Energy balance, thermogenesis and brown adipose tissue activity in tube-fed rats.
Young adult male rats were given a portion (42%) of their normal daily food intake by stomach tube (tube-fed), but they were also allowed free access to the same powdered diet. Total metabolizable energy intake was identical to that of controls, but tube-fed rats gained 25% weight and 50% more body energy than controls over 15 days. Total energy expenditure and resting oxygen consumption, measured during the latter part of the day, were reduced in tube-fed rats. Intubated animals showed a lower thermogenic response to noradrenaline and depressed activity of the mitochondrial proton conductance pathway in brown adipose tissue (assessed from GDP-binding), but brown fat mass, protein content, the density of beta-adrenoreceptors in brown fat cell membranes and plasma triiodothyronine (T3) levels did not differ between groups. These data indicate that the enhanced energetic efficiency and fat deposition of tube-fed rats is due to a lower energy expenditure, resulting, at least in part, from lower levels of thermogenesis in brown adipose tissue.
D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects; D001835:Body Weight; D004734:Energy Metabolism; D007441:Intubation, Gastrointestinal; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010101:Oxygen Consumption; D051381:Rats; D011919:Rats, Inbred Strains
D009638:Norepinephrine