Thyrotrophin‐Releasing Hormone Decreases Feeding and Increases Body Temperature, Activity and Oxygen Consumption in Siberian Hamsters

Abstract

Thyrotrophin-releasing hormone (TRH) is known to play an important role in the control of food intake and energy metabolism in addition to its actions on the pituitary-thyroid axis. We have previously shown that central administration of TRH decreases food intake in Siberian hamsters. This species is being increasingly used as a physiological rodent model in which to understand hypothalamic control of long-term changes in energy balance because it accumulates fat reserves in long summer photoperiods, and decreases food intake and body weight when exposed to short winter photoperiods. The objectives of our study in Siberian hamsters were: (i) to investigate whether peripheral administration of TRH would mimic the effects of central administration of TRH on food intake and whether these effects would differ dependent upon the ambient photoperiod; (ii) to determine whether TRH would have an effect on energy expenditure; and (iii) to investigate the potential sites of action of TRH. Both peripheral (5-50 mg/kg body weight; i.p.) and central (0.5 microg/ml; i.c.v.) administration of TRH decreased food intake, and increased locomotor activity, body temperature and oxygen consumption in the Siberian hamster, with a rapid onset and short duration of action. Systemic treatment with TRH was equally effective in suppressing feeding regardless of ambient photoperiod. The acute effects of TRH are likely to be centrally mediated and independent of its role in the control of the production of thyroid hormones. We conclude that TRH functions to promote a catabolic energetic state by co-ordinating acute central and chronic peripheral (thyroid-mediated) function.

Immunohistochemical localization of thyrotropin-releasing hormone in the brain of reptiles

“…The wide distribution of TRH receptors in the brain of several mammalian species (Burt and Taylor, 1980;Ogawa et al, 1981;Taylor and Burt, 1982;Wu et al, 1992;Satoh et al, 1993;Calza et al, 1992;Mitsuma et al, 1995;O'Dowd et al, 2000;Heuer et al, 2000) corroborates this fact, relating this neuropeptide with analgesia (Boschi et al, 1983;Tanabe et al, 2007), arousal and sexual excitation (Prange, 1974;Horita et al, 1976;Ervin et al, 1981;Rezvani et al, 1997;Horita, 1998), thermoregulation (Fiedler et al, 2006;Schuhler et al, 2007), food intake behavior (Ao et al, 2006;Gotoh et al, 2007), dream control (Reichlin, 1986) and autonomic functions (Helke and Phillips, 1988), among others.…”

Adeno-associated virus-mediated knockdown of melanocortin-4 receptor in the paraventricular nucleus of the hypothalamus promotes high-fat diet-induced hyperphagia and obesity

“…Moreover, food deprivation inhibits TRH mRNA expression in the PVN (Fekete et al 2000). Central administration of TRH decreases food intake independent of its actions on thyroid function (Choi et al 2002, Steward et al 2003, Schuhler et al 2007. Taken together, these findings suggest that CRH and TRH neurons may be effector neurons of Quantitative data indicate that (B) AAV-MC4R-shRNA-EGFP significantly reduces the level of MC4R mRNA expression in the PVN, but exhibits (C) no significant effects on aVP mRNA expression in the PVN.…”

Overnight Access to Sugar Solutions Affects mRNA Expression of Several Neuropeptides in Different Hypothalamic Regions in Rats

“…TRH has an anorexigenic effect both by central or peripheral administration [37]. In contrast to the results from the whole hypothalamus reported earlier [12], fructose failed to significantly decrease TRH in the PVN, the VMH or the LH.…”