Interaction of type I and type II corticosteroid receptor stimulation on carcass energy and carcass water

The effects of chronic type I and type II corticosteroid receptor stimulation were examined in adrenalectomized Sprague-Dawley rats to quantify the relative contribution of body energy and body water changes to changes in body weight. Adrenalectomy caused a decrease in both body energy and water. Aldosterone (type I agonist) treatment increased body weight gain and returned energy accretion to the level of sham-operated animals. However, most of the change in body weight (72%) was attributable to a change in body water. The aldosterone-induced increase in body weight gain and carcass water were attenuated by RU-28362 (type II receptor agonist) infusion, suggesting that type II receptor stimulation can antagonize the effect of type I receptor stimulation. Changes in carcass water were paralleled by changes in soluble carcass sodium. Despite alterations in soluble body sodium, no measurable differences in cumulative sodium retention were found. These findings confirm previous studies suggesting an effect of type I receptor stimulation on energy accretion. However, they also caution that changes in body weight cannot be equated with changes in body energy.