title: Melatonin-synthesizing enzymes and melatonin receptor in rat thyroid cells.
abstract: Melatonin is an indoleamine with a wide spectrum of biological activities other than transmitting photoperiod information, including antioxidant, oncostatic, anti-aging and immunomodulatory properties. Although melatonin is synthesized mainly in the pineal gland, other tissues have the same capacity. In the present study, we examined whether two key enzymes in melatonin biosynthesis, arylalkylamine Nacetyltransferase (AANAT) and hydroxyindole-O-methyltransferase (HIOMT) and its receptor MT₁ are expressed in the two endocrine thyroid cells of the rat, follicular cells and C cells. Reverse transcriptase polymerase chain reaction analyses demonstrated that both AANAT and HIOMT mRNAs are expressed in the rat thyroid C-cells, and MT₁ expression has been detected in C cells and follicular cells. Immunofluorescence revealed that AANAT protein is localized in C-cell cytoplasm, and MT₁ protein in both cell populations. These findings demonstrate that the rat thyroid expresses AANAT, HIOMT, and its receptor MT₁, showing that C cells are the main melatonin-synthesizing sites in the thyroid. This local C-cell-secreted melatonin may protect follicular cells from the oxidative stress inherent to the thyroid gland, and could also have paracrine and autocrine functions.
authors.affiliation: Department of Normal and Pathological Cytology and Histology, School of Medicine, University of Seville, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: García-Marín
authors.forename: Manuel
authors.initials: M
authors.lastname: de Miguel
authors.forename: José María
authors.initials: JM
authors.lastname: Fernández-Santos
authors.forename: Antonio
authors.initials: A
authors.lastname: Carrillo-Vico
authors.forename: José Carmelo
authors.initials: JC
authors.lastname: Utrilla
authors.forename: Jesús
authors.initials: J
authors.lastname: Morillo-Bernal
authors.forename: Eduardo
authors.initials: E
authors.lastname: Díaz-Parrado
authors.forename: Ismael
authors.initials: I
authors.lastname: Rodríguez-Prieto
authors.forename: Juan Miguel
authors.initials: JM
authors.lastname: Guerrero
authors.forename: Inés
authors.initials: I
authors.lastname: Martín-Lacave
mesh_terms: D000121:Acetylserotonin O-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D008550:Melatonin / Q000096:biosynthesis*; D051381:Rats; D044094:Receptors, Melatonin / Q000235:genetics / Q000378:metabolism*; D013961:Thyroid Gland / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*
chemical_list: D044094:Receptors, Melatonin; D000121:Acetylserotonin O-Methyltransferase; D047068:Arylalkylamine N-Acetyltransferase; D008550:Melatonin