5-hydroxytryptamine 1A receptor activation reduces cutaneous vasoconstriction and fever associated with the acute inflammatory response in rabbits.
ABSTRACT 5-Hydroxytryptamine(1A) (5-HT1A) receptor activation reduces body temperature partially by dilating the thermoregulatory cutaneous vascular bed, thereby increasing heat transfer to the environment. Constriction of this vascular bed, with consequent reduction of heat transfer to the environment, contributes to fever associated with the acute inflammatory response. Thus activation of 5-HT1A receptors might inhibit thermoregulatory cutaneous vasoconstriction and reduce the fever associated with the acute inflammatory response. The present study tested this hypothesis in conscious unrestrained rabbits. The acute inflammatory reaction was induced with i.v. lipopolysaccharide (LPS, 0.5 microg/kg). Body temperature was measured with an i.p. telemetric probe, and ear pinna blood flow was measured with a chronically implanted Doppler ultrasonic probe. 5-HT1A receptors were activated with i.v. 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). LPS increased body temperature by +1.7+/-0.2 degrees C during the first hour after administration. The ear pinna Doppler blood flow signal fell from 69+/-11 to 5+/-1 cm/s within 15 min (n=7, P<0.01) and remained at a low level for approximately 1 h after LPS. When administered 45 min after LPS, 8-OH-DPAT (0.1 mg/kg i.v.) reversed this fall, increasing the Doppler signal from 6+/-1 to 55+/-7 cm/s (P<0.01, n=6), and reduced the rise in body temperature. Treatment with 8-OH-DPAT (0.1 mg/kg i.v.) 5 min before and 30 min after LPS entirely prevented the LPS-induced fall in ear pinna blood flow, and reduced the rise in body temperature from 1.7+/-0.2 degrees C to 0.7+/-0.2 (n=7, P<0.01). Treatment with WAY-100635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide trihydrochloride) (0.1 mg/kg i.v.) prevented and reversed the effects of 8-OH-DPAT. Thus activation of 5-HT1A receptors reduces thermoregulatory cutaneous vasoconstriction and fever occurring as part of the acute inflammatory response. Our findings elucidate the neurotransmitter mechanisms underlying expression of an important component of the febrile response, and suggest that drugs with 5-HT1A agonist properties might be therapeutically useful when it is clinically important to reduce this response.
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ABSTRACT: Fever is a prominent feature of diseases and is an ongoing process that is always accompanied by metabolic changes in the body system. Despite the success of temperature regulation theory, the underlying biological process remains unclear. To truly understand the nature of the febrile response, it is crucial to confirm the biomarkers during the entire biological process. In the current study, a 73-h metabolic footprint analysis of the urine from yeast-induced pyrexia rats was performed using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Potential biomarkers were selected using orthogonal partial least squares-discriminate analysis (OPLS-DA), the rational biomarkers were verified by Pearson correlation analysis, and the predictive power was evaluated using receiver operator characteristic (ROC) curves. A metabolic network constructed using traditional Chinese medicine (TCM) grammar systems was used to validate the rationality of the verified biomarkers. Finally, five biomarkers, including indoleacrylic acid, 3-methyluridine, tryptophan, nicotinuric acid and PI (37:3), were confirmed as rational biomarkers because their correlation coefficients were all greater than 0.87 and because all of the correlation coefficients between any pair of these biomarkers were higher than 0.75. The areas under the ROC curves were all greater than 0.84, and their combined predictive power was considered reliable because the greatest area under the ROC curve was 0.968. A metabolic network also demonstrated the rationality of these five biomarkers. Therefore, these five metabolites can be adopted as rational biomarkers to reflect the process of the febrile response in inflammation-induced pyrexia.Journal of pharmaceutical and biomedical analysis 02/2014; 95C:68-75. · 2.45 Impact Factor
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ABSTRACT: The serotonin (5-HT) system plays a key role in the pathophysiology of psychiatric disorders including mood and anxiety disorders. A role for serotonin in stress-related disorders is further supported by the fact that clinically effective treatments for these disorders alter serotonergic neurotransmission. The therapeutic potential of serotonergic pharmacological interventions has resulted in a variety of preclinical approaches to study the serotonin system. Of these, the stress-induced hyperthermia (SIH) paradigm has been extensively used to study the serotonin system at a preclinical level. The SIH response uses the transient rise in body temperature in response to a stressor which can be reduced using anxiolytic drugs including benzodiazepines, CRF receptor antagonists and serotonergic ligands. The present review aims to discuss the acute and chronic effects of 5-HT ligands on the SIH response. Also, the SIH response in genetically modified mice that lack or overexpress specific serotonergic receptor subtypes or the serotonin transporter will be summarized. 5-HT 1A receptor ligands reduce the SIH response, whereas acute administration of other serotonergic drugs (including 5-HT 1B , 5-HT 2 and 5-HT 3 modulators and SSRIs) generally does not influence the SIH response. Also, the SIH paradigm is generally insensitive to detect the anxiolytic effects of chronic serotonergic antidepressants in rodents, and serotonergic drugs that have been found to reduce the SIH response acutely do so irrespective of the healthy or pathological status of an individual.The Open Pharmacology Journal 01/2010; 410(15):15-29.