Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020505 (hyperphagia)
 6,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Brown adipose tissue (BAT) is characterized by the existence of a unique mitochondrial protein (uncoupling protein or UCP) that uncouples oxidative phosphorylation and thus allows heat production. Its role in thermogenesis has been emphasized in recent years in response to cold stress (nonshivering thermogenesis, NST) as well as to hyperphagia (diet-induced thermogenesis, DIT). The present work was a first attempt to determine whether varying nutritional conditions could affect UCP gene expression. Total RNA was isolated from interscapular BAT and hybridized with a cDNA probe for UCP. Changes in UCP mRNA level were studied in rats fasted and refed for various periods at 23 or 28 degrees C. A 2 d fast at 23 degrees C reduced UCP mRNA level, whereas refeeding increased it. A prolonged starvation (53 h) induced an unexpected rise in UCP mRNA, which was associated with a fall in body temperature. Increasing the ambient temperature to thermoneutrality (28 degrees C) suppressed the fall in body temperature as well as the rise in UCP mRNA, which could then be characterized as a cold-induced response. Under the same environmental conditions (28 degrees C), refeeding still triggered a sharp, though transient, increase in UCP mRNA, showing that DIT was dissociated from NST.
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PMID:Effects of fasting and refeeding on the level of uncoupling protein mRNA in rat brown adipose tissue: evidence for diet-induced and cold-induced responses. 226 17

This study examined the involvement of caudal brainstem projections of the hypothalamic paraventricular nucleus (PVN) in the medial hypothalamic (MH) hyperphagia-obesity syndrome. Experiment 1 demonstrated that a unilateral parasagittal knife cut in the MH combined with a contralateral coronal knife cut in either the ventrolateral pons (vP) or ventrolateral medulla (vM) significantly increased food intake and body weight in adult female rats. Overeating and overweight were also produced by a unilateral MH knife cut combined with a contralateral oblique cut under the nucleus of the solitary tract and dorsal motor nucleus of the vagus complex (NST/DX). In contrast, an MH cut x dorsolateral medullary cut combination did not increase food intake or body weight compared to a MH cut alone or sham surgery. Experiment 2 demonstrated that the hyperphagia/obesity effect of MH x vP knife cuts was comparable to that obtained with bilateral PVN lesions, but less than that produced by bilateral MH knife cuts. Bilateral vP cuts also increased body weight but the effect was less than that obtained with the other experimental treatments. Feeding the rats a high-fat diet rather than chow potentiated the hyperphagia and obesity syndromes produced by the various lesion conditions. Taken together, these findings suggest that the medial hypothalamic hyperphagia and obesity syndrome is due, in part, to damage to PVN projections to the caudal brainstem, the NST/DX complex in particular. The functional significance of this PVN-hindbrain "feeding" pathway and the identity of extra-PVN components of the hyperphagia-obesity syndrome remain to be established.
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PMID:PVN-hindbrain pathway involved in the hypothalamic hyperphagia-obesity syndrome. 316 42

The past 10-15 years have produced a significant increase in knowledge and theories concerning the regulation of energy balance, but the precision of this regulation is still uncertain. However, the fact that investigators have had to resort to a variety of techniques and ploys (some of them bizarre) to produce marked pertubations in body weight is in itself an indication that the regulatory system can be very robust. Although control of food intake obviously plays a major role in this system, control of energy expenditure (i.e. DIT) also has to be considered as an important factor in the maintenance of energy balance. In this review most of the evidence for DIT and its biochemical origins has been derived from studies on experimental animals. Many of the overfeeding studies carried out on man are consistent with the animal work, but because of differences in interpretation and some equivocal results, the role of DIT in human metabolism is still a contentious issue. This problem may not be fully resolved to everyone's satisfaction until complete, continuous, and very precise energy balance measurements are made on chronically overfed lean subjects. Before this expensive and arduous experiment is undertaken, evidence for thermogenesis in man will continue to depend on acute measurements of the metabolic response to various stimuli. An increasing number of studies (e.g. 35, 80) have demonstrated the existence of NST in man, and the possibility that this could originate from BAT is supported by histological (62, 148) and thermographic data (130). Conversely, reductions in cold tolerance (2, 18) and thermogenic responses to noradrenaline (82) with increasing adiposity are similar to the blunted responses seen in genetically obese animals, which suggests that human obesity may also involve an impairment in thermogenesis. At the present time these ideas concerning the important of DIT in man and its role in obesity remain somewhat speculative, but no doubt this area will now be the subject of further research. Similarly, the impact of early nutritional influences on subsequent energy balance regulation and resistance to obesity will receive more attention following the report (144) that hyperphagia in rats during early life results in a reduced body fat content and leanness in adulthood. The relative contributions and interactions between intake and output in energy balance need clarifying, and in terms of central organization, the mechanisms of appetite control should now be considered for their relevance to the control of thermogenesis.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Regulation of energy balance. 676 16