Brameld J M, Weller P A, Saunders J C, Buttery P J, Gilmour R S
Department of Applied Biochemistry and Food Science, University of Nottingham, Loughborough, Leicestershire, UK.
J Endocrinol. 1995 Aug;146(2):239-45. doi: 10.1677/joe.0.1460239.
The effects of various hormones commonly added to hepatocyte culture media upon the expression of the GH receptor (GHR) and insulin-like growth factor-I (IGF-I) genes in cultured porcine hepatocytes were investigated. Preliminary investigations indicated that there was an absolute requirement only for insulin, with high losses of cell viability upon long term exclusion of insulin from the culture medium. The decline in GHR expression with time in culture was found to be less when high levels of glucose were included in the medium. Therefore the basal culture medium used in these studies was Williams' medium E supplemented with 0.2% (w/v) BSA, 5000 mg glucose/l and 100 nmol porcine insulin/l. The addition of dexamethasone (10 nmol/l) increased the expression of both GHR and IGF-I (class 1 transcripts only) mRNA (p < 0.001 and P < 0.05 respectively), and resulted in an increased responsiveness of IGF-I mRNA expression to GH (1 microgram/ml), when the two were added in combination (although only class 1 transcripts were shown to be statistically significant, P < 0.01). The addition of either thyroid hormone (1 nmol/l T3 or T4) alone also increased the expression of GHR mRNA (P < 0.01) in addition to the dexamethasone stimulated expression, with T4 appearing to decrease IGF-I expression slightly (P < 0.05) (either on its own or with T3). As with dexamethasone, the thyroid hormones increased the response of IGF-I mRNA expression to GH (1 microgram/ml) when added in combination with GH (P < 0.001). These observations demonstrate one possible mechanism for the interactions of glucocorticoids and thyroid hormones with the GH-IGF axis.
研究了通常添加到肝细胞培养基中的各种激素对培养的猪肝细胞中生长激素受体（GHR）和胰岛素样生长因子-I（IGF-I）基因表达的影响。初步研究表明，仅对胰岛素有绝对需求，当长期从培养基中排除胰岛素时，细胞活力会大幅丧失。发现培养基中含有高水平葡萄糖时，培养过程中GHR表达随时间的下降较少。因此，这些研究中使用的基础培养基是补充了0.2%（w/v）牛血清白蛋白、5000 mg葡萄糖/升和100 nmol猪胰岛素/升的Williams E培养基。添加地塞米松（10 nmol/升）可增加GHR和IGF-I（仅1类转录本）mRNA的表达（分别为p < 0.001和P < 0.05），并且当两者联合添加时（尽管仅1类转录本显示具有统计学意义，P < 0.01），会导致IGF-I mRNA表达对生长激素（1微克/毫升）的反应性增加。单独添加甲状腺激素（1 nmol/升T3或T4）除了增加地塞米松刺激的表达外，还增加了GHR mRNA的表达（P < 0.01），T4似乎会使IGF-I表达略有下降（P < 0.05）（单独或与T3一起）。与地塞米松一样，甲状腺激素与生长激素联合添加时会增加IGF-I mRNA表达对生长激素（1微克/毫升）的反应（P < 0.001）。这些观察结果证明了糖皮质激素和甲状腺激素与生长激素-胰岛素样生长因子轴相互作用的一种可能机制。
