title: Immunocytochemical localization of secretogranin III in the anterior lobe of male rat pituitary glands.
abstract: Secretogranin III (SgIII) is one of the acidic secretory proteins, designated as granins, which are specifically expressed in neuronal and endocrine cells. To clarify its precise distribution in the anterior lobe of the rat pituitary gland, we raised a polyclonal antiserum against rat SgIII for immunocytochemical analyses. By immunohistochemistry using semithin sections, positive signals for SgIII were detected intensely in mammotropes and thyrotropes, moderately in gonadotropes and corticotropes, but not in somatotropes. The distribution pattern of SgIII in the pituitary gland was similar to that of chromogranin B (CgB), also of the granin protein family, suggesting that the expressions of these two granins are regulated by common mechanisms. The localization of SgIII in endocrine cells was confirmed by immunoelectron microscopy. In particular, secretory granules of mammotropes and thyrotropes were densely and preferentially co-labeled for SgIII and CgB in their periphery. Moreover, positive signals for SgIII were occasionally found in cells containing both prolactin and TSH in secretory granules. These lines of evidence suggest that SgIII and CgB are closely associated with the secretory granule membrane and that this membrane association might contribute to gathering and anchoring of other soluble constituents to the secretory granule membrane.
authors.affiliation: Department of Anatomy II, Asahikawa Medical College, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sakai
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hosaka
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Hira
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Harumi
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ohsawa
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Takeuchi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Uchiyama
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D002864:Chromogranins; D007106:Immune Sera; D007150:Immunohistochemistry; D008297:Male; D016253:Microscopy, Immunoelectron; D010903:Pituitary Gland, Anterior / Q000378:metabolism* / Q000648:ultrastructure; D011506:Proteins / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D002864:Chromogranins; D007106:Immune Sera; D011506:Proteins; D011994:Recombinant Proteins