Effects of the β-agonist, cimaterol, on growth, body composition and energy expenditure in rats

Abstract

1. Male Sprague-Dawley rats weighing 146.5 (SE 4.3) g were fed on a semi-synthetic diet containing 0, 25 or 150 mg cimaterol/kg for 12 d. Net changes in weight and composition of carcass, liver, heart, gastrointestinal tract, gastrocnemius plus plantaris muscles, skin and remainder were estimated by comparative slaughter.2. Cimaterol increased protein gains in gastrocnemius plus plantaris muscles from 0.09 g in controls to 0 14 and 012 g in 25 and 150 mg cimaterol/kg groups respectively. Carcass protein gains increased from 6.27 g in controls to 8.00 and 7.05 g in 25 and 150 mg cimaterol/kg groups respectively.3. Rats treated with cimaterol either gained less fat or actually lost fat from all tissues studied, whilst control rats gained fat. These changes were reflected in lower energy retention in cimaterol-fed rats.4. Energy intake was not affected by treatment. Cimaterol increased heat production from 776 kJ/kg bodyweight' 75 in controls to 863 kJ/kg body-weight' 75 in both treated groups. Gross efficiency was reduced from 17.4% in controls to 8.0 and 7.7% in rats fed on 25 and 150 mg cimaterol/kg diets respectively.5. These results indicate that cimaterol increases protein gain at the expense of fat in rats. In addition, subcutaneous adipose tissue appears to be more sensitive than abdominal fat, whilst protein gains are particularly enhanced in skeletal muscle relative to other body tissues.Some P-adrenergic agonists have the ability to increase lean gain at the expense of fat, which has led to the use of the term repartitioning agents (Asato et al. 1984). Clenbuterol (4-amino-cr-(t-butylamino-methyl)-3,5-dichlorobenzyl alcohol) and cimaterol (5-(l-hydroxy-2-(isopropylamino)-ethyl)anthranilonitrile) were identified by their ability to increase body-weight gain and decrease uterine fat pad weight in mice (Asato et al. 1984). Both compounds have been shown to increase carcass protein and decrease fat in sheep Thornton et al. 1985;Wolff et al. 1987), cattle (Ricks et al. 1984, poultry (Asato et al. 1984;Dalrymple et al. 1984) and pigs (Jones et al. 1985). These changes are desirable in view of consumer demand for leaner meat. In addition, P-agonists provide a powerful tool for understanding the factors determining body composition in general and muscle growth in particular. Accordingly, several studies have been aimed at elucidating the mechanism of action of these compounds (Emery et al. 1984;Thornton et al. 1985;Reeds et al. 1986;Bohorov et al. 1987). However, none of the studies to date have included detailed information on initial and final weights of body components, as well as feed intakes. Here we report on quantitative effects of cimaterol on changes in the weight and composition of various tissues in growing rats and on feed intake and energetic efficiency. MATERIALS A N D METHODSMale Sprague-Dawley rats, 6 7 weeks of age and mean body-weight 146.5 (SE 4.3) g, were housed in individual stainless-steel cages and fed on a semi-synthetic diet (obtained from

The effect of acute and chronic administration of the β-agonist, cimaterol, on protein synthesis in ovine skin and muscle

“…This combination of techniques has been applied to study both short-and longer-term effects of cimaterol on protein synthesis in ovine muscle and skin. The latter tissue was examined because of reports that the muscle hypertrophy may be associated with a reduction in the growth rate of other tissues (Reeds et al 1986;Williams et al 1987;Sainz & Wolff, 1988), including lamb wool production (Sainz & Wolff, 1987) and mink pelt quality (Slayden et al 1991), which may have profound effects on net S-amino acid availability for carcass gain. The mechanisms underlying reduced anabolism in non-muscle tissues following P-agonist administration have not been examined in the farm species, and such information may be important to understand the basis of the induced N repartitioning.…”

Effect of dietary cimaterol on performance and carcass traits in bulls and on aspects of digestion in cattle and sheep

“…Obviously, other mechanisms adversely affect feed conversion. A higher energy requirement for maintenance due to an increased heat production has been reported for (3-agonist-treated rats (Sainz and Wolff, 1988), lambs (MacRae et al, 1988) and calves (Williams et al, 1987). If this mechanism affects the efficiency of energy utilization, then there is no reason to suppose that it is more important towards the end of the experiment, on the contrary.…”

Influence of the β-adrenergic agonist cimaterol on energetic efficiency and oxygen consumption in liver tissue of growing lambs

“…in experiments involving comparative slaughter which results in the accumulation of small differences in daily heat production, increases in heat production due to treatment with B-adrenergic agonists have generally been found (e.g., Emery etal. 1984;Williams et al 1987; Sainz and Wolff 1988;Kim et al 1989). However, Sainz et al (1990) did not observe an increase in heat production due to cimaterol.using this procedure.…”