Chromogranin B-like immunoreactivity in the mouse submandibular salivary gland during postnatal development

Presence and distribution, developmental changes, and molecular features of chromogranin B proteins within the submandibular salivary glands of male mice were investigated by 2-dimensional electrophoresis and PAP immunostaining. Chromogranin B-like immunoreactivity was detected in the juxta-acinar (JA)) cells of the submandibular salivary gland during the first week of postnatal development. During the 2nd and 3rd weeks, chromogranin B-like immunoreactivity reached the plateau level, while its reduction seemed to be occurred in correspondence to the appearance of the granular convoluted tubule cells, in which they did not show any chromogranin B-like immunoreactivity. Up to 7 weeks of age, chromogranin B-like immunoreactivity was substantially decreased, but not completely. A few JA cells, chromogranin B-like immunoreactive, retained even in the adult morphologically matured submandibular salivary gland of mice. A predominant protein which can be revealed by 2-dimensional electrophoresis and by immunocytochemistry, was chromogranin A. Chromogranin C was not detected in any cell type of the submandibular salivary gland of mice from early postnatal period up to 35 d of age. Physiological significance and possible function as well as an application of these findings were discussed.