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 cyto plasm of hormone-secreting cells in anterior and intermediate lobes of human and rat pituitary glands. Tissue homogenate fractions of anteri or and intermediate pituitary lobes showed strong DNase I-specific enz ymatic activity. Immunofluorescence, with several specific antibodies against human and rat DNase I, indicated strong immunoreactivity in th e cytoplasm of hormone-secreting cells within the gland. In situ hybri dization demonstrated high levels of DNase I mRNA in the cells. By imm unoelectron microscopy, immunogold particles were found in the rough e ndoplasmic reticulum, Golgi apparatus and secretory granules. Exocytot ic secretory granules were also immunopositive. These results indicate that endocrine cells in the pituitary gland synthesize and secrete DN ase I together with their respective pituitary hormones.