title: Effects of epidermal growth factor, phorbol ester, and retinoic acid on hormone synthesis and morphology in porcine thyroid follicles cultured in collagen gel.
abstract: Epidermal growth factor (EGF), phorbol esters (PEs), and retinoic acid (RA) inhibit differentiated functions of thyrocytes. In the present study the inhibitory effects of these growth-promoting factors on hormone synthesis were studied in thyroid follicles cultured in type-I collagen gel, and morphologic alteration by these factors was examined by light and electron microscopy (EM). Porcine open thyroid follicles obtained by treatment with 0.1% collagenase were embedded in collagen gel and cultured in Ham's F12 medium supplemented with 6H (insulin, hydrocortisone, somatostatin, transferrin, glycyl-his-lys, and thyrotropin) + 0.5% fetal bovine serum (FBS). After 1 week these open follicles developed to closed follicles, and the medium was changed to one containing 6H + 0.5% FBS + 0.1 microM sodium iodide (NaI). Some media were supplemented with either EGF, phorbol 12-myristate 13-acetate (PMA), or all-trans RA. The closed follicles retained ability for hormone synthesis for 2 weeks after the medium change in the presence of 6H + FBS + NaI. The amounts of T4 and T3 secreted into the culture medium from day 9 to day 12 after the medium change were 60% and 45% of those from day 0 to day 4, respectively. EGF reduced production of T4 and T3 by 61% and 69%, respectively; PMA, by 87% and 99%; and RA, by 55% and 44%. In the medium supplemented with 6H + 0.5% FBS, the follicles exhibited intact polarity. Apical surfaces with microvilli were oriented to the follicular lumen and tight junctions were on the apical side of cell-to-cell contacts. Desmosomes were found on both the apical and basal halves of the cell contacts.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Department of Endocrinology, Dokkyo University School of Medicine, Tochigi, Japan.
authors: A
authors: A
authors: Hishinuma
authors: K
authors: K
authors: Kasai
authors: K
authors: K
authors: Ichimura
authors: T
authors: T
authors: Emoto
authors: S
authors: S
authors: Shimoda
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003094:Collagen; D003470:Culture Media; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D004848:Epithelium / Q000648:ultrastructure; D007365:Intercellular Junctions / Q000648:ultrastructure; D008854:Microscopy, Electron; D012974:Sodium Iodide / Q000494:pharmacology; D013552:Swine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D013963:Thyroid Hormones / Q000096:biosynthesis*; D013974:Thyroxine / Q000096:biosynthesis; D014212:Tretinoin / Q000494:pharmacology*; D014284:Triiodothyronine / Q000096:biosynthesis
chemical_list: D003470:Culture Media; D013963:Thyroid Hormones; D014284:Triiodothyronine; D014212:Tretinoin; D004815:Epidermal Growth Factor; D003094:Collagen; D012974:Sodium Iodide; D013755:Tetradecanoylphorbol Acetate; D013974:Thyroxine