title: Thermoregulatory vasomotor tone of the rat tail and paws in thermoneutral conditions and its impact on a behavioral model of acute pain.
abstract: The tail and paws in rodents are heat exchangers involved in the maintenance of core body temperature (T(core)). They are also the most widely used target organs to study acute or chronic "models" of pain. We describe the fluctuations of vasomotor tone in the tail and paws in conditions of thermal neutrality and the constraints of these physiological processes on the responses to thermal nociceptive stimuli, commonly used as an index of pain. Skin temperatures were recorded with a calibrated thermal camera to monitor changes of vasomotor tone in the tail and paws of awake and anesthetized rats. In thermoneutral conditions, the sympathetic tone fluctuated at a rate of two to seven cycles/h. Increased mean arterial blood pressure (MAP; ∼46 mmHg) was followed by increased heart rate (HR; ∼45 beats/min) within 30 s, vasoconstriction of extremities (3.5-7°C range) within 3-5 min, and increased T(core) (∼0.7°C) within 6 min. Decreased MAP was followed by opposite events. There was a high correlation between HR and T(core) recorded 5-6 min later. The reaction time of the animal's response to a radiant thermal stimulus-heat ramp (6°C/s, 20 mm(2) spot) generated by a CO2 laser-directed to the tail depends on these variations. Consequently, the fluctuations in tail and paw temperature thus represent a serious confound for thermal nociceptive tests, particularly when they are conducted at thermal neutrality.
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and.
authors.forename: Nabil
authors.initials: N
authors.lastname: El Bitar
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and.
authors.forename: Bernard
authors.initials: B
authors.lastname: Pollin
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and.
authors.forename: Elias
authors.initials: E
authors.lastname: Karroum
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and.
authors.forename: Ivanne
authors.initials: I
authors.lastname: Pincedé
authors.affiliation: Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: André
authors.initials: A
authors.lastname: Mouraux
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Faculté de Médecine Paris, France; Neurosciences Paris-Seine, Institut National de la Santé et de la Recherche Médicale UMRS-1130, Centre National de la Recherche Scientifique UMR-8246, Paris, France; and daniel.le_bars@upmc.fr.
authors.forename: Daniel
authors.initials: D
authors.lastname: Le Bars
mesh_terms: D000818:Animals; D001794:Blood Pressure; D001833:Body Temperature Regulation; D005121:Extremities / Q000098:blood supply / Q000294:innervation / Q000502:physiology*; D006339:Heart Rate; D059225:Nociception; D011177:Postal Service; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D013623:Tail / Q000098:blood supply / Q000294:innervation / Q000502:physiology*; D014661:Vasoconstriction; D014664:Vasodilation; D014666:Vasomotor System / Q000502:physiology*
keywords: blood pressure variability; heart-rate variability; pain tests and models; thermoneutrality; vasomotion