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Food-Restricted and Dehydrated-Induced Anorexic Rats Present Differential TRH Expression in Anterior and Caudal PVN. Role of Type 2 Deiodinase and Pyroglutamyl Aminopeptidase II.
MedLine Citation:
PMID:  22719053     Owner:  NLM     Status:  Publisher    
TRH synthesized in hypothalamic paraventricular nucleus (PVN) regulates thyroid axis function and is also implicated in anorexigenic effects. Under energy deficit, animals present decreased PVN TRH expression and release, low TSH levels, and increased appetite. Dehydration-induced anorexia (DIA) model allows insight into underlying mechanisms of feeding regulation. Animals drinking a 2.5% NaCl solution for 7 d present body weight reduction; despite their negative energy balance, they avoid food and have increased PVN TRH expression and TSH serum levels. These findings support an inhibiting role of PVN TRH in feeding control. We compared TRH expression by in situ hybridization in PVN subdivisions of 7-d dehydrated male rats to those of a pair-fed group (forced food-restricted) with similar metabolic changes than DIA, but motivated to eat, and to controls. We measured peripheral deiodinase activities, and expression and activity of medial basal hypothalamic type 2 deiodinase and pyroglutamyl-aminopeptidase II, to understand their regulating role in PVN TRH changes between food restriction and anorexia. TRH mRNA levels increased in anterior (aPVN) and medial-caudal subdivisions in DIA rats, whereas it decreased in medial PVN in both experimental groups. We confirmed the nonhypophysiotropic nature of aPVN TRHergic cells by injecting ip fluorogold tracer. Findings support a subspecialization of TRHergic hypophysiotrophic cells that responded differently between anorexic and food-restricted animals; also, that aPVN TRH participates in food intake regulation. Increased type 2 deiodinase activity seemed responsible for low medial PVN TRH synthesis, whereas increased medial basal hypothalamic pyroglutamyl-aminopeptidase II activity in DIA rats might counteract their high TRH release.
E Alvarez-Salas; C Aceves; B Anguiano; R M Uribe; C García-Luna; E Sánchez; P de Gortari
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-6-19
Journal Detail:
Title:  Endocrinology     Volume:  -     ISSN:  1945-7170     ISO Abbreviation:  -     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-6-21     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375040     Medline TA:  Endocrinology     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Neurofisiología Molecular (E.A.-S., C.G.-L.,, Neuroendocrinoligía Molecular (E.S.), Dirección de Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente, México D.F., México; Instituto de Neurobiología (C.A., B.A.), Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, 76230, México; Instituto de Biotecnología (R.M.U.), Universidad Nacional Autónoma de México, A.P. 510-3, Mor 62210 Cuernavaca, Morelos, México.
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