Progesterone binding to mineralocorticoid receptors: in vitro and in vivo studies.

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Myles K, Funder JW

Progesterone binding to mineralocorticoid receptors: in vitro and in vivo studies.

Am J Physiol. 1996 Apr;270(4 Pt 1):E601-7. doi: 10.1152/ajpendo.1996.270.4.E601.

PubMed ID

8928765 [ View in PubMed

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Abstract

In previous studies using expressed recombinant human mineralocorticoid receptors (MR), progesterone was reported to have widely divergent affinity, from approximately 10 nM to < 10 pM. In the present studies, cytosol preparations of colon or hippocampus were incubated with [3H]aldosterone or [3H]progesterone, alone or with excess RU-486, and the ability of each steroid to compete for MR was determined. In guinea pigs, progesterone has equivalent affinity to aldosterone for MR in vitro, and in rats three times of that aldosterone, with no differences between tissues. In vivo, in both epithelial (kidney, colon) and nonepithelial tissues (heart, hippocampus), progesterone was 10- to 100-fold less potent a competitor than aldosterone for MR, both in the absence of transcortin (8-day-old rats) and in adult mice. Bolus injection of [3H]progesterone was not specifically bound in any of the four tissues. Whether progesterone at steady state may bid for MR occupancy under conditions of high circulating free levels (in utero, luteal phase, pregnancy), presumably to act as an antagonist to cortisol/corticosterone in unprotected nonepithelial receptors, thus remains to be determined.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Progesterone	Mineralocorticoid receptor	Protein	Humans	Yes	Antagonist Agonist	Details