Animal models for the study of energy balance

Abstract

Dairying, University of Reading, Shinfield, Reading RG2 @T The most obvious outcome of the failure to regulate energy balance effectively in animals and man is obesity. To learn how obesity arises and may be prevented, we must understand how animals regulate energy balance or metabolism, but a concentration on obesity as such may focus too much research attention on the adipose tissue, a proliferation of which is the outward sign of a tendency towards positive energy balance though not necessarily the cause of it.Rather than attempting a complete review, I shall select several current areas of research to illustrate specific points in connexion with the question: why do we need 'models'? The concept of energy balanceAn animal is said to be in energy balance when his body energy stores remain constant. His energy intake (metabolizable energy of food) then equals his energy expenditure (total heat output). Energy balance is positive if intake exceeds output; negative if output exceeds input. E,, -Eow = A body energy At least two terms in the equation should be measured. This is accomplished more simply and with greater accuracy over longer periods with animals than with man: a compelling reason for studying animal models to understand basic mechanisms. Changes in body energy are quite difficult to assess properly in man. Deposition of adipose tissue is associated with increases in protein and water as well as fat. Changes in carcass energy can be measured accurately in animals by direct chemical analysis, but it is surprising how frequently this is omitted. It is common for authors to refer only to weight gain as though this can fully describe a change in energy balance. Energy balance can change quite dramatically without any change in weight as illustrated by an example from our work with piglets (Gurr et al. 1980). A group of piglets was fed on a diet of low-protein content (approximately 2% of metabolizable energy) ad lib. The protein level was adjusted so that animals maintained weight. A second group was fed on a high-protein diet

SGLT2 selective inhibitor ipragliflozin reduces body fat mass by increasing fatty acid oxidation in high-fat diet-induced obese rats

“…Therefore, the daily net energy balance (intake-loss) in vehicle-and ipragliflozin-treated rats was 91.0 and 77.9 kcal/day, respectively, with the net energy balance in ipragliflozin-treated rats coming out to 85.6% that of vehicle-treated rats. Assuming 6.16 kcal/g body fat for rodents (Gurr, 1980), this deficit of 13.1 kcal/day in the ipragliflozin-treated group could explain the fat weight loss of 2.13 g/day and a 63.9 g total body weight loss after 30-day treatment. Interestingly, this degree of weight loss is consistent with the differences in actual body weight between the vehicle and ipragliflozin groups (61.8 g) (Figure 1A), strongly suggesting that ipragliflozin reduced fat weight by promoting negative energy balance in HFD rats.…”

Weight Loss Induced by Chronic Dapagliflozin Treatment Is Attenuated by Compensatory Hyperphagia in Diet‐Induced Obese (DIO) Rats

“…Dapagliflozin is a potent and selective SGLT2 inhibitor (16) which has been shown to induce glucose excretion by 20–85 g/day in humans (17,18,19) and 0.5–1.9 g/day in 200 g rats (20), which would be roughly equivalent to a caloric deficit of 80–340 kcal/day in humans and 2–7.6 kcal/day in a 200 g rodent. Assuming 6.16 kcal/g body fat for rodents (21) and 3,500 kcal/lb body fat for humans, these caloric deficits would predict weight loss of 0.32–1.2 g/day in a rat and 0.022–0.097 lb/day in a human. Zhang (22) reported an average weight loss of 2.5 kg in early‐stage diabetic patients where average urinary glucose excretion was 71.2 g/24 h, which is 20% less than the 3.05 kg which would have been predicted from the glucose excretion values.…”

Energiebilanz und Energieverwertung bei Kühen während und nach überhöhter Proteinzufuhr

“…Zu beachten ist, daR zum Vergleich der absoluten Warmeproduktion nur Versuche mit konstanten Mengen an zugefuhrter Bruttoenergie bei den einzelnen Versuchsgruppen herangezogen werden diirfen. Bei unterschiedlicher Energiezufuhr ist namlich mit bedeutend starkerer Beeinflussung der Warmebildung zu rechnen (GURR 1980;KIRCHGESSNER et al 1983a).…”