title: Nitric oxide and fever: immune-to-brain signaling vs. thermogenesis in chicks.
abstract: Nitric oxide (NO) plays a role in thermogenesis but does not mediate immune-to-brain febrigenic signaling in rats. There are suggestions of a different situation in birds, but the underlying evidence is not compelling. The present study was designed to clarify this matter in 5-day-old chicks challenged with a low or high dose of bacterial LPS. The lower LPS dose (2 μg/kg im) induced fever at 3-5 h postinjection, whereas 100 μg/kg im decreased core body temperature (Tc) (at 1 h) followed by fever (at 4 or 5 h). Plasma nitrate levels increased 4 h after LPS injection, but they were not correlated with the magnitude of fever. The NO synthase inhibitor (N(G)-nitro-l-arginine methyl ester, l-NAME; 50 mg/kg im) attenuated the fever induced by either dose of LPS and enhanced the magnitude of the Tc reduction induced by the high dose in chicks at 31-32°C. These effects were associated with suppression of metabolic rate, at least in the case of the high LPS dose. Conversely, the effects of l-NAME on Tc disappeared in chicks maintained at 35-36°C, suggesting that febrigenic signaling was essentially unaffected. Accordingly, the LPS-induced rise in the brain level of PGE2 was not affected by l-NAME. Moreover, l-NAME augmented LPS-induced huddling, which is indicative of compensatory mechanisms to run fever in the face of attenuated thermogenesis. Therefore, as in rats, systemic inhibition of NO synthesis attenuates LPS-induced fever in chicks by affecting thermoeffector activity and not by interfering with immune-to-brain signaling. This may constitute a conserved effect of NO in endotherms.
authors.affiliation: Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil; National Institute of Science and Technology-Comparative Physiology (INCT-Fisiologia Comparada), Rio Claro, São Paulo, Brazil;
authors.forename: Valter
authors.initials: V
authors.lastname: Dantonio
authors.affiliation: Nursing School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil;
authors.forename: Marcelo E
authors.initials: ME
authors.lastname: Batalhão
authors.affiliation: Department of Animal Science, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil;
authors.forename: Marcia H M R
authors.initials: MH
authors.lastname: Fernandes
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, Brazil; and.
authors.forename: Evilin N
authors.initials: EN
authors.lastname: Komegae
authors.affiliation: Department of Physics and Chemistry, Núcleo de Pesquisa em Produtos Naturais e Sintéticos, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Gabriela A
authors.initials: GA
authors.lastname: Buqui
authors.affiliation: Department of Physics and Chemistry, Núcleo de Pesquisa em Produtos Naturais e Sintéticos, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Norberto P
authors.initials: NP
authors.lastname: Lopes
authors.affiliation: Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil; National Institute of Science and Technology-Comparative Physiology (INCT-Fisiologia Comparada), Rio Claro, São Paulo, Brazil;
authors.forename: Luciane H
authors.initials: LH
authors.lastname: Gargaglioni
authors.affiliation: Nursing School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil;
authors.forename: Évelin C
authors.initials: ÉC
authors.lastname: Carnio
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, Brazil; and.
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: Steiner
authors.affiliation: Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil; National Institute of Science and Technology-Comparative Physiology (INCT-Fisiologia Comparada), Rio Claro, São Paulo, Brazil; keniacb@fcav.unesp.br keniacb@yahoo.com.br.
authors.forename: Kênia C
authors.initials: KC
authors.lastname: Bícego
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D001833:Body Temperature Regulation / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D002645:Chickens / Q000502:physiology*; D015232:Dinoprostone / Q000378:metabolism; D005334:Fever / Q000139:chemically induced*; D008070:Lipopolysaccharides / Q000633:toxicity*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D008070:Lipopolysaccharides; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D015232:Dinoprostone; D019331:NG-Nitroarginine Methyl Ester
keywords: body temperature; huddling; l-NAME; lipopolysaccharide; nitrate; oxygen consumption