title: Identification of M2 macrophages in anterior pituitary glands of normal rats and rats with estrogen-induced prolactinoma.
abstract: Macrophages are present throughout the anterior pituitary gland. However, the features and function of macrophages in the gland are poorly understood. Recent studies have indicated that there are two main macrophage classes: M1 (classically activated) and M2 (alternatively activated). In this study, we examine whether both M1 and M2 macrophages are present in the anterior pituitary gland of rats. Our findings indicate that macrophages that are positive for CD68 (a pan-macrophage marker) were localized near capillaries in rat anterior pituitary gland. These macrophages were positive for iNOS or mannose receptor (MR), which are markers of M1 and M2 macrophages, respectively. To determine the morphological characteristics of M2 macrophages under pathological conditions, diethylstilbestrol (DES)-treated rats were used as an animal model of prolactinoma. After 2 weeks of DES treatment, a number of MR-immunopositive cells were present in the gland. Immunoelectron microscopy revealed that MR-immunopositive M2 macrophages had many small vesicles and moderately large vacuoles in cytoplasm. Phagosomes were sometimes present in cytoplasm. Interestingly, M2 macrophages in prolactinoma tissues did not usually exhibit distinct changes or differences during the normal, hyperplasia and adenoma stages. This study is the first to confirm that both M1 and M2 macrophages are present in the anterior pituitary gland of rats. Moreover, the number of M2 macrophages was greatly increased in rats with DES-induced prolactinoma. Future studies should attempt to characterize the functional role of M2 macrophages in the gland.
authors.affiliation: Division of Histology and Cell Biology, Department of Anatomy, Jichi Medical University School of Medicine, Tochigi, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Fujiwara
authors.affiliation: Division of Histology and Cell Biology, Department of Anatomy, Jichi Medical University School of Medicine, Tochigi, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Yatabe
authors.affiliation: Division of Histology and Cell Biology, Department of Anatomy, Jichi Medical University School of Medicine, Tochigi, Japan.
authors.forename: Alimuddin
authors.initials: A
authors.lastname: Tofrizal
authors.affiliation: Division of Histology and Cell Biology, Department of Anatomy, Jichi Medical University School of Medicine, Tochigi, Japan.|Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Depicha
authors.initials: D
authors.lastname: Jindatip
authors.affiliation: Division of Histology and Cell Biology, Department of Anatomy, Jichi Medical University School of Medicine, Tochigi, Japan. tyashiro@jichi.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yashiro
authors.affiliation: Jichi Medical University, Tochigi, Japan.
authors.forename: Ryozo
authors.initials: R
authors.lastname: Nagai
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D016764:Cell Polarity; D004054:Diethylstilbestrol; D004967:Estrogens / Q000009:adverse effects*; D007150:Immunohistochemistry; D037181:Lectins, C-Type / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D015175:Prolactinoma / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000378:metabolism; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D004054:Diethylstilbestrol; D004967:Estrogens; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; C067980:CD68 antigen, human; D000097382:CD68 Molecule
keywords: Anterior pituitary gland; Electron microscopy; M2; Macrophage; Prolactinoma