A histochemical study on the expression and localization of growth factors

我们采用免疫组织化学和原位杂交技术，测定了各种生长因子在整个大鼠体内的免疫反应性定位位点和mRNA信号，得到以下结果：在大鼠颌下腺中发现了肝细胞生长因子（HGF）的表达。HGF的mRNA信号和免疫反应性均定位于颗粒曲小管上皮细胞。这一发现将HGF添加到啮齿动物颌下腺产生的许多生长因子列表中。作为电镜原位杂交的尝试，我们首先用^<35> s标记的EGF探针对大鼠颌下腺低温恒温切片进行原位杂交，然后包埋在环氧树脂中进行电镜放射自显影。结果表明，与确定mRNA的亚细胞定位相比，该方法更有助于从形态学上鉴定mRNA阳性细胞的类型。一项使用抗酸性成纤维细胞生长因子（aFGF）抗体的免疫组织化学研究显示，胰腺和小肠粘膜的内分泌细胞亚群在其分泌颗粒中呈阳性免疫染色。这一结果表明，一种afgf样物质是由表达胰高血糖素前体的细胞群产生的。血管内皮生长因子（VEGF）在正常大鼠颌下腺中表达极低。然而，异丙肾上腺素刺激颌下腺生长导致该器官中VEGF表达率短暂上升，并在刺激后1小时达到峰值。mRNA定位于腺泡细胞。提示异丙肾上腺素诱导的颌下腺生长与VEGF对血管的作用有一定关系。

We have used both immunohistochemistry and in situ hybridization techniques to determine the sites of localization of immunoreactivity and mRNA signal of various growth factors in the entire rat body, and have obtained the following results :The expression of hepatocyte growth factor (HGF) was demonstrated in the submandibular gland of rats. Both the mRNA signal and immunoreactivity for HGF were localized to the epithelial cells of granular convoluted tubules. This finding added HGF to the list of many growth factors produced in the rodent submandibular gland.As an attempt for the electron microscopic in situ hybridization, the cryostat sections of rat submandibular gland were first treated for in situ hybridization with ^<35>S-labelled EGF probe and then embedded in epoxy resin for electron microscopic radioautography. The result suggested that this method is more useful for identifying morphologically the type of mRNA-positive cells than determining the subcellular localization of mRNA.An immunohistochemical study using an antibody against acidic fibroblast growth factor (aFGF) revealed that subpopulations of endocrine cells in the pancreas and small intestinal mucosa are positively immunostained in their secretory granules. This result suggested that an aFGF-like substance is produced by the cell populations that express glucagon-precursor.The expression of vascular endothelial growth factor (VEGF) is very low in the normal rat submandibular gland. However, a stimulation of submandibular gland to grow by isoproterenol caused a transient rise in the rate of expression of VEGF in this organ that peaked at 1 h after the stimulation. The mRNA was localized to the acinar cells. This result suggested a certain relation between isoproterenol-induced growth of submandibular gland and VEGF effects on the blood vessels.