Ahmad I, Finkelstein J A, Downs T R, Frohman L A
Department of Anatomy, Northeastern Ohio Universities College of Medicine, NEOUCOM, Rootstown 44272.
Neuroendocrinology. 1993 Sep;58(3):332-7. doi: 10.1159/000126558.
The secretion of growth hormone (GH) is impaired in the genetically obese Zucker rat where GH gene expression and plasma GH levels are depressed; however, the underlying mechanism of this abnormality remains unclear. We have evaluated the potential causative role of hypothalamic GH-releasing hormone (GHRH) and somatostatin (SRIH) gene expression in the onset of the decreased GH mRNA levels by studying both GHRH and SRIH mRNA and peptide levels in obese and lean rats at 5 weeks of age when the decrease in GH mRNA is first detected. At that age both GHRH content and GHRH mRNA were significantly reduced in obese rats as compared to lean controls; hypothalamic SRIH content was also decreased in obese rats, but SRIH mRNA levels did not differ. Since GHRH is capable of stimulating GH gene expression, the decreased GHRH mRNA level could be a critical factor in causing the attenuation in GH gene expression and consequent diminution of circulating plasma GH.
在遗传性肥胖的Zucker大鼠中，生长激素（GH）的分泌受损，其GH基因表达和血浆GH水平均降低；然而，这种异常的潜在机制仍不清楚。通过研究5周龄肥胖和瘦大鼠的生长激素释放激素（GHRH）和生长抑素（SRIH）mRNA及肽水平，我们评估了下丘脑GHRH和SRIH基因表达在GH mRNA水平降低起始过程中的潜在致病作用，此时首次检测到GH mRNA下降。在那个年龄，与瘦对照组相比，肥胖大鼠的GHRH含量和GHRH mRNA均显著降低；肥胖大鼠下丘脑SRIH含量也降低，但SRIH mRNA水平无差异。由于GHRH能够刺激GH基因表达，GHRH mRNA水平降低可能是导致GH基因表达减弱及循环血浆GH随之减少的关键因素。
