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.