Dynamics of glucocorticoid and mineralocorticoid receptors in the Xenopus laevis pituitary pars intermedia.

We showed the presence of glucocorticoid (GR) and mineralocorticoid (MR) receptors in different populations of Xenopus laevis melanotrope cells and revealed their downregulation (MR) and upregulation (GR) during dark background adaptation. Corticosterone did not affect short-term intracellular calcium dynamics and alpha-melanophore-stimulating hormone secretion, suggesting a role for GR and MR in long-term processes in the melanotropes.