桂枝汤对发热及低体温大鼠下丘脑可溶性一氧化氮合酶的影响

Effect of Guizhi Tang on Hypothalamic Cytosolic NOS in Fever Rats and in Hypothermia Rats

目的 :研究发热和低体温大鼠下丘脑可溶性N0S活性的变化及桂枝汤对之的影响。方法 :利用分光光度法测定酵母性发热大鼠、安痛定性低体温大鼠及桂枝汤治疗组下丘脑部位N0S活性。结果 :皮下注射酵母 5 5h后大鼠下丘脑组织内N0S活性显著升高 ,而腹腔注射安痛定可使该部位N0S活性明显降低 ,与体温变化呈正相关 ;桂枝汤 (p .o.)可剂量依赖性地对抗酵母诱导的大鼠下丘脑N0S活性升高 ,与其解热作用平行 ;但在低体温模型上可进一步降低该区N0S活性 ,该作用与抗低体温作用呈负相关。结论 :下丘脑可溶性N0S可能参与了大鼠体温调节 ;桂枝汤抑制酵母诱导的下丘脑N0S活性升高可能是其解热作用机制之一 ,但其抗低体温作用可能与该区N0S变化无关。

It has been demonstrated that nitric oxide play a role in thermoregulation,but very little is known about the mechanism in yeast induced fever and aminopyrine evoked hypothermia in rats. We have a hypothesis that Guizhi Tang,a formulum possesses dual thermoregulatory action, may exhibit anapyrexia or anti hypothermia action via NO. To test the hypothesis,the cytosolic nitric oxide synthase in hypothalamus in both the fever and the hypothermia rats induced by yeast or aminopyrine accordingly was determined using a colorimetric assay. The NOS activity enhanced after a s.c. yeast injection and decreased after an i.p. treatment of aminopyrine. Reversion in NOS and body temperature were observed in fever rats after the administration of Guizhi Tang orally at a dose dependent manner. While a confusing result obtained from the hypothermia rats treated with Guizhi Tang was that a recover of body temperature paraileled a continual decrease in NOS activity.Data suggested that the cytosolic NOS in hypothalamus participates the thermoregulation in rats and may also play a role in antipyretic action of Guizhi Tang, but not in its anti hypothermia action.