Lin M T, Uang W N, Ho L T, Chuang J, Fan L J
Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan, Republic of China.
Pflugers Arch. 1989 Mar;413(5):528-32. doi: 10.1007/BF00594185.
The changes in both the thermoregulatory responses and brain somatostatin (SS) levels produced by ambient temperature (Ta) changes were assessed in rats after they had been equilibrated to each of the Ta for a period of about 90 min. Cold exposure, in addition to elevating hypothalamic SS-levels, led to increased metabolism and cutaneous vasoconstriction at Ta = 8 degrees C. In contrast, heat exposure, in addition to lowering hypothalamic SS-levels, resulted in decreased metabolism and cutaneous vasodilation at Ta = 30 degrees C. Rats were chronically implanted with a hypothalamic cannula to allow intrahypothalamic injection of SS on the conscious rats. Direct administration of SS (0.1-0.3 micrograms) into the preoptic anterior hypothalamic area caused a dose-related rise in colon temperature at three Ta tested. The SS-induced hyperthermia was produced by increased metabolism at Ta = 8 degrees C, whereas at Ta = 30 degrees C, it was caused by cutaneous vasoconstriction. At Ta = 22 degrees C, the hyperthermia was caused by increased metabolism and cutaneous vasoconstriction. Systemic administration of cysteamine, in addition to lowering hypothalamic SS-levels, produced a dose-related fall in colon temperature at Ta of 8 degrees C and 22 degrees C. The hypothermia induced by cysteamine was produced by decreased metabolism at Ta = 8 degrees C, whereas at Ta = 22 degrees C, it was caused by both decreased metabolism and cutaneous vasodilation. The data indicate that the hypothalamic SS-levels mediate normal body temperature responses in rats.
在大鼠适应每种环境温度（Ta）约90分钟后，评估环境温度变化所引起的体温调节反应和脑内生长抑素（SS）水平的变化。冷暴露除了会提高下丘脑SS水平外，在Ta = 8摄氏度时还会导致新陈代谢增加和皮肤血管收缩。相反，热暴露除了会降低下丘脑SS水平外，在Ta = 30摄氏度时会导致新陈代谢降低和皮肤血管舒张。给大鼠长期植入下丘脑套管，以便对清醒大鼠进行下丘脑内注射SS。在三个测试的Ta条件下，向视前区下丘脑前部直接注射SS（0.1 - 0.3微克）会导致结肠温度呈剂量相关的升高。在Ta = 8摄氏度时，SS诱导的体温过高是由新陈代谢增加引起的，而在Ta = 30摄氏度时，是由皮肤血管收缩引起的。在Ta = 22摄氏度时，体温过高是由新陈代谢增加和皮肤血管收缩引起的。全身注射半胱胺，除了会降低下丘脑SS水平外，在Ta为8摄氏度和22摄氏度时还会导致结肠温度呈剂量相关的下降。半胱胺诱导的体温过低在Ta = 8摄氏度时是由新陈代谢降低引起的，而在Ta = 22摄氏度时，是由新陈代谢降低和皮肤血管舒张共同引起的。这些数据表明，下丘脑SS水平介导大鼠正常的体温反应。
