HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

 

Melatonin-synthesizing enzymes and melatonin receptor in rat thyroid cells

Rocío García-Marín1, Manuel de Miguel1, José Mª Fernández-Santos1, Antonio Carrillo-Vico2,3, José Carmelo Utrilla1, Jesús Morillo-Bernal1, Eduardo Díaz-Parrado1, Ismael Rodríguez-Prieto2,3, Juan Miguel Guerrero2,3 and Inés Martín-Lacave1

1Department of Normal and Pathological Cytology and Histology, School of Medicine, 2Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC and 3Department of Biochemistry and Molecular Biology, School of Medicine, University of Seville, Spain.

Offprint requests to: Dra. Inés Martín-Lacave, Department of Normal and Pathological Cytology and Histology, School of Medicine, University of Seville, Av. Sánchez-Pizjuán s/n. 41009-Seville. Spain. e-mail: ilacave@us.es


Summary. 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
. Histol Histopathol 27, 1429-1438 (2012)

Key words: Melatonin, MT1, Thyroid, C cells, Follicular cells

DOI: 10.14670/HH-27.1429