Hata I, Shigematsu Y, Ohshima Y, Tsukahara H, Fujisawa K, Hiraoka M, Nakamura H, Masutani H, Yodoi J, Kotsuji F, Sudo M, Mayumi M
Department of Pediatrics, Fukui Medical University, Fukui 910-1193, Japan.
Am J Physiol Endocrinol Metab. 2001 Aug;281(2):E269-74. doi: 10.1152/ajpendo.2001.281.2.E269.
We report here an examination of the effect of thioredoxin (TRX) on the secretion of growth hormone (GH) from rat anterior pituitary cells in vitro. Treatment of rat pituitary cells with growth hormone-releasing factor (GRF), but not GH, led to a significant increase in intracellular TRX protein levels. GRF, recombinant human TRX (rhTRX), and a combination thereof were all shown to induce immediate GH secretion from pituitary cells, as evidenced by perifusion experiments. RhTRX, but not other reducing agents such as beta-mercaptoethanol and N-acetyl-L-cysteine, augmented GRF-stimulated and -unstimulated GH secretion from rat pituitary cells in a dose-dependent manner. RhTRX did not significantly affect the GH mRNA expression of pituitary cells stimulated in the presence or absence of GRF. In addition, rhTRX-augmented GH secretion was not significantly affected by the presence of cycloheximide. Collectively, these findings suggest that TRX is induced by stimulation with GRF and plays a regulatory role in GH secretion from rat anterior pituitary cells by enhancing the secretion of stored GH, rather than by the synthesis of GH.
我们在此报告一项关于硫氧还蛋白（TRX）对体外培养的大鼠垂体前叶细胞生长激素（GH）分泌影响的研究。用生长激素释放因子（GRF）而非GH处理大鼠垂体细胞，可导致细胞内TRX蛋白水平显著升高。通过灌流实验证明，GRF、重组人TRX（rhTRX）及其组合均能诱导垂体细胞立即分泌GH。RhTRX而非其他还原剂如β-巯基乙醇和N-乙酰-L-半胱氨酸，能以剂量依赖方式增强GRF刺激和未刺激的大鼠垂体细胞的GH分泌。RhTRX对存在或不存在GRF刺激的垂体细胞的GH mRNA表达无显著影响。此外，环己酰亚胺的存在对rhTRX增强的GH分泌无显著影响。总体而言，这些发现表明TRX由GRF刺激诱导产生，并通过增强储存GH的分泌而非GH的合成，在大鼠垂体前叶细胞的GH分泌中发挥调节作用。
