1. Localization of endothelin A receptors in the rat pituitary TSH cells: light- and electron-microscopic immunohistochemical studies.
- Author
-
Furuya S, Hiroe T, Ozaki T, Takimoto M, and Hori S
- Subjects
- Adrenocorticotropic Hormone analysis, Animals, Antibodies, Antibody Specificity, CHO Cells, Cell Membrane ultrastructure, Cricetinae, Humans, Immunohistochemistry methods, Luteinizing Hormone analysis, Microscopy, Immunoelectron methods, Pituitary Gland, Anterior cytology, Rats, Rats, Mutant Strains, Receptor, Endothelin A, Receptor, Endothelin B, Receptors, Endothelin genetics, Recombinant Proteins analysis, Sequence Deletion, Pituitary Gland, Anterior physiology, Receptors, Endothelin analysis, Thyrotropin analysis
- Abstract
Endothelins modulate hormonal secretion in the pituitary gland. Intense signaling of endothelin A receptors (ET(A)R) has been detected by in situ hybridization, binding assay and receptor autoradiography. We used light- and electron-microscopic immunohistochemistry of ET(A)R with polyclonal antibody against a synthetic peptide corresponding to the carboxyl terminus (403-427) of human ET(A)R. Immunoreactivity was observed in 6-8% of anterior pituitary cells, which were rather large polygonal or stellate cells. These cells were often clustered. Double-staining immunofluorescence showed that the ET(A)R-positive cells immunoreacted with antibody against the beta-subunit of thyroid-stimulating hormone (TSH), but not adrenocorticotropic hormone (ACTH) or lutenizing hormone beta (LHbeta). Pre- and postembedding electron-microscopic immunohistochemistry showed that ET(A)R-positive cells had vacuolated or parallel-lined rough endoplasmic reticulum (rER) and numerous round granules in their periphery and the elongated processes. By pre-embedding immunohistochemistry, diaminobenzidine tetrahydrochloride (DAB) products were shown to be mostly located around the granules and occasionally underneath the plasma membrane. By postembedding immunohistochemistry, granules in the ET(A)R-positive cells were 90-150 nm in diameter, and colloidal gold particles due to ET(A)R were associated with about 10% of these granules. These results indicate that ET(A) receptors are associated mostly with the secretory granules of TSH cells.
- Published
- 2000
- Full Text
- View/download PDF