Ulshen M H, Dowling R H, Fuller C R, Zimmermann E M, Lund P K
Department of Pediatrics, University of North Carolina, Chapel Hill.
Gastroenterology. 1993 Apr;104(4):973-80. doi: 10.1016/0016-5085(93)90263-c.
Transgenic mice with a bovine growth hormone gene linked to a mouse metallothionein I promoter (growth hormone transgenics) are a model of chronic growth hormone excess.
Growth of small bowel mucosa in ad libitum-fed growth hormone transgenics and wild type littermates and in growth hormone transgenics pair fed with wild-type littermates were compared.
In both groups, body weight and small bowel weight were greater in growth hormone transgenics. Similarly, mucosal mass was 50%-100% greater in growth hormone transgenics, and the effect was greatest in proximal bowel. Villus height, measured in jejunum, was also greater in growth hormone transgenics. Measurements of mucosal proliferation did not differ between the growth hormone transgenics and wild type. Abundance of insulin-like growth factor-I messenger RNA in bowel was greater in growth hormone transgenics.
Chronic growth hormone excess results in increased growth of small bowel mucosa. This effect appears to be specific because it occurred in ad libitum-fed and diet-restricted growth hormone transgenics, influenced villus height, and was more pronounced in upper than lower small bowel. The effect of chronic growth hormone excess does not appear to be secondary to an increase in the rate of mucosal proliferation, suggesting an effect on lifespan of mucosal cells.
带有与小鼠金属硫蛋白I启动子相连的牛生长激素基因的转基因小鼠（生长激素转基因小鼠）是慢性生长激素过量的一种模型。
比较了自由进食的生长激素转基因小鼠和野生型同窝小鼠以及与野生型同窝小鼠配对饲养的生长激素转基因小鼠的小肠黏膜生长情况。
在两组中，生长激素转基因小鼠的体重和小肠重量均更大。同样，生长激素转基因小鼠的黏膜质量大50%-100%，且在近端肠段效果最为明显。在空肠中测量的绒毛高度，生长激素转基因小鼠也更高。生长激素转基因小鼠和野生型小鼠之间的黏膜增殖测量结果没有差异。生长激素转基因小鼠肠道中胰岛素样生长因子-I信使核糖核酸的丰度更高。
慢性生长激素过量导致小肠黏膜生长增加。这种效应似乎具有特异性，因为它在自由进食和饮食受限的生长激素转基因小鼠中均出现，影响绒毛高度，且在小肠上段比下段更明显。慢性生长激素过量的效应似乎并非继发于黏膜增殖速率的增加，提示对黏膜细胞寿命有影响。
