The role of 11β-hydroxysteroid dehydrogenase in steroid hormone specificity

ABSTRACT Of the information available on steroid hormone metabolism in responsive tissues, only that relating hormone metabolism to physiological activity is reviewed, i. e. metabolite activity in isolated in vitro systems, binding of metabolites to target tissue receptors, specific steroid hormone metabolizing enzymes and relationship of hormone metabolism to target organ physiological state. Further, evidence is presented in the androgen field, demonstrating 5α-reduced metabolites, formed inside the target cells, as active compounds. This has led to a consideration of testosterone as a »prehormone«. The possibility that similar events take place in tissues responding to progesterone is discussed. Finally, the role of hormone metabolism in the regulation of hormone availability and/or renewal in target cells is discussed. In this context, reference is made to the potential role of plasma binding proteins and cytosol receptors.

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ZUR BEDEUTUNG DES HYPOPHYSÄREN LUTEINISIERUNGSHORMONS FÜR SCHWANGERSCHAFT, GEBURT UND LACTATION BEI DER RATTE

Acta Endocrinologica ◽

10.1530/acta.0.065s005 ◽

1970 ◽

Vol 65 (3_Suppl) ◽

pp. S5-S32 ◽

Cited By ~ 2

Author(s):

K. Loewit

Keyword(s):

Luteinizing Hormone ◽

Early Pregnancy ◽

Hydroxysteroid Dehydrogenase ◽

The State ◽

Termination Of Pregnancy ◽

Progesterone Level ◽

Corpora Lutea ◽

Regulatory Properties ◽

Duration Of Pregnancy

ABSTRACT The role of luteinizing hormone (LH) for the maintenance of pregnancy, parturition and lactation was investigated by immunological and histochemical methods in the rat. Neutralisation of endogenous rat-LH with Rabbit-Anti-Bovine-LH-Serum (selective hypophysectomy) from days 7-12 of pregnancy resulted in reabsorption of the foetuses and the reappearance of strong 20α-hydroxysteroid-dehydrogenase (20α-OHSD) activity in the corpora lutea (CL) of pregnancy, which normally show no such activity at that time. This effect could be prevented in part by concurrent pregnenolone administration and fully by progesterone, but was not influenced by oestrogen or prolactin. It is concluded that in early pregnancy LH is the main luteotrophic hormone in the rat even though prolactin might act synergistically with it. Antiserum treatment after the 12th day of gestation had no influence on the state or duration of pregnancy or on parturition. LH-injections during the first half of pregnancy had no luteolytic effects i. e. they did not activate 20α-OHSD activity. After day 16 they advanced the reappearance of the enzyme, but delayed parturition or resulted in stillbirths. Neither LH nor antiserum seemed to alter lactation. Since progesterone prevented both the termination of pregnancy and the recurrence of 20α-OHSD activity, it should have some regulatory properties on the enzyme. It is discussed whether the gonadotrophin-dependent progesterone level could regulate the 20α-OHSD activity rather than result from it.

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