Safaei R, Timiras P S
J Neurochem. 1985 Nov;45(5):1405-10. doi: 10.1111/j.1471-4159.1985.tb07206.x.
Two neuroblastoma cell lines were cultured in control (euthyroid) and hypothyroid media and examined for protein, RNA and DNA content, activity of the catecholaminergic enzymes tyrosine hydroxylase (TH, EC 1.14.16.2) and monoamine oxidase-A (MAO-A, EC 1.4.3.4), and for L-triiodothyronine (T3) nuclear receptors. In the hypothyroid condition, the rate of cell division and the levels of RNA and protein as well as the activities of TH and MAO were lower than in the euthyroid condition, the reduction being more marked in the E than in the A2(1) cell line. T3 nuclear receptors, unaltered in affinity, were increased in number in the hypothyroid medium, possibly as a regulatory response to hormonal deficiency. Examination of a possible relationship between T3 occupancy and TH activity in the E cells, most sensitive to thyroid hormone deficiency, revealed that induction of TH activity by T3 is dose-dependent and correlates with the number of nuclear sites occupied by the hormone. When neuroblastoma cells were induced to differentiate by the addition of sodium butyrate to the medium, parameters of cell growth (protein, RNA) and enzyme activity (TH and MAO-A) increased in both cell lines irrespective of the presence of thyroid hormones. These data indicate that thyroid hormones, through their nuclear receptors, directly affect the activity of catecholaminergic enzymes in cultured, immature (undifferentiated) neurons.
将两种神经母细胞瘤细胞系分别培养于对照（甲状腺功能正常）和甲状腺功能减退的培养基中，检测其蛋白质、RNA和DNA含量、儿茶酚胺能酶酪氨酸羟化酶（TH，EC 1.14.16.2）和单胺氧化酶-A（MAO-A，EC 1.4.3.4）的活性以及L-三碘甲状腺原氨酸（T3）核受体。在甲状腺功能减退的条件下，细胞分裂速率、RNA和蛋白质水平以及TH和MAO的活性均低于甲状腺功能正常的条件，E细胞系的降低比A2(1)细胞系更明显。T3核受体亲和力未改变，但在甲状腺功能减退的培养基中数量增加，这可能是对激素缺乏的一种调节反应。对甲状腺激素缺乏最敏感的E细胞中T3占据与TH活性之间可能关系的研究表明，T3对TH活性的诱导呈剂量依赖性，且与激素占据的核位点数量相关。当向培养基中添加丁酸钠诱导神经母细胞瘤细胞分化时，无论是否存在甲状腺激素，两种细胞系中细胞生长参数（蛋白质、RNA）和酶活性（TH和MAO-A）均增加。这些数据表明，甲状腺激素通过其核受体直接影响培养的未成熟（未分化）神经元中儿茶酚胺能酶的活性。
