Walter Dr Elger

Dihydrospirorenone (ZK30595): A novel synthetic progestagen-characterization of binding to different receptor proteins

Dihydrospirorenone (6 beta, 7 beta, 15 beta, 16 beta-dimethylen-3-oxo-17a-pregn-4-en-21, 17-carbolacton) is a new type of progestin with no other agonistic activities, in particular no estrogenic, androgenic or glucocorticoid activity. Dihydrospirorenone is a potent aldosterone antagonist 8 times as potent as spironolactone and antiandrogenic (0.3 times cyproterone acetate). The aim of the present study is to make a broad characterization of dihydrospirorenone at the receptor level and to discuss the results in comparison to those of established progestins. Kinetic studies of 3H-dihydrospirorenone uptake show a rapid increase in the amount of specific binding during the first three hours. The dissociation of 3H-dihydrospirorenone from the cytoplasmic human uterine progesterone receptor, measured by displacement of labeled steroid with dextran-coated charcoal treatment at 4 degrees C at various times, showed a monophasic or one-component, first order dissociation curve like progesterone. Sucrose density gradient centrifugation of the 3H-dihydrospirorenone-labeled myometrial cytosol showed that the dihydrospirorenone binding components sedimented in the 4S and 8S region which is typical for the progesterone receptor under low salt conditions. The high binding affinity of dihydrospirorenone to the binding sites of the mineralocorticoid receptor of rat kidney with an RBA value of 230% compared to aldosterone is remarkable. This reflects the strong antimineralocorticoid activity of this compound which was evaluated in adrenalectomized rats. Furthermore, competitive studies indicated that dihydrospirorenone also displays high affinity for the androgen and some affinity for the glucocorticoid receptors but no measurable affinity for the estrogen receptor.

Immunocytochemical localization of uteroglobin in the genital tract of male rabbits

SummaryUsing the immunoperoxidase technique and specific goat antiserum to uteroglobin, selective immunochemical staining products are localized in the epididymal epithelium of the caput and proximal corpus region, at the adluminal border of the cauda epididymidis and, as well known, in epithelial cells of the endometrium of pregnant and progesterone-treated rabbits. Specific staining is also seen on spermatozoa. A uteroglobin-like antigen has been similarly localized in alveolar and bronchial epithelial cells of the lung. Testis, prostate, seminal vesicle and ductus deferens do not seem to contain in their tissues immunoreactive uteroglobin-like antigens. Similarly, the uterus and ductus epididymidis of immature rabbits are devoid of immunoreactivity. The presence of uteroglobin-like antigens in tissues other than the endometrium, particularly the ductus epididymidis, stimulates new discussions on the function of this protein in reproductive physiology and fertility research.

Receptor binding of norgestimate — A new orally active synthetic progestational compound

Binding of the new progestagen, norgestimate (D-(-)-13 beta-ethyl-17 beta-acetoxy-17-ethinyl-4-gonen-3-one-oxime), and its metabolites (levonorgestrel-3-oxime, levonorgestrel-17-acetate and levonorgestrel) to the progesterone receptor was investigated by competition experiments using cytosol from human myometrial tissue. Compared to R5020, a highly potent synthetic ligand for progesterone receptor analysis, the L-isomer of norgestimate shows only a weak specific behaviour with regard to binding to the progesterone receptor from uterine cytosol with an RBA value of 0.8%, whereas the D-isomer of this compound is characterized by a lack of binding activity to the progesterone receptor. Levonorgestrel-3-oxime, one of the possible metabolites of norgestimate, binds to the progesterone receptor with an RBA value of 8%, whereas levonorgestrel-17-acetate, the other possible metabolite of norgestimate, binds with a binding affinity of 110% which is in the same order of magnitude as levonorgestrel itself. The competition experiments suggest that norgestimate is a prodrug and that the metabolites, levonorgestrel and levonorgestrel-17-acetate, which actively bind to the progesterone receptor, must first be formed from the parent drug via metabolic processes in vivo. These are the actual biologically active compounds which are responsible for the gestagenic potency.

Suitability of the beagle dog as a test model for the tumorigenic potential of contraceptive steroids “short review”

Abstract The purpose of this short review is to assess the present state of knowledge on the suitability of the beagle dog as a test model for the tumorigenic potential of contraceptive steroids. The beagle dog differs markedly from other species, including man, as regards its reproductive physiology and endocrinology. Studies on the influence of contraceptive steroids on canine mammary gland, pituitary gland and uterus have led to the conclusion that the stimulation of development of mammary tumours in dogs by certain progestagens or progestagen-oestrogen combinations must be considered as being a species-specific effect, related to the high hormonal potency (progestational activity) of these compounds in the dog and their stimulatory effect on canine growth hormone. Based on the present state of our knowledge and because of the marked interspecies differences of action of contraceptive steroids in dog and man, the steroid-related canine mammary tumours, especially with regard to the doses necessary for contraception, are unlikely to be indicative of a potential hazard to the human female.

The progestational activity of different gestagens used for human contraception in the beagle bitch

Abstract In long-term studies chlormadinone acetate (CMA) and cyproterone acetate (CPA) have much more pronounced mammotropic effects in dogs than norethisterone acetate (NA) or levonorgestrel (LN). To evaluate gestagenic potency of these compounds in dogs as a potential determinant of these substance differences, a quantitative canine gestagen bioassay was developed. Ovariectomized adult beagles were sequentially treated with 30 μg estradiol (E 2 )/d s.c. for 15 days and gestagen (s.c., p.o.) + 3 μ g E 2 / d s.c. days 16–29. This regimen was found optimal for endometrial gestagen effects. According to their s.c. transformatory potency in day 29 endometrial biopsies, the compounds could be ranked as follows; progesterone (P) Related to p, LN and NA have a much lower gestagenic potency in dogs than in humans. The opposite is true for CMA and CPA. The low oral activity of NA and LN in dogs points to an important first liver passage metabolism of both compounds in this species. Serum determinations substantiate the very low or high oral. bioavailability in case of LN, NA and CPA. Clinically, by the oral route of administration, there is no doubt of the fact that CMA is markedly less potent than NA which itself is less potent than LN whereas in the dogs, CMA is unequivocally the most potent of the progestagens under consideration. This implies that the dogs are overdosed with several human multiples when CMA is administered and probably underdosed with NA, at least on a comparative basis. Our data are consistent with the view that the ability or inability of gestagens to induce mammary tumours in chronic toxicity studies might reflect a dog-specific high or low gestagenicity.

3H-cyproterone acetate: binding characteristics to human uterine progestagen receptors

The availability of tritium labeled cyproterone acetate (CPA) facilitated the systematic investigation of the binding characteristics of this compound for human uterine progesterone receptors (PgR). The binding parameters of 3H-CPA are compared to those of 3H-R5020 and 3H-progesterone. The rate constants of association (k1M-1sec-1) to PgR were 7.8 x 103 for 3H-R5020, 4.5 x 104 for 3H-progesterone and 4.0 x 104 for 3H-CPA. The rate constants of dissociation (k-1, sec-1) were 3.6 x 10-5 for 3H-R5020, 21.3 x 10-5 for 3H-progesterone and 17.8 x 10-5 for 3H-CPA. The Kd-values (M), as obtained by titration analysis and subsequent Scatchard plot analysis were 1.2 x 10-9 for 3H-R5020, 6.0 x 10-9 for 3H-progesterone and 5.2 x 10-9 for 3H-CPA. On sucrose density gradient analysis binding in the 3.5, 5 and 8 S area could be observed using 3H-R5020. For 3H-progesterone and 3H-CPA binding was exclusively found in the 5 S area. The specificity of the steroid binding site of PgR is identical for 3H-R5020 and 3H-CPA. The order of potency of binding for various competitors decreases identically for both radioactive ligands: R5020 < progesterone < R1881< CPA < dihydrotestosterone < dexamethasone < cyproterone < 15β-OH-cyproterone. CPA resembles progesterone very closely in its binding characteristics to human uterine PgR.

The Significance of Hormones in Mammalian Sex Differentiation as Evidenced by Experiments with Synthetic Androgens and Antiandrogens

Since it became possible to do experiments with synthetic androgens, the role of androgens in the differentiation of the male external genital organs could be elucidated (Dantchakoff, 1936; Jost, 1947, 1955).

Reversibility of antigestagenic action of antiprogestin onapristone by exogenous progestagens during early pregnancy in guinea pig

Ability of progesterone, gestodene, promegestone and cyproterone acetate (CPA) to reverse antigestagenic action of onapristone in adult female guinea pigs was investigated. Onapristone (10 mg/kg, s.c.) administered on post-conception days 8-11 caused resorption of implantations and vaginal bleeding in all animals. Simultaneous administration of progesterone, gestodene or promegestone on days 7-13 successfully reversed antigestagenic action of this antiprogestin, since most animals supplemented with these progestagens had viable implantations at autopsy on day 14. CPA was, however, ineffective and animals supplemented with it had only resorbed implantations and blood in uterus and vagina like that in onapristone per se treated animals. High plasma progesterone and low PGFM concentration were generally observed in all pregnant animals bearing viable implantations. PGFM (13, 14-dihydro-15-keto PGF2 alpha) was significantly elevated by day 14 in onapristone-treated (Group II) and CPA-supplemented (Group X) animals. No discernible effect on pregnancy or post-implantation embryonic development was observed in animals treated per se with these progestagens.

Vergleichende Untersuchungen der synthetischen Antigestagene RU 38486, ZK 98734 und ZK 98299 auf der Rezeptorebene

Csapo formulierte das Konzept, das der Entzug von Progesteron unter der Schwangerschaft zwangslaufig zu einer Beendigung dieser fuhren mus. Seitdem Antigestagene vom RU-486-Typ existieren, die als kompetitive Progesteron-Antagonisten die Wirkung von Progesteron dosisabhangig am Uterus blockieren, ist es moglich, Csapo’s Hypothese sowohl klinisch als auch auf der tierexperimentellen wie molekularbiologischen Ebene kritisch zu uberprufen.

Die Bedeutung der Androgene fUr die "Pragung des Gehirns"

Treatment of newborn male rats with an anti-androgen (cyproterone acetate = 6-chloro-17a-acetoxy-1a, 2a-methylene-4, 6-pregnadiene-3, 20-dione) results firstly in permanent modification of the secretion pattern of gonadotropic hormones and secondly in deviations of certain aspects of behaviour. Those hypothalamic sites which regulate the secretion of gonadotropins take on the cyclic character typical of the female, if there is no control by androgens during certain special phases of development. In addition, in adult life such animals exhibit a feminine pattern of behaviour (sexual behaviour, maternal instinct, aggressiveness, etc.).