Hasegawa Hiroshi, Ishiwata Takayuki, Saito Takehito, Yazawa Toru, Aihara Yasutsugu, Meeusen Romain
Dept. of Human Physiology and Sportsmedicine, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
J Appl Physiol (1985). 2005 Apr;98(4):1458-62. doi: 10.1152/japplphysiol.00916.2004. Epub 2004 Dec 23.
We have previously demonstrated a functional role of the preoptic area and anterior hypothalamus (PO/AH) in thermoregulation in freely moving rats at various temperature conditions by using microdialysis and biotelemetry methods. In the present study, we perfused tetrodotoxin (TTX) solution into the PO/AH to investigate whether this manipulation can modify thermoregulation in exercising rats. Male Wistar rats were trained for 3 wk by treadmill running. Body core temperature (Tb), heart rate (HR), and tail skin temperature (Ttail) were measured. Rats ran for 120 min at speed of 10 m/min, with TTX (5 microM) perfused into the left PO/AH during the last 60 min of exercise through a microdialysis probe (control, n=12; TTX, n=12). Tb, HR, and Ttail increased during the first 20 min of exercise. Thereafter, Tb, HR, and Ttail were stable in both groups. Perfusion of TTX into the PO/AH evoked an additional rise in Tb (control: 38.2 +/- 0.1 degrees C, TTX: 39.3 +/- 0.2 degrees C; P <0.001) with a significant decrease in Ttail (control: 31.2 +/- 0.5 degrees C, TTX: 28.3 +/- 0.7 degrees C; P <0.01) and a significant increase in HR (control: 425.2 +/- 12 beats/min, TTX: 502.1 +/- 13 beats/min; P <0.01). These results suggest that the TTX-induced hyperthermia was the result of both an impairment of heat loss and an elevation of heat production during exercise. We therefore propose the PO/AH as an important thermoregulatory site in the brain during exercise.
我们之前已经通过微透析和生物遥测方法，证明了视前区和下丘脑前部（PO/AH）在不同温度条件下自由活动大鼠的体温调节中发挥的功能作用。在本研究中，我们将河豚毒素（TTX）溶液灌注到PO/AH中，以研究这种操作是否会改变运动大鼠的体温调节。雄性Wistar大鼠通过跑步机跑步训练3周。测量体核温度（Tb）、心率（HR）和尾部皮肤温度（Ttail）。大鼠以10米/分钟的速度跑120分钟，在运动的最后60分钟通过微透析探针将TTX（5微摩尔）灌注到左侧PO/AH中（对照组，n = 12；TTX组，n = 12）。运动的前20分钟内，Tb、HR和Ttail升高。此后，两组的Tb、HR和Ttail均保持稳定。向PO/AH灌注TTX导致Tb进一步升高（对照组：38.2±0.1℃，TTX组：39.3±0.2℃；P<0.001），Ttail显著降低（对照组：31.2±0.5℃，TTX组：28.3±0.7℃；P<0.01），HR显著升高（对照组：425.2±12次/分钟，TTX组：502.1±13次/分钟；P<0.01）。这些结果表明，TTX诱导的体温过高是运动期间散热受损和产热增加共同作用的结果。因此，我们提出PO/AH是运动期间大脑中一个重要的体温调节部位。
