甲亢大鼠肝脏肾上腺素α_1受体测定及养阴益气中药作用机制初探

Determination of Hepatocyte Adrenergic α_1 Receptor and Study on Actions of Nourishing Yin and Replenishing Qi(养阴益气）Drugs in Experimental Hyperthyroid Rats

我们用肌肉注射甲状腺素的方法制备大鼠甲状腺机能亢进症（甲亢）模型，并将动物分对照、甲亢与甲亢加养阴益气中药组，成型后的大鼠具典型甲亢症状，且血ＴＴ３、ＴＴ４明显升高。用３Ｈ－哌唑嗪作放射配基进行肝细胞膜肾上腺素α１受体的结合分析。结果发现，甲亢组受体最大结合容量（Ｂｍａｘ）低于对照组，但无统计学意义；甲亢组受体解离常数（Ｋｄ）值显著低于对照组（Ｐ＜０．０５）；加药组Ｋｄ值介于其余两组之间，与对照组比较差别无显著性。提示甲亢时肾上腺素α１受体亲和力明显升高，而养阴益气中药对于甲亢时过高的亲和力有一定程度的纠正作用。

In this study,hyperthyroid rat models(group l) were established by daily intramuscular injections of thyroxine for 7 days.Group 2 were hyperthyroid rats receiving at the same time NourishingYin and Replenishing Qi drugs(Ophiopogonis japonis,Pseudostellariae heterophylla and Rehmanniaglutinosa).Normal rats served as controls.Group 1 and group 2 rats showed manifestations ofhyperthyroidism,higher rectal temperature,increased O2 consumption,as well as significantly higherserum TT3 and TT4 levels.Receptor proteins of liver cell membrane were prepared.Receptorbinding assay was performed using 3`H-prazosin(adrenergicα1 receptor antagonist) as radioligand,maximal binding capacity(Bmax) and dissociation constant(Kd) were calculated from Scatchardcurve.It was found Bmax(fmol/mg protein) in model groups were lower than that of the controlgroup,but the differences were not statistically significant.Kd(nM) in group 1 was significantlylower than that of control group(2.32±1.09 vs 5.42±2.54,P<0.05),indicating that receptor affinitywas increased in hyperthyroid rats.Kd in group 2(3.11±1.48) was intermediate between that in group1 and controls,suggesting that these Chinese herbal medicine might have an effect in loweringreceptor affinity and the(peripheral conversion of T4 to T3.