title: Mct8 and trh co-expression throughout the hypothalamic paraventricular nucleus is modified by dehydration-induced anorexia in rats.
abstract: Thyrotropin-releasing hormone (TRH) is a neuropeptide with endocrine and neuromodulatory effects. TRH from the paraventricular hypothalamic nucleus (PVN) participates in the control of energy homeostasis; as a neuromodulator TRH has anorexigenic effects. Negative energy balance decreases PVN TRH expression and TSH concentration; in contrast, a particular model of anorexia (dehydration) induces in rats a paradoxical increase in TRH expression in hypophysiotropic cells from caudal PVN and high TSH serum levels, despite their apparent hypothalamic hyperthyroidism and low body weight. We compared here the mRNA co-expression pattern of one of the brain thyroid hormones' transporters, the monocarboxylate transporter-8 (MCT8) with that of TRH in PVN subdivisions of dehydration-induced anorexic (DIA) and control rats. Our aim was to identify whether a low MCT8 expression in anorexic rats could contribute to their high TRH mRNA content.We registered daily food intake and body weight of 7-day DIA and control rats and analyzed TRH and MCT8 mRNA co-expression throughout the PVN by double in situ hybridization assays. We found that DIA rats showed increased number of TRHergic cells in caudal PVN, as well as a decreased percentage of TRH-expressing neurons that co-expressed MCT8 mRNA signal. Results suggest that the reduced proportion of double TRH/MCT8 expressing cells may be limiting the entry of hypothalamic triiodothyronine to the greater number of TRH-expressing neurons from caudal PVN and be in part responsible for the high TRH expression in anorexia rats and for the lack of adaptation of their hypothalamic-pituitary-thyroid axis to their low food intake.
authors.affiliation: Molecular Neurophysiology, Department of Neuroscience Research, National Institute of Psychiatry Ramón de la Fuente Muñiz (INPRFM), México; School of Dietetics and Nutrition, ISSSTE, Callejón Vía San Fernando 12, México City, Mexico. Electronic address: gmtrejor@imp.edu.mx.
authors.forename: Elena
authors.initials: E
authors.lastname: Alvarez-Salas
authors.affiliation: Department of Neurochemistry and Neuropharmachology, Institut d'Investigacions, Biomèdiques de Barcelona, CSIC-IDIBAPS, CIBERNED, c/Rosselló 161, 6a, E-08036 Barcelona, Spain. Electronic address: guadalupe.mengod@iibb.csic.es.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Mengod
authors.affiliation: Molecular Neurophysiology, Department of Neuroscience Research, National Institute of Psychiatry Ramón de la Fuente Muñiz (INPRFM), México. Electronic address: garcialuna@imp.edu.mx.
authors.forename: Cinthia
authors.initials: C
authors.lastname: García-Luna
authors.affiliation: Molecular Neurophysiology, Department of Neuroscience Research, National Institute of Psychiatry Ramón de la Fuente Muñiz (INPRFM), México. Electronic address: paulinasoberanes@imp.edu.mx.
authors.forename: Paulina
authors.initials: P
authors.lastname: Soberanes-Chávez
authors.affiliation: Molecular Neurophysiology, Department of Neuroscience Research, National Institute of Psychiatry Ramón de la Fuente Muñiz (INPRFM), México. Electronic address: gmtrejo@imp.edu.mx.
authors.forename: Gilberto
authors.initials: G
authors.lastname: Matamoros-Trejo
authors.affiliation: Molecular Neurophysiology, Department of Neuroscience Research, National Institute of Psychiatry Ramón de la Fuente Muñiz (INPRFM), México. Electronic address: gortari@imp.edu.mx.
authors.forename: Patricia
authors.initials: P
authors.lastname: de Gortari
mesh_terms: D000818:Animals; D000855:Anorexia / Q000378:metabolism*; D003681:Dehydration; D008297:Male; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*
chemical_list: D027501:Monocarboxylic Acid Transporters; D012333:RNA, Messenger; C478998:monocarboxylate transporter 8, rat; D013973:Thyrotropin-Releasing Hormone
keywords: Anorexia; Hypothalamic paraventricular nucleus; Monocarboxylate transporter-8; Thyrotropin-releasing hormone