Glucocorticoids down-regulate the number of 1,25-dihydroxyvitamin D 3 receptors in mouse intestine

Abstract

This study examined the hypothesis that glucocorticoids might regulate intestinal receptors for 1,25(OH) 2vitamin D 3. Mice were treated with saline vehicle or dexamethasone in doses of 50–200 μg/100 gm body weight for 7 days. A dose-dependent fall in the number of receptors was found in dexamethasone treated animals (∼30%); there was no change in the receptor affinity for 1,25(OH) 2D 3 (0.2 nM). The decline in receptor number required 5–7 days of dexamethasone treatment depending on dose. Adrenalectomy led to a 30% rise in receptor number which could be prevented by the 50 μg dose of dexamethasone. Receptor changes of equal magnitude were exhibited in vitamin D replete or deplete mice.