Corbett S W, Roland B, Keesey R E
Department of Psychology, University of Wisconsin, Madison 53706.
Am J Physiol. 1990 Oct;259(4 Pt 1):E534-41. doi: 10.1152/ajpendo.1990.259.4.E534.
Responses to several thermogenic stimuli were measured in rats maintaining stable but reduced body weights following lateral hypothalamic (LH) lesions. Oxygen consumption was monitored in open-circuit respirometers before and after exposure to cold (16.5 degrees C), intubation of a meal, and isoproterenol injection (40 micrograms/kg 0.75). Observations were made in both warm- (28 degrees C) and cold-acclimated (9 degrees C) LH-lesioned rats. Cold exposure, intubation, and drug injection each caused marked increases in heat production in sham- and LH-lesioned rats. This thermogenic response was similar in magnitude and form for both groups. Acclimation to 9 degrees C caused increased baseline levels of heat production when measured at 28 degrees C. Subsequent exposure to thermogenic stimuli revealed an exaggerated response to isoproterenol but not intubation in cold-acclimated groups. The LH-lesioned cold-acclimated rats responded in the same manner as sham-lesioned cold-acclimated rats. These findings are in contrast to the immediate postlesion period when rats show enhanced thermogenic activity. At reduced body weights LH-lesioned rats show normal rates of heat production and make normal responses to thermogenic stimuli. Enhanced thermogenesis does not appear to play a role in the maintenance of chronically reduced body mass in LH-lesioned rats.
在患有下丘脑外侧（LH）损伤且体重稳定但减轻的大鼠中，测量了对几种产热刺激的反应。在暴露于寒冷环境（16.5摄氏度）、插管喂食和注射异丙肾上腺素（40微克/千克，0.75）前后，使用开路呼吸计监测氧气消耗。对处于温暖环境（28摄氏度）和冷适应环境（9摄氏度）的LH损伤大鼠都进行了观察。寒冷暴露、插管和药物注射均使假手术组和LH损伤组大鼠的产热显著增加。两组的这种产热反应在幅度和形式上相似。适应9摄氏度环境后，在28摄氏度测量时，基础产热水平升高。随后对冷适应组大鼠暴露于产热刺激，结果显示其对异丙肾上腺素的反应增强，但对插管的反应未增强。LH损伤的冷适应大鼠与假手术的冷适应大鼠反应方式相同。这些发现与损伤后即刻大鼠产热活动增强的时期形成对比。在体重减轻的情况下，LH损伤大鼠的产热速率正常，对产热刺激的反应也正常。产热增强似乎在LH损伤大鼠长期体重减轻的维持过程中不起作用。
