Ultrastructural colocalization of growth hormone binding protein and pituitary hormones in adenohypophyseal cells of the rat
| Autor: | Esmond J. Sanders, H Sadeghi, Steve Harvey, W R Baumbach |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
endocrine system
medicine.medical_specialty Pituitary gland Somatotropic cell Thyrotropin Biology Gonadotropic cell Cytoplasmic Granules Prolactin cell Endocrinology Adrenocorticotropic Hormone Thyrotropic cell Growth hormone-binding protein Pituitary Gland Anterior Internal medicine medicine Animals Microscopy Immunoelectron Colocalization Antibodies Monoclonal Luteinizing Hormone Immunohistochemistry Prolactin Rats Pituitary Hormones medicine.anatomical_structure Growth Hormone Corticotropic cell Follicle Stimulating Hormone Carrier Proteins hormones hormone substitutes and hormone antagonists |
| Zdroj: | Endocrinology. 133(3) |
| ISSN: | 0013-7227 |
| Popis: | GH receptor immunoreactivity is widely distributed within the rat pituitary gland, although apart from somatotrophs the cell types with GH receptor immunoreactivity have yet to be identified. It is also unknown whether this immunoreactivity reflects the presence of GH binding proteins (GHBPs) or authentic receptors. The possible colocalization of GHBPs and pituitary hormones in somatotrophs, lactotrophs, gonadotrophs, thyrotrophs, and corticotrophs was therefore examined using immunogold electron microscopy. Pituitary sections were indirectly immunostained with antibodies for GH, PRL, LH, FSH, TSH, or ACTH using gold-labeled immunoglobulin G. The same grids were also immunostained with a polyclonal antibody raised against rat GHBP using protein A conjugated to gold particles of a different size. Some sections were gold-labeled using a monoclonal antibody (MAb 4.3) raised against the unique hydrophobic tail of the GHBP, using gold-labeled immunoglobulin G. The cellular and ultrastructural distribution of immunoreactivity within the pituitary gland was similar after labeling with either GHBP antiserum. In all immunoreactive cells the labeling was most intense in secretory granules. Specific staining was not, however, demonstrated in the nucleus, in contrast with earlier findings using MAb 263. Moreover, while staining with MAb 263 appeared to be ubiquitous, some pituitary cells were not labeled by the polyclonal GHBP antiserum or by MAb 4.3. GHBP immunoreactivity was, however, colocalized with hormones in all pituitary cell-types, although in some cells GHBP immunoreactivity was not present in all secretory granules. These results clearly demonstrate the presence of GHBPs in adenohypophyseal cells, in which they appear to be stored or secreted with GH, PRL, LH, FSH, TSH, and ACTH. The function of GHBPs in the pituitary gland is, however, uncertain. |
| Databáze: | OpenAIRE |
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