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Liddle LJ, Dirks CA, Almekhlafi M, Colbourne F. An Ambiguous Role for Fever in Worsening Outcome After Intracerebral Hemorrhage. Transl Stroke Res 2023; 14:123-136. [PMID: 35366212 PMCID: PMC9995537 DOI: 10.1007/s12975-022-01010-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/17/2022] [Accepted: 03/20/2022] [Indexed: 11/25/2022]
Abstract
Intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes and leaves most survivors with impairments. Fever, a rise in the thermoregulatory set point, complicates ICH. This review summarizes ICH fever studies and employs meta-analytic techniques to explore the relationship between fever and ICH. We discuss methodological considerations for future studies and provide an overview of mechanisms by which fever, and its treatment, may impact ICH. We searched the PubMed database using the following terms: ((fever OR hyperthermia) AND (intracerebral hemorrhage OR intraparenchymal hemorrhage OR intracerebral haemorrhage OR intraparenchymal haemorrhage)). Our search returned 727 studies, of which 21 were included in our final analysis, consisting of 19 clinical, and two preclinical, studies. We conducted a meta-analysis on the clinical data to quantify how fever is related to mortality, functional outcomes, and intraventricular hemorrhage. Analysis of clinical studies suggested that fever causes an increased risk of mortality but does not appear to be associated with poor outcomes among survivors, making it difficult to ascertain the extent of harm caused by post-ICH fever or the benefits of its treatment. Perhaps these inconsistencies stem from variable fever definitions, and temperature measurement and fever treatment protocols. Additionally, the lack of mechanistic data in clinical studies coupled with preclinical studies showing no harmful effects of moderate bouts of hyperthermia raise concerns about the direct contribution of hyperthermia and fever in post ICH outcome. Overall, the significance of temperature increases after ICH is unclear, making this an important area for future research.
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Affiliation(s)
- Lane J Liddle
- Department of Psychology, University of Alberta, Edmonton, AB, Canada
| | - Christine A Dirks
- Department of Psychology, University of Alberta, Edmonton, AB, Canada
| | | | - Frederick Colbourne
- Department of Psychology, University of Alberta, Edmonton, AB, Canada.
- Neuroscience and Mental Health Institute, University of Alberta, P217 Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada.
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Uyanga VA, Wang M, Tong T, Zhao J, Wang X, Jiao H, Onagbesan OM, Lin H. L-Citrulline Influences the Body Temperature, Heat Shock Response and Nitric Oxide Regeneration of Broilers Under Thermoneutral and Heat Stress Condition. Front Physiol 2021; 12:671691. [PMID: 34456742 PMCID: PMC8385788 DOI: 10.3389/fphys.2021.671691] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 07/21/2021] [Indexed: 12/29/2022] Open
Abstract
Heat stress (HS) adversely affects several physiological responses in organisms, but the underlying molecular mechanisms involved are yet to be fully understood. L-Citrulline (L-Cit) is a nutraceutical amino acid that is gaining research interest for its role in body temperature regulation and nitric oxide synthesis. This study investigated whether dietary supplementation with L-Cit (1% of basal diet) could ameliorate the effects of acute HS on thermotolerance, redox balance, and inflammatory responses of broilers. Ross 308 broilers (288 chicks) were subjected to two environments; thermoneutral at 24°C (TNZ) or HS at 35°C for 5 h, and fed two diets; control or L-Cit. The results showed that HS increased the ear, rectal (RT), and core body (CBT) temperatures of broilers, along with higher respiratory rate. The RT and CBT readings were intermittently affected with time effect, whereas, L-Cit supplementation lowered the mean CBT than the control diet. Antioxidant assays showed that superoxide dismutase was increased during HS, while, catalase was promoted by L-Cit supplementation. In addition, L-Cit induced glutathione peroxidase activity compared to the control diet during HS. Hypothalamic heat shock protein (HSP)-90 was upregulated by HS, but L-Cit downregulated heat shock factor (HSF)-1, and HSP 60 mRNA expressions. HSF 3 mRNA expression was downregulated by L-Cit under TNZ condition. More so, HS increased the plasma nitric oxide (NO) concentration but lowered the total NO synthase (tNOS) activity. In contrast, L-Cit supplementation limited NO production but increased the tNOS activity. Arginase activity was increased in the control fed group during HS but L-Cit supplementation lowered this effect. The NOS-COX pathway was significantly affected under TNZ condition, since L-Cit supplementation downregulated the mRNA expression of iNOS-COX2 in the hypothalamus, and further reduced the serum PGE2 concentration. Together, these data indicates that L-Cit influenced the antioxidant defense, heat shock response and nitric oxide regeneration both under thermoneutral and HS conditions; and that L-Cit may be directly and/or indirectly involved in the central regulation of body temperature.
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Affiliation(s)
- Victoria A. Uyanga
- Department of Animal Science, College of Animal Science and Veterinary Medicine, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control, Shandong Agricultural University, Tai’an, China
| | - Minghui Wang
- Department of Animal Science, College of Animal Science and Veterinary Medicine, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control, Shandong Agricultural University, Tai’an, China
| | - Tian Tong
- Department of Animal Science, College of Animal Science and Veterinary Medicine, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control, Shandong Agricultural University, Tai’an, China
| | - Jingpeng Zhao
- Department of Animal Science, College of Animal Science and Veterinary Medicine, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control, Shandong Agricultural University, Tai’an, China
| | - Xiaojuan Wang
- Department of Animal Science, College of Animal Science and Veterinary Medicine, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control, Shandong Agricultural University, Tai’an, China
| | - Hongchao Jiao
- Department of Animal Science, College of Animal Science and Veterinary Medicine, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control, Shandong Agricultural University, Tai’an, China
| | | | - Hai Lin
- Department of Animal Science, College of Animal Science and Veterinary Medicine, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control, Shandong Agricultural University, Tai’an, China
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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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Expression of angiotensin II and its receptors in activated microglia in experimentally induced cerebral ischemia in the adult rats. Mol Cell Biochem 2013; 382:47-58. [DOI: 10.1007/s11010-013-1717-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 05/29/2013] [Indexed: 10/26/2022]
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Yao X, Dai Y, Johnson A, Hass MA, Feleder C. Determination of prostaglandin profiles in lipopolysaccharide-challenged guinea pig spleen. Biomed Chromatogr 2012; 27:284-91. [DOI: 10.1002/bmc.2789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Revised: 06/15/2012] [Accepted: 06/25/2012] [Indexed: 11/11/2022]
Affiliation(s)
| | - Y. Dai
- Department of Pharmacology of Chinese Materia Medica; China Pharmaceutical University; 24 Tongjia Xiang; Nanjing; 210038; China
| | - A. Johnson
- Albany College of Pharmacy and Health Sciences; Departments of Pharmaceutical Sciences and Arts and Sciences; 106 New Scotland Avenue; Albany; NY; 12208; USA
| | - M. A. Hass
- Albany College of Pharmacy and Health Sciences; Departments of Pharmaceutical Sciences and Arts and Sciences; 106 New Scotland Avenue; Albany; NY; 12208; USA
| | - C. Feleder
- Albany College of Pharmacy and Health Sciences; Departments of Pharmaceutical Sciences and Arts and Sciences; 106 New Scotland Avenue; Albany; NY; 12208; USA
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Hunt JL, Zaretsky DV, Sarkar S, Dimicco JA. Dorsomedial hypothalamus mediates autonomic, neuroendocrine, and locomotor responses evoked from the medial preoptic area. Am J Physiol Regul Integr Comp Physiol 2009; 298:R130-40. [PMID: 19923355 DOI: 10.1152/ajpregu.00574.2009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Previous studies suggest that sympathetic responses evoked from the preoptic area in anesthetized rats require activation of neurons in the dorsomedial hypothalamus. Disinhibition of neurons in the dorsomedial hypothalamus in conscious rats produces physiological and behavioral changes resembling those evoked by microinjection of muscimol, a GABA(A) receptor agonist and neuronal inhibitor, into the medial preoptic area. We tested the hypothesis that all of these effects evoked from the medial preoptic area are mediated through neurons in the dorsomedial hypothalamus by assessing the effect of bilateral microinjection of muscimol into the DMH on these changes. After injection of vehicle into the dorsomedial hypothalamus, injection of muscimol into the medial preoptic area elicited marked increases in heart rate, arterial pressure, body temperature, plasma ACTH, and locomotor activity and also increased c-Fos expression in the hypothalamic paraventricular nucleus, a region known to control the release of ACTH from the adenohypophysis. Prior bilateral microinjection of muscimol into the dorsomedial hypothalamus produced a modest depression of baseline heart rate and body temperature but completely abolished all changes evoked from the medial preoptic area. Microinjection of muscimol just anterior to the dorsomedial hypothalamus had no effect on autonomic and neuroendocrine changes evoked from the medial preoptic area. Thus, activity of neurons in the dorsomedial hypothalamus mediates a diverse array of physiological and behavioral responses elicited from the medial preoptic area, suggesting that the latter region represents an important source of inhibitory tone to key neurons in the dorsomedial hypothalamus.
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Affiliation(s)
- Joseph L Hunt
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Abstract
After defining hyperthermia and fever, this article describes the complete chain of events leading to the genesis of fever, starting with the lipopolysaccharide-induced formation of endogenous pyrogens (cytokines), their interactions with relevant targets in the brain, the induction of enzymes responsible for the formation of prostaglandin E2, the activation of descending neuronal pathways via the EP3 receptor, and the stimulation of thermogenesis via this pathway to support the febrile shift of the thermoregulatory set point. This article also summarizes an alternative hypothesis to account for a rapid induction of the early phase of lipopolysaccharide-induced fever before the release of larger amounts of cytokines into the bloodstream. Other topics discussed include malignant hypothermia, drug-induced hypothermia, and the heat stroke syndrome.
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Feleder C, Perlik V, Blatteis CM. Preoptic norepinephrine mediates the febrile response of guinea pigs to lipopolysaccharide. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1135-43. [PMID: 17584956 DOI: 10.1152/ajpregu.00067.2007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Norepinephrine (NE) microdialyzed in the preoptic area (POA) raises core temperature (Tc) via 1) α1-adrenoceptors (AR), quickly and independently of POA PGE2, and 2) α2-AR, after a delay and PGE2 dependently. Since systemic lipopolysaccharide (LPS) activates the central noradrenergic system, we investigated whether preoptic NE mediates LPS fever. We injected LPS (2 μg/kg iv) in guinea pigs prepared with intra-POA microdialysis probes and determined POA cerebrospinal (CSF) NE levels. We similarly microdialyzed prazosin (α1 blocker, 1 μg/μl), yohimbine (α2 blocker, 1 μg/μl), SC-560 [cyclooxygenase (COX)-1 blocker, 5 μg/μl], acetaminophen (presumptive COX-1v blocker, 5 μg/μl), or MK-0663 (COX-2 blocker, 0.5 μg/μl) in other animals before intravenous LPS and measured CSF PGE2. All of the agents were perfused at 2 μg/min for 6 h. Tc was monitored constantly. POA NE peaked within 30 min after LPS and then returned to baseline over the next 90 min. Tc increased within 12 min to a first peak at ∼60 min and to a second at ∼150 min and then declined over the following 2.5 h. POA PGE2 followed a concurrent course. Prazosin pretreatment eliminated the first Tc rise but not the second; PGE2 rose normally. Yohimbine pretreatment did not affect the first Tc rise, which continued unchanged for 6 h; the second rise, however, was absent, and PGE2 levels did not increase. SC-560 and acetaminophen did not alter the LPS-induced PGE2 and Tc rises; MK-0663 prevented both the late PGE2 and Tc rises. These results confirm that POA NE is pivotal in the development of LPS fever.
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Affiliation(s)
- Carlos Feleder
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, 894 Union Avenue, Memphis, TN 38163, USA
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Roth J, Rummel C, Barth SW, Gerstberger R, Hübschle T. Molecular Aspects of Fever and Hyperthermia. Neurol Clin 2006; 24:421-39, v. [PMID: 16877116 DOI: 10.1016/j.ncl.2006.03.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
A rise in core temperature during fever usually results from change in the thermocontroller characteristics, resulting in an elevation of the set point of body temperature. Time course and extent of natural fevers are variable, but an upper limit (41 degrees C in humans), at which core temperature is maintained for some time and reduced when the set point of body temperature returns to its normal level, rarely is exceeded. Although any rise in body temperature may result from fever, those rises that are not accompanied by supportive changes in thermoeffector activities are termed hyperthermia.
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Affiliation(s)
- Joachim Roth
- Department of Veterinary Physiology, Faculty of Veterinary Medicine, Justus-Liebig-University, Giessen, Germany.
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Zaretsky DV, Hunt JL, Zaretskaia MV, DiMicco JA. Microinjection of prostaglandin E2 and muscimol into the preoptic area in conscious rats: comparison of effects on plasma adrenocorticotrophic hormone (ACTH), body temperature, locomotor activity, and cardiovascular function. Neurosci Lett 2006; 397:291-6. [PMID: 16406311 DOI: 10.1016/j.neulet.2005.12.032] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Revised: 11/30/2005] [Accepted: 12/12/2005] [Indexed: 11/29/2022]
Abstract
The preoptic area (POA) is thought to play an important role in thermoregulation and fever. Local application of prostaglandin E2 (PGE2) to this region elicits increases in core body temperature, heart rate, and plasma levels of adrenocorticotrophic hormone (ACTH). Similar effects on body temperature and heart rate have also been reported after local application of the GABAA receptor agonist muscimol to the preoptic area. The purpose of this study was to assess and compare the effects of microinjection of PGE2 and muscimol into the preoptic area in the same chronically instrumented conscious rats on plasma levels of ACTH. Injection of either PGE2 (150 pmol/100 nL) or muscimol (20 or 80 pmol/100 nL) into the same sites in the preoptic area evoked increases in body temperature, heart rate, blood pressure, and plasma levels of ACTH, while significant increases in locomotor activity were apparent only after muscimol. These data confirm and extend previous findings and support the notion that neurons in the region of the preoptic area exert tonic inhibition on downstream mechanisms capable of increasing the activity of the hypothalamic-pituitary-adrenal (HPA) axis as well as sympathetic thermogenic and cardiac activity.
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Affiliation(s)
- Dmitry V Zaretsky
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
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Ivanov AI, Steiner AA, Patel S, Rudaya AY, Romanovsky AA. Albumin is not an irreplaceable carrier for amphipathic mediators of thermoregulatory responses to LPS: compensatory role of alpha1-acid glycoprotein. Am J Physiol Regul Integr Comp Physiol 2004; 288:R872-8. [PMID: 15576666 DOI: 10.1152/ajpregu.00514.2004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In view of the potential involvement of peripherally synthesized, circulating amphipathic mediators [such as platelet-activating factor (PAF) and prostaglandin E(2)] in the systemic inflammatory response to lipopolysaccharide (LPS), we hypothesized that transport of amphipaths by albumin is essential for conveying peripheral inflammatory signals to the brain. Our first specific aim was to test this hypothesis by studying LPS-induced fever and hypothermia in Nagase analbuminemic rats (NAR). NAR from two different colonies and normalbuminemic Sprague-Dawley rats were preimplanted with jugular catheters, and their febrile responses to a mild dose of LPS (10 microg/kg i.v.) at thermoneutrality and hypothermic responses to a high dose of LPS (500 microg/kg i.v.) in the cold were studied. NAR of both colonies developed normal febrile and hypothermic responses, thus suggesting that transport of amphipathic mediators by albumin is not indispensable for LPS signaling. Although alternative carrier proteins [such as alpha(1)-acid glycoprotein (AGP)] are known to assume transport functions of albumin in NAR, it is unknown whether inflammatory mediators are capable of inducing their actions when bound to alternative carriers. To test whether PAF, the most potent amphipathic pyrogen, causes fever when administered in an AGP-bound form was our second aim. Sprague-Dawley rats were preimplanted with jugular catheters, and their thermal responses to infusion of a 1:1 [PAF-AGP] complex (40 nmol/kg i.v.), AGP (40 nmol/kg i.v.), or various doses of free (aggregated) PAF were studied. The complex, but neither free PAF nor AGP, caused a high ( approximately 1.5 degrees C) fever with a short (< 10 min) latency. This is the first demonstration of a pyrogenic activity of AGP-bound PAF. We conclude that, in the absence of albumin, AGP and possibly other carriers participate in immune-to-brain signaling by binding and transporting amphipathic inflammatory mediators.
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Affiliation(s)
- Andrei I Ivanov
- Systemic Inflammation Laboratory, Trauma Research, St. Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA
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Morrison SF. Raphe pallidus neurons mediate prostaglandin E2-evoked increases in brown adipose tissue thermogenesis. Neuroscience 2003; 121:17-24. [PMID: 12946696 DOI: 10.1016/s0306-4522(03)00363-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To elucidate central neural pathways contributing to the febrile component of the acute phase response to pyrogenic insult, I sought to determine whether activation of neurons in the rostral raphe pallidus (RPa) is required for the increase in brown adipose tissue (BAT) thermogenesis evoked by i.c.v. prostaglandin E(2) (PGE(2)) in urethane-chloralose-anesthetized, ventilated rats. BAT sympathetic nerve activity (SNA; +224% of control), BAT temperature (+1.8 degrees C), expired CO(2) (+1.3%), mean arterial pressure (+23 mm Hg), and heart rate (+73 beats per minute) were significantly increased after i.c.v. PGE(2) (2 microg). Microinjection of either the GABA(A) receptor agonist, muscimol (2 mM, 60 nl), or glycine (0.5M, 60 nl) into RPa resulted in a prompt reversal of the PGE(2)-evoked stimulation of BAT SNA, BAT thermogenesis and heart rate, with these variables returning to control levels prior to i.c.v. PGE(2) following the long-lasting, muscimol-induced inhibition of RPa neurons. In conclusion, activation of neurons in RPa, possibly BAT sympathetic premotor neurons, is essential for the increases in BAT SNA and BAT thermogenesis stimulated by i.c.v. administration of PGE(2). The increased heart rate likely contributing to an augmented cardiac output supporting the increased BAT thermogenesis in response to PGE(2) is also dependent on neurons in RPa. These results contribute to our understanding of central neural substrates for the augmented thermogenesis during fever.
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Affiliation(s)
- S F Morrison
- Neurological Sciences Institute, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA
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Ivanov AI, Patel S, Kulchitsky VA, Romanovsky AA. Platelet-activating factor: a previously unrecognized mediator of fever. J Physiol 2003; 553:221-8. [PMID: 14565987 PMCID: PMC2343477 DOI: 10.1113/jphysiol.2003.055616] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Lipopolysaccharide (LPS)-induced systemic inflammation is accompanied by either hypothermia (prevails when the ambient temperature (Ta) is subneutral) or fever (prevails when Ta is neutral or higher). Because platelet-activating factor (PAF) is a proximal mediator of LPS inflammation, it should mediate both thermoregulatory responses to LPS. That PAF possesses hypothermic activity and mediates LPS-induced hypothermia is known. We asked whether PAF possesses pyrogenic activity (Expt 1) and mediates LPS fever (Expt 2). The study was conducted in Long-Evans rats implanted with jugular catheters. A complex with bovine serum albumin (BSA) was infused as a physiologically relevant form of PAF; free (aggregated) PAF was used as a control. In Expt 1, either form of PAF caused hypothermia when infused (83 pmol kg-1 min-1, 60 min, i.v.) at a subneutral Ta of 20 degrees C, but the response to the PAF-BSA complex (-4.5 +/- 0.5 degrees C, nadir) was ~4 times larger than that to free PAF. At a neutral Ta of 30 degrees C, both forms caused fever preceded by tail skin vasoconstriction, but the febrile response to PAF-BSA (1.0 +/- 0.1 degrees C, peak) was > 2 times higher than that to free PAF. Both the hypothermic (at 20 degrees C) and febrile (at 30 degrees C) responses to PAF-BSA started when the total amount of PAF infused was extremely small, < 830 pmol kg-1. In Expt 2 (conducted at 30 degrees C), the PAF receptor antagonist BN 52021 (29 micromol kg-1, i.v.) had no thermal effect of itself. However, it strongly (~2 times) attenuated the febrile response to PAF (5 nmol kg-1, i.v.), implying that this response involves the PAF receptor and is not due to a detergent-like effect of PAF on cell membranes. BN 52021 (but not its vehicle) was similarly effective in attenuating LPS (10 microg kg-1, i.v.) fever. It is concluded that PAF is a highly potent endogenous pyrogenic substance and a mediator of LPS fever.
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Affiliation(s)
- Andrei I Ivanov
- Systemic Inflammation Laboratory, Trauma Research, St Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
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Ross G, Hübschle T, Pehl U, Braun HA, Voigt K, Gerstberger R, Roth J. Fever induction by localized subcutaneous inflammation in guinea pigs: the role of cytokines and prostaglandins. J Appl Physiol (1985) 2003; 94:1395-402. [PMID: 12482772 DOI: 10.1152/japplphysiol.00485.2002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In guinea pigs, dose-dependent febrile responses can be induced by injection of a high (100 micro g/kg) or low (10 micro g/kg) dose of bacterial lipopolysaccharide (LPS) into artificial subcutaneously implanted Teflon chambers. In this fever model, LPS does not enter the systemic circulation from the site of localized tissue inflammation in considerable amounts but causes a local induction of the proinflammatory cytokines tumor necrosis factor (TNF) and interleukin-6 (IL-6), which can be measured in lavage fluid collected from the chamber area. Only in response to the high LPS dose, small traces of TNF are measurable in blood plasma. A moderate increase of circulating IL-6 occurs in response to administration of both LPS doses. To investigate the putative roles of TNF and prostaglandins in this fever model, a neutralizing TNF binding protein (TNF-bp) or a nonselective inhibitor of cyclooxygenases (diclofenac) was injected along with the high or low dose of LPS into the subcutaneous chamber. In control groups, both doses of LPS were administered into the chamber along with the respective vehicles for the applied drugs. The fever response to the high LPS dose remained unimpaired by treatment with TNF-bp despite an effective neutralization of bioactive TNF in the inflamed tissue area. In response to the low LPS dose, there was an accelerated defervescence under the influence of TNF-bp. Blockade of prostaglandin formation with diclofenac completely abolished fever in response to both LPS doses. In conclusion, prostaglandins seem to be essential components for the manifestation of fever in this model.
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Affiliation(s)
- Gunter Ross
- Institut für Veterinär-Physiologie, Justus-Liebig-Universität, D-35392 Giessen, Germany
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Ivanov AI, Scheck AC, Romanovsky AA. Expression of genes controlling transport and catabolism of prostaglandin E2 in lipopolysaccharide fever. Am J Physiol Regul Integr Comp Physiol 2003; 284:R698-706. [PMID: 12399253 DOI: 10.1152/ajpregu.00570.2002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prostaglandin (PG) E(2) is a principal downstream mediator of fever and other symptoms of systemic inflammation. Its inactivation occurs in peripheral tissues, primarily the lungs and liver, via carrier-mediated cellular uptake and enzymatic oxidation. We hypothesized that inactivation of PGE(2) is suppressed during LPS fever and that transcriptional downregulation of PGE(2) carriers and catabolizing enzymes contributes to this suppression. Fever was induced in inbred Wistar-Kyoto rats by intravenous LPS (50 microg/kg); the controls received saline. Samples of the liver, lungs, and hypothalamus were harvested 0, 0.5, 1.5, and 5 h postinjection. The expression of the two principal transmembrane PGE(2) carriers (PG transporter and multispecific organic anion transporter) and the two key PGE(2)-inactivating enzymes [15-hydroxy-PG dehydrogenase (15-PGDH) and carbonyl reductase] was quantified by RT-PCR. All four genes of interest were downregulated in peripheral tissues (but not the brain) during fever. Most remarkably, the expression of hepatic 15-PGDH was decreased 26-fold 5 h post-LPS, whereas expression of pulmonary 15-PGDH was downregulated (as much as 18-fold) throughout the entire febrile course. The transcriptional downregulation of several proteins involved in PGE(2) inactivation, first reported here, is an unrecognized mechanism of systemic inflammation. By increasing the blood-brain gradient of PGE(2), this mechanism likely facilitates penetration of PGE(2) into the brain and prevents its elimination from the brain.
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Affiliation(s)
- Andrei I Ivanov
- Trauma Research and Neurology Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013, USA
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Lawrence CB, Baudoin FMH, Luckman SM. Centrally administered galanin-like peptide modifies food intake in the rat: a comparison with galanin. J Neuroendocrinol 2002; 14:853-60. [PMID: 12421338 DOI: 10.1046/j.1365-2826.2002.00846.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Galanin-like peptide (GALP) is a recently identified neuropeptide that shares sequence homology with the orexigenic neuropeptide, galanin. In contrast to galanin, GALP is reported to bind preferentially to the galanin receptor 2 subtype (GalR2) compared to GalR1. The aim of this study was to determine the effect of GALP on feeding, body weight and core body temperature after central administration in rats compared to the effects of galanin. Intracerebroventricular (i.c.v.) injection of GALP (1 micro g-10 micro g) significantly stimulated feeding at 1 h in both satiated and fasted Sprague-Dawley rats. However, 24 h after GALP injection, body weight gain was significantly reduced and food intake was also usually decreased. In addition, i.c.v. GALP caused a dose-related increase in core body temperature, which lasted until 6-8 h after injection, and was reduced by peripheral administration of the cyclooxygenase inhibitor, flurbiprofen (1 mg/kg). Similar to GALP, i.c.v. injection of galanin (5 micro g) significantly increased feeding at 1 h in satiated rats. However, there was no difference in food intake and body weight at 24 h, and galanin only caused a transient rise in body temperature. Thus, similar to galanin, GALP has an acute orexigenic effect on feeding. However, GALP also has an anorectic action, which is apparent at a later time. Therefore, GALP has complex opposing actions on energy homeostasis.
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Affiliation(s)
- C B Lawrence
- School of Biological Sciences, University of Manchester, UK
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Endo S, Nomura T, Chan BS, Lu R, Pucci ML, Bao Y, Schuster VL. Expression of PGT in MDCK cell monolayers: polarized apical localization and induction of active PG transport. Am J Physiol Renal Physiol 2002; 282:F618-22. [PMID: 11880322 DOI: 10.1152/ajprenal.00150.2001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The PG transporter (PGT) is expressed in subapical vesicles in the kidney collecting duct. To gain insight into the possible function of the PGT in this tubule segment, we tagged rat PGT with green fluorescent protein at the COOH terminus and generated stable PGT-expressing Madin-Darby canine kidney cell lines. When grown on permeable filters, green fluorescent protein-PGT was expressed predominantly at the apical membrane. Although the basal-to-apical transepithelial flux of [(3)H]PGE(2) was little changed by PGT expression, the apical-to-basolateral flux was increased 100-fold compared with wild-type cells. Analysis of driving forces revealed that this flux represents PGT-mediated active transepithelial PGE(2) transport. We propose that endogenous PGT is exocytically inserted into the collecting duct apical membrane, where it could control the concentration of luminal PGs.
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Affiliation(s)
- Shinichi Endo
- Department of Medicine, Division of Nephrology, Albert Einstein College of Medicine, New York, New York 10461, USA
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19
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Morrison SF. Differential regulation of sympathetic outflows to vasoconstrictor and thermoregulatory effectors. Ann N Y Acad Sci 2001; 940:286-98. [PMID: 11458686 DOI: 10.1111/j.1749-6632.2001.tb03684.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The medullary premotor neurons determining the sympathetic outflow regulating cardiac function and vasoconstriction are located in the rostral ventrolateral medulla (RVLM). The present study sought evidence for differential characteristics and baroreceptor reflex sensitivities between the sympathetic nerve activity (SNA) controlling brown adipose tissue (BAT) metabolism and thermogenesis and cardiovascular SNA such as that controlling mesenteric vasoconstriction via the splanchnic (SPL) nerve. The tonic discharge of sympathetic nerves is determined by the inputs to functionally specific sympathetic preganglionic neurons from supraspinal populations of premotor neurons. Under normothermic conditions, BAT SNA was nearly silent, while SPL SNA exhibited sustained, large-amplitude bursts. Disinhibition of neurons in the rostral raphe pallidus (RPa), a potential site of sympathetic premotor neurons controlling BAT SNA, or icv injection of prostaglandin E2, a pyrogenic stimulus, elicited a dramatic increase in BAT SNA. SPL SNA was strongly influenced by the baroreceptor reflex as indicated by a high coherence to the arterial pressure, while activated BAT SNA exhibited no correlation with the arterial pressure. Since these characteristics and reflex responses in sympathetic outflow have been shown to arise from the ongoing or altered discharge of sympathetic premotor neurons, the marked differences between SPL SNA and BAT SNA provide strong evidence supporting the hypothesis that vasoconstriction and thermogenesis (metabolism) are controlled by distinct populations of sympathetic premotor neurons, the former in the RVLM and strongly baroreceptor-modulated and the latter potentially in the RPa exhibiting little influence of baroreceptor reflex activation.
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Affiliation(s)
- S F Morrison
- Department of Physiology (M211), Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL 60611, USA.
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20
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Soszynski D. The inhibition of nitric oxide synthase suppresses LPS- and psychological-stress-induced fever in rats. Physiol Behav 2001; 72:65-72. [PMID: 11239982 DOI: 10.1016/s0031-9384(00)00375-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to assess the effects of a non-selective nitric oxide synthase (NOS) inhibitor on changes in fever response due to injection of lipopolysaccharide (LPS) or on stress fever caused by exposure to an open field in freely moving biotelemetered rats. N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of all NOS-isoforms, was injected intraperitoneally (ip) at a dose of 50 mg/kg just before intraperitoneal injection of LPS at a dose of 50 microg/kg or exposure to open field. L-NAME at a dose of 50 mg/kg had no effect on normal day-time body temperature (T(b)) and normal night-time T(b). The same dose of L-NAME administered intraperitoneally caused a significant attenuation of LPS-induced fever. The thermal index calculated for rats pretreated with L-NAME and injected with LPS was reduced by approximately 75% compared to that calculated for saline-pretreated and LPS-injected rats. To examine the effect of NOS inhibition on psychological-stress-induced elevation in T(b), rats were injected intraperitoneally with L-NAME and then immediately exposed to open field for 60 min. After exposure to the open field, rats not treated with NOS inhibitor responded with a rapid rise in T(b), and it was accompanied with an increase of motor activity. L-NAME significantly suppressed the stress fever without any effect on changes in motor activity. Presented data provide clear evidence that NO formation is involved in LPS- and psychological-stress-induced fevers in rats.
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Affiliation(s)
- D Soszynski
- Department of Physiology, The Ludwik Rydygier Medical University, 24 Karlowicza Str., PL-85-092 Bydgoszcz, Poland. dareks!aci.amb.bydgoszcz.pl
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21
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Abstract
The multiple effects of vagotomy on the thermoregulatory response to systemic inflammation are reviewed (primarily, for the model of intravenous lipopolysaccharide administration in the rat). The following conclusions are drawn. (1) Vagotomy-associated thermoeffector insufficiency is likely to account for the attenuation of the fever response observed in some--but not all--studies; such an insufficiency is, however, preventable by postoperative care, including the use of a liquid diet. (2) The febrile response to low doses of lipopolysaccharide (monophasic fever) is mediated by the hepatic (but not gastric or celiac) vagal fibers, presumably afferent; the same fibers are likely to be involved in the development of tolerance to low doses of circulating endotoxins. (3) Phase 1 of the polyphasic febrile response to moderate doses of lipopolysaccharide involves capsaicin-sensitive afferents (either nonvagal only or both nonvagal and vagal), does not involve cholecystokinin A-receptors, and may involve peripheral prostaglandins. (4) Febrile phase 2 does not require the integrity of abdominal nerve fibers, either vagal or nonvagal, at least in the rat. (5) Phase 3 of the febrile response to intravenous lipopolysaccharide (and perhaps the response to intraperitoneal lipopolysaccharide) involves capsaicin-insensitive vagal fibers, presumably efferent; the involvement of these fibers in febrigenic mechanisms is strongly modulated by an unknown factor. (6) A hepatoceliac vagal, presumably efferent, mechanism ('an anti-inflammatory pathway') counteracts the development of lipopolysaccharide-induced hypothermia and shock.
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Affiliation(s)
- A A Romanovsky
- Trauma Research, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
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Fraifeld V, Paul L, Kaplanski J. The relationship between hypothalamic prostaglandin E2 or leukotrienes and the body temperature response to lipopolysaccharide in different murine strains. J Therm Biol 2000. [DOI: 10.1016/s0306-4565(99)00047-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Aging is associated with a blunted or absent fever response to naturally occurring infections or to the peripheral administration of bacterial products and proinflammatory cytokines. We have recently shown that old Long-Evans rats are not defective in their capacity to develop a fever in response to brain administration of interleukin-1beta (IL-1beta). Here, we investigated the fever response of young (3-5-month) and old (24-26-month) Long-Evans rats to the intracerebroventricular (i.c.v.) microinfusion of prostaglandin E2 (PGE2), a final common mediator for the production of fever in the brain. Core body temperature was monitored by telemetry in freely moving rats. i.c.v. administered PGE2 (100 ng) induced comparable increases in body temperature in young and old Long-Evans rats. In the two groups, PGE2-induced fever was similar both in latency-to-peak fever and maximal fever response. These data, and the previous data on IL-1beta, demonstrate that the brains of old and young rats are similar with respect to fever generation in response to the i.c.v. administration of two classes of immunomodulators.
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Affiliation(s)
- E Satinoff
- Department of Psychology, University of Deleware, Newark 19716-2590, USA.
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Romanovsky AA, Ivanov AI, Karman EK. Blood-borne, albumin-bound prostaglandin E2 may be involved in fever. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:R1840-4. [PMID: 10362768 DOI: 10.1152/ajpregu.1999.276.6.r1840] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Although the involvement of blood-borne PGE2 in fever has been hypothesized by several authors and has substantial experimental support, the current literature often rejects this hypothesis because several attempts to induce fever by a peripheral PGE2 failed. However, it is usually ignored that the amphipathic molecules of PGE2 are readily self-associating and that such an aggregation could have prevented the peripherally administered PGE2 (free form) from expressing its pyrogenic activity, thus leading to false negative results. To ensure disaggregation of PGE2, we prepared its complex within a carrier protein, human serum albumin (HSA). HSA was purified with activated charcoal and polymixin B-polyacrylamide gel and incubated with PGE2 for 1 h at 37 degrees C. Adult Chinchilla rabbits were injected intravenously with PGE2-HSA complex in either the higher (75 micrograms/kg PGE2:30 mg/kg HSA) or the lower (15 micrograms/kg:6 mg/kg) dose, and the rectal temperature (Tr) was measured. In the controls, either the ligand alone or the carrier alone was administered. At the higher dose, neither free PGE2 nor albumin alone was pyrogenic, whereas the PGE2-HSA complex produced a fever characterized by a short latency (<10 min) and a maximal Tr rise of 0.7 +/- 0.2 degrees C. At the lower dose, none of the substances affected the Tr. This study demonstrates a marked pyrogenic activity of the intravenous PGE2-HSA, but not of the free PGE2. Administration of a preformed complex may be more physiologically relevant than administration of the free ligand because of the ligand's disaggregation, protection from enzymatic degradation, and facilitated delivery to targets. Our study supports the hypothesis that peripheral PGE2 is involved in fever genesis.
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Affiliation(s)
- A A Romanovsky
- Thermoregulation Laboratory, Legacy Holladay Park Medical Center, Portland, Oregon 97208, USA.
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Paul L, Fraifeld V, Kaplanski J. Evidence supporting involvement of leukotrienes in LPS-induced hypothermia in mice. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:R52-8. [PMID: 9887177 DOI: 10.1152/ajpregu.1999.276.1.r52] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of the present study was to examine a possible involvement of leukotrienes (LTs) in lipopolysaccharide (LPS)-induced body temperature (Tb) response. We examined the effect of MK-886, an inhibitor of LT synthesis, on changes in Tb, plasma tumor necrosis factor-alpha (TNF-alpha), hypothalamic LT, and PGE2 production. Intraperitoneal injection of LPS (50 microgramg/mouse) led to a decrease in Tb starting 1 h after the injection. The hypothermic effect of LPS was accompanied by a significant elevation in TNF-alpha level in plasma and in LT and PGE2 production by ex vivo-incubated hypothalamus. MK-886 (1 mg/kg ip) administered 4 h before LPS efficaciously prevented LPS-induced hypothermia in mice. Pretreatment of mice with MK-886 did not alter the LPS-stimulated increase in plasma TNF-alpha. MK-886 significantly inhibited LT and enhanced PGE2 production in hypothalamus compared with LPS alone. These results suggest that 1) LPS-induced hypothermia may be mediated by LTs and 2) the antihypothermic effect of MK-886 is not associated with TNF-alpha bioactivity.
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Affiliation(s)
- L Paul
- Department of Clinical Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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