Changes of salt intake and of (Na+K)-ATPase activity in brain after high dose treatment with deoxycorticosterone.

Mineralocorticoids (MC) have a dual effect on salt intake: in adrenalectomized rats, they reduce previously elevated salt intake; and in intact rats a high MC dose increases salt intake. We have studied the activity of (Na+K)-ATPase and [3H]ouabain binding in rats treated with deoxycorticosterone (DOC) in doses that elicited a salt appetite. Brains were removed from control and treated animals, and 20 different areas were punched out from brain slices cut every 300 microns. DOC treatment significantly reduced (Na+K)-ATPase activity in the lateral hypothalamic area, anterior amygdaloid and lateral amygdaloid nuclei, while increasing it in the periventricular gray matter; changes in other regions were not significant. Binding of [3H]ouabain was not modified by DOC treatment. In parallel experiments, we determined MC receptors in adrenalectomized rats. Binding of [3H]aldosterone was preferentially found in hippocampus, followed by lateral septum, anterior, posterior and lateral amygdaloid areas, with lower levels in other regions. However, there was no correlation between [3H]aldosterone binding and (Na+K)-ATPase activity in brain punches from either control or DOC-treated rats. Further experiments are needed to ascertain if (Na+K)-ATPase changes in discrete areas of the brain containing moderate levels of mineralocorticoid receptors, are related to the behavioral effects of DOC.