Immunocytochemical analysis of cyclic AMP receptor proteins in the developing rat parotid gland.
Previous studies showed that regulatory subunits of type II cyclic AMP-dependent protein kinase (RII) are present in adult rat parotid acinar cells, and are secreted into saliva. If the synthesis and intracellular distribution of RII exhibit developmental specificity, then RII can be an indicator of secretory and regulatory activity of salivary glands.


OBJECTIVE
To determine the expression and distribution of RII in the rat parotid at specific ages representing defined developmental stages.


METHODS
Parotid glands of fetal, neonatal and adult rats were prepared for morphologic and immunocytochemical study. The cellular distribution of RII was studied using light microscopic immunogold silver staining with anti-RII, and its intracellular distribution using electron microscopic immunogold labeling.


RESULTS
In utero, parotid RII levels were low; 5-18 days after birth, labeling of secretory granules and cytoplasm rose to a peak, followed by a rapid decrease in both compartments at 25 days. At 60 days, granule labeling increased to levels near those at 18 days, whereas cytoplasmic labeling remained low. Nuclear labeling was highest during the first 3 weeks after birth, and then declined.


CONCLUSIONS
The higher nuclear and cytoplasmic labeling during the neonatal period may reflect RII involvement in acinar cell differentiation. The accumulation of RII in secretory granules is similar to the pattern of the major salivary proteins, amylase and PSP. The redistribution of RII in these compartments during development may reflect changing gene expression patterns, and may be useful for identification of genetic or metabolic abnormalities.
Mednieks
Maija
M
University of Connecticut Health Center, Farmington, CT, United States. mednieks@nso1.uchc.edu
Lin
Marcus
M
Hand
Arthur R
AR
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002467:Cell Nucleus / Q000737:chemistry; D002373:Cyclic AMP Receptor Protein / Q000032:analysis*; D054746:Cyclic AMP-Dependent Protein Kinase Type II / Q000032:analysis*; D003593:Cytoplasm / Q000737:chemistry; D007150:Immunohistochemistry / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods; D010306:Parotid Gland / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development; D051381:Rats; D017207:Rats, Sprague-Dawley
D000911:Antibodies, Monoclonal; D002373:Cyclic AMP Receptor Protein; D054746:Cyclic AMP-Dependent Protein Kinase Type II