The role of autonomic control in cardiovascular system: Summary of basic principles (original) (raw)
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Nerve Centers Affecting the Function of the Cardiovascular System
Journal of Babol University of Medical Sciences, 2021
BACKGROUND AND OBJECTIVE: The activity of the cardiovascular system is carried out by the Autonomic Nervous System (ANS). ANS itself is controlled by multiple nerve centers. At present, there is little and scattered information about them in Persian language. The aim of this review article is to collect information about nerve centers that control ANS and their relationship with cardiovascular activity in Persian. METHODS: In this review article, by searching the international and national databases of web of science, Scopus, Google Scholar, PubMed, ISC and Magiran until 2020 and using the keywords cardiovascular system, baroreflex, the rostral ventrolateral medulla (RVLM), the caudal ventrolateral medulla (CVLM), the nucleus tractus solitarius (NTS), the hypothalamic paraventricular nucleus (PVN), the hypothalamic supraoptic nucleus (SON), amygdala, raphe nucleus, the periaqueductal gray (PAG), cuneiform nucleus (CnF), the rostral ventromedial medulla (RVM) and the pedunculopontine tegmental nucleus (PPT), data about Autonomic Nervous System were collected. FINDINGS: Evaluations have shown that the most important brain centers for regulating blood pressure are the rostral ventrolateral medulla, the nucleus tractus solitarius, the hypothalamic paraventricular nucleus, the periaqueductal gray, and raphe nucleus, which control cardiovascular activity mainly by affecting the sympathetic system. CONCLUSION: According to the results of this study, the maintenance of basal blood pressure, heart rate regulation and reflex control of blood pressure and heart rate are mainly done by autonomic and especially sympathetic nerve centers.
Autonomic processing of the cardiovascular reflexes in the nucleus tractus solitarii
Brazilian Journal of Medical and Biological Research, 1997
The nucleus tractus solitarii (NTS) receives afferent projections from the arterial baroreceptors, carotid chemoreceptors and cardiopulmonary receptors and as a function of this information produces autonomic adjustments in order to maintain arterial blood pressure within a narrow range of variation. The activation of each of these cardiovascular afferents produces a specific autonomic response by the excitation of neuronal projections from the NTS to the ventrolateral areas of the medulla (nucleus ambiguus, caudal and rostral ventrolateral medulla). The neurotransmitters at the NTS level as well as the excitatory amino acid (EAA) receptors involved in the processing of the autonomic responses in the NTS, although extensively studied, remain to be completely elucidated. In the present review we discuss the role of the EAA L-glutamate and its different receptor subtypes in the processing of the cardiovascular reflexes in the NTS. The data presented in this review related to the neurotransmission in the NTS are based on experimental evidence obtained in our laboratory in unanesthetized rats. The two major conclusions of the present review are that a) the excitation of the cardiovagal component by cardiovascular reflex activation (chemo-and Bezold-Jarisch reflexes) or by L-glutamate microinjection into the NTS is mediated by N-methyl-D-aspartate (NMDA) receptors, and b) the sympatho-excitatory component of the chemoreflex and the pressor response to L-glutamate microinjected into the NTS are not affected by an NMDA receptor antagonist, suggesting that the sympatho-excitatory component of these responses is mediated by non-NMDA receptors.
Landmarks in understanding the central nervous control of the cardiovascular system
Experimental Physiology, 2007
In this Paton Lecture I have tried to trace the key experiments that have developed ideas on how the brain regulates the cardiovascular system. It is a personal view and inevitably, owing to constraints on space and time, I have not been able to cover areas such as the nucleus tractus solitarius and cardiac vagal neurones, although I acknowledge that some may consider the story is incomplete without them. Starting with the crucial discovery of vasomotor nerves and 'vasomotor tone', the patterns of activity in sympathetic nerves which led to the important idea of central oscillating networks of neurones are described. I discuss how this knowledge has informed current controversies on the origin of vasomotor activity in presympathetic neurones in the ventral medulla, which identify intrinsic pacemaker activity or synaptic input from multiple oscillators as prime mechanisms. I present an emerging view that the role of other regions of the brain, in particular supramedullary sites, has been underplayed. These regions are pivotal for the non-uniform distribution of cardiac output that is unique to each reflex and behavioural state. I discuss the most recent evidence for 'central command' neurones that offers a plausible explanation for how these patterns of sympathetic activity are achieved. Finally, I stress the importance of these current ideas to the understanding of pathological changes in sympathetic activity in cardiovascular diseases such as hypertension or congestive heart failure.
Brain Research, 1995
The human medulla contains catecholamine-and NADPH-diaphorase (NADPH-d) neurons in both the ventrolateral medulla (VLM) and nucleus of the solitary tract (NTS). There is abundant experimental evidence for the critical role of these areas in control of arterial pressure. We sought to determine the pattern of distribution and topographic relationship between tyrosine hydroxylase (TH)-immunoreactive and NADPH-d-reactive cell groups in normal human VLM and NTS, in view of their potential implications in human autonomic control and involvement in central autonomic disorders. Medullae from three patients with no neurologic disease were obtained at autopsy within 24 h of death. Individual sections, obtained from the rostral and caudal medulla, were stained for TH, NADPH-d or both. We found that: (1) TH-and NADPH-d positive neurons are topographically segregated in the VLM; (2) in the VLM, TH and NADPH-d neurons may coexist within a given area but both markers do not appear to coexist in single neuron; (3) NADPH-d-reactive fibers and processes overlap the distribution of TH neurons within the VLM; and (4) both TH-and NADPH-d-reactive processes appear to innervate intrinsic blood vessels in the VLM and NTS. Thus, there are important topographic relationships between catecholamine-and NO-synthesizing neurons in hllman VLM and perhaps NTS, including innervation of intrinsic blood vessels. This may have important implications in regulation of autonomic reflexes, sympathetic excitatory drive and intrinsic control of cerebral blood flow in humans.
Distribution and Coexistence of Neuropeptides in Bulbospinal and Medullary Autonomic Pathways
Annals of the New York Academy of Sciences, 1990
Neuropeptide modulation of sympathetic control of cardiovascular activity may consist of both excitatory and inhibitory influences from neurons of the medullary midline raphe and parapyramidal region. Several putative neurotransmitter systems were identified in the midline medullary raphe (raphe pallidus, magnus obscurus) and in the parapyramidal region (located close to the ventral surface and lateral to the pyramidal tract) of the ventral medulla oblongata (FIG. 1). Many of the neurons contained serotonin (5HT) and thus are part of the midline B1 and B3 cell groups and their lateral exten~ions.'-~ In addition, many of the neurons contained immunoreactivity (ir) for neuropeptides (TABLE 1). Neurons of the midline raphe and the parapyramidal region project to the intermediolateral cell column (IML) of the thoracic spinal ~o r d '~, '~~'~ and to the nucleus of the solitary tract (NTS).*.*".*' The IML is the site of origin of sympathetic preganglionic neurons and the NTS is the site of termination of visceral afferent fibers including those from baroreceptors. Thus, a neuroanatomical substrate for effects on cardiovascular regulation by these medullary regions exists. In addition, activation of the midline raphe and the parapyramidal region affects mean arterial blood pressure .22-24
Anatomical substrates of cholinergic-autonomic regulation in the rat
Journal of Comparative Neurology, 1990
Acetylcholine (ACh) plays a major role in central autonomic regulation, including the control of arterial blood pressure (AP). Previously unknown neuroanatomic substrates of cholinergic - autonomic control were mapped in this study. Cholinergic perikarya and bouton-like varicosities were localized by an immunocytochemical method empolying a monoclonal antiserum against choline acetyltransferase (ChAT), the enzyme synthesizing ACh.In the forebrain, bouton-like varicosities and/or perikarya were detected in the septum, bed nucleus of the stria terminalis, amygdala (in particular, autonomic projection areas AP1 and AP2 bordering the central subnucleus, hypothalamus rostrolateral/innominata transitional area, perifornical, dorsal, incertal, caudolateral, posterior [PHN], subparafascicular, supramammillary and mammillary nuclei. Few or no punctate varicosities were labeled in the paraventricular (PVN) or supraoptic (SON) hypothalamic nuclei.In the mid and hindbrain, immunoreactive cells and processes were present in the nucleus of Edinger-Westphal, periaqueductal gray, parabrachial complex (PBC), a periceruleal zone avoiding the locus ceruleus (LC), pontine micturition field, pontomedullary raphe, paramedian reticular formation and periventricular gray, A5 area, lateral tegmental field, nucleus tractus solitarii (NTS), nucleus commissuralis, nucleus reticularis rostroventrolateralis (RVL), and the ventral medullary surface (VMS).In the PBC, immunoreactive varicosities identified areas previously unexplored for cholinergic autonomic responsivity superior, internal, dorsal, and central division of the lateral subnucleus, nucleus of Koelliker-Fuse and the medial subnucleus. In the NTS, previously undescribed ChAT-immunolabeled cells and processes were concentrated at intermediate and subpostermal levels and distributed viscerotopically in areas receiving primary cardiopulmonary afferents. In the nucleus RVL, cholinergic perikarya were in proximity to the VMS and medial to adrenergic cell bodies of the C1 area. Punctate varicosities of unknown origin and dendrites extending ventrally from the nucleus ambiguus overlapped the C1 area and immediate surround of RVL.In conclusion: 1) Cholinergic perikarya and putative terminal fields, overlap structures that are rich in cholinoreceptors and express autonomic, neuroendocrine, or behavioral responsivity to central cholinergic stimulation (PHN, NTS, RVL). The role of ACh in most immunolabeled areas, however, has yet to be determined. Overall, these data support the concept that cholinergic agents act at multiple sites in the CNS and with topographic specificity. (2) The absence of immunoreactive elements in the LC, PVN, and SON was unexpected and suggests that cholinergic processing attributed to these nuclei is mediated polysynaptically or by synapses on processes extending into adjacent cholinoreceptor fields. (3) Putative cholinergic terminals overlapping sites that relay primary (NTS) or higher-order visceral afferents suggest anatomical substrates for cholinergic regulation of autonomic reflexes. (4) ChAT-immunoreactive terminals in areas where cells project to the IML support the view that central cholinergic stimulation provoking sympathoexcitation may be mediated by bulbospinal neurons. A rich plexus of varicose fibers overlapping the C7 area of RVL, which provides the excitatory drive for tonic sympathetic discharge, may form the anatomical basis for the increases in sympathetic nerve activity provoked by systemic or central administration of cholinergic agents.