Abstract

DE GORTARI, Patricia et al. Thyrotropin-releasing hormone from the hypothalamic paraventricular nucleus and limbic system regulates energy homeostasis and feeding behavior in fasted, food retricted and anorexic animals. Salud Ment [online]. 2012, vol.35, n.5, pp.385-393. ISSN 0185-3325.

TRH expression and release from hypothalamic paraventricular nucleus (PVN) change with environmental stimuli. Fasted and food-restricted animals present decreased TRH synthesis and release, decelerating metabolic rate and utilization of energy stores, which is an advantageous adaptation of animals with nutrient deficit. Comparing thyroid axis function between prepuberal vs. adult male fasted animals, we found a greater body weight reduction than in adults (30% vs.11%) and TRH release was not decreased; TRH degradation by pituitary PPII enzyme decreased, which maintained energy waste. TRH content of fasted-prepuberal animals changed in hippocampus and nucleus accumbens, and in amygdala of adults vs. ad libitum fed animals. PVN TRH role in food-avoiding behavior was studied by comparing its expression levels and of adolescent, adult females and male animals with anorexic conduct when drinking 2.5% of NaCl solution (AN) vs. a group forced to ingest the amount of food consumed by AN (FFR); also vs. a control group fed ad libitum (C). PVN TRH mRNA and TSH serum levels increased in AN vs. C; both decreased in FFR, supporting the putative anorexigenic role for the peptide. TRH content differentially changed in hippocampus and in frontal cortex of AN and FFR, suggesting its participation in taste perception and memory association. Orexinergic and NPYergic pathways are inactive in anorexic animals. Blocking corticotrophin-releasing hormone signal by an antagonist of CRH-R2 in the PVN reverses TRH high expression and TSH serum levels in AN.

Keywords : TRH; anorexia; feeding; amygdala; hippocampus; nucleus accumbens.

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