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Oka K, Tokumasu K, Hagiya H, Otsuka F. Characteristics of Functional Hyperthermia Detected in an Outpatient Clinic for Fever of Unknown Origin. J Clin Med 2024; 13:889. [PMID: 38337583 PMCID: PMC10856695 DOI: 10.3390/jcm13030889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 01/31/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024] Open
Abstract
Background: Functional hyperthermia (FH) is characterized by hyperthermia resulting from sympathetic hyperactivity rather than inflammation, and it is frequently overlooked by medical practitioners due to the absence of abnormalities in a medical examination. Although FH is an important differential diagnosis for fever of unknown origin (FUO), the literature on FUO cases in Japan lacks information on FH. In this study, we aimed to uncover the population of FH patients hidden in FUO cases. Methods: An outpatient clinic for FUO was established at Okayama University Hospital, and 132 patients were examined during the period from May 2019 to February 2022. Results: A diagnosis of FH was made in 31.1% of the FUO cases, and FH predominantly affected individuals in their third and fourth decades of life with a higher incidence in females (68.3%). The frequency of a history of psychiatric illness was higher in patients with FH than in patients with other febrile illnesses. Although the C-reactive protein (CRP) is generally negative in FH cases, some obese patients, with a body mass index ≥ 25 had slightly elevated levels of CRP but were diagnosed with FH. Conclusions: The results showed the importance of identifying FH when encountering patients with FUO without any organic etiology.
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Affiliation(s)
- Kosuke Oka
- Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan; (K.T.); (F.O.)
| | - Kazuki Tokumasu
- Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan; (K.T.); (F.O.)
| | - Hideharu Hagiya
- Department of Infectious Diseases, Okayama University Hospital, Okayama 700-8558, Japan;
| | - Fumio Otsuka
- Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan; (K.T.); (F.O.)
- Department of Infectious Diseases, Okayama University Hospital, Okayama 700-8558, Japan;
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2
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Robertson JK, Mastromonaco G, Burness G. Evidence that stress-induced changes in surface temperature serve a thermoregulatory function. J Exp Biol 2020; 223:jeb213421. [PMID: 31974220 DOI: 10.1242/jeb.213421] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/20/2020] [Indexed: 08/26/2023]
Abstract
The fact that body temperature can rise or fall following exposure to stressors has been known for nearly two millennia; however, the functional value of this phenomenon remains poorly understood. We tested two competing hypotheses to explain stress-induced changes in temperature, with respect to surface tissues. Under the first hypothesis, changes in surface temperature are a consequence of vasoconstriction that occur to attenuate blood loss in the event of injury and serve no functional purpose per se; defined as the 'haemoprotective hypothesis'. Under the second hypothesis, changes in surface temperature reduce thermoregulatory burdens experienced during activation of a stress response, and thus hold a direct functional value: the 'thermoprotective hypothesis'. To understand whether stress-induced changes in surface temperature have functional consequences, we tested predictions of these two hypotheses by exposing black-capped chickadees (n=20) to rotating stressors across an ecologically relevant ambient temperature gradient, while non-invasively monitoring surface temperature (eye region temperature) using infrared thermography. Our results show that individuals exposed to rotating stressors reduce surface temperature and dry heat loss at low ambient temperature and increase surface temperature and dry heat loss at high ambient temperature, when compared with controls. These results support the thermoprotective hypothesis and suggest that changes in surface temperature following stress exposure have functional consequences and are consistent with an adaptation. Such findings emphasize the importance of the thermal environment in shaping physiological responses to stressors in vertebrates, and in doing so, raise questions about their suitability within the context of a changing climate.
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Affiliation(s)
- Joshua K Robertson
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario, Canada, K9L 0G2
- Department of Reproductive Physiology, The Toronto Zoo, Scarborough, Ontario, Canada, M1B 5K7
| | - Gabriela Mastromonaco
- Department of Reproductive Physiology, The Toronto Zoo, Scarborough, Ontario, Canada, M1B 5K7
| | - Gary Burness
- Department of Biology, Trent University, Peterborough, Ontario, Canada, K9L 0G2
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Jędrzejewski T, Piotrowski J, Pawlikowska M, Wrotek S, Kozak W. Extract from Coriolus versicolor fungus partially prevents endotoxin tolerance development by maintaining febrile response and increasing IL-6 generation. J Therm Biol 2019; 83:69-79. [PMID: 31331527 DOI: 10.1016/j.jtherbio.2019.05.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 11/25/2022]
Abstract
Endotoxin tolerance is defined as a reduced endotoxin-induced fever following repeated injections of lipopolysaccharide (LPS). Clinical examples of endotoxin tolerance include sepsis or cystic fibrosis. This state is characterized by inhibition of pro-inflammatory cytokines production and decrease in nuclear factor-kappa B (NF-κB) activation. Extract from Coriolus versicolor (CV) fungus is classified as a biological response modifier, which exhibits various biological activities, including immunopotentiating properties. The aim of study was to examine the effect of CV extract injection on body core temperature of Wistar rats during LPS-induced endotoxin tolerance. Body temperature was measured using biotelemetry. CV extract was injected intraperitoneally (100 mg kg-1) 2 h prior to the first LPS peritoneal administration (50 μg/kg). Endotoxin tolerance was induced by three consecutive daily injections of LPS at the same dose. We also investigated the influence of CV extract pre-injection on the properties of peripheral blood mononuclear cells (PBMCs) isolated from LPS-treated rats in response to LPS stimulation ex vivo. PBMCs were isolated 2 h after the first LPS injection. After 24 h pre-incubation, the cells were stimulated with LPS (1 μg ml-1) for 4 h. Our results revealed that CV extract partially prevents endotoxin tolerance through maintaining febrile response in rats following consecutive exposure to LPS. This state was accompanied by the ability of PBMCs isolated from rats injected with CV extract and LPS to release larger amounts of interleukin 6 and greater NF-κB activation in response to LPS stimulation ex vivo compared with the cells derived from rats injected only with LPS. Data also showed that CV extract augmented mitogenic effect of LPS on PBMCs and caused increase in reactive oxygen species generation. We concluded that CV extract, by a modifying effect on body temperature during endotoxin tolerance, can be consider as the immunostimulating agent, which prevents the non-specific refractoriness described in patients with sepsis or ischemia.
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Affiliation(s)
- Tomasz Jędrzejewski
- Department of Immunology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, Torun, 87-100, Poland.
| | - Jakub Piotrowski
- Department of Immunology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, Torun, 87-100, Poland.
| | - Małgorzata Pawlikowska
- Department of Immunology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, Torun, 87-100, Poland.
| | - Sylwia Wrotek
- Department of Immunology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, Torun, 87-100, Poland.
| | - Wieslaw Kozak
- Department of Immunology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, Torun, 87-100, Poland.
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4
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Abstract
Stress affects core body temperature (Tc). Many kinds of stress induce transient, monophasic hyperthermia, which diminishes gradually if the stressor is terminated. Stronger stressors produce a longer-lasting effect. Repeated/chronic stress induces anticipatory hyperthermia, reduces diurnal changes in Tc, or slightly increases Tc throughout the day. Animals that are exposed to chronic stress or a cold environment exhibit an enhanced hyperthermic response to a novel stress. These changes persist for several days after cessation of stress exposure. In contrast, long-lasting inescapable stress sometimes induces hypothermia. In healthy humans, psychologic stress induces slight increases in Tc, which are within the normal range of Tc or just above it. Some individuals, however, develop extremely high Tc (up to 41°C) when they are exposed to emotional events or show persistent low-grade high Tc (37-38°C) during or after chronic stress situations. In addition to the nature of the stressor itself, such stress-induced thermal responses are modulated by sex, age, ambient temperature, cage mates, past stressful experiences and cold exposure, and coping. Stress-induced hyperthermia is driven by mechanisms distinct from infectious fever, which requires inflammatory mediators. However, both stress and infection activate the dorsomedial hypothalamus-rostral medullary raphe region-sympathetic nerve axis to increase Tc.
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Affiliation(s)
- Takakazu Oka
- Department of Psychosomatic Medicine, International University of Health and Welfare Hospital, Tochigi-ken, Japan.
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5
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Oka T. Psychogenic fever: how psychological stress affects body temperature in the clinical population. Temperature (Austin) 2015; 2:368-78. [PMID: 27227051 PMCID: PMC4843908 DOI: 10.1080/23328940.2015.1056907] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 05/24/2015] [Accepted: 05/25/2015] [Indexed: 12/22/2022] Open
Abstract
Psychogenic fever is a stress-related, psychosomatic disease especially seen in young women. Some patients develop extremely high core body temperature (Tc) (up to 41°C) when they are exposed to emotional events, whereas others show persistent low-grade high Tc (37-38°C) during situations of chronic stress. The mechanism for psychogenic fever is not yet fully understood. However, clinical case reports demonstrate that psychogenic fever is not attenuated by antipyretic drugs, but by psychotropic drugs that display anxiolytic and sedative properties, or by resolving patients' difficulties via natural means or psychotherapy. Animal studies have demonstrated that psychological stress increases Tc via mechanisms distinct from infectious fever (which requires proinflammatory mediators) and that the sympathetic nervous system, particularly β3-adrenoceptor-mediated non-shivering thermogenesis in brown adipose tissue, plays an important role in the development of psychological stress-induced hyperthermia. Acute psychological stress induces a transient, monophasic increase in Tc. In contrast, repeated stress induces anticipatory hyperthermia, reduces diurnal changes in Tc, or slightly increases Tc throughout the day. Chronically stressed animals also display an enhanced hyperthermic response to a novel stress, while past fearful experiences induce conditioned hyperthermia to the fear context. The high Tc that psychogenic fever patients develop may be a complex of these diverse kinds of hyperthermic responses.
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Affiliation(s)
- Takakazu Oka
- Department of Psychosomatic Medicine; Graduate School of Medical Sciences; Kyushu University; Fukuoka, Japan
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Banasikowski TJ, Cloutier CJ, Ossenkopp KP, Kavaliers M. Repeated exposure of male mice to low doses of lipopolysaccharide: dose and time dependent development of behavioral sensitization and tolerance in an automated light-dark anxiety test. Behav Brain Res 2015; 286:241-8. [PMID: 25746457 DOI: 10.1016/j.bbr.2015.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 02/26/2015] [Accepted: 03/02/2015] [Indexed: 10/23/2022]
Abstract
Although lipopolysaccharide (LPS) is widely used to examine immune behavior relationships there has been little consideration of the effects of low doses and the roles of sensitization and, or tolerance. Here low doses of LPS (1.0, 5.0 and 25.0 μg/kg) were peripherally administered to male mice on Days 1, 4, 28 and 32 after a baseline recording of anxiety-like behaviors in an automated light-dark apparatus (total time in the light chamber, number of light-dark transitions, nose pokes into the light chamber). LPS at 1.0 μg/kg, while having no significant effects on anxiety-like behaviors in the light-dark test on Days 1 and 4, displayed sensitization with the mice exhibiting significantly enhanced anxiety-like responses on Days 28 and 32. LPS at 5.0 μg/kg had no consistent significant effects on anxiety-like behavior on Days 1 and 4, with sensitization and enhanced anxiety-like behaviors on Day 28 followed by tolerance on Day 32. LPS at 25 μg/kg significantly enhanced anxiety-like behaviors on Day 1, followed by tolerance on Day 4, which was not evident by Day 28 and re-emerged on Day 32. There was a similar overall pattern of sensitization and tolerance for LPS-induced decreases in locomotor activity in the safe dark chamber, without, however, any significant effects on activity in the riskier light chamber. This shows that low doses of LPS induce anxiety-like behavior and these effects are subject to sensitization and tolerance in a dose, context, and time related manner.
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Affiliation(s)
| | - Caylen J Cloutier
- Department of Psychology, University of Western Ontario, London, ON, Canada
| | - Klaus-Peter Ossenkopp
- Department of Psychology, University of Western Ontario, London, ON, Canada; Neuroscience Graduate Program, University of Western Ontario, London, ON, Canada
| | - Martin Kavaliers
- Department of Psychology, University of Western Ontario, London, ON, Canada; Neuroscience Graduate Program, University of Western Ontario, London, ON, Canada.
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7
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Vinkers CH, Groenink L, van Bogaert MJ, Westphal KG, Kalkman CJ, van Oorschot R, Oosting RS, Olivier B, Korte SM. Stress-induced hyperthermia and infection-induced fever: Two of a kind? Physiol Behav 2009; 98:37-43. [DOI: 10.1016/j.physbeh.2009.04.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Revised: 03/31/2009] [Accepted: 04/08/2009] [Indexed: 11/16/2022]
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8
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Vinkers CH, van Bogaert MJV, Klanker M, Korte SM, Oosting R, Hanania T, Hopkins SC, Olivier B, Groenink L. Translational aspects of pharmacological research into anxiety disorders: the stress-induced hyperthermia (SIH) paradigm. Eur J Pharmacol 2008; 585:407-25. [PMID: 18420191 DOI: 10.1016/j.ejphar.2008.02.097] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 02/01/2008] [Accepted: 02/13/2008] [Indexed: 11/29/2022]
Abstract
In anxiety research, the search for models with sufficient clinical predictive validity to support the translation of animal studies on anxiolytic drugs to clinical research is often challenging. This review describes the stress-induced hyperthermia (SIH) paradigm, a model that studies the activation of the autonomic nervous system in response to stress by measuring body temperature. The reproducible and robust SIH response, combined with ease of testing, make the SIH paradigm very suitable for drug screening. We will review the current knowledge on the neurobiology of the SIH response, discuss the role of GABA(A) and serotonin (5-HT) pharmacology, as well as how the SIH response relates to infectious fever. Furthermore, we will present novel data on the SIH response variance across different mice and their sensitivity to anxiolytic drugs. The SIH response is an autonomic stress response that can be successfully studied at the level of its physiology, pharmacology, neurobiology and genetics and possesses excellent animal-to-human translational properties.
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Affiliation(s)
- Christiaan H Vinkers
- Department of Psychopharmacology, Utrecht Institute for Pharmaceutical Sciences (UIPS) and Rudolf Magnus Institute of Neuroscience, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.
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9
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10
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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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11
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Gordon CJ, Puckett E, Padnos B. Rat tail skin temperature monitored noninvasively by radiotelemetry: characterization by examination of vasomotor responses to thermomodulatory agents. J Pharmacol Toxicol Methods 2002; 47:107-14. [PMID: 12459150 DOI: 10.1016/s1056-8719(02)00219-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Measurement of tail skin temperature (T(sk)) of the rat can provide important information on mechanisms pertaining to physiology, pharmacology, and toxicology. T(sk) is largely under control of peripheral vascular tone, which is also sensitive to most experimental manipulations such as handling and restraint. Hence, it is extremely difficult to acquire long-term measurements of T(sk) that are free of artifacts from experimental manipulation. The purpose of this study is to demonstrate the utility of a radiotelemetric probe to provide continuous, long-term measurements of T(sk) in undisturbed rats. METHODS A telemetry probe is placed on the base of the tail and secured with a protective guard to prevent the rat from chewing on the probe. T(sk) is continuously monitored with standard radiotelemetric software and computer technology. Core temperature (T(c)) is monitored in duplicate sets of rats at the same time but the current system does not allow for simultaneous measurement of T(sk) and T(c) from the same animal. Rats were subjected to a variety of experimental manipulations to demonstrate the utility of the probe. RESULTS/DISCUSSION A marked increase in T(sk) was seen during the transition from light to dark phase, reflecting an increase in heat loss to lower T(c); a decrease in T(sk) during the development of endotoxin-induced fever, reflecting a reduction in heat loss to facilitate an elevation in T(c); an increase in T(sk) following exposure to the organophosphate insecticide chlorpyrifos, reflecting an increase in heat loss to facilitate a hypothermia response; and a direct effect of increasing ambient temperature on T(sk). The probe is relatively inexpensive and is used with no surgery and provides long-term measurement (e.g., >24 h) of T(sk) in unrestrained rats.
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Affiliation(s)
- Christopher J Gordon
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Kamerman PR, Brooksbank R, Pitts N, Laburn HP. Heat stress increases the rate of tolerance development to lipopolysaccharide in rats. J Therm Biol 2001. [DOI: 10.1016/s0306-4565(01)00005-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
OBJECTIVE Despite numerous case reports on "psychogenic fever," it remains uncertain how psychological stress raises core temperature and whether the rise in core temperature is a real fever or a hyperthermia. This article reviews studies on the psychological stress-induced rise in core temperature (PSRCT) in animals with the aim to facilitate studies on the mechanisms of so-called psychogenic fever in humans. METHODS To address this question, we reviewed the mechanisms and mediators of the PSRCT and classic conditioning of the fever response in animals. RESULTS The PSRCT is not due to the increased locomotor activity during stress, and the magnitude of the PSRCT is the same in warm and cold environments, indicating that it is a centrally regulated rise in temperature due to an elevated thermoregulatory "set point." The PSRCT caused by conventional psychological stress models, such as open-field stress, is attenuated by cyclooxygenase inhibitors, which block prostaglandin synthesis. On the other hand, the PSRCT elicited by an "anticipatory anxiety stress" is not inhibited by cyclooxygenase inhibitors but by benzodiazepines and serotonin Type 1A receptor agonists. The febrile response can be conditioned to neutral stimuli after paired presentation with unconditioned stimuli such as injection of lipopolysaccharide, a typical pyrogen. CONCLUSIONS Most findings indicate that the PSRCT is a fever, a rise in the thermoregulatory set point. The PSRCT may occur through prostaglandin E2-dependent mechanisms and prostaglandin E2-independent, 5-HT-mediated mechanisms. The febrile response can be conditioned. Thus, these mechanisms might be involved in psychogenic fever in humans.
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Affiliation(s)
- T Oka
- Department of Psychosomatic Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
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Hayley S, Lacosta S, Merali Z, van Rooijen N, Anisman H. Central monoamine and plasma corticosterone changes induced by a bacterial endotoxin: sensitization and cross-sensitization effects. Eur J Neurosci 2001; 13:1155-65. [PMID: 11285013 DOI: 10.1046/j.0953-816x.2001.01496.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Low doses of lipopolysaccharide, tumour necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), or exposure to a stressor (restraint) increased plasma corticosterone levels. In animals pretreated with lipopolysaccharide, a marked sensitization of the corticosterone response was evident upon subsequent exposure to lipopolysaccharide, TNF-alpha, or restraint, 1 day later. As well, the sickness-inducing effects of lipopolysaccharide, TNF-alpha and IL-1 beta were markedly increased in mice pretreated with lipopolysaccharide. The sensitization effects were marked when the second treatment was administered 1 day after lipopolysaccharide administration, but not when a 28-day interval elapsed. In a second experiment, TNF-alpha influenced monoamine functioning in the paraventricular nucleus of the hypothalamus and within extrahypothalamic regions, including the central amygdala, locus coeruleus, prefrontal cortex. Moreover, serotonin activity within the central amygdala, as well as dopamine activity within the prefrontal cortex, were subject to a sensitization effect in animals pretreated with lipopolysaccharide 1 day earlier. Macrophage depletion by a suspension of clodronate liposomes attenuated the plasma corticosterone changes induced by TNF-alpha, but did not affect the sensitization. In contrast, the acute effects of TNF-alpha on central neurotransmitters were unaffected by the liposome suspension, but this treatment prevented the sensitization. These data may be relevant to clinical situations in which individuals exposed to bacterial infections may be rendered more susceptible to the behavioural and neurochemical effects of subsequently encountered stressors and immunological challenges.
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Affiliation(s)
- S Hayley
- Institute of Neuroscience, Carleton University, Ottawa, Ontario K1S 5B6, Canada.
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15
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De Paula D, Steiner AA, Branco LG. The nitric oxide pathway is an important modulator of stress-induced fever in rats. Physiol Behav 2000; 70:505-11. [PMID: 11111004 DOI: 10.1016/s0031-9384(00)00295-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Psychological stress evokes a number of physiological responses, including a rise in body temperature (T(b)), which has been suggested to be the result of an elevation in the thermoregulatory set point, i.e., a fever. This response seems to share similar mechanisms with infectious fever. A growing number of studies have provided evidence that nitric oxide (NO) has a modulatory role in infectious fever, but no report exists about the participation of NO in stress fever. Thus, the present study aimed to verify the hypothesis that NO modulates stress fever by using restraint stress as a model. To this end, we tested the effects of the non-specific NO synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) or its inactive enantiomer N(G)-nitro-D-arginine methyl ester (D-NAME) on colonic T(b) of restrained or unrestrained rats. A rapid increase in T(b) was observed when animals were submitted to restraint. Intravenous (i.v.) injection of L-NAME at a dose (10 mg/kg) that caused no change in T(b) when administered alone significantly attenuated the elevation in T(b) elicited by stress, indicating that the NO pathway may mediate stress fever. Moreover, intracerebroventricular (i.c.v.) L-NAME (250 microg/microl) caused a rise in T(b) of euthermic animals and enhanced stress fever, supporting that NO in the central nervous system (CNS) leads to a reduction in T(b) and, therefore, this is unlikely to be the site where NO may mediate stress fever. Taken together, these data indicate that the NO pathway plays an important role in modulating restraint stress-induced fever in rats.
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Affiliation(s)
- D De Paula
- Departamento de Morfologia, Estomatologia e Fisiologia, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo (USP), 14040-904 Ribeirão Preto, São Paulo, Brazil
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