Yang Xiao-Feng, Chang Jong Hee, Rothman Steven M
Department of Neurology, Room 12E/25, St. Louis Children's Hospital, Washington University, St. Louis, MO 63110, USA.
Epilepsy Res. 2002 Dec;52(2):97-105. doi: 10.1016/s0920-1211(02)00193-6.
Because focal seizures produce an increase in local cerebral metabolism and blood flow, we wanted to determine whether they might lead to changes in brain temperature. We induced focal neocortical seizures by microinjection of 4-aminopyridine (4-AP) into the rat motor cortex. The temperature on the dura immediately over the injection site, or 8 mm away, was measured with a thermocouple and in some experiments relative blood flow was monitored with a laser Doppler probe. In animals that did not receive 4-AP, brain and rectal temperature remained fairly constant at 33.5 and 37.2 degrees C, respectively, over a 2 h monitoring period. In animals treated with 4-AP, brain temperature over the seizure focus rose an average of 0.3 degrees C, within a few seconds of seizure onset, while rectal temperature remained constant. The seizure-induced temperature rise was preceded by an increase in cortical blood flow. The temperature, but not blood flow, was also elevated 8 mm away from the seizure focus. When blood flow was increased independently of neuronal activity, by elevating pCO(2), brain temperature also rose by about 0.3 degrees C. Focal seizures in anesthetized rats produce a small, but statistically significant increase in local brain temperature, as a result of increased blood flow that brings brain temperature closer to body temperature. In humans, seizures could actually cause a reduction in brain temperature, because brain temperature is normally higher than body temperature.
由于局灶性癫痫发作会使局部脑代谢和血流增加，我们想确定它们是否可能导致脑温变化。我们通过向大鼠运动皮层微量注射4-氨基吡啶（4-AP）来诱发局灶性新皮层癫痫发作。用热电偶测量注射部位正上方或8毫米远处硬脑膜上的温度，在一些实验中用激光多普勒探头监测相对血流。在未接受4-AP的动物中，在2小时的监测期内，脑温和直肠温度分别相当稳定地保持在33.5摄氏度和37.2摄氏度。在用4-AP治疗的动物中，癫痫发作起始后几秒钟内，癫痫发作灶上方的脑温平均升高0.3摄氏度，而直肠温度保持不变。癫痫发作引起的体温升高之前有皮层血流增加。在距癫痫发作灶8毫米处，温度升高但血流未增加。当通过提高pCO₂使血流独立于神经元活动而增加时，脑温也升高约0.3摄氏度。麻醉大鼠的局灶性癫痫发作会使局部脑温出现微小但具有统计学意义的升高，这是由于血流增加使脑温更接近体温所致。在人类中，癫痫发作实际上可能导致脑温降低，因为脑温通常高于体温。
