Wang P S, Porter J C
Proc Natl Acad Sci U S A. 1986 Dec;83(24):9804-6. doi: 10.1073/pnas.83.24.9804.
The role of ovarian hormones in the control of the quantity and activity of tyrosine hydroxylase (TyrOHase) in neurites of the median eminence of the rat was investigated. TyrOHase was quantified by an immunoblot assay using purified rat TyrOHase as the standard. Treatment of ovariectomized animals with progesterone, but not estradiol, resulted in a significant reduction in the amount of TyrOHase in the median eminence. The in situ activity of the enzyme was assayed by measuring the rate of synthesis of L-3,4-dihydroxyphenylalanine (dopa), and the results were expressed as mol of dopa per hr per mol of TyrOHase. In animals treated with both estradiol and progesterone for 3 days, the in situ activity of TyrOHase in the median eminence was 114 +/- 13.5 (mean +/- SEM) compared to 26 +/- 4.7 for the controls. Estradiol or progesterone alone was much less effective than was the combination of estradiol and progesterone. To ascertain whether the effect of estradiol and progesterone on TyrOHase activity was reflected in the secretion of dopamine into hypophyseal portal blood, ovariectomized rats were treated for 3 days with both estradiol and progesterone or with the solvent vehicle. The concentration of dopamine in portal plasma of the hormone-treated animals was 1.93 +/- 0.533 ng/ml compared to 0.34 +/- 0.094 ng/ml in vehicle-treated animals. We conclude that the quantity and in situ molar activity of TyrOHase in neurites of the median eminence as well as the secretion of dopamine from these neurites are modulated by the combined action of estradiol and progesterone.
研究了卵巢激素在控制大鼠正中隆起神经突中酪氨酸羟化酶（TyrOHase）的数量和活性方面的作用。以纯化的大鼠TyrOHase为标准，通过免疫印迹法对TyrOHase进行定量。用孕酮而非雌二醇处理去卵巢动物，导致正中隆起中TyrOHase的量显著减少。通过测量L-3,4-二羟基苯丙氨酸（多巴）的合成速率来测定该酶的原位活性，结果以每小时每摩尔TyrOHase合成的多巴摩尔数表示。用雌二醇和孕酮联合处理3天的动物，正中隆起中TyrOHase的原位活性为114±13.5（平均值±标准误），而对照组为26±4.7。单独使用雌二醇或孕酮的效果远不如雌二醇和孕酮联合使用。为了确定雌二醇和孕酮对TyrOHase活性的影响是否反映在多巴胺向垂体门脉血中的分泌上，用雌二醇和孕酮或溶剂载体对去卵巢大鼠进行3天的处理。激素处理动物的门脉血浆中多巴胺浓度为1.93±0.533 ng/ml，而溶剂处理动物为0.34±0.094 ng/ml。我们得出结论，正中隆起神经突中TyrOHase的数量和原位摩尔活性以及这些神经突中多巴胺的分泌受到雌二醇和孕酮联合作用的调节。
