Everts M E, Docter R, van Buuren J C, van Koetsveld P M, Hofland L J, de Jong M, Krenning E P, Hennemann G
Department of Internal, Erasmus University Medical School, Rotterdam, The Netherlands.
Endocrinology. 1993 Mar;132(3):1278-85. doi: 10.1210/endo.132.3.8440189.
T3 uptake and TSH secretion were investigated in anterior pituitary cells isolated from adult fed Wistar rats and cultured for 3 days in medium containing 10% fetal calf serum. TSH release during culture increased linearly with the number of cells in the range of 80,000-800,000 cells/well. Uptake and incubation experiments were performed at 37 C in medium containing 0.5% BSA. Incubation with TRH (0.1 microM) for 2 h stimulated TSH release 2.6-fold, and this effect was partly (approximately 45%) suppressed by preexposure for 2 h to T3 (0.01-1 microM) or T4 (1 microM). Similar concentrations of T3 and T4 reduced the cellular uptake of [125I]T3 (50 pM) during 1 h of incubation by 55%. After 15 min of incubation, [125I]T3 uptake (percent dose) amounted to 1.26 +/- 0.05% (mean +/- SE; n = 9)/500,000 cells. The major part (75%) of the [125I]T3 was found in the extranuclear fraction. Simultaneous incubation with unlabeled T3 (1 or 10 microM) reduced [125I]T3 uptake by 43% (n = 3; P < 0.001) and 52% (n = 6; P < 0.001), respectively. Reduction of the temperature to 20 C diminished the T3-suppressible fraction of [125I]T3 uptake approximately 3-fold. After preincubation (30 min) and incubation (15 min) with monodansylcadaverine (100 microM), the uptake of [125I]T3 was reduced by 32% (n = 3; P < 0.01). When the Na+ gradient was reduced by preincubation and incubation with ouabain (0.5 mM) or monensin (10 or 100 microM), T3 uptake was inhibited by 25% (n = 5; P < 0.01), 37% (n = 6; P < 0.001), and 61% (n = 3; P < 0.001), respectively. It is concluded that 1) T3 is taken up by the pituitary by a carrier-mediated mechanism, and 2) this uptake is at least partly dependent on the Na+ gradient.
对从成年喂食的Wistar大鼠分离出的垂体前叶细胞进行了研究，这些细胞在含有10%胎牛血清的培养基中培养3天。培养期间促甲状腺激素（TSH）的释放随细胞数量在80,000 - 800,000个细胞/孔范围内呈线性增加。摄取和孵育实验在37℃下于含有0.5%牛血清白蛋白（BSA）的培养基中进行。用促甲状腺激素释放激素（TRH，0.1微摩尔）孵育2小时可刺激TSH释放增加2.6倍，并且这种效应在预先暴露于三碘甲状腺原氨酸（T3，0.01 - 1微摩尔）或甲状腺素（T4，1微摩尔）2小时后被部分（约45%）抑制。相似浓度的T3和T4在孵育1小时期间使[125I]T3（50皮摩尔）的细胞摄取减少了55%。孵育15分钟后，[125I]T3摄取（剂量百分比）为1.26±0.05%（平均值±标准误；n = 9）/500,000个细胞。[125I]T3的大部分（75%）存在于核外部分。与未标记的T3（1或10微摩尔）同时孵育分别使[125I]T3摄取减少了43%（n = 3；P < 0.001）和52%（n = 6；P < 0.001）。将温度降至20℃使[125I]T3摄取的T3可抑制部分减少约3倍。用单丹磺酰尸胺（100微摩尔）预孵育（30分钟）和孵育（15分钟）后，[125I]T3摄取减少了32%（n = 3；P < 0.01）。当通过用哇巴因（0.5毫摩尔）或莫能菌素（10或100微摩尔）预孵育和孵育来降低钠梯度时，T3摄取分别被抑制25%（n = 5；P < 0.01）、37%（n = 6；P < 0.001）和61%（n = 3；P < 0.001）。得出的结论是：1）T3通过载体介导机制被垂体摄取；2）这种摄取至少部分依赖于钠梯度。
