Detection of deoxyribonuclease I in a hormone-secretory pathway of pituitary cells in humans and rats

High levels of deoxyribonuclease I (DNase I) were detected in the cytoplasm of hormone-secreting cells in anterior and intermediate lobes of human and rat pituitary glands. Tissue homogenate fractions of anterior and intermediate pituitary lobes showed strong DNase I-specific enzymatic activity. Immunofluorescence, with several specific antibodies against human and rat DNase I, indicated strong immunoreactivity in the cytoplasm of hormone-secreting cells within the gland. In situ hybridization demonstrated high levels of DNase I mRNA in the cells. By immunoelectron microscopy, immunogold particles were found in the rough endoplasmic reticulum, Golgi apparatus and secretory granules. Exocytotic secretory granules were also immunopositive. These results indicate that endocrine cells in the pituitary gland synthesize and secrete DNase I together with their respective pituitary hormones.