Acta Medica 29. (1972)

1972 / 1-2. szám - The 5th Hungarian Endocrine Congress was held in Szeged, Szeptember 1-4, 1971. - Julesz, M.†: Experimental and Clinical Aspects of the Biosynthesis of Androgenic Steroids

1* BIOSYNTHESIS OK ANDROGENIC STEROIDS 3 the periphery is, therefore, not only of theoretical but also of clinical impor­tance. The concept also implicates that all endocrine syndromes, irrespective of their origin, invariably manifest themselves at the periphery. This makes it our objective to follow up the various hormones formed in the individual endocrine glands all along their pathways down to the target organs, as far as the cellular and subcellular elements and to locate the individual cell struc­tures— microsomes, mitochondria, cell membrane, nucleus — which may con­stitute the site of action of the given hormone. The question whether there exist any specific androgenophile receptors also belongs to this line of studv-The main sources of androgens are the testicles, the ovaries, the adrenal cortex and the placenta. There has been some uncertainty concerning the question whether the biosynthesis of androgens is confined to the last-named organs. On the evidence of our studies (Julesz et al., 1971) the human skin is provided by all enzyme systems required for androgen synthesis. As regards the site of production, we have two sources of information. Estimation of an­drogens in the r spective organs provide reliable evidence. Studies of the other type are based on the hormone concentration in the plasma of effluent venous blood of the organ. If it exceeds that of peripheral blood, the respective endo­crine organ is presumably the site of production of the androgen in question. The pathway of transport is the blood plasma. Transformation of andro­gens begins as soon as they enter the blood stream, though at this phase it is prevalently a binding to the plasma proteins rather than a radical transfor­mation that takes place (Westfahl, 1970). The essential factor here is the re­versibility of binding. Earlier, binding to proteins was regarded as part of the transport function. The present view is that the binding of steroids to proteins serves for the biological inactivation of the hormones. Release of the bonds makes the reactivated hormone available at the necessary site at the required time. The blood plasma is thus considered a reservoir of active steroids and of other hormones. Binding to protein weight also provides a protective barrier to the hor­mone against chemical or enzymatic damage. The question which now arises concerns the other end of the path. What happens in the target organs? Our knowledge concerning this point is still uncertain. We do not know whether it is the hormone which passes the nuclear membrane and occupies the place of the receptor after its release from the carrier-protein, or whether it is rather the carrier-protein which forms links with the receptor-structures. Certain new facts may, however, furnish some clues to the understanding of the problem. It has been found, for instance, that testosterone administered in vivo to normal rats significantly stimulates lipid biosynthesis in the mitochondria of the accessory sexual glands (Doeg, 1969). Other authors (Tweter and Unhjem, 1969) noted a selective uptake of andro­gens in a macromolecular fraction of the supernatant of ultracentrifuged Acta Medica Academiae Scienliarum Hungaricae 29, 1972

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