Differential response of TRHergic neurons of the hypothalamic paraventricular nucleus (PVN) in female animals submitted to food-restriction or dehydration-induced anorexia and cold exposure

Effect of Manganese Chloride on the Neurochemical Profile of the Rat Hypothalamus

“…Under restricted food regime, rats show decreased thyrotropin-releasing hormone expression in the PVN while anorexic animals show increased thyrotropin-releasing hormone expression in the PVN. However, a reduction of CRH expression compared with CTL animals (Jaimes-Hoy et al, 2008) in the PVN was found in both food-restricted and DIA animals but to a greater extent in DIA rats. This finding parallels the increase of GABA seen in DIA and OFS rats but to a greater extent in DIA rats.…”

“…The majority of stress-responsive corticotropinreleasing hormone (CRH) neuronal inputs to the PVN contain the inhibitory neurotransmitter GABA, highlighting the importance of GABAergic neurotransmission in the regulation of the neuroendocrine stress response (Cullinan et al, 2008). Neurons of the PVN synthesize thyrotropin-releasing hormone and CRH hormones having an important role in energy homeostasis (Jaimes-Hoy et al, 2008). Under restricted food regime, rats show decreased thyrotropin-releasing hormone expression in the PVN while anorexic animals show increased thyrotropin-releasing hormone expression in the PVN.…”

Regulation of TRH neurons and energy homeostasis-related signals under stress

“…Ovariectomized rats with increased body weight and high leptin serum concentration respond to cold stimulation augmenting Trh mRNA levels in the PVN, but the effect is suppressed by high doses of 17b-estradiol, while serum TSH and corticosterone levels are similar to those found in the ovariectomized animals (Uribe et al 2009). In contrast, food-restricted female rats display greater increases in Trh mRNA levels in the PVN than controls after cold exposure, but TSH response is blunted (Jaimes-Hoy et al 2008). These results exemplify situations in which the response to a life-threatening situation such as cold exposure is altered by stress, corticosterone, sex, and other as yet unidentified effectors.…”

Differential Adaptations of the Hypothalamus-Pituitary-Thyroid Axis Between Food Restriction and Anorexia

“…In DIA paradigm (Jaimes-Hoy et al, 2008;Watts et al, 1999), CRH expression in the PVN decreases in a greater extent than in food restricted rats (Brady et al, 1990;Isse et al, 1999) after 7 days. Although expression of CRH-R1 receptor in the PVN is up-regulated in several stressful conditions supposedly by CRH release into the PVN which in turn, up-regulates CRH expression (Imaki et al, 1996;Mansi et al, 1996;Turnbull & Rivier, 1997), CRH-R1 mRNA levels are unchanged in DIA animals.…”

“…The involvement of some hypothalamic peptides in feeding motivation may be identified using this paradigm, since changes in their synthesis due to dehydration in DIA animals are compared to those of a forced food-restricted group (pair-fed, FFR) that eat the exact amount of food ingested by DIA Studies from other laboratories and ours have shown that when sacrificed either after 5 or 7 days (Jaimes-Hoy et al, 2008;Watts et al, 1999), both experimental animals from DIA and FFR groups present reduced leptin serum levels and high corticosterone concentrations (Table 1). Thus, both groups have a negative energy balance that only in FFR animals, activates feeding.…”