| Nerve growth factor(NGF) is a kind of polypeptide, which could yield many kinds of biologic effects by binding to specific GF-receptor of target cell surface. Nerve growth factor receptor (NGFR) is divided into two types of high affinity(TrkA) and low affinity(p75). TrkA is the functional receptor of nerve growth factor that could bind to NGF with high affinity, and it is also membrane receptor possessing the latent activity of tyrosine kinase. p75 is the auxiliary receptor of NGF, and its affinity to NGF is low. But p75 could not only enhance the affinity of NGF to TrkA and modulate the signal transduction, also relate to cell differentiation by adjusting cell program death. There are many reports that NGF and its receptor were expressed not only in normal tissue, but also in tumorderived from many different tissues. Nevertheless, there are not too many reports on the significance and expression of NGF and its receptor in salivary gland tumor.To investigate the role and significance of NGF and its receptor in the biologic behaviors of salivary gland tumor such as development, differentiation, invasion and metastasis, immunohistochemistric technique were adopted in this investigation to localize and quantify the distribution of NGF, TrkA and p75 in salivary gland tissue around neoplasm, adenoid cystic carcinoma and mucoepidermoid carcinoma, which aimed to study the mechanism of the growth, differentiation and invasion of salivary gland tumor on a molecular basis, and thus to provide theoretical foundation for the diagonosis, differential diagnosis and treatment of salivary gland diseases.The specimens, namely 15 salivary gland tissues around neoplasm and 18 each for adenoid cysticcarcinoma and mucoepidermoid carcinoma, were collected from pathologic wax blocks kept in archives after final diagnosis in Stomatology College of JiLin University from the year 1996 to 2002. The immunohistochemistric staining technique and image Analysis technique were adopted to investigate the expression of NGF and its receptor in salivary gland tissues around neoplasm,ACC and MEC with rabbit antihuman NGF TrkA and p75 polyclonal antibody. Results: NGF and TrkA were mainly distributed in intercalated duct, striated duct, excretory duct cells in salivary gland tissues around neoplasm, proven by pale brown positive response in cell membrane and plasm. p75 was not only found in duct epithelial cells in salivary gland tissues around neoplasm, but also apparently in serous acinus plasm. These indicated that duct cells of salivary gland could produce NGF, and were an important source of human NGF. The change in locus and quantity of NGF and NGFR indifferent development stages modulated biologic issues in salivary gland, including the survival and maturation of neurons and the growth, differentiation and proliferation of epithelial tissue and nerve fiber.In salivary gland tumors, NGF and TrkA were mainly distributed in middle cells and epidermis-like cells in MEC. p75 was not only positive in middle cells and epidermis-like cells, but also positive in mucous cells in MEC. In ACC, NGF,TrkA and p75 mainly existed in cells of duct-like, cribriform and mass-like structures.According to the optical density scanning of immunohistochemistric stain of NGF and TrkA in salivary gland and tumor tissues and quantification analysis, it was shown that the average optical density of NGF and TrkA increased in order of salivary gland tissues around neoplasm, mucoepidermiod carcinoma, and adenoid cystic carcinoma. The difference was statistically significant(p<0.01). That indicated thatNGF and TrkA modulate the growth and proliferation of adenoid cystic carcinoma and mucoepidermiod carcinoma by autocrine and the invasion to nerve milieu by paracrine. It was possible that they play an important role in the occurance, development, invasion and metastasis of salivary gland malignant tumors.According to the optical density scanning of immunohistochemistric stain of p75 in salivary gland and tumor tissues and quantification analysis, it wa...
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