Effects on energy utilization of a beta3-adrenergic agonist in rats fed on a cafeteria diet.

The antiobesity potential of a new beta3-adrenergic agonist (Trecadrine) was assessed in a cafeteria model of obesity through body composition, thermogenesis and oxygen consumption indicators. Animals fed on a cafeteria diet for 75 days increased body weight and fat content, while muscle mass as a percentage of body weight was reduced in relation to control fed rats. In addition, in vitro brown adipose tissue (BAT) and white adipose tissue (WAT) oxygen consumption was increased in these obese animals as compared with controls. Trecadrine administration reduced weight gain, BAT and WAT stores as well as the respiratory quotient, which was accompanied by an increase in WAT and BAT oxygen consumption and rectal temperature. Moreover, muscle mass as a percentage of body weight maintained the same values as non-obese animals, while an increase in absolute muscle weight was found in Trecadrine-treated obese rats. However, liver weights and in vitro oxygen consumption remained unaltered after cafeteria feeding and Trecadrine administration. Since chronic administration of Trecadrine had no effect on food intake, the stimulation of thermogenesis and oxygen consumption by the beta3-adrenergic agonist in white and brown adipose tissue are apparently responsible for the rise in energy expenditure as well as for the lower weight gain and fat deposition in obese treated rats. Thus, Trecadrine exhibits some promise as a potential treatment for obesity.