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Gano A, Wojcik H, Danseglio NC, Kelliher K, Varlinskaya EI, Deak T. Adolescent intermittent ethanol (AIE) sensitized fever in male Sprague Dawley rats exposed to poly I:C in adulthood. Brain Behav Immun 2024; 120:82-97. [PMID: 38777284 PMCID: PMC11269031 DOI: 10.1016/j.bbi.2024.05.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/13/2024] [Accepted: 05/19/2024] [Indexed: 05/25/2024] Open
Abstract
Fever plays an indispensable role in host defense processes and is used as a rapid index of infection severity. Unfortunately, there are also substantial individual differences in fever reactions with biological sex, immunological history, and other demographic variables contributing to adverse outcomes of infection. The present series of studies were designed to test the hypothesis that a history of adolescent alcohol misuse may be a latent experiential variable that determines fever severity using polyinosinic:polycytidylic acid (poly I:C), a synthetic form of double-stranded RNA that mimics a viral challenge. Adult male and female Sprague Dawley rats were injected with 0 (saline) or 4 mg/kg poly I:C to first establish sex differences in fever sensitivity in Experiment 1 using implanted radiotelemetry devices for remote tracking. In Experiments 2 and 3, adolescent males and females were exposed to either water or ethanol (0 or 4 g/kg intragastrically, 3 days on, 2 days off, ∼P30-P50, 4 cycles/12 exposures total). After a period of abstinence, adult rats (∼P80-96) were then challenged with saline or poly I:C, and fever induction and maintenance were examined across a prolonged time course of 8 h using implanted probes. In Experiments 4 and 5, adult male and female subjects with a prior history of adolescent water or adolescent intermittent ethanol (AIE) were given saline or poly I:C, with tissue collected for protein and gene expression analysis at 5 h post-injection. Initial sex differences in fever sensitivity were minimal in response to the 4 mg/kg dose of poly I:C in ethanol-naïve rats. AIE exposed males injected with poly I:C showed a sensitized fever response as well as enhanced TLR3, IκBα, and IL-1β expression in the nucleus of the solitary tract. Other brain regions related to thermoregulation and peripheral organs such as spleen, liver, and blood showed generalized immune responses to poly I:C, with no differences evident between AIE and water-exposed males. In contrast, AIE did not affect responsiveness to poly I:C in females. Thus, the present findings suggest that adolescent binge drinking may produce sex-specific and long-lasting effects on fever reactivity to viral infection, with preliminary evidence suggesting that these effects may be due to centrally-mediated changes in fever regulation rather than peripheral immunological mechanisms.
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Affiliation(s)
- Anny Gano
- Developmental Exposure Alcohol Research Center (DEARC), Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, 13902-6000, USA
| | - Hannah Wojcik
- Developmental Exposure Alcohol Research Center (DEARC), Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, 13902-6000, USA
| | - Nina C Danseglio
- Developmental Exposure Alcohol Research Center (DEARC), Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, 13902-6000, USA
| | - Kaitlyn Kelliher
- Developmental Exposure Alcohol Research Center (DEARC), Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, 13902-6000, USA
| | - Elena I Varlinskaya
- Developmental Exposure Alcohol Research Center (DEARC), Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, 13902-6000, USA
| | - Terrence Deak
- Developmental Exposure Alcohol Research Center (DEARC), Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, 13902-6000, USA.
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Aleksandrova NP, Klinnikova AA, Danilova GA. Cyclooxygenase and nitric oxide synthase pathways mediate the respiratory effects of TNF-α in rats. Respir Physiol Neurobiol 2020; 284:103567. [PMID: 33161117 DOI: 10.1016/j.resp.2020.103567] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 09/23/2020] [Accepted: 10/25/2020] [Indexed: 01/22/2023]
Abstract
TNF-α is the key inflammatory cytokine. TNF-α receptors are expressed in brain stem regions involved in respiratory control and also in the carotid bodies, which are the sensory organs monitoring arterial blood O2. We hypothesised that the circulating tumour necrosis factor (TNF)-α may affect the lung ventilation and modulate the hypoxic ventilatory response via activation of cyclooxygenase (COX) and nitric oxide synthase (NOS) pathways. The aim of the current study was to compare the respiratory effects of TNF-α before and after pretreatment with diclofenac or L-NG-nitro arginine methyl ester (L-NAME) nonspecific inhibitors of COX and NOS, respectively. The hypoxic ventilatory response was measured in anaesthetised rats using rebreathing techniques. We found that TNF-α increased the lung ventilation in normoxia but decreased the ventilatory response to hypoxia. Pretreatment with each of these inhibitors reduced respiratory effects of TNF-α. We believe that activation of COX and NOS-related pathways and also "cross-talk" between them mediates the TNF-α respiratory effects and underlies the impact of inflammation on the respiratory function.
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Affiliation(s)
- Nina Pavlovna Aleksandrova
- Head of Laboratory of Respiratory Physiology, Pavlov Institute of Physiology of RAS, nab Makarova6, St.-Petersburg, Russian Federation.
| | - Anna Andreevna Klinnikova
- Researcher of Laboratory of Respiratory Physiology, Pavlov Institute of Physiology of RAS, nab Makarova6, St.-Petersburg, Russian Federation.
| | - Galina Anatolevna Danilova
- Researcher of Laboratory of Respiratory Physiology, Pavlov Institute of Physiology of RAS, nab Makarova6, St.-Petersburg, Russian Federation.
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3
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Litvin DG, Denstaedt SJ, Borkowski LF, Nichols NL, Dick TE, Smith CB, Jacono FJ. Peripheral-to-central immune communication at the area postrema glial-barrier following bleomycin-induced sterile lung injury in adult rats. Brain Behav Immun 2020; 87:610-633. [PMID: 32097765 PMCID: PMC8895345 DOI: 10.1016/j.bbi.2020.02.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 02/02/2020] [Accepted: 02/13/2020] [Indexed: 02/07/2023] Open
Abstract
The pathways for peripheral-to-central immune communication (P → C I-comm) following sterile lung injury (SLI) are unknown. SLI evokes systemic and central inflammation, which alters central respiratory control and viscerosensory transmission in the nucleus tractus solitarii (nTS). These functional changes coincide with increased interleukin-1 beta (IL-1β) in the area postrema, a sensory circumventricular organ that connects P → C I-comm to brainstem circuits that control homeostasis. We hypothesize that IL-1β and its downstream transcriptional target, cyclooxygenase-2 (COX-2), mediate P → C I-comm in the nTS. In a rodent model of SLI induced by intratracheal bleomycin (Bleo), the sigh frequency and duration of post-sigh apnea increased in Bleo- compared to saline- treated rats one week after injury. This SLI-dependent change in respiratory control occurred concurrently with augmented IL-1β and COX-2 immunoreactivity (IR) in the funiculus separans (FS), a barrier between the AP and the brainstem. At this barrier, increases in IL-1β and COX-2 IR were confined to processes that stained for glial fibrillary acidic protein (GFAP) and that projected basolaterally to the nTS. Further, FS radial-glia did not express TNF-α or IL-6 following SLI. To test our hypothesis, we blocked central COX-1/2 activity by intracerebroventricular (ICV) infusion of Indomethacin (Ind). Continuous ICV Ind treatment prevented Bleo-dependent increases in GFAP + and IL-1β + IR, and restored characteristics of sighs that reset the rhythm. These data indicate that changes in sighs following SLI depend partially on activation of a central COX-dependent P → C I-comm via radial-glia of the FS.
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Affiliation(s)
- David G Litvin
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States; Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States; Department of Fundamental Neuroscience, University of Lausanne, 1005 Lausanne, Switzerland
| | - Scott J Denstaedt
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States; Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Lauren F Borkowski
- Department of Biomedical Sciences, University of Missouri College of Veterinary Medicine, Columbia, MO 65212, United States
| | - Nicole L Nichols
- Department of Biomedical Sciences, University of Missouri College of Veterinary Medicine, Columbia, MO 65212, United States
| | - Thomas E Dick
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States; Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States
| | - Corey B Smith
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States
| | - Frank J Jacono
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, United States; Division of Pulmonary, Critical Care and Sleep Medicine, Louis Stokes VA Medical Center, Cleveland, OH 44106, United States.
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Gano A, Pautassi RM, Doremus-Fitzwater TL, Barney TM, Vore AS, Deak T. Conditioning the neuroimmune response to ethanol using taste and environmental cues in adolescent and adult rats. Exp Biol Med (Maywood) 2019; 244:362-371. [PMID: 30808184 PMCID: PMC6488863 DOI: 10.1177/1535370219831709] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 01/28/2019] [Indexed: 11/16/2022] Open
Abstract
IMPACT STATEMENT A combined odor and taste cue was paired with a binge-like ethanol exposure (4 g/kg intraperitoneal) using a single-trial learning paradigm. Re-exposure to the CS alone was sufficient to evoke a conditioned Interleukin (IL)-6 elevation in the amygdala in adolescents, an effect that was not observed in young adults. This demonstrates a particular sensitivity of adolescents to alcohol-associated cues and neuroimmune learning, whereas prior work indicated that adults require multiple pairings of ethanol to the CS in order to achieve a conditioned amygdala IL-6 response. While the role of immune conditioning has been studied in other drugs of abuse, these findings highlight a previously unknown aspect of alcohol-related learning. Given the emergent importance of the neuroimmune system in alcohol abuse, these findings may be important for understanding cue-induced reinstatement of alcohol intake among problem drinkers.
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Affiliation(s)
- Anny Gano
- Department of Psychology, Developmental Exposure Alcohol
Research Center (DEARC), Behavioral Neuroscience Program, Binghamton University,
Binghamton, NY 13902-6000, USA
| | - Ricardo M Pautassi
- Instituto de Investigación Médica M. y M. Ferreyra
(INIMEC–CONICET-Universidad Nacional de Córdoba) and Facultad de Psicología,
UNC, Córdoba, CP 5000, Argentina
| | | | - Thaddeus M Barney
- Department of Psychology, Developmental Exposure Alcohol
Research Center (DEARC), Behavioral Neuroscience Program, Binghamton University,
Binghamton, NY 13902-6000, USA
| | - Andrew S Vore
- Department of Psychology, Developmental Exposure Alcohol
Research Center (DEARC), Behavioral Neuroscience Program, Binghamton University,
Binghamton, NY 13902-6000, USA
| | - Terrence Deak
- Department of Psychology, Developmental Exposure Alcohol
Research Center (DEARC), Behavioral Neuroscience Program, Binghamton University,
Binghamton, NY 13902-6000, USA
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Sabino JPJ, Soriano RN, Donatti AF, Fernandez RR, Kwiatkoski M, Francescato HD, Coimbra TM, Branco LG. Involvement of endogenous central hydrogen sulfide (H2S) in hypoxia-induced hypothermia in spontaneously hypertensive rats. Can J Physiol Pharmacol 2017; 95:157-162. [DOI: 10.1139/cjpp-2016-0033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Spontaneously hypertensive rats (SHR) display autonomic imbalance and abnormal body temperature (Tb) adjustments. Hydrogen sulfide (H2S) modulates hypoxia-induced hypothermia, but its role in SHR thermoregulation is unknown. We tested the hypothesis that SHR display peculiar thermoregulatory response to hypoxia and that endogenous H2S overproduced in the caudal nucleus of the solitary tract (NTS) of SHR modulates this response. SHR and Wistar rats were microinjected into the fourth ventricle with aminooxyacetate (AOA, H2S-synthezing enzyme inhibitor) or sodium sulfide (Na2S, H2S donor) and exposed to normoxia (21% inspired O2) or hypoxia (10% inspired O2, 30 min). Tb was continuously measured, and H2S production rate was assessed in caudal NTS homogenates. In both groups, AOA, Na2S, or saline (i.e., control; 1 μL) did not affect euthermia. Hypoxia caused similar decreases in Tb in both groups. AOA presented a longer latency to potentiate hypoxic hypothermia in SHR. Caudal NTS H2S production rate was higher in SHR. We suggest that increased bioavailability of H2S in the caudal NTS of SHR enables the adequate modulation of excitability of peripheral chemoreceptor-activated NTS neurons that ultimately induce suppression of brown adipose tissue thermogenesis, thus accounting for the normal hypoxic hypothermia.
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Affiliation(s)
- João Paulo J. Sabino
- Dental School of Ribeirão Preto, 14040-904, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Renato N. Soriano
- Division of Physiology and Biophysics, Department of Basic Life Sciences, Federal University of Juiz de Fora, 35020-220, Governador Valadares, MG, Brazil
| | - Alberto F. Donatti
- Dental School of Ribeirão Preto, 14040-904, University of São Paulo, Ribeirão Preto, SP, Brazil
| | | | - Marcelo Kwiatkoski
- Dental School of Ribeirão Preto, 14040-904, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Heloísa D.C. Francescato
- School of Medicine of Ribeirão Preto, 14040-904, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Terezila M. Coimbra
- School of Medicine of Ribeirão Preto, 14040-904, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Luiz G.S. Branco
- Dental School of Ribeirão Preto, 14040-904, University of São Paulo, Ribeirão Preto, SP, Brazil
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6
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Roth J, Blatteis CM. Mechanisms of fever production and lysis: lessons from experimental LPS fever. Compr Physiol 2015; 4:1563-604. [PMID: 25428854 DOI: 10.1002/cphy.c130033] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fever is a cardinal symptom of infectious or inflammatory insults, but it can also arise from noninfectious causes. The fever-inducing agent that has been used most frequently in experimental studies designed to characterize the physiological, immunological and neuroendocrine processes and to identify the neuronal circuits that underlie the manifestation of the febrile response is lipopolysaccharide (LPS). Our knowledge of the mechanisms of fever production and lysis is largely based on this model. Fever is usually initiated in the periphery of the challenged host by the immediate activation of the innate immune system by LPS, specifically of the complement (C) cascade and Toll-like receptors. The first results in the immediate generation of the C component C5a and the subsequent rapid production of prostaglandin E2 (PGE2). The second, occurring after some delay, induces the further production of PGE2 by induction of its synthesizing enzymes and transcription and translation of proinflammatory cytokines. The Kupffer cells (Kc) of the liver seem to be essential for these initial processes. The subsequent transfer of the pyrogenic message from the periphery to the brain is achieved by neuronal and humoral mechanisms. These pathways subserve the genesis of early (neuronal signals) and late (humoral signals) phases of the characteristically biphasic febrile response to LPS. During the course of fever, counterinflammatory factors, "endogenous antipyretics," are elaborated peripherally and centrally to limit fever in strength and duration. The multiple interacting pro- and antipyretic signals and their mechanistic effects that underlie endotoxic fever are the subjects of this review.
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Affiliation(s)
- Joachim Roth
- Department of Veterinary Physiology and Biochemistry, Justus-Liebig-University, Giessen, Germany; Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee
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7
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Lukewich MK, Rogers RC, Lomax AE. Divergent neuroendocrine responses to localized and systemic inflammation. Semin Immunol 2014; 26:402-8. [PMID: 24486057 DOI: 10.1016/j.smim.2014.01.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 01/09/2014] [Indexed: 12/19/2022]
Abstract
The sympathetic nervous system (SNS) is part of an integrative network that functions to restore homeostasis following injury and infection. The SNS can provide negative feedback control over inflammation through the secretion of catecholamines from postganglionic sympathetic neurons and adrenal chromaffin cells (ACCs). Central autonomic structures receive information regarding the inflammatory status of the body and reflexively modulate SNS activity. However, inflammation and infection can also directly regulate SNS function by peripheral actions on postganglionic cells. The present review discusses how inflammation activates autonomic reflex pathways and compares the effect of localized and systemic inflammation on ACCs and postganglionic sympathetic neurons. Systemic inflammation significantly enhanced catecholamine secretion through an increase in Ca(2+) release from the endoplasmic reticulum. In contrast, acute and chronic GI inflammation reduced voltage-gated Ca(2+) current. Thus it appears that the mechanisms underlying the effects of peripheral and systemic inflammation neuroendocrine function converge on the modulation of intracellular Ca(2+) signaling.
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Affiliation(s)
- Mark K Lukewich
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Richard C Rogers
- Laboratory for Autonomic Neuroscience, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - Alan E Lomax
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada; Department of Medicine, Queen's University, Kingston, Ontario, Canada.
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Quinson N, Vitton V, Bouvier M, Grimaud JC, Abysique A. Effects of tumor necrosis factor α on leptin-sensitive intestinal vagal mechanoreceptors in the cat. Can J Physiol Pharmacol 2013; 91:941-50. [PMID: 24117262 DOI: 10.1139/cjpp-2013-0025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The involvement of tumour necrosis factor α (TNF-α) in inflammatory bowel disease (IBD) has been established, and anti-TNF-α has been suggested as a therapeutic approach for the treatment of these pathologies. We studied the effects of TNF-α on leptin-sensitive intestinal vagal units to determine whether TNF-α exerts its effects through the intestinal vagal mechanoreceptors and to investigate its interactions with substances regulating food intake. The activity of intestinal vagal mechanoreceptors was recorded via microelectrodes implanted into the nodose ganglion in anesthetized cats. TNF-α (1 μg, i.a.) increased the discharge frequency of leptin-activated units (type 1 units; P < 0.05) and had no effect on the discharge frequency of leptin-inhibited units (type 2 units). When TNF-α was administered 20 min after sulfated cholecystokinin-8 (CCK), its excitatory effects on type 1 units were significantly enhanced (P < 0.0001) and type 2 units were significantly (P < 0.05) activated. Pre-treatment with Il-1ra (250 μg, i.a.) blocked the excitatory effects of TNF-α on type 1 units whereas the excitatory effects of TNF-α administration after CCK treatment on type 2 units were not modified. The activation of leptin-sensitive units by TNF-α may explain, at least in part, the weight loss observed in IBD.
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Affiliation(s)
- Nathalie Quinson
- a Aix Marseille Université, Physiologie et Physiopathologie du Système Nerveux Somatomoteur et Neurovégétatif (PPSN, EA4674), Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 20, France
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9
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Jacono FJ, Mayer CA, Hsieh YH, Wilson CG, Dick TE. Lung and brainstem cytokine levels are associated with breathing pattern changes in a rodent model of acute lung injury. Respir Physiol Neurobiol 2011; 178:429-38. [PMID: 21569869 PMCID: PMC3170447 DOI: 10.1016/j.resp.2011.04.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 04/22/2011] [Accepted: 04/27/2011] [Indexed: 02/07/2023]
Abstract
Acute lung injury evokes a pulmonary inflammatory response and changes in the breathing pattern. The inflammatory response has a centrally mediated component which depends on the vagi. We hypothesize that the central inflammatory response, complimentary to the pulmonary inflammatory response, is expressed in the nuclei tractus solitarii (nTS) and that the expression of cytokines in the nTS is associated with breathing pattern changes. Adult, male Sprague-Dawley rats (n=12) received intratracheal instillation of either bleomycin (3units in 120μl of saline) or saline (120μl). Respiratory pattern changed by 24h. At 48h, bronchoalveolar lavage fluid and lung tissue had increased IL-1β and TNF-α levels, but not IL-6. No changes in these cytokines were noted in serum. Immunocytochemical analysis of the brainstem indicated increased expression of IL-1β in the nTS commissural subnucleus that was localized to neurons. We conclude that breathing pattern changes in acute lung injury were associated with increased levels of IL-1β in brainstem areas which integrate cardio-respiratory sensory input.
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Affiliation(s)
- Frank J Jacono
- Division of Pulmonary, Critical Care and Sleep Medicine, CWRU School of Medicine and University Hospitals Case Medical Center, United States.
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10
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An inflammatory pathway to apnea and autonomic dysregulation. Respir Physiol Neurobiol 2011; 178:449-57. [DOI: 10.1016/j.resp.2011.06.026] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 06/29/2011] [Accepted: 06/29/2011] [Indexed: 01/04/2023]
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11
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Rogers RC, McDougal DH, Hermann GE. Leptin amplifies the action of thyrotropin-releasing hormone in the solitary nucleus: an in vitro calcium imaging study. Brain Res 2011; 1385:47-55. [PMID: 21334313 DOI: 10.1016/j.brainres.2011.02.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 02/11/2011] [Accepted: 02/11/2011] [Indexed: 12/28/2022]
Abstract
Leptin exerts a powerful permissive influence on neurogenic thermogenesis. During starvation and an absence of leptin, animals cannot produce thermogenic reactions to cold stress. However, thermogenesis is rescued by restoring leptin. We have previously observed a highly cooperative interaction between leptin and thyrotropin-releasing hormone [TRH] to activate hindbrain-generated thermogenic responses (Hermann et al., 2006). In vivo physiological studies (Rogers et al., 2009) suggested that the thermogenic impact of TRH in the hindbrain is amplified by the action of leptin through a leptin receptor-mediated production of phosphoinositol-trisphosphate [PIP3]. In turn, PIP3 can activate a tyrosine kinase whose target is the Src-SH2 regulatory site on the phospholipase C [PLC] complex. The TRH receptor signals through the PLC complex. Our immunohistochemical studies (Barnes et al., 2010) suggest that this transduction interaction between leptin and TRH occurs within neurons of the solitary nucleus [NST], though this interaction had not been verified. The present in vitro live cell calcium imaging study shows that while medial NST neurons are rarely activated by leptin alone, leptin pre-treatment significantly augments NST neurons' responsiveness to TRH. This leptin-mediated priming of NST neurons was uncoupled by pre-treatment with the phosphoinositide 3-kinase [PI3K] inhibitor [wortmannin], the phospholipase C inhibitor [U73122] and the Src-SH2 antagonist [PP2]. TTX did not eliminate the synergistic response of the agonists, thus the sensitization cannot be attributed to pre-synaptic mechanisms. It seems likely that NST neurons are involved in the leptin-mediated increase in BAT temperature by sensitizing the TRH-PLC-IP3-calcium release mechanism.
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Affiliation(s)
- Richard C Rogers
- Laboratory of Autonomic Neurosciences, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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12
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Cao WH, Madden CJ, Morrison SF. Inhibition of brown adipose tissue thermogenesis by neurons in the ventrolateral medulla and in the nucleus tractus solitarius. Am J Physiol Regul Integr Comp Physiol 2010; 299:R277-90. [PMID: 20410479 DOI: 10.1152/ajpregu.00039.2010] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Neurons in the ventrolateral medulla (VLM) and in the nucleus tractus solitarius (NTS) play important roles in the regulation of cardiovascular and other autonomic functions. In the present study, we demonstrate an inhibition of brown adipose tissue (BAT) thermogenesis evoked by activation of neurons in the VLM, as well as by neurons in the intermediate NTS, of chloralose/urethane-anesthetized, artificially ventilated rats. Activation of neurons in either rostral VLM or caudal VLM with N-methyl-d-aspartate (12 nmol) reversed the cold-evoked increase in BAT sympathetic nerve activity (SNA), BAT temperature, and end-expired CO(2). Disinhibition of neurons in either VLM or NTS with the GABA(A) receptor antagonist, bicuculline (30 pmol), reversed the increases in BAT SNA, BAT temperature, and end-expired CO(2) that were elicited 1) by cold defense; 2) during the febrile model of nanoinjection of prostaglandin E(2) into the medial preoptic area; 3) by activation of neurons in the dorsomedial hypothalamus or in the rostral raphe pallidus (rRPa); or 4) by the micro-opioid receptor agonist fentanyl. Combined, but not separate, inhibitions of neurons in the VLM and in the NTS, with the GABA(A) receptor agonist, muscimol (120 pmol/site), produced increases in BAT SNA, BAT temperature, and expired CO(2), which were reversed by nanoinjection of glycine (30 nmol) into the rRPa. These findings suggest that VLM and NTS contain neurons whose activation inhibits BAT thermogenesis, that these neurons receive GABAergic inputs that are active under these experimental conditions, and that neurons in both sites contribute to the tonic inhibition of sympathetic premotor neuronal activity in the rRPa that maintains a low level of BAT thermogenesis in normothermic conditions.
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Affiliation(s)
- Wei-Hua Cao
- Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon 97006, USA
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13
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Bonham AC, Sekizawa SI, Chen CY, Joad JP. Plasticity of brainstem mechanisms of cough. Respir Physiol Neurobiol 2006; 152:312-9. [PMID: 16554189 DOI: 10.1016/j.resp.2006.02.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2005] [Revised: 02/07/2006] [Accepted: 02/09/2006] [Indexed: 11/27/2022]
Abstract
The cough reflex is a brainstem reflex, consisting of specific sensory afferent nerves which trigger the reflex, by transmitting the sensory input over vagal or laryngeal nerves to a brainstem circuitry which processes and ultimately transforms the sensory input into a complex motor output to generate cough. The first synaptic target for the primary cough-related sensory input is the second-order neurons in the nucleus tractus solitarius (NTS). This position in the reflex pathway and intricate local circuits within the nucleus make it a strategic site where the sensory information can be modified. Plasticity at this synapse will change the nature of the output--exaggerating it, suppressing it or transforming it into some other complex pattern. This review integrates evidence implicating the NTS in exaggerated cough with proof of the concept that NTS neurons undergo plasticity to contribute to an exaggeration of cough.
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Affiliation(s)
- Ann C Bonham
- Department of Pharmacology, University of California, Davis School of Medicine, 4150 V Street, 1104 PSSB, Sacramento, CA 95817, USA.
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Bonham AC, Chen CY, Sekizawa SI, Joad JP. Plasticity in the nucleus tractus solitarius and its influence on lung and airway reflexes. J Appl Physiol (1985) 2006; 101:322-7. [PMID: 16484366 DOI: 10.1152/japplphysiol.00143.2006] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The nucleus tractus solitarius (NTS) is the first central nervous system (CNS) site for synaptic contact of the primary afferent fibers from the lungs and airways. The signal processing at these synapses will determine the output of the sensory information from the lungs and airways to all downstream synapses in the reflex pathways. The second-order NTS neurons bring to bear their own intrinsic and synaptic properties to temporally and spatially integrate the sensory information with inputs from local networks, higher brain regions, and circulating mediators, to orchestrate a coherent reflex output. There is growing evidence that NTS neurons share the rich repertoire of forms of plasticity demonstrated throughout the CNS. This review focuses on existing evidence for plasticity in the NTS, potential targets for plasticity in the NTS, and the impact of this plasticity on lung and airway reflexes.
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Affiliation(s)
- Ann C Bonham
- Department of Medical Pharmacology, University of California, Davis, CA, USA.
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Blatteis CM, Li S, Li Z, Feleder C, Perlik V. Cytokines, PGE2 and endotoxic fever: a re-assessment. Prostaglandins Other Lipid Mediat 2005; 76:1-18. [PMID: 15967158 DOI: 10.1016/j.prostaglandins.2005.01.001] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2005] [Accepted: 01/08/2005] [Indexed: 12/31/2022]
Abstract
The innate immune system serves as the first line of host defense against the deleterious effects of invading infectious pathogens. Fever is the hallmark among the defense mechanisms evoked by the entry into the body of such pathogens. The conventional view of the steps that lead to fever production is that they begin with the biosynthesis of pyrogenic cytokines by mononuclear phagocytes stimulated by the pathogens, their release into the circulation and transport to the thermoregulatory center in the preoptic area (POA) of the anterior hypothalamus, and their induction there of cyclooxygenase (COX)-2-dependent prostaglandin (PG)E(2), the putative final mediator of the febrile response. But data accumulated over the past 5 years have gradually challenged this classical concept, due mostly to the temporal incompatibility of the newer findings with this concatenation of events. Thus, the former studies generally overlooked that the production of cytokines and the transduction of their pyrogenic signals into fever-mediating PGE(2) proceed at relatively slow rates, significantly slower certainly than the onset latency of fever produced by the i.v. injection of bacterial endotoxic lipopolysaccharides (LPS). Here, we review the conflicts between the earlier and the more recent findings and summarize new data that reconcile many of the contradictions. A unified model based on these data explicating the generation and maintenance of the febrile response is presented. It postulates that the steps in the production of LPS fever occur in the following sequence: the immediate activation by LPS of the complement (C) cascade, the stimulation by the anaphylatoxic C component C5a of Kupffer cells, their consequent, virtually instantaneous release of PGE(2), its excitation of hepatic vagal afferents, their transmission of the induced signals to the POA via the ventral noradrenergic bundle, and the activation by the thus, locally released norepinephrine (NE) of neural alpha(1)- and glial alpha(2)-adrenoceptors. The activation of the first causes an immediate, PGE(2)-independent rise in core temperature (T(c)) [the early phase of fever; an antioxidant-sensitive PGE(2) rise, however, accompanies this first phase], and of the second a delayed, PGE(2)-dependent T(c) rise [the late phase of fever]. Meanwhile-generated pyrogenic cytokines and their consequent upregulation of blood-brain barrier cells COX-2 also contribute to the latter rise. The consecutive steps that initiate the febrile response to LPS would now appear, therefore, to occur in an order different than conceived originally.
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Affiliation(s)
- Clark M Blatteis
- Department of Physiology, College of Medicine, The University of Tennessee, Health Science Center, Memphis, 38163, USA.
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Almeida MC, Steiner AA, Coimbra NC, Branco LGS. Thermoeffector neuronal pathways in fever: a study in rats showing a new role of the locus coeruleus. J Physiol 2004; 558:283-94. [PMID: 15146040 PMCID: PMC1664907 DOI: 10.1113/jphysiol.2004.066654] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
It is known that brain noradrenaline (norepinephrine) mediates fever, but the neuronal group involved is unknown. We studied the role of the major noradrenergic nucleus, the locus coeruleus (LC), in lipopolysaccharide (LPS)-induced fever. Male Wistar rats had their LC completely ablated electrolytically or their catecholaminergic LC neurones selectively lesioned by microinjection of 6-hydroxydopamine; the controls were sham-operated. Both lesions resulted in a marked attenuation of LPS (1 or 10 microg kg(-1), i.v.) fever at a subneutral (23 degrees C) ambient temperature (Ta). Because electrolytic and chemical lesions produced similar effects, the role of the LC in fever was further investigated using electrolytic lesions only. The levels of prostaglandin (PG) E2, the terminal mediator of fever, were equally raised in the anteroventral third ventricular region of LC-lesioned and sham-operated rats during the course of LPS fever, indicating that LC neurones are not involved in febrigenic signalling to the brain. To investigate the potential involvement of the LC in an efferent thermoregulatory neuronal pathway, the thermoregulatory response to PGE(2) (25 ng, i.c.v.) was studied at a subneutral (23 degrees C, when fever is brought about by thermogenesis) or neutral (28 degrees C, when fever is brought about by tail skin vasoconstriction) Ta. The PGE2-induced increases in metabolic rate (an index of thermogenesis) and fever were attenuated in LC-lesioned rats at 23 degrees C, whereas PGE2-induced skin vasoconstriction and fever normally developed in LC-lesioned rats at 28 degrees C. The LC-lesioned rats had attenuated PGE2 thermogenesis despite the fact that they were fully capable of activating thermogenesis in response to noradrenaline and cold exposure. It is concluded that LC neurones are part of a neuronal network that is specifically activated by PGE2 to increase thermogenesis and produce fever.
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Affiliation(s)
- Maria C Almeida
- Medical School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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Marvel FA, Chen CC, Badr N, Gaykema RPA, Goehler LE. Reversible inactivation of the dorsal vagal complex blocks lipopolysaccharide-induced social withdrawal and c-Fos expression in central autonomic nuclei. Brain Behav Immun 2004; 18:123-34. [PMID: 14759590 DOI: 10.1016/j.bbi.2003.09.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Revised: 09/01/2003] [Accepted: 09/01/2003] [Indexed: 11/19/2022] Open
Abstract
Peripheral administration of lipopolysaccharide (LPS), a potent activator of the immune system, induces symptoms of behavioral depression, such as social withdrawal, concommitant with increases in c-Fos expression in central autonomic network nuclei. Previous studies implicated vagal visceral sensory nerves in transduction of immune-related signals relevant to for the induction of social withdrawal, a symptom of behavioral depression. Vagal sensory nerves terminate in the dorsal vagal complex (DVC) of the brainstem, a region that functions to integrate visceral signals and may also play a role in modulating arousal and affect. The objective of the current study was to determine whether the DVC contributes to immunosensory pathways driving symptoms of social withdrawal associated with LPS-induced behavioral depression, using a reversible lesion technique to temporarily inactivate the DVC. To assess the effects of DVC inactivation on LPS-induced social withdrawal and the subsequent changes in brain activation, we used behavioral assessment of social withdrawal, and analyzed c-Fos expression, a marker of neuronal activation, in the central nucleus of the amygdala (CEA), bed nucleus of the stria terminalis (BST), hypothalamic paraventricular nucleus (PVN), and ventromendial preoptic area (VMPO). Two hours following intraperitoneal LPS injection, there was a significant increase in c-Fos immunoreactivity in forebrain regions in animals treated with LPS. DVC inactivation completely blocked LPS-induced social withdrawal and dramatically reduced LPS-induced Fos expression in all four forebrain regions assessed. Collectively, these findings support the idea that the DVC acts as an immune-behavior interface between the peripheral stimuli and brain areas involved in modulating social behavior.
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Affiliation(s)
- Françoise A Marvel
- Department of Psychology and Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22904, USA
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Gaigé S, Abou E, Abysique A, Bouvier M. Effects of interactions between interleukin-1 beta and leptin on cat intestinal vagal mechanoreceptors. J Physiol 2003; 555:297-310. [PMID: 14645453 PMCID: PMC1664812 DOI: 10.1113/jphysiol.2003.054379] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In a previous study, we established that leptin acts on chemosensitive intestinal vagal mechanoreceptors and that its excitatory effects are blocked by the endogenous interleukin-1beta receptor antagonist (Il-1ra). To determine how interleukin-1beta (Il-1beta) is involved in the action of leptin, we studied the effects of this drug on the single vagal afferent activities of intestinal mechanoreceptors in anaesthetized cats. For this purpose, the activity of 34 intestinal vagal mechanoreceptors was recorded via glass microelectrodes implanted in the nodose ganglion. Il-1beta (1 microg) administered into the artery irrigating the upper part of the intestine activated both the 16 leptin-activated units (type 1 units; P < 0.01) and the 12 leptin-inhibited units (type 2 units; P < 0.001), but had no effect on the six leptin-insensitive units. Cholecystokinin (CCK, 10 microg) induced an activatory response only in the two types of Il-1beta-sensitive units. When Il-1beta was administered after CCK, its excitatory effects on type 1 units were enhanced, whereas the excitatory effects on type 2 units were abolished. Pre-treatment with Il-1ra (250 microg) blocked all the effects of Il-1beta and the excitatory effects of leptin on type 1 units, whereas it enhanced the inhibitory effects of leptin on type 2 units. It can therefore be concluded that (i) leptin acts on intestinal vagal mechanoreceptors via Il-1beta in the case of the type 1 units and independently of Il-1beta in the case of the type 2 units, and (ii) type 1 and type 2 units belong to two different populations of vagal afferents that transmit different information about ingestion or inflammation to the CNS, depending on the chemical environment.
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Affiliation(s)
- Stéphanie Gaigé
- Laboratoire de Physiologie Neurovégétative (UMR CNRS 6153, UMR INRA 1147), Faculté des Sciences et Techniques Saint-Jérôme, Université Aix-Marseille 3, Cases postales 351-352, Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 20, France
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Maier SF. Bi-directional immune-brain communication: Implications for understanding stress, pain, and cognition. Brain Behav Immun 2003; 17:69-85. [PMID: 12676570 DOI: 10.1016/s0889-1591(03)00032-1] [Citation(s) in RCA: 215] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
The immune system and the central nervous system form a bi-directional communication network. The critical roles of pro-inflammatory cytokines in both the periphery and the nervous system are discussed. In the periphery, these cytokines initiate the processes that signal the brain that immune activation has occurred, and communicate this information over both neural and blood-borne routes. The arrival of these signals in the central nervous system induces a neural cascade that includes the de novo induction of pro-inflammatory cytokines. The functions of these cytokines in the nervous system are discussed, and it is argued that they play a key role in regulating the neural control of immune processes in the periphery. In addition, it is argued that these cytokines play a variety of other roles, and some implications of the cytokine network for understanding stress, behavior, sensory processing, mood, and cognition are described. The overall argument is that because brain-mediated host defense involves behavioral, sensory, mood, and cognitive alterations, immune activation, and immune products such as the cytokines can have a pervasive effect on these functions. Finally, these phenomena are placed in an evolutionary perspective.
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Affiliation(s)
- Steven F Maier
- Department of Psychology and Center for Neuroscience, University of Colorado, Campus box 345 80309-0345, Boulder, CO, USA.
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Abstract
Inflammation is a local, protective response to microbial invasion or injury. It must be fine-tuned and regulated precisely, because deficiencies or excesses of the inflammatory response cause morbidity and shorten lifespan. The discovery that cholinergic neurons inhibit acute inflammation has qualitatively expanded our understanding of how the nervous system modulates immune responses. The nervous system reflexively regulates the inflammatory response in real time, just as it controls heart rate and other vital functions. The opportunity now exists to apply this insight to the treatment of inflammation through selective and reversible 'hard-wired' neural systems.
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Affiliation(s)
- Kevin J Tracey
- Laboratory of Biomedical Science, North Shore-LIJ Research Institute, Manhasset, New York 11030, USA.
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Wang X, Wang BR, Zhang XJ, Xu Z, Ding YQ, Ju G. Evidences for vagus nerve in maintenance of immune balance and transmission of immune information from gut to brain in STM-infected rats. World J Gastroenterol 2002; 8:540-5. [PMID: 12046088 PMCID: PMC4656439 DOI: 10.3748/wjg.v8.i3.540] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine whether Salmonella Typhimurium (STM) in gastrointestinal tract can induce the functional activation of brain, whether the vagus nerve involves in signaling immune information from gastrointestinal tract to brain and how it influences the immune function under natural infection condition.
METHODS: Animal model of gastrointestinal tract infection in the rat was established by an intubation of Salmonella Typhimurium (STM) into stomach to mimic the condition of natural bacteria infection. Subdiagphragmatic vagotomy was performed in some of the animals 28 days before infection. The changes of Fos expression visualized with immunohistochemistry technique in hypothalamic paraventricular nucleus (PVN) and superaoptic nucleus (SON) were counted. Meanwhile, the percentage and the Mean Intensities of Fluorescent (MIFs) of CD4+ and CD8+ T cells in peripheral blood were measured by using flow cytometry (FCM), and the pathological changes in ileum and mesenteric lymph node were observed in HE stained sections.
RESULTS: In bacteria-stimulated groups, inflammatory pathological changes were seen in ileum and mesenteric lymph node. The percentages of CD4+ T cells in peripheral blood were decreased from 42% ± 4.5% to 34% ± 4.9% (P < 0.05) and MIFs of CD8+ T cells were also decreased from 2.9 ± 0.39 to 2.1 ± 0.36 (P < 0.05) with STM stimulation. All of them proved that our STM-infection model was reliable. Fos immunoreactive (Fos-ir) cells in PVN and SON increased significantly with STM stimulation, from 189 ± 41 to 467 ± 62 (P < 0.05) and from 64 ± 21 to 282 ± 47 (P < 0.05) individually, which suggested that STM in gastrointestinal tract induced the functional activation of brain. Subdiagphragmatic vagotomy attenuated Fos expression in PVN and SON induced by STM, from 467 ± 62 to 226 ± 45 (P < 0.05) and from 282 ± 47 to 71 ± 19 (P < 0.05) individually, and restored the decreased percentages of CD4+ T cells induced by STM from 34% ± 4.9% to original level 44% ± 6.0% (P < 0.05). In addition, subdiagphragmatic vagotomy itself also decreased the percentages of CD8+ T cells (from 28% ± 3.0% to 21% ± 5.9%, P < 0.05) and MIFs of CD4+ (from 6.6 ± 0.6 to 4.9 ± 1.0, P < 0.05) and CD8+ T cells (from 2.9 ± 0.39 to1.4 ± 0.34, P < 0.05). Both of them manifested the important role of vagus nerve in transmitting immune information from gut to brain and maintaining the immune balance of the organism.
CONCLUSION: Vagus nerve does involve in transmitting abdominal immune information into the brain in STM infection condition and play an important role in maintenance of the immune balance of the organism.
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Affiliation(s)
- Xi Wang
- Institute of Neurosciences, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
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Catalina F, Milewich L, Frawley W, Kumar V, Bennett M. Decrease of core body temperature in mice by dehydroepiandrosterone. Exp Biol Med (Maywood) 2002; 227:382-8. [PMID: 12037127 DOI: 10.1177/153537020222700603] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Dietary dehydroepiandrosterone (DHEA) reduces food intake in mice, and this response is under genetic control. Moreover, both food restriction and DHEA can prevent or ameliorate certain diseases and mediate other biological effects. Mice fed DHEA (0.45% w/w of food) and mice pair-fed to these mice (food restricted) for 8 weeks were tested for changes in body temperature. DHEA was more efficient than food restriction alone in causing hypothermia. DHEA injected intraperitoneally also induced hypothermia that reached a nadir at 1 to 2 hr, and slowly recovered by 20 to 24 hr. This effect was dose dependent (0.5-50 mg). Each mouse strain tested (four) was susceptible to this effect, suggesting that the genetics differ for induction of hypophagia and induction of hypothermia. Because serotonin and dopamine can regulate (decrease) body temperature, we treated mice with haloperidol (dopamine receptor antagonist), 5,7-dihydroxytryptamine (serotonin production inhibitor), or ritanserin (serotonin receptor antagonist) prior to injection of DHEA. All of these agents increased rather than decreased the hypothermic effects of DHEA. DHEA metabolites that are proximate (5-androstene-3beta, 17beta-diol and androstenedione) or further downstream (estradiol-17beta) were much less effective than DHEA in inducing hypothermia. However, the DHEA analog, 16alpha-chloroepiandrosterone, was as active as DHEA. Thus, DHEA administered parentally seems to act directly on temperature-regulating sites in the body. These results suggest that DHEA induces hypothermia independent of its ability to cause food restriction, to affect serotonin or dopamine functions, or to act via its downstream steroid metabolites.
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Affiliation(s)
- Fernando Catalina
- Departments of Pathology, Obstetrics and Gynecology, and Academic Computing Services, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9072, USA
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Abstract
The role of nitric oxide (NO) was investigated in endotoxin (lipopolysaccharide, LPS) tolerance in freely moving biotelemetered rats. We monitored changes in febrile response and feeding behavior (food intake, water intake) during the development of tolerance to repeated intraperitoneal injections of LPS (50 microg/kg) along with injections of N(omega)-nitro-L-arginine methyl ester (L-NAME; 50 mg/kg), an inhibitor of NO synthase. Rats were treated with LPS and L-NAME for three consecutive days. On the fourth day, all rats were injected with LPS alone. Control rats were injected with saline along with saline or with L-NAME for four consecutive days. Rats repeatedly injected with LPS became tolerant to pyrogenic and hypophagic/cachexic effects of LPS as early as on the second day of experiment. The treatment with L-NAME prevented the attenuation of febrile response following the second LPS injection. Moreover, the depressive effects of LPS on body weight as well as on water and food intake were prolonged in rats treated with a combination of L-NAME and LPS. Injection of LPS caused a 3.5-fold increase in plasma nitrite within 3 h and nitrite levels remained significantly elevated 6 and 24 h after LPS. Rats injected secondly with LPS did have still 2.5- to 3-fold increase in plasma nitrite levels 3 and 6 h, but not 24 h, after injection. Third injection of LPS did not elevate nitrite level in plasma. Taken together, presented data provide clear evidence that NO formation is involved in mechanisms responsible for development of early-stage tolerance to endotoxin.
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Affiliation(s)
- Dariusz Soszynski
- Department of Physiology, The Ludwik Rydygier Medical University, 24 Karlowicza Street, Bydgoszcz PL-85-092, Poland.
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Chen CY, Bonham AC, Schelegle ES, Gershwin LJ, Plopper CG, Joad JP. Extended allergen exposure in asthmatic monkeys induces neuroplasticity in nucleus tractus solitarius. J Allergy Clin Immunol 2001; 108:557-62. [PMID: 11590381 DOI: 10.1067/mai.2001.118132] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND Extended exposure to allergen exacerbates asthma symptoms, in part via complex interactions between inflammatory cells and mediators. One consequence of these interactions is the triggering of local and central nervous system (CNS) neuronal activity that might further exacerbate the asthma-like symptoms by causing bronchoconstriction, mucous secretion, increased microvascular leak, and cough. One CNS region that might be particularly important is the caudomedial nucleus tractus solitarius (NTS). NTS neurons not only integrate primary afferent inputs from lung sensory nerve fibers but also have direct exposure to inhaled allergens and allergen-induced blood-borne inflammatory mediators via a deficient blood-brain barrier. Given the capacity of CNS neurons to undergo plasticity, allergen-induced changes in NTS neuronal properties could contribute to the exaggerated respiratory responses to extended allergen exposure. OBJECTIVE In a recently developed rhesus monkey model of allergic asthma, we tested the hypothesis that extended exposure to allergen increases the intrinsic excitability of NTS neurons. METHODS Three adult monkeys were sensitized and then repeatedly exposed to aerosols of house dust mite allergen; 4 monkeys served as controls. Whole-cell current-clamp recordings were made to measure 3 indices of excitability: resting membrane potential, input resistance, and number of action potentials evoked by current injections. RESULTS Extended allergen exposure depolarized the resting membrane potential by 14% and increased the number of action potentials evoked by current injections (5-fold). CONCLUSION The finding that NTS neurons in a primate model of allergic asthma undergo intrinsic increases in excitability suggests that CNS mechanisms might contribute to the exaggerated symptoms in asthmatic individuals exposed to allergen.
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Affiliation(s)
- C Y Chen
- Department of Internal Medicine, School of Medicine, University of California at Davis, Sacramento, 95817, USA
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