Epidermal dexamethasone receptors in dogs with confirmed hyperadrenocorticalism, hypothyroidism or undiagnosed hormonal alopecia

Low capacity, high affinity [ 3H] dexamethasone binding receptors were identified in cytosolic preparations of the skin (mean number 42·0 ± 25·2 mg −1 protein, apparent dissociation constant (1 nM ± 0·23) of clinically normal dogs. No [ 3H] dexamethasone binding was observed in the skin of nine out of 10 dogs with confirmed spontaneous hyperadrenocorticism or in the skin of three out of six dogs with undiagnosed hormonal alopecia. A reduction was detected in the number of [ 3H] dexamethasone binding receptors in the skin of one dog with confirmed hypothyroidism. This study provides evidence for the susceptibility of canine glucocorticoid receptors to down regulation by imbalances of endogenous hormones, particularly increased glucocorticoid concentrations.