Philipp E, Pirke K M
Brain Res. 1987 Jun 9;413(1):53-9. doi: 10.1016/0006-8993(87)90153-3.
The activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in norepinephrine synthesis, was determined in the mediobasal hypothalamus of adult male rats during acute and semistarvation. 3,4-Dihydroxyphenylalanine (DOPA) formed by TH was measured using high-performance liquid chromatography (HPLC). Acute starvation, as well as 3 weeks of semistarvation on a high-protein low-carbohydrate diet (CST PR) reduced TH activity significantly. Three weeks of a low-protein high-carbohydrate diet (CST KH) did not affect TH activity. While maximal velocity (Vmax) is significantly diminished in acute starvation and in semistarvation with a high-protein low-carbohydrate diet, Kd-values for tyrosine were not changed. These results suggest that TH activity in the brain contributes to decreased norepinephrine (NE) turnover in starvation.
在成年雄性大鼠急性饥饿和半饥饿期间，测定了去甲肾上腺素合成限速酶酪氨酸羟化酶（TH）在下丘脑中间基底部的活性。使用高效液相色谱法（HPLC）测量由TH形成的3,4-二羟基苯丙氨酸（DOPA）。急性饥饿以及高蛋白低碳水化合物饮食（CST PR）的3周半饥饿显著降低了TH活性。低蛋白高碳水化合物饮食（CST KH）的3周未影响TH活性。虽然在急性饥饿和高蛋白低碳水化合物饮食的半饥饿状态下最大速度（Vmax）显著降低，但酪氨酸的Kd值没有变化。这些结果表明，大脑中的TH活性导致饥饿时去甲肾上腺素（NE）周转率降低。
