Progesterone in the uterus X. dependence of the in vitro progesterone metabolism on progesterone binding in rat uterus

ABSTRACT In vitro experiments carried out with uterus preparations of ovariectomized adult rats indicate the presence in this tissue of a 20β-hydroxysteroid-oxidoreductase which catalyzes the conversion of 20β-hydroxy-4-pregnen-3-one to progesterone. Since a hepatic 20β-hydroxysteroid-oxidoreductase is absent in adult female rats, the myometrial enzyme can be responsible for the biological activity of 20β-hydroxy-4-pregnen-3-one in these animals. Besides progesterone five metabolites were isolated and identified after incubation of [4-14C]20β-hydroxy-4-pregnen-3-one with uterine tissue: 20β-hydroxy-5α-pregnan-3-one, 20β-hydroxy-5β-pregnan-3-one, 5α-pregnane-3α,20β-diol, 4-pregnene-3α,20β-diol and 4-pregnene-3β,20β-diol. The conversion of 20β-hydroxy-4-pregnen-3-one to progesterone permits us to regard all five steroids isolated as progesterone metabolites in the rat uterus. 20β-hydroxy-5β-pregnan-3-one is the first C21-metabolite with a 5β(H)-configuration isolated in the rat uterus, which indicates the presence of 5β-reductase in this tissue.

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Stimulation of contraction of pregnant rat uterus in vitro by non-dechlorinated and microbially dechlorinated mixtures of polychlorinated biphenyls.

Environmental Health Perspectives ◽

10.1289/ehp.01109275 ◽

2001 ◽

Vol 109 (3) ◽

pp. 275-282 ◽

Cited By ~ 15

Author(s):

J Bae ◽

M A Mousa ◽

J F Quensen ◽

S A Boyd ◽

R Loch-Caruso

Keyword(s):

Polychlorinated Biphenyls ◽

Rat Uterus ◽

Pregnant Rat ◽

Stimulation Of

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Autoradiographic localization of beta-adrenoreceptors in rat uterus.

Journal of Histochemistry & Cytochemistry ◽

10.1177/36.12.2848069 ◽

1988 ◽

Vol 36 (12) ◽

pp. 1475-1479 ◽

Cited By ~ 6

Author(s):

M Tolszczuk ◽

G Pelletier

Keyword(s):

Quantitative Estimation ◽

Cell Types ◽

Receptor Subtypes ◽

High Concentration ◽

Rat Uterus ◽

Beta Adrenergic ◽

Adrenergic Antagonist ◽

Beta 2 ◽

Different Cell Types

The inhibitory effects of catecholamines on uterine smooth muscle are known to be mediated through beta-adrenergic receptors. To investigate further the distribution of these receptors in the rat uterus, we utilized in vitro autoradiography using [125I]-cyanopindolol [CYP], a specific beta-receptor ligand that has equal activity for both beta 1- and beta 2-receptor subtypes. The specificity of the labeling and the characterization of receptor subtypes in different cell types were achieved by displacement of radioligand with increasing concentrations of zinterol, a beta-adrenergic agonist with preferential affinity for the beta 2-adrenoreceptor subtype, and practolol, a beta-adrenergic antagonist that binds preferentially to the beta 1-subtype. Quantitative estimation of ligand binding was performed by densitometry. It was shown that the vast majority of beta-adrenoreceptors were of the beta 2-subtype and were found in high concentration not only in the myometrium but also in the endometrial and serosal epithelia. Specific labeling was also observed in glandular elements. These results suggest that beta-adrenoreceptors might be involved in different functions in the uterus.

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