EPIDERMAL GROWTH-FACTOR AND NERVE GROWTH-FACTOR IN MOUSE SALIVA - COMPARATIVE-STUDY

It has recently been determined (Murphyet al., 1977a) that the submandibular gland of the adult mouse is an exocrine rather than endocrine organ for nerve growth factor (NGF). Present results, together with the work of others, suggest the gland is serving the same function with respect to epidermal growth factor (EGF). Radioimmunoassay data indicate that EGF is secreted in saliva at concentrations which are similar to that of NGF. Highest levels of the molecules are present in saliva from male mice stimulated with α-adrenergic and β-adrenergic secretagogues. A cholinergic agonist elicits saliva containing appreciably lower amounts of both proteins. Saliva EGF stimulates division of epithelial cells in chick cornea grown in culture, suggesting that the molecule is secreted in a form which is biologically active. Chemical studies indicate that the molecular properties of saliva EGF vary depending upon the concentration at which the molecule is studied. In concentrated saliva, EGF elutes from gel filtration columns in a position which suggests the protein is part of a high molecular weight complex. At levels where EGF is biologically activein vitro, however, the complex dissociates and EGF displays a molecular weight close to 6000 g/mole in dilute solution. This behavior is identical to that of EGF in salivary gland extracts. Saliva NGF, on the other hand, remains in a high molecular weight form when studied at biologically effective levels. © 1979 Academic Press, Inc. All rights reserved.