Energy balance in rats given chronic hormone treatment

Abstract

1. Sprague-Dawley rats were injected for 16 d with long-acting insulin, and energy balance was calculated using the comparative carcass technique. Two experiments were carried out with females (starting weights 150 and 90 g respectively), and one with males (starting weight 150 8). In a fourth experiment, cytochrome c oxidasc (EC 1 .9.3.1) activity was measured as an indicator of the capacity for substrate oxidation. 2.Insulin increased weight gain by up to 57% ( P < 0.01 for all studies). Metabolizable energy intake (kJ/d) was also consistently higher in the treated groups, by up to 34% (P < 0.01 for all studies). The excess weight gained by the insulin-treated rats was predominantly due to fat deposition.3. Energy expenditure, calculated as the difference between metabolizable intake and carcass energy gain. was expressed on a whole-body basis, or relative to either metabolic body size (kg body-weight"75) or fat-free mass. Insulin consistently raised energy expenditure, regardless of the method of expression, but this change reached statistical significance in only two of the nine comparisons.4. Cytochrome c oxidase activity was not affected by insulin treatment in either interscapular brown adipose tissue or gastrocnemius muscle. In liver, total enzyme activity (U/tissue) was increased from 2928 (SF 162) in the controls to 3940 (SE 294) in the treated group ( P i 002), but specific activity (U/mg protein) was unchanged.5. It is concluded that, despite causing substantial hyperphagia, insulin treatment only slightly increases energy expenditure in rats. The costs of increased tissue deposition may account for this change.

Insulin detemir attenuates food intake, body weight gain and fat mass gain in diet-induced obese Sprague–Dawley rats

“…39, 40, 41, 42, 43, 44, 45 Notably, only a study by Vanderweele 46 showed an 11% reduction of spontaneous daily food intake in normal-weight chow-fed rats administered 2 U per day of regular insulin via an osmotic minipump implanted into the peritoneal cavity. Thus, our findings with insulin Det appear to be fundamentally novel.…”

Variation of plasma parameters and nitrogen metabolism in finishing Belgian Blue double‐muscled cull females

“…Although the mean GH values for the females were similar to those reported by Hornick and colleagues (1998) and Cabaraux and colleagues (2003b), in young fattening BB males, the increase of plasma GH however remains unexplained, as was the decrease of insulin concentration at the end of finishing. Indeed, insulin concentration is positively related to fat accretion rather than protein accretion (Spencer, 1985; Woodward and Emery, 1989; Schwarz et al., 1992). These observations thus appears contradictory but could be explained by feeding behaviour alterations at the end of finishing, as a result of a satiety phenomenon in animals showing an innate inclination to deposit very low amounts of fat.…”

Plasma hormones and metabolites in cattle in relation to breed (Belgian Blue vs Holstein) and conformation (double-muscled vs dual-purpose type)

“…This was not surprising since there is no convincing evidence that insulin exerts positive effects upon muscle growth (Grizard et al, 1988;Reeds and Davis, 1992). The high insulin concentration may have been related to increased accretion of fat rather than protein (Spencer, 1985;Woodward and Emery, 1989;Schwarz et al, 1992). Insulin is the endocrine substance most associated with adipocyte function.…”