AJP - Endocrinology and Metabolism, Vol 263, Issue 6 E1054-E1062, Copyright © 1992 by American Physiological Society
Upregulation of V1a vasopressin receptors by glucocorticoids
P. Colson, J. Ibarondo, G. Devilliers, M. N. Balestre, A. Duvoid and G. Guillon
Centre National de la Recherche Scientifique-Institut National de la Sante et de la Recherche Medicale de Pharmacologie-Endocrinologie, Montpellier, France.
WRK1 cells (a rat mammary tumor cell line) exhibit a vasopressinergic
receptor of V1a subtype tightly coupled to phospholipase C. Addition of
dexamethasone to the culture medium principally potentiated the
vasopressin-sensitive accumulation of inositol phosphates and to a lesser
extent the NaF-sensitive phospholipase C activity. On the opposite, such
treatment was without effect on the basal level of intracellular inositol
phosphates or on bradykinin- or serotonin-sensitive phosphoinositide
metabolisms. Glucocorticoid receptors were probably involved in these
actions since dexamethasone was found to be more potent than aldosterone or
corticosterone. Dexamethasone treatment also increased the number of
vasopressin binding sites without affecting its affinity for vasopressin or
other specific vasopressin analogues. These results strongly suggest that
dexamethasone principally acts at the vasopressin receptor level by
affecting its synthesis and/or the translation of its mRNA and also affects
the G protein that couples the V1a receptor to the phospholipase C. These
results explain how glucocorticoids may regulate the transduction
mechanisms involved in vasopressin actions on WRK1 cells. They provide
explanations for understanding the cross talk between adrenal steroids and
hormones, which mobilize intracellular calcium.
