin 7A binds to β1 integrin to promote axon growth in the mouse embryo [31], and α4 integrin interacts with VCAM-1 to mediate the innervation of the heart by sympathetic axons in rats [32]. Whether β1 integrin and α4/9 integrin are also required for the exit of retinal ganglion axons from the optic disk in mammals, however, remains unclear. ...
Coordinated development of neurons and glia is essential for the establishment of neuronal circuits during embryonic development. In the developing Drosophila visual system, photoreceptor (R cell) axons and wrapping glial (WG) membrane extend from the eye disc through the optic stalk into the optic lobe. Extensive studies have identified a number of genes that control the establishment of R-cell axonal projection pattern in the optic lobe. The molecular mechanisms directing the exit of R-cell axons and WG membrane from the eye disc, however, remain unknown. In this study, we show that integrins are required in R cells for the extension of R-cell axons and WG membrane from the eye disc into the optic stalk. Knockdown of integrins in R cells but not WG caused the stalling of both R-cell axons and WG membrane in the eye disc. Interfering with the function of Rhea (i.e. the Drosophila ortholog of vertebrate talin and a key player of integrin-mediated adhesion), caused an identical stalling phenotype. These results support a key role for integrins on R-cell axons in directing R-cell axons and WG membrane to exit the eye disc.
... They showed that hearts of neonatal rats expressed VCAM-1 and are in contact with sympathetic neurons through an α4β1 integrin-VCAM-1 interaction. Furthermore, the blockade of this interaction by immunological strategy produced a deterioration of the innervation of the heart [148]. Taking this information, VCAM-1 is essential to the sympathetic innervation of the heart through an interaction of cardiomyocytes with sympathetic innervation neurons, and an alteration of the VCAM-1 expression in cardiac tissue could trigger electrical abnormalities in the heart as occur in atrial tissue and AF. ...
The vascular cellular adhesion molecule-1 (VCAM-1) is a protein that canonically participates in the adhesion and transmigration of leukocytes to the interstitium during inflammation. VCAM-1 expression, together with soluble VCAM-1 (sVCAM-1) induced by the shedding of VCAM-1 by metalloproteinases, have been proposed as biomarkers in immunological diseases, cancer, autoimmune myocarditis, and as predictors of mortality and morbidity in patients with chronic heart failure (HF), endothelial injury in patients with coronary artery disease, and arrhythmias. This revision aims to discuss the role of sVCAM-1 as a biomarker to predict the occurrence, development, and preservation of atrial fibrillation (AF).
... Относительно специализации постсинаптического региона в нейро-кардиальном соединении известно мало. В процессе развития формирование контакта между пресинаптическим варикозом и кардиомиоцитом требует взаимодействия интегрина α4β1 на пресинаптической стороне и молекулы адгезии VCAM-1 на кардиомиоцитах [48]. В ко-культуре в формировании нейро-кардиального соединения принимают участие кадгерины и β-катенины, формирующие адгезивные комплексы, стабилизирующие синаптический контакт [14]. ...
Один из важных механизмов сердечной регуляции реализуется через иннервацию кардиомиоцитов нейронами симпатической нервной системы. Симпатические аксоны ветвятся и формируют на своем протяжении расширения (варикозы), содержащие синаптические везикулы с основным нейромедиатором (норадреналином) и ко-нейромедиаторами. Варикозы тесно контактируют с кардиомиоцитами, в результате могут формироваться нейро-кардиальные соединения, имеющие
синапс-подобную организацию – специализированные пре- и постсинаптические регионы, разделенные узкой щелью. Эти синаптические образования подвержены пластичности и освобождение нейромедиатора из пресинаптических
варикозов плотно регулируется, в том числе, со стороны ауторецепторов. Нейрокардиальная передача имеет быстрые хронотропный и инотропный эффекты, а также управляет трофическими процессами, определяющими размеры кардио-
миоцитов и архитектуру сердечной стенки. Разные подтипы постсинаптических адренорецепторов вовлечены в эти кратковременные и долговременные эффекты нейро-кардиальных взаимодействий. Изменения в адренергической нейропередаче в сердце часто сопровождают многие распространенные патологии (сердечная недостаточность, аритмии, гипертония), внося вклад в их развитие. В представленном обзоре мы систематизировали и обобщили экспериментальные данные, свидетельствующие о существовании в сердце синаптической передачи, которая может иметь решающее значение в коммуникации между мозгом и сердцем.
... The neuro-cardiac synapse is a highly specialised zone 28,31,[55][56][57] that is structurally dependent on the activity of the sympathetic neurons 31 . The activity-dependence of such processes could have significant relevance to conditions of autonomic imbalance such as hypertension and heart failure since emerging evidence suggests the early hallmarks of the disease appear to present themselves in the nervous system 13,15,17 . ...
Many therapeutic interventions in disease states of heightened cardiac sympathetic activity are targeted to the myocytes. However, emerging clinical data highlights a dominant role in disease progression by the neurons themselves. Here we describe a novel experimental model of the peripheral neuro-cardiac axis to study the neuron’s ability to drive a myocyte cAMP phenotype. We employed a co-culture of neonatal ventricular myocytes and sympathetic stellate neurons from normal (WKY) and pro-hypertensive (SHR) rats that are sympathetically hyper-responsive and measured nicotine evoked cAMP responses in the myocytes using a fourth generation FRET cAMP sensor. We demonstrated the dominant role of neurons in driving the myocyte ß-adrenergic phenotype, where SHR cultures elicited heightened myocyte cAMP responses during neural activation. Moreover, cross-culturing healthy neurons onto diseased myocytes rescued the diseased cAMP response of the myocyte. Conversely, healthy myocytes developed a diseased cAMP response if diseased neurons were introduced. Our results provide evidence for a dominant role played by the neuron in driving the adrenergic phenotype seen in cardiovascular disease. We also highlight the potential of using healthy neurons to turn down the gain of neurotransmission, akin to a smart pre-synaptic ß-blocker.
... Among these, vascular cell adhesion molecule-1 (VCAM1) and α4β1 integrins seem to have a structural role in the cell–cell interaction between SNs and cardiac cells during heart innervation. Consistently, treatment with antibodies to VCAM1 or anti α4 integrins led to cardiac sympathetic denervation in neonatal rats [102]. The neuro-cardiac interaction site was further studied using cocultures of sympathetic ganglia neurons and CMs. ...
Starting from the late embryonic development, the sympathetic nervous system extensively innervates the heart and modulates its activity during the entire lifespan. The distribution of myocardial sympathetic processes is finely regulated by the secretion of limiting amounts of pro-survival neurotrophic factors by cardiac cells. Norepinephrine release by the neurons rapidly modulates myocardial electrophysiology, and increases the rate and force of cardiomyocyte contractions. Sympathetic processes establish direct interaction with cardiomyocytes, characterized by the presence of neurotransmitter vesicles and reduced cell–cell distance. Whether such contacts have a functional role in both neurotrophin- and catecholamine-dependent communication between the two cell types, is poorly understood.
... Indeed, interaction between α4β1 and VCAM-1 is important in myogenic differentiation and α4 expression is induced during differentiation of C2C12 cells (a mouse myoblast cell line) and during muscle differentiation [30]. In vivo, antibodies that block either α4 or VCAM-1 inhibit the development of the sympathetic innervation of the heart [38]. Knockout mice lacking α4 die at embryonic day 11 due to cardiac and placental formation failure [29] [39]. ...
... Expression of the α4 integrin subunit in native RPE cells has been previously documented [42]. However, as RPE cells are mitotically inactive in situ, α4 expression in RPE cells is intriguing given its well-known role in the regulation of the immune response [24] [25], as well as in development, cell differentiation and migration [29] [30] [38] [39] [50]. In diseases such as proliferative vitreous retinopathy, the normally quiescent RPE cells dedifferentiate, proliferate and secrete extracellular matrix molecules that form fibrocellular membranes [51]. ...
Integrins are a family of transmembrane glycoproteins that mediate cell-cell and cell-extracellular matrix interactions. The integrin α4 subunit is widely expressed by cells from the immune system and its expression by non-hematopoietic cells is scarce. In the present study, gene and protein expression of this integrin subunit was characterized in proliferating and quiescent human RPE cells. Immunofluorescent studies confirm that the α4 subunit is expressed in vitro by RPE cells, a result that has been validated by immunofluorescence and FACS analyses. The accumulation of the α4 integrin at cell-cell junctions in post-confluent RPE cell cultures negatively correlated with the level of expression of the mRNA transcript. Accordingly, transient transfection analyses reveal that the α4 promoter activity is considerably reduced when RPE cells form a confluent monolayer. Moreover, transfection of recombinant constructs bearing 5’-deletions of the α4 promoter segment allows the localization of strong negative regulatory elements on the -76 to -300 region of the α4 gene suggesting that its expression is intimately linked to the proliferative state of primary cultured RPE cells.
... Also, VLA-4 antagonists, including monoclonal antibodies for 4 subunits, are reported to have efficacy in the treatment of multiple sclerosis [3], spinal cord injury [4], and epilepsy [5]. It is also considered that VLA-4's low affinity state (non-activated state concerned in development) plays important roles in hematopoiesis [6], differentiation of skeletal muscle [7], and heart development [8]. Homozygous VLA-4 subunit 4-null mutation leads to lethality of embryos in mice. ...
Very late antigen-4 (VLA-4), which is concerned with cell-cell adhesion, plays important roles in development of the heart, and some VLA-4 antagonists cause cardiac anomalies. In this study, we evaluated the teratogenic potential of VLA-4 antagonist derivatives as screening, and investigated the conditions that induce cardiac anomalies. Seventeen compounds were orally administered to pregnant rats throughout the organogenesis period, and fetal examinations were performed. In addition, drug concentrations in the embryos were assayed. As a result, the incidence of ventricular septal defect (VSD) ranged from 0 to 100% depending on the compound. Plasma drug concentrations in the dams were related to increased incidence of VSD; however, these incidences were not increased when the concentration of the compound in the embryos at 24 hours after dosing was low. It is considered that continuous pharmacological activity in the embryo for more than 24 hours might disrupt closure of the ventricular septum.
... Thus, it is likely that basal release would affect the concentration of NE at sympathetic neurovascular junctions and thus affect vascular function. It is well known that targets affect the function of the postganglionic sympathetic neurons that innervate them (2,3,4,19,23,32,37). In most cases, these effects are mediated via soluble target-derived factors (2,3,4,19,23,32). ...
Ephs and ephrins are membrane-bound proteins that interact to modulate axon growth and neuronal function. We tested the hypothesis that eph/ephrin interactions affected the growth and function of vascular sympathetic innervation. Using RT-PCR analyses, we detected both classes of ephs (A and B) and both classes of ephrins (A and B) in sympathetic ganglia from neonatal and adult rats. Both classes of ephs (A and B) and both classes of ephrins (A and B) bound to the cell bodies and neurites of dissociated postganglionic sympathetic neurons. Messenger RNAs encoding for both classes of ephs (A and B) and both classes of ephrins (A and B) were also detected in sympathetically innervated arteries from neonatal and adult rats. These data suggest that ephrins/ephs on nerve fibers of postganglionic sympathetic neurons could interact with ephs/ephrins on cells in innervated arteries. We found that ephA4 reduced reinnervation of denervated femoral arteries. Reinnervation in the presence of ephA4-Fc (38.9±6.6%) was significantly less than that in the presence of IgG-Fc (62±10%; n=5; p<0.05; one-tailed unpaired t-test). These data indicate that eph/ephrin interactions modulated the growth of vascular sympathetic innervation. We also found that ephA4 increased basal release of norepinephrine from nerve terminals of isolated tail arteries. These data indicate that eph/ephrin interactions affect the growth and function of vascular sympathetic innervation.
... Vascular cells express neurotrophins and axon guidance molecules, known to affect vascular morphogenesis and angiogenesis as well as axon outgrowth and guidance (Adams et al., 1999; Carmeliet, 2003; Enomoto et al., 2001; Herzog et al., 2001; Honma et al., 2002). Angiogenic factors exert neurotrophic and neuroprotective effects in-vivo and in-vitro (Cheng et al., 2004; Rosenstein and Krum, 2004; Schwarz et al., 2004; Sondell and Kanje, 2001; Sondell et al., 1999; Sondell et al., 2000; Storkebaum et al., 2005; Wingerd et al., 2002 ). VEGF- A promotes axon outgrowth and neuronal survival in-vitro by paracrine and autocrine pathways in dorsal root ganglion (DRG) and SCG via flk-1 (VEGFR2) signaling (Ogunshola et al., 2002; Lin et al., 2003; Sondell and Kanje, 2001) and has been shown to modulate sympathetic growth cone collapse and spreading and promote reinnervation following local nerve damage (Damon, 2006; Marko and Damon, 2008). ...
Sympathetic nerve activity regulates blood pressure by altering peripheral vascular resistance. Variations in vascular sympathetic innervation suggest that vascular-derived cues promote selective innervation of particular vessels during development. As axons extend towards peripheral targets, they migrate along arterial networks following gradients of guidance cues. Collective ratios of these gradients may determine whether axons grow towards and innervate vessels or continue past non-innervated vessels towards peripheral targets. Utilizing directed neurite outgrowth in a three-dimensional (3D) co-culture, we observed increased axon growth from superior cervical ganglion explants (SCG) towards innervated compared to non-innervated vessels, mediated in part by vascular endothelial growth factor (VEGF-A) and Semaphorin3A (Sema3A) which both signal via neuropilin-1 (Nrp1). Exogenous VEGF-A, delivered by high-expressing VEGF-A-LacZ vessels or by rhVEGF-A/alginate spheres, increased sympathetic neurite outgrowth while exogenous rhSema3A/Fc decreased neurite outgrowth. VEGF-A expression is similar between the innervated and non-innervated vessels examined. Sema3A expression is higher in non-innervated vessels. Spatial gradients of Sema3A and VEGF-A may promote differential Nrp1 binding. Vessels expressing high levels of Sema3A favor Nrp1-PlexinA1 signaling, producing chemorepulsive cues limiting sympathetic neurite outgrowth and vascular innervation; while low Sema3A expressing vessels favor Nrp1-VEGFR2 signaling providing chemoattractive cues for sympathetic neurite outgrowth and vascular innervation.
... After a 7-day treatment with either atorvastatin or equal amounts of vehicle (20% sucrose), SCG were harvested, fixed, and individual neurons labeled for morphometric analyses by Diolistics (Grutzendler et al. 2003). We focused these studies on the SCG for technical and scientific reasons: (i) SCG are the largest sympathetic ganglia and the easiest to access in adult rats, which optimizes harvest of structurally intact ganglia and (ii) while stellate ganglia provide the primary sympathetic innervation of the heart, SCG also innervate the heart (Miura and Okada 1981;Korsching and Thoenen 1988;Pardini et al. 1989;Verberne et al. 1999;Hansson 2002;Wingerd et al. 2002) in addition to innervating the cerebrovasculature (Camargos and Machado 1988;Lincoln 1995;Miller et al. 1995;Furuichi et al. 1999). ...
Clinical and experimental evidence suggest that statins decrease sympathetic activity, but whether peripheral mechanisms involving direct actions on post-ganglionic sympathetic neurons contribute to this effect is not known. Because tonic activity of these neurons is directly correlated with the size of their dendritic arbor, we tested the hypothesis that statins decrease dendritic arborization in sympathetic neurons. Oral administration of atorvastatin (20 mg/kg/day for 7 days) significantly reduced dendritic arborization in vivo in sympathetic ganglia of adult male rats. In cultured sympathetic neurons, statins caused dendrite retraction and reversibly blocked bone morphogenetic protein-induced dendritic growth without altering cell survival or axonal growth. Supplementation with mevalonate or isoprenoids, but not cholesterol, attenuated the inhibitory effects of statins on dendritic growth, whereas specific inhibition of isoprenoid synthesis mimicked these statin effects. Statins blocked RhoA translocation to the membrane, an event that requires isoprenylation, and constitutively active RhoA reversed statin effects on dendrites. These observations that statins decrease dendritic arborization in sympathetic neurons by blocking RhoA activation suggest a novel mechanism by which statins decrease sympathetic activity and protect against cardiovascular and cerebrovascular disease.
