探讨小剂量雌激素对老年雌性大鼠下丘脑雌激素受体（ER）表达及β-内啡肽肚（β-EP）的影响。建立自然衰老的18月龄雌性大鼠模型，用放射配体结合法检测ER，用Northernblot分析ERmRNA的改变，用放射免疫分析法检测β-EP含量。结果表明：雌激素对ER和ERmRNA呈显著的负向调节作用，ER表达被抑制；β-EP水平明显提高。雌激素的这些作用与其剂量之间并非简单的线性关系。提示：外源性雌激素对体内的神经内分泌平衡有多种影响，在进行雌激素替代治疗时应尽可能选择小剂量。 To investigate the effect of low dose estrogen on hypothalamic estrogen receptor (ER) expression and beta-endorphin (β-EP) in aged female rats. A 18-month-old female rat model of natural aging was established. ER was detected by radioligand binding assay and ERmRNA by Northern blot analysis. The level of β-EP was detected by radioimmunoassay. The results showed that estrogen showed a significant negative regulation on ER and ERmRNA, ER expression was inhibited; β-EP levels were significantly increased. These effects of estrogen are not linearly related to their dose. Tip: Exogenous estrogen on the body’s neuroendocrine balance has a variety of effects, estrogen replacement therapy should be as small as possible to choose a small dose.