Larsson B, Andersson K E, Batra S, Mattiasson A, Sjögren C
J Pharmacol Exp Ther. 1984 May;229(2):557-63.
Several studies have revealed that estrogen treatment increases the reactivity to catecholamines of various tissues. In the present study it was found that estrogen treatment caused an increased sensitivity to norepinephrine (NE) of the isolated female rabbit urethra. There was a 3-fold shift to the left of the concentration-response curve for longitudinal tension in perfused urethras and for tension in urethral ring preparations. Possible mechanisms for this increase in sensitivity were investigated by studying radioligand binding to the alpha adrenoceptors and by measuring the NE content of the urethras. Using [3H]dihydro-alpha-ergocryptine as a marker for alpha adrenoceptors, a more than 2-fold increase in the receptor number was found after estrogen treatment. This is suggested to be attributable to a selective increase in the number of alpha-2 adrenoceptors. No significant change was found in the affinity of [3H]dihydro-alpha-ergocryptine to the receptor. The total NE content in the urethra was not changed by estrogen treatment. However, if calculated per milligram of wet weight, the NE content was reduced to half in estrogen treated animals. It is suggested that in the rabbit urethra the estrogen-induced increased sensitivity to the contractant effects of NE, at least in part, is attributable to an increase in the number of postjunctional alpha-2 adrenoceptors.
多项研究表明，雌激素治疗可增强各种组织对儿茶酚胺的反应性。在本研究中发现，雌激素治疗可使离体雌性兔尿道对去甲肾上腺素（NE）的敏感性增加。灌注尿道纵向张力和尿道环制剂张力的浓度-反应曲线向左移动了3倍。通过研究放射性配体与α肾上腺素能受体的结合以及测量尿道的NE含量，对这种敏感性增加的可能机制进行了研究。使用[3H]二氢-α-麦角隐亭作为α肾上腺素能受体的标记物，发现雌激素治疗后受体数量增加了2倍多。这被认为是由于α2肾上腺素能受体数量的选择性增加。未发现[3H]二氢-α-麦角隐亭与受体的亲和力有显著变化。雌激素治疗后尿道中的总NE含量没有改变。然而，按每毫克湿重计算，雌激素处理动物的NE含量降至一半。提示在兔尿道中，雌激素诱导的对NE收缩作用敏感性增加至少部分归因于节后α2肾上腺素能受体数量的增加。
