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Stavres J, Aultman RS, Newsome TA. Exercise pressor responses are exaggerated relative to force production during, but not following, thirty-minutes of rhythmic handgrip exercise. Eur J Appl Physiol 2024; 124:1547-1559. [PMID: 38155209 DOI: 10.1007/s00421-023-05390-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 11/29/2023] [Indexed: 12/30/2023]
Abstract
PURPOSE This study tested the hypothesis that blood pressure responses would increase relative to force production in response to prolonged bouts of muscular work. METHODS Fifteen individuals performed two minutes of static handgrip (SHG; 35% MVC), followed by three minutes of post-exercise-cuff-occlusion (PECO), before and after thirty minutes of rest (control), or rhythmic handgrip exercise (RHG) of the contralateral and ipsilateral forearms. Beat-by-beat recordings of mean arterial pressure (MAP), heart rate (HR), and handgrip force (kg) were averaged across one-minute periods at baseline, and minutes 5, 10, 15, 20, 25, and 30 of RHG. MAP was also normalized to handgrip force, providing a relative measure of exercise pressor responses (mmHg/kg). Hemodynamic responses to SHG and PECO were also compared before and after contralateral RHG, ipsilateral RHG, and control, respectively. Similar to the RHG trial, areas under the curve were calculated for MAP (blood pressure index; BPI) and normalized to the time tension index (BPInorm). RESULTS HR and MAP significantly increased during RHG (15.3 ± 1.4% and 20.4 ± 3.2%, respectively, both p < 0.01), while force output decreased by up to 36.6 ± 8.0% (p < 0.01). This resulted in a 51.6 ± 9.4% increase in BPInorm during 30 min of RHG (p < 0.01). In contrast, blood pressure responses to SHG and PECO were unchanged following RHG (all p ≥ 0.07), and only the mean HR (4.2 ± 1.5%, p = 0.01) and ΔHR (67.2 ± 18.1%, p < 0.01) response to SHG were exaggerated following ipsilateral RHG. CONCLUSIONS The magnitude of exercise pressor responses relative to force production progressively increases during, but not following, prolonged bouts of muscular work.
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Affiliation(s)
- Jon Stavres
- School of Kinesiology and Nutrition, University of Southern Mississippi, 118 College Drive, Hattiesburg, MS, USA.
| | - Ryan S Aultman
- School of Kinesiology and Nutrition, University of Southern Mississippi, 118 College Drive, Hattiesburg, MS, USA
| | - Ta'Quoris A Newsome
- School of Kinesiology and Nutrition, University of Southern Mississippi, 118 College Drive, Hattiesburg, MS, USA
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2
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Neuhuber WL, Berthoud HR. Functional anatomy of the vagus system: How does the polyvagal theory comply? Biol Psychol 2022; 174:108425. [PMID: 36100134 DOI: 10.1016/j.biopsycho.2022.108425] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 09/07/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022]
Abstract
Due to its pivotal role in autonomic networks and interoception, the vagus attracts continued interest from both basic scientists and therapists of various clinical disciplines. In particular, the widespread use of heart rate variability as an index of autonomic cardiac control and a proposed central role of the vagus in biopsychological concepts, e.g., the polyvagal theory, provide a good opportunity to recall basic features of vagal anatomy. In addition to the "classical" vagal brainstem nuclei, i.e., dorsal motor nucleus, nucleus ambiguus and nucleus tractus solitarii, the spinal trigeminal and paratrigeminal nuclei come into play as targets of vagal afferents. On the other hand, the nucleus of the solitary tract receives and integrates not only visceral but also somatic afferents.
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Affiliation(s)
- Winfried L Neuhuber
- Institute of Anatomy and Cell Biology, Friedrich-Alexander-Universität, Krankenhausstrasse 9, Erlangen, Germany.
| | - Hans-Rudolf Berthoud
- Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
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3
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Holt MK. The ins and outs of the caudal nucleus of the solitary tract: An overview of cellular populations and anatomical connections. J Neuroendocrinol 2022; 34:e13132. [PMID: 35509189 PMCID: PMC9286632 DOI: 10.1111/jne.13132] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 02/25/2022] [Accepted: 03/22/2022] [Indexed: 11/29/2022]
Abstract
The body and brain are in constant two-way communication. Driving this communication is a region in the lower brainstem: the dorsal vagal complex. Within the dorsal vagal complex, the caudal nucleus of the solitary tract (cNTS) is a major first stop for incoming information from the body to the brain carried by the vagus nerve. The anatomy of this region makes it ideally positioned to respond to signals of change in both emotional and bodily states. In turn, the cNTS controls the activity of regions throughout the brain that are involved in the control of both behaviour and physiology. This review is intended to help anyone with an interest in the cNTS. First, I provide an overview of the architecture of the cNTS and outline the wide range of neurotransmitters expressed in subsets of neurons in the cNTS. Next, in detail, I discuss the known inputs and outputs of the cNTS and briefly highlight what is known regarding the neurochemical makeup and function of those connections. Then, I discuss one group of cNTS neurons: glucagon-like peptide-1 (GLP-1)-expressing neurons. GLP-1 neurons serve as a good example of a group of cNTS neurons, which receive input from varied sources and have the ability to modulate both behaviour and physiology. Finally, I consider what we might learn about other cNTS neurons from our study of GLP-1 neurons and why it is important to remember that the manipulation of molecularly defined subsets of cNTS neurons is likely to affect physiology and behaviours beyond those monitored in individual experiments.
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Affiliation(s)
- Marie K. Holt
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUK
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4
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Neuhuber WL, Berthoud HR. Functional anatomy of the vagus system - Emphasis on the somato-visceral interface. Auton Neurosci 2021; 236:102887. [PMID: 34634680 PMCID: PMC8627476 DOI: 10.1016/j.autneu.2021.102887] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 09/02/2021] [Accepted: 09/21/2021] [Indexed: 11/18/2022]
Abstract
Due to its pivotal role in autonomic networks, the vagus attracts continuous interest from both basic scientists and clinicians. In particular, recent advances in vagus nerve stimulation strategies and their application to pathological conditions beyond epilepsy provide a good opportunity to recall basic features of vagal peripheral and central anatomy. In addition to the "classical" vagal brainstem nuclei, i.e., dorsal motor nucleus, nucleus ambiguus and nucleus tractus solitarii, the spinal trigeminal and paratrigeminal nuclei come into play as targets of vagal afferents. On the other hand, the nucleus of the solitary tract receives and integrates not only visceral but also somatic afferents. Thus, the vagus system participates significantly in what may be defined as "somato-visceral interface".
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Affiliation(s)
- Winfried L Neuhuber
- Institute of Anatomy and Cell Biology, Friedrich-Alexander University, Krankenhausstrasse 9, Erlangen, Germany.
| | - Hans-Rudolf Berthoud
- Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, Louisiana State University, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
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5
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Brasileiro-Santos MDS, Santos ADC. Neural mechanismsand post-exercise hypotension: The importance of experimental studies. MOTRIZ: REVISTA DE EDUCACAO FISICA 2017. [DOI: 10.1590/s1980-6574201700si0006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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6
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Papaioannou V, Chouvarda I, Gaertner E, Benyamina M, Ferry A, Maurel V, Soussi S, Blet A, Chaouat M, Plaud B, Mebazaa A, Legrand M. Heart rate variability and cardiac baroreflex inhibition-derived index predicts pain perception in burn patients. Burns 2016; 42:1445-1454. [PMID: 27170468 DOI: 10.1016/j.burns.2016.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/18/2016] [Accepted: 04/22/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Dressing changes induce acute pain in burn patients. This pain is difficult to predict and may be therefore undertreated. Two different non-invasive electrophysiological indices from heart rate variability and baroreflex inhibition-derived indices, analgesia/nociception index (ANI) and cardiovascular depth of analgesia (CARDEAN), have been proposed to predict and better assess adequacy of anti-nociception. The aim of this study was to evaluate these techniques as early pain alert tools in conscious burnt patients during dressing changes' procedures. METHODS Twenty adult burnt patients undergoing scheduled wound treatment procedures were included in this prospective observational study. Pain intensity was assessed using a 0-10 numerical rating scale (NRS) and was compared with both ANI and CARDEAN, during the procedures. Non parametric rank sum test and linear discriminant analysis were used for evaluating potential differences of measured variables between periods with different pain intensities. Receiver-operating characteristic (ROC) curves were built to assess their performance to detect pain within following 15s. RESULTS The sensitivity and specificity of ANI to detect pain were 67% and 70% and those of CARDEAN were 77% and 80%, with area under the curve (AUC) values of 0.75 and 0.83, respectively. Their combination increased AUC to 0.87. CONCLUSIONS Both ANI and CARDEAN indices during wound treatment procedures seem to discriminate periods with and without pain within 15s, serving as a potential complementary tool for early optimized pain control.
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Affiliation(s)
- Vasilios Papaioannou
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France.
| | - Ioanna Chouvarda
- Aristotle University of Thessaloniki, Lab of Medical Informatics, School of Medicine, Thessaloniki 54124, Greece.
| | - Elizabeth Gaertner
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France.
| | - Mourad Benyamina
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France.
| | - Axelle Ferry
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France.
| | - Veronique Maurel
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France.
| | - Sabri Soussi
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France.
| | - Alice Blet
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France; University of Paris Diderot, Paris, France; U-942 INSERM, 75475 Paris, France.
| | - Marc Chaouat
- Department of Plastic Surgery and Burn Unit, St-Louis Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France.
| | - Benoît Plaud
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France; University of Paris Diderot, Paris, France; U-942 INSERM, 75475 Paris, France.
| | - Alexandre Mebazaa
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France; University of Paris Diderot, Paris, France; U-942 INSERM, 75475 Paris, France.
| | - Matthieu Legrand
- Department of Anesthesiology and Critical Care and Burn Unit, Hôpitaux Universitaire St-Louis-Lariboisière, Assistance Publique-Hôpitaux de Paris (AP-HP), 75010 Paris, France; University of Paris Diderot, Paris, France; U-942 INSERM, 75475 Paris, France.
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Sévoz-Couche C, Brouillard C. Key role of 5-HT 3 receptors in the nucleus tractus solitarii in cardiovagal stress reactivity. Neurosci Biobehav Rev 2016; 74:423-432. [PMID: 27131969 DOI: 10.1016/j.neubiorev.2016.04.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 04/18/2016] [Accepted: 04/20/2016] [Indexed: 01/01/2023]
Abstract
Serotonin plays a modulatory role in central control of the autonomic nervous system (ANS). The nucleus tractus solitarii (NTS) in the medulla is an area of viscerosomatic integration innervated by both central and peripheral serotonergic fibers. Influences from different origins therefore trigger the release of serotonin into the NTS and exert multiple influences on the ANS. This major influence on the ANS is also mediated by activation of several receptors in the NTS. In particular, the NTS is the central zone with the highest density of serotonin3 (5-HT3) receptors. In this review, we present evidence that 5-HT3 receptors in the NTS play a key role in one of the crucial homeostatic responses to acute and chronic stress: inhibitory modulation of the parasympathetic component of the ANS. The possible functional interactions of 5-HT3 receptors with GABAA and NK1 receptors in the NTS are also discussed.
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Affiliation(s)
- Caroline Sévoz-Couche
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France.
| | - Charly Brouillard
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
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8
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O'Callaghan EL, McBryde FD, Burchell AE, Ratcliffe LEK, Nicolae L, Gillbe I, Carr D, Hart EC, Nightingale AK, Patel NK, Paton JFR. Deep brain stimulation for the treatment of resistant hypertension. Curr Hypertens Rep 2015; 16:493. [PMID: 25236853 DOI: 10.1007/s11906-014-0493-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hypertension is a leading risk factor for the development of several cardiovascular diseases. As the global prevalence of hypertension increases, so too has the recognition of resistant hypertension. Whilst figures vary, the proportion of hypertensive patients that are resistant to multiple drug therapies have been reported to be as high as 16.4 %. Resistant hypertension is typically associated with elevated sympathetic activity and abnormal homeostatic reflex control and is termed neurogenic hypertension because of its presumed central autonomic nervous system origin. This resistance to conventional pharmacological treatment has stimulated a plethora of medical devices to be investigated for use in hypertension, with varying degrees of success. In this review, we discuss a new therapy for drug-resistant hypertension, deep brain stimulation. The utility of deep brain stimulation in resistant hypertension was first discovered in patients with concurrent neuropathic pain, where it lowered blood pressure and improved baroreflex sensitivity. The most promising central target for stimulation is the ventrolateral periaqueductal gray, which has been well characterised in animal studies as a control centre for autonomic outflow. In this review, we will discuss the promise and potential mechanisms of deep brain stimulation in the treatment of severe, resistant hypertension.
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Affiliation(s)
- Erin L O'Callaghan
- School of Physiology & Pharmacology, University of Bristol, Bristol, BS8 1TD, UK
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9
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Pelosi GG, Busnardo C, Tavares RF, Corrêa FMA. Cardiovascular responses to glutamate microinjection in the dorsomedial periaqueductal gray of unanesthetized rats. J Neurosci Res 2012; 90:2193-200. [DOI: 10.1002/jnr.23094] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 04/23/2012] [Accepted: 05/07/2012] [Indexed: 11/07/2022]
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10
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de Freitas RL, Kübler JML, Elias-Filho DH, Coimbra NC. Antinociception induced by acute oral administration of sweet substance in young and adult rodents: The role of endogenous opioid peptides chemical mediators and μ1-opioid receptors. Pharmacol Biochem Behav 2012; 101:265-70. [DOI: 10.1016/j.pbb.2011.12.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 11/23/2011] [Accepted: 12/10/2011] [Indexed: 01/05/2023]
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11
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McMullan S, Pilowsky PM. Sympathetic premotor neurones project to and are influenced by neurones in the contralateral rostral ventrolateral medulla of the rat in vivo. Brain Res 2012; 1439:34-43. [PMID: 22264491 DOI: 10.1016/j.brainres.2011.12.058] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 12/08/2011] [Accepted: 12/28/2011] [Indexed: 02/07/2023]
Abstract
The tonic activity of bulbospinal neurones in the rostral ventrolateral medulla (RVLM) is thought to underlie basal sympathetic nerve activity. A key research objective is to delineate the mechanisms that contribute to the firing of these neurones. In the current study we investigate the hypothesis that inputs arising in the contralateral RVLM converge on barosensitive bulbospinal neurones and contribute to their discharge pattern. Extracellular recordings were made from 24 barosensitive bulbospinal neurones in urethane anaesthetised, vagotomised and artificially ventilated rats during activation (glutamate or D,L-homocysteic acid microinjection, 50 nl, 50mM, or monopolar electrical stimulation) or inhibition (microinjection of GABA receptor agonists muscimol or isoguvacine, 50 nl, 10mM) of the contralateral RVLM. Chemical RVLM activation strongly increased (10/17) or inhibited (6/17) the spontaneous activity of neurones recorded in the contralateral RVLM. Electrical RVLM stimulation evoked a combination of short latency (median 6 ms) inhibitory and longer latency (median 9.1 ms, P<0.01) excitatory orthodromic responses in contralateral sympathetic premotor neurones and in some cases evoked antidromic action potentials that collided with spontaneous spikes. RVLM inhibition increased the discharge rate of sympathetic premotor neurones in the contralateral brainstem by 21 ± 13% (P<0.05) and reduced the variability of unit firing by 37 ± 12% (n=5, p<0.05). These findings indicate that sympathetic premotor neurones receive inhibitory and excitatory input from the contralateral RVLM, that inhibitory inputs predominate under baseline conditions, and that a population of sympathetic premotor neurones project to the contralateral RVLM in addition to their spinal targets.
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Affiliation(s)
- Simon McMullan
- Australian School of Advanced Medicine, Macquarie University, NSW, Australia.
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12
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Topographical distributions of endomorphinergic pathways from nucleus tractus solitarii to periaqueductal gray in the rat. J Chem Neuroanat 2010; 39:166-74. [DOI: 10.1016/j.jchemneu.2009.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 10/20/2009] [Accepted: 11/11/2009] [Indexed: 01/09/2023]
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13
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Influence of dorsal periaqueductal gray activation on respiratory occlusion reflexes in rats. Auton Neurosci 2009; 150:62-9. [DOI: 10.1016/j.autneu.2009.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 03/10/2009] [Accepted: 04/29/2009] [Indexed: 01/10/2023]
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Exercise reduces GABA synaptic input onto nucleus tractus solitarii baroreceptor second-order neurons via NK1 receptor internalization in spontaneously hypertensive rats. J Neurosci 2009; 29:2754-61. [PMID: 19261870 DOI: 10.1523/jneurosci.4413-08.2009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A single bout of mild to moderate exercise can lead to a postexercise decrease in blood pressure in hypertensive subjects, namely postexercise hypotension (PEH). The full expression of PEH requires a functioning baroreflex, hypertension, and activation of muscle afferents (exercise), suggesting that interactions in the neural networks regulating exercise and blood pressure result in this fall in blood pressure. The nucleus tractus solitarii (NTS) is the first brain site that receives inputs from nerves carrying blood pressure and muscle activity information, making it an ideal site for integrating cardiovascular responses to exercise. During exercise, muscle afferents excite NTS GABA neurons via substance P and microinjection of a substance P-neurokinin 1 receptor (NK1-R) antagonist into the NTS attenuates PEH. The data suggest that an interaction between the substance P NK1-R and GABAergic transmission in the NTS may contribute to PEH. We performed voltage clamping on NTS baroreceptor second-order neurons in spontaneously hypertensive rats (SHRs). All animals were killed within 30 min and the patch-clamp recordings were performed 2-8 h after the sham/exercise protocol. The data showed that a single bout of exercise reduces (1) the frequency but not the amplitude of GABA spontaneous IPSCs (sIPSCs), (2) endogenous substance P influence on sIPSC frequency, and (3) sIPSC frequency response to exogenous application of substance P. Furthermore, immunofluorescence labeling in NTS show an increased substance P NK1-R internalization on GABA neurons. The data suggest that exercise-induced NK1-R internalization results in a reduced intrinsic inhibitory input to the neurons in the baroreflex pathway.
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Xing J, Li DP, Li J. Role of GABA receptors in nitric oxide inhibition of dorsolateral periaqueductal gray neurons. Neuropharmacology 2008; 54:734-44. [PMID: 18222497 DOI: 10.1016/j.neuropharm.2007.12.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Revised: 11/26/2007] [Accepted: 12/07/2007] [Indexed: 01/24/2023]
Abstract
Nitric oxide (NO) affects neuronal activity of the midbrain periaqueductal gray (PAG). The purpose of this report was to investigate the role of GABA receptors in NO modulation of neuronal activity through inhibitory and excitatory synaptic inputs within the dorsolateral PAG (dl-PAG). First, spontaneous miniature inhibitory postsynaptic currents (mIPSCs) and excitatory postsynaptic currents (mEPSCs) were recorded using whole cell voltage-clamp methods. Increased NO by either S-nitroso-N-acetyl-penicillamine (SNAP, 100 microM) or L-arginine (50 microM) significantly augmented the frequency of mIPSCs of the dl-PAG neurons without altering their amplitudes or decay time constants. The effects were eliminated after bath application of carboxy-PTIO (NO scavenger), and 1-(2-trifluorom-ethylphenyl) imidazole (NO synthase inhibitor). In contrast, SNAP and L-arginine did not alter mEPSCs in dl-PAG neurons. However the frequency of mEPSCs was significantly increased with prior application of the GABA(B) receptors antagonist, CGP55845. In addition, NO significantly decreased the discharge rate of spontaneous action potentials in the dl-PAG neurons and the effect was reduced in the presence of the GABA(A) receptor antagonist, bicuculline. Our data show that within the dl-PAG NO potentiates the synaptic release of GABA, while NO-induced GABA presynaptically inhibits glutamate release through GABA(B) receptors. Overall, NO suppresses neuronal activity of the dl-PAG via a potentiation of GABAergic synaptic inputs and via GABA(A) receptors.
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Affiliation(s)
- Jihong Xing
- Heart and Vascular Institute and Department of Medicine, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
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Green AL, Wang S, Owen SLF, Paterson DJ, Stein JF, Aziz TZ. Controlling the Heart Via the Brain: A Potential New Therapy for Orthostatic Hypotension. Neurosurgery 2006; 58:1176-83; discussion 1176-83. [PMID: 16723897 DOI: 10.1227/01.neu.0000215943.78685.01] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
OBJECTIVE:
Electrical stimulation of the midbrain is known to influence blood pressure in animals. In humans, it is used for the treatment of chronic neuropathic pain. Our aim was to assess whether orthostatic hypotension can be successfully treated with deep brain stimulation of the periventricular/periaqueductal gray areas in humans.
METHODS:
We recruited 11 patients who had chronic neuropathic pain and who had undergone implantation of a deep brain stimulator in the periventricular/periaqueductal gray areas. Patients were divided into three groups depending on whether they had orthostatic hypotension (one patient), mild orthostatic intolerance (five patients), or no orthostatic intolerance (five patients). Postoperatively, we continuously recorded blood pressure and heart rate with stimulation off and on and in both sitting and standing positions. From these values, we derived the blood pressure changing rate. Using autoregressive modeling techniques, we calculated changes in low- and high-frequency power spectra of heart rate and baroreflex sensitivity.
RESULTS:
Electrical stimulation reduced the decrease in systolic blood pressure on standing from 28.2 to 11.1% in one patient with orthostatic hypotension (P < 0.001). In the mild orthostatic intolerance group, an initial drop in systolic blood pressure of 15.4% was completely reversed (P < 0.001). There were no side effects in the remaining group. These changes were accompanied by increases in the blood pressure changing rate, the baroreflex sensitivity, and the baseline (sitting) low-frequency power of the RR interval, but not the high-frequency power.
CONCLUSION:
Electrical stimulation of the human periventricular/periaqueductal gray areas can reverse orthostatic hypotension. The cause seems to be an increase in sympathetic outflow and in baroreflex sensitivity. This has important implications for future therapies.
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Sekizawa SI, Bonham AC. Group I Metabotropic Glutamate Receptors on Second-Order Baroreceptor Neurons Are Tonically Activated and Induce a Na+–Ca2+Exchange Current. J Neurophysiol 2006; 95:882-92. [PMID: 16192328 DOI: 10.1152/jn.00772.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The nucleus tractus solitarius (NTS) is essential for coordinating baroreflex control of blood pressure. The baroreceptor sensory fibers make glutamatergic synapses onto second-order NTS neurons. Glutamate spillover activates Group II and III presynaptic metabotropic glutamate receptors (mGluRs) on the baroreceptor central terminals to inhibit synaptic transmission, but the role of postsynaptic mGluRs is less understood. We used whole cell patch-clamping in anatomically identified second-order baroreceptor neurons in a brain stem slice to test whether Group I, II, and III mGluRs had postsynaptic effects at this first central synapse in the baroreceptor afferent pathway. The Group I agonist DHPG induced a depolarization and spiking that was mimicked by endogenous glutamate. Group I mGluR blockade prevented the depolarization and slightly hyperpolarized the neurons, suggesting a small tonic Group I mGluR activation. The DHPG-induced inward current consisted of voltage-dependent and -independent components; the former was blocked by TEA and the latter was blocked by replacing extracellular NaCl with LiCl or Tris-HCl. The DHPG current was potentiated in a Ca2+-free external solution and was diminished by intracellular dialysis with BAPTA and by perfusion with Na+–Ca2+exchanger blockers, KB-R7943 or 3′,4′-dichlorobenzamil. Intracellular dialysis with GDPβS or heparin and perfusion with the PLC inhibitor U-73122 or the Ca2+-calmodulin inhibitor W-7 significantly decreased the DHPG current. The data suggest that Group I mGluRs on baroreceptor neurons are functional; are activated by endogenous glutamate; and activate a Na+–Ca2+exchanger through G-protein, PLC, IP3, and Ca2+-calmodulin mechanisms to excite the cell, thus providing postsynaptic mechanisms to enhance or prolong baroreceptor signal transmission.
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Affiliation(s)
- Shin-ichi Sekizawa
- Department of Pharmacology, School of Medicine, University of California, Davis, CA 95817, USA
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Kishi R, Bongiovanni R, de Nadai TR, Freitas RL, de Oliveira R, Ferreira CMDR, Coimbra NC. Dorsal raphe nucleus and locus coeruleus neural networks and the elaboration of the sweet-substance-induced antinociception. Neurosci Lett 2006; 395:12-7. [PMID: 16289556 DOI: 10.1016/j.neulet.2005.10.046] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Revised: 09/16/2005] [Accepted: 10/17/2005] [Indexed: 11/26/2022]
Abstract
In order to investigate the effects of monoaminergic neurons of the dorsal raphe nucleus (DRN) and locus coeruleus (LC) on the elaboration and control of sweet-substance-induced antinociception, male albino Wistar rats weighing 180-200 g received sucrose solution (250 g/L) for 7-14 days as their only source of liquid. After the chronic consumption of sucrose solution, each animal was pretreated with unilateral microinjection of ibotenic acid (1.0 microg/0.2 microL) in the DRN or in the LC. The tail withdrawal latencies of the rats in the tail-flick test were measured immediately before and 7 days after this treatment. The neurochemical lesion of locus coeruleus, but not of DRN neural networks with ibotenic acid, after the chronic intake of sweetened solution, decreased the sweet-substance-induced antinociception. These results indicate the involvement of noradrenaline-containing neurons of the LC in the sucrose-induced antinociception. We also consider the possibility of DRN serotonergic neurons exerting some inhibitory effect on the LC neural networks involved with the elaboration of the sweet-substance-induced antinociception.
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Affiliation(s)
- Renato Kishi
- Laboratório de Neuroanatomia e Neuropsicobiologia, Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (FMRP-USP), Avenida dos Bandeirantes, 3900 Ribeirão Preto (SP) 14049-900, Brasil
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de Vries A, Paton JFR, Lightman SL, Lowry CA. Characterisation of c-Fos expression in the central nervous system of mice following right atrial injections of the 5-HT3 receptor agonist phenylbiguanide. Auton Neurosci 2005; 123:62-75. [PMID: 16298172 DOI: 10.1016/j.autneu.2005.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Revised: 10/12/2005] [Accepted: 10/14/2005] [Indexed: 11/24/2022]
Abstract
Cardiopulmonary receptors relay signals to the central nervous system via vagal and spinal visceral afferents. To date there are no detailed topographical studies in mice indicating the distribution of central neurones activated following stimulation of cardiopulmonary afferents. In anaesthetised mice, we injected the 5-HT(3) receptor agonist phenylbiguanide (PBG), a drug that is known to stimulate cardiopulmonary afferent C-fibres, into the right atrium of the heart and mapped c-Fos expression within specific regions of the central nervous system. Intra-atrial injection of PBG produced a reflex cardiorespiratory response including a pronounced bradycardia and a respiratory depression. Using immunohistochemical detection of the protein product of the immediate-early gene c-fos, we mapped the brain regions affected by cardiopulmonary 5-HT(3) receptor stimulation. Within the nucleus of the solitary tract (nTS) of PBG-injected mice, we detected an increased number of c-Fos-positive nuclei in the dorsolateral and gelatinous parts at the level of the area postrema (-7.48 mm bregma) but not at more rostral or caudal levels (-7.76, -7.20, -6.84 and -6.36 mm bregma) relative to vehicle-injected control mice. In addition, c-Fos expression in the crescent part of the lateral parabrachial nucleus was decreased in PBG-injected mice whereas no significant differences were detected between PBG-injected and control mice in the number of c-Fos-positive nuclei in the dorsal part of the lateral parabrachial nucleus. PBG injections had no significant effects on the number of c-Fos-positive catecholaminergic neurones within the C1/A1, C2/A2, A5, A6 and A7 cell groups. Likewise, PBG injections had no significant effects on c-Fos expression in other central regions involved in cardiorespiratory control or cardiorespiratory reflexes (selected non-catecholaminergic nuclei in the medulla and midbrain periaqueductal gray, the paraventricular nucleus of the hypothalamus and the central nucleus of the amygdala). Identification of specific regions of the nTS complex involved in relaying signals from afferent cardiopulmonary C-fibres to the central nervous system will be useful for future studies aimed at understanding neural mechanisms underlying cardiopulmonary reflexes and physiological responses to cardiopulmonary disease.
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Affiliation(s)
- Annick de Vries
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Dorothy Hodgkin Building, Bristol, UK
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Pelosi GG, Corrêa FMA. Cardiovascular effects of noradrenaline microinjected into the dorsal periaqueductal gray area of unanaesthetized rats. Eur J Neurosci 2005; 22:3188-94. [PMID: 16367785 DOI: 10.1111/j.1460-9568.2005.04511.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The periaqueductal grey area (PAG) is a mesencephalic region that is involved in the modulation of cardiovascular changes associated with behavioural responses. Among the neurotransmitters present in the PAG, noradrenaline (NA) is also known to be involved in central nervous system cardiovascular regulation. In the present study we report the cardiovascular effects of the microinjection of NA into the dorsal portion of the PAG (dPAG) of unanaesthetized rats and the peripheral mechanism involved in their mediation. Injection of NA in the dPAG of unanaesthetized rats evoked a dose-dependent pressor response accompanied by bradycardia. The magnitude of the pressor responses was higher at more rostral sites in the dPAG and decreased when NA was injected into the caudal portion of the dPAG. The responses to NA were markedly reduced in urethane-anaesthetized rats. The pressor response was potentiated by i.v. pretreatment with the ganglion blocker pentolinium and blocked by i.v. pretreatment with the vasopressin antagonist dTyr(CH2)5(Me)AVP. The results suggest that activation of noradrenergic receptors within the dPAG can evoke pressor responses, which are mediated by acute vasopressin release.
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Affiliation(s)
- Gislaine Garcia Pelosi
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Avenue Bandeirantes 3900, 14040-900, Ribeirão Preto, São Paulo, Brazil
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Miyase CI, Kishi R, de Freitas RL, Paz DA, Coimbra NC. Involvement of pre- and post-synaptic serotonergic receptors of dorsal raphe nucleus neural network in the control of the sweet-substance-induced analgesia in adult Rattus norvegicus (Rodentia, Muridae). Neurosci Lett 2005; 379:169-73. [PMID: 15843057 DOI: 10.1016/j.neulet.2004.12.058] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Revised: 12/19/2004] [Accepted: 12/23/2004] [Indexed: 11/27/2022]
Abstract
In order to investigate the effects of monoaminergic mechanisms of the dorsal raphe nucleus on the elaboration and control of sweet-substance-induced antinociception, male albino Wistar rats weighing 180-200 g received sucrose solution (250 g/L) for 14 days as their only source of liquid. After the chronic consumption of sucrose solution, each animal was pretreated with unilateral microinjection of methiothepin mesylate (5.0 microg/0.2 microL), or methysergide maleate (5.0 microg/0.2 microL) in the dorsal raphe nucleus. Each rat consumed an average of 15.6g sucrose/day. Their tail withdrawal latencies in the tail-flick test were measured immediately before and after this treatment. An analgesia index was calculated from the withdrawal latencies before and after the pharmacological treatment. The blockade of serotonergic receptor in the dorsal raphe nucleus with methysergide after the chronic intake of sucrose decreased the sweet-induced antinociception. However, microinjections of methiothepin in the dorsal raphe nucleus did not cause a similar effect on the tail-flick latencies after the chronic intake of sucrose solution, increasing the sweet-substance-induced analgesia. These results indicate the involvement of serotonin as a neurotransmitter in the sucrose-produced antinociception. Considering that the blockade of pre-synaptic serotonergic receptors of the neural networks of the dorsal raphe nucleus with methiothepin did not decrease the sweet-substance-induced antinociception, and the central blockade of post-synaptic serotonergic receptors decreased the sucrose-induced analgesia, the modulation of the release of serotonin in the neural substrate of the dorsal raphe nucleus seems to be crucial for the organization of this interesting antinociceptive process.
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Affiliation(s)
- Cátia Isumi Miyase
- Laboratório de Neuroanatomia e Neuropsicobiologia, Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (FMRP-USP), Avenida dos Bandeirantes 3900, Ribeirão Preto (SP) 14049-900, Brazil
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