期刊
AMERICAN JOURNAL OF PATHOLOGY
卷 156, 期 3, 页码 1009-1015出版社
AMER SOC INVESTIGATIVE PATHOLOGY, INC
DOI: 10.1016/S0002-9440(10)64968-1
关键词
-
类别
Growth hormone (GH) modulates the hypothalamic release of somatostatin and GH-releasing hormone; however, there has been no evidence of GH autoregulation on the pituitary somatotroph. To determine the effects of GH on its own regulation, we examined the pituitaries of giant transgenic mice expressing a GH agonist (E117L), dwarf transgenic mice expressing a GH antagonist (G119K), and dwarf mice devoid of the GH receptor/binding protein (GHR/BP). In the E117L, transgenic mice, the number and distribution of pituitary GH-immunoreactive cells were unchanged from nontransgenic littermate controls; an ultrastructural examination revealed typical, densely granulated somatotrophs. In contrast, the pituitaries of the G119K mice contained both moderately granulated somatotrophs and a sparsely granulated (SG) population with well-developed synthetic organelles and a distinct juxtanuclear globular GH-staining pattern, GHR/BP-deficient mice exhibited a marked reduction in the intensity of cytoplasmic GH immunoreactivity; however, prominent GH staining in the juxtanuclear Golgi was seen. GH-immunoreactive cells were increased in number, and the reticulin network pattern was distorted; stains for proliferating cell nuclear antigen confirmed mild hyperplasia, Electron microscopy showed that the somatotrophs were hyperactive SG tells with prominent endoplasmic reticulum membranes, large Golgi complexes, and numerous mitochondria, These findings are consistent with synthetic and secretory hyperactivity in pituitary somatotrophs due to the reduced GH feedback regulation, The changes are most striking in animals that are devoid of GHR/BP and less marked in animals expressing a GH antagonist; both models had reduced insulin-like growth factor-I levels, but the more dramatic change in the GHR/BP animals can be explained by abrogated GH signaling, This represents the first evidence of direct GH feedback inhibition on pituitary somatotrophs, which may have implications for the use of GH analogs in different clinical settings.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据