title: Secretion-related structures of hypothalamo-hypophysial terminals in the rat posterior pituitary.
abstract: Hypothalamic terminals were investigated in the rat posterior pituitary (PP). Injection of wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP) and co-injection of WGA-HRP with Rab3A-siRNA were made into the hypothalamus, respectively. Additional injection of WGA-HRP was made into the hypothalamus in the animals exposed to ethanol. These injections resulted in heavy labeling of fibers exclusively confined to the PP. Ultrastructural observations showed terminals, fibers, pituicytes, capillaries and vascular spaces in the PP. Although the majority of terminals were observed to contain large dense core vesicles (LDCVs) and HRP-reaction products (HRP-RPs), exocytosis of LDCVs in close proximity to cell membrane was not found. Interestingly, a few terminals showed alteration of cell membrane called "apocrine-like structure" containing LDCV and RP. The narrow neck portion of the structure gave the appearance that it may have been in some stage of separating from terminals. Other remarkable feature was that terminals occasionally reveal the structure of "leakage" of RP discharged into vascular spaces crossing cell membrane. Such hormone-releasing mechanism might be involved in one of "diacrine-like secretion". In the present study secretion-related structures of hypothalamic terminals in the PP are quite different from normal vesicular exocytosis.
authors.affiliation: Department of Anatomy and Neurobiology, Faculty of Medicine, Kagawa University.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: Jun-Qian
authors.initials: JQ
authors.lastname: Liu
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Takanori
authors.initials: T
authors.lastname: Miki
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Ohta
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Warita
authors.forename: Shingo
authors.initials: S
authors.lastname: Suzuki
authors.forename: Motoki
authors.initials: M
authors.lastname: Tamai
mesh_terms: D000818:Animals; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism; D008297:Male; D010904:Pituitary Gland, Posterior / Q000294:innervation* / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
chemical_list: D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate