| Sumario: | In the rat, the conformationally highly befit steroid 21-hydroxy-6,19- oxidoprogesterone efficiently displaces [3H]corticostetone from thymus- glucocorticoid receptors and blocks type II receptors in kidney cytosols but competes with neither [3H]aldosterona for kidney-mineralocorticoid receptors nor [3H]progesterone for uterus-progesterone receptors. It evokes Na+ retention only at very high doses (~100 μg/100 g of rat weight) and is unable to induce tyrosine aminotransferase or to increase glycogen deposits in rat liver. When coincubated with corticostarone or dexamethasone, 2.5 μM 21OH-6OP inhibits 80% of tyrosine, aminotransferase induction. It may therefore be used experimentally as an antiglucocorticoid virtually lacking mineralocorticoid or glucocorticoid properties as well as affinity for mineralocorticoid or progesterone receptors.
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