El Bitar Nabil, Pollin Bernard, Karroum Elias, Pincedé Ivanne, Mouraux André, Le Bars Daniel
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.
Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium.
J Neurophysiol. 2014 Nov 1;112(9):2185-98. doi: 10.1152/jn.00721.2013. Epub 2014 Jul 9.
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.
啮齿动物的尾巴和爪子是参与维持核心体温（T(core)）的热交换器。它们也是研究急慢性疼痛“模型”时使用最广泛的靶器官。我们描述了在热中性条件下尾巴和爪子血管运动张力的波动，以及这些生理过程对热伤害性刺激反应的限制，热伤害性刺激通常用作疼痛指标。使用校准的热成像相机记录皮肤温度，以监测清醒和麻醉大鼠尾巴和爪子血管运动张力的变化。在热中性条件下，交感神经张力以每小时两到七个周期的速率波动。平均动脉血压（MAP；约46 mmHg）升高后，30秒内心率（HR；约45次/分钟）升高，3至5分钟内四肢血管收缩（3.5 - 7°C范围），6分钟内T(core)升高（约0.7°C）。MAP降低后则出现相反的情况。5 - 6分钟后记录的HR和T(core)之间存在高度相关性。动物对二氧化碳激光导向尾巴产生的辐射热刺激——热斜坡（6°C/s，20 mm(2)光斑）的反应时间取决于这些变化。因此，尾巴和爪子温度的波动对热伤害性测试来说是一个严重的干扰因素，尤其是在热中性条件下进行测试时。
