Male contraception: hormonal, mechanical and other

Methods of male contraception that have been developed so farhave mainly focused on the inhibition of spermatogenesis throughsuppression of the hypothalamo- pituitary secretion of gonodotrophins,and simultaneous supplementation with androgens. These methodsinclude the use of combinations of progestogens or luteinizinghormone-releasing hormone antagonists and testosterone derivatives,or high dose testosterone. Though effective contraception canbe obtained, side-effects and/or the high cost of treatmentlimit the widespread use of these approaches. Inhibition ofsperm maturation in the epididymis, or direct interference withspermatogenic cells or the cells of Sertoli by e.g. gossypolhave been abandoned because of toxic side-effects. Voluntarysterilization by vasectomy is the most commonly used methodof male contraception, but its surgical nature, problematicreversibility and suspected link with subsequent prostate cancerrender the method far from ideal. Non-surgical vas occlusionmay overcome some of these problems, but data on long-term side-effectsand reversibility are lacking. New contraceptive developmentsshould focus on interfering with highly specific aspects ofspermatogenesis such as unique enzymatic processes and intercellularcommunication through cytokines, or application of antibodiesagainst antigens of the epididymis or the spermatozoa. Onlythrough better understanding of normal and pathological spermatogenesiswill it be possible to develop an acceptable male contraceptive.     

Early onset vulvar Lichen Sclerosus in premenopausal women and oral contraceptives

OBJECTIVE: For vulvar Lichen sclerosus (LS) immunological factors, genetic predisposition, and decreased 5 alpha-reductase activity have been discussed as aetiological factors. During the last decade an increase of LS in young women has been suspected. Aim of this study was to evaluate data of premenopausal women with early onset LS to find potential risk factors focussing on the use of oral contraceptives. STUDY DESIGN: We retrospectively analyzed the data of 40 premenopausal patients with early onset LS regarding use of oral contraceptives (OCPs), and first occurrence of LS. To compare these data in a case-control study we analyzed a matched control group of 110 healthy women. RESULTS: All our LS patients were using OCPs compared to 73 women (66.4%) in the control group. OCPs with anti-androgenic activity (chlormadinone acetate, cyproterone acetate, dienogest, and drospirenone) were used by 28 (70%) of the LS patients and by 35 (47.9%) of the 73 women using OCPs in the control group. Thus, the odds ratio for early onset LS for women using anti-androgenic OCPs was 2.53 (95% CI: 1.12-5.75). CONCLUSION: Our data suggest that disturbance of the androgen dependent growth of the vulvar skin by OCPs and especially by OCPs with anti-androgenic properties might trigger the early onset of LS in a subgroup of susceptible young women.     

Routes of delivery for progesterone and progestins

The trends in postmenopausal hormonal therapy (HT) seem to favor the non-oral delivery routes for both the estrogen and the progestin for women with an intact uterus. Targeting the lowest possible dose of the progestin or of the natural hormone progesterone to be delivered directly to the uterus, the target organ for which it is designed, would avoid the possible drawbacks of systemic effects of progestins on other targets. Several delivery systems are either available or in development including vaginal gels and vaginal rings delivering the physiological hormone progesterone or intrauterine systems delivering very low doses of levonorgestrel. In addition, transdermal gels and spray are under development and can deliver very low doses of Nestorone a 19-norprogesterone derivative, not active orally but with high progestational activity when given via non-oral routes. The assumption that these new delivery systems should lead to an improved risk/benefit ratio in HT will need to be demonstrated in larger randomized controlled studies.     

Risks and benefits of hormone replacement therapy

Menopause, the permanent cessation of menstruation, is due to ovarian failure, which may lead to oestrogen deficiency diseases, particularly osteoporosis, cardiovascular disease and cerebrovascular disease. Mortality and morbidity caused by these conditions can be modified by using hormone replacement therapy, but the benefits of this therapy must be weighed against the increased risk of breast cancer and the symptomatic side-effects the treatment may cause. The combination of transdermal oestrogen and natural progesterone offers the most favourable risk-to-benefit profile.     

Norethisterone is bioconverted to oestrogenic compounds that activate both the oestrogen receptor alpha and oestrogen receptor beta in vitro

In the present study, we used [3H]norethisterone to explore the bioconversion of this compound to A-ring reduced metabolites in African Green Monkey Kidney CV-1 cells and breast cancer T-47D cells. Additionally, we analyzed the capability of each norethisterone tetrahydro-reduced compound to bind the human oestrogen receptors alpha and beta and transactivate an oestrogen-sensitive reporter gene. The results showed that norethisterone is mainly metabolized to 3 alpha,5 alpha-norethisterone (>85% of total [3H]norethisterone added) by CV-1 and T-47D cells, and that both A-ring tetrahydro-reduced metabolites exhibit different capabilities to displace [3H]17beta-oestradiol from the oestrogen receptor alpha and beta, being 3 alpha,5 alpha-norethisterone the weakest competitor. We also found that 3 alpha,5 alpha-norethisterone and 3beta,5 alpha-norethisterone activate both oestrogen receptors at nanomolar concentrations and that the transactivation induced by the oestrogen receptor alpha was generally higher (1.7- to 4.0-fold) than that provoked by the beta receptor isoform. In oestrogen receptor alpha-transfected CV-1 and T-47 D cells, the oestrogenic-like potency of the 3beta,5 alpha-tetrahydro-reduced form was similar to that exhibited by 17beta-oestradiol and 2.5- to 4.0-fold higher than that shown by the 3 alpha,5 alpha-reduced compound; conversely, in the oestrogen receptor beta system the potency of the natural ligand was higher than that presented by the 3beta,5 alpha-tetrahydro-reduced metabolite. In CV-1 cells expressing the oestrogen receptor beta, the transactivation potency of 3beta,5 alpha-norethisterone was approximately 2-fold higher than that exhibited by its 3 alpha,5 alpha-tetrahydro-reduced isomer, whereas in T-47D cells the potency of the 3 alpha,5 alpha-tetrahydro-reduced compound was slightly higher than that shown by the 3beta,5 alpha A-ring reduced norethisterone metabolite. These results demonstrate that CV-1 and T-47D cells possess the enzymatic machinery to bioconvert norethisterone into the 5 alpha-reduced, 3 alpha-hydroxylated form and that neither 3 alpha,5 alpha- or 3beta,5 alpha-norethisterone exhibit preference or selectivity towards a particular oestrogen receptor isoform to induce a particular oestrogenic effect in these cell lines.     

Kinetic analysis of the binding of nomegestrol acetate to the progesterone receptors in rat uterus by competition studies

The characteristics of binding (Kinetic and equilibrium binding analysis) of nomegestrol acetate (NOM, 17 alpha-acetoxy-6 alpha-methyl-19-nor-pregna-4.6-diene-3.20-dione) to the progesterone receptor (PgR) in rat uterine cytosolic fraction were determined in comparison to progesterone (P), to fully appreciate the amplitude and specificity of the induced biological response. Since an appropriate radio-labelled form of this steroid molecule was not available, competition studies were performed against the synthetic progestin: [3H]-Organon 2058 [( 3H]-ORG). This allowed a direct comparison between the unlabelled forms of NOM and P, the kinetic constants of which were respectively: Inhibition constant (Ki): 22.8 and 34.3 nM; Association rate constant (k1): 0.39 X 10(3) and 0.21 X 10(3) M-1.s-1; Dissociation rate constant (k-1): 1.81 X 10(-5) and 2.16 X 10(-5) s-1. These results are much more informative than the mere determination of relative binding affinities which only reflect the specificity of the PgR. It was concluded that NOM behaves like the natural hormone in the cytosol of rat uterus.     

Effects of progestins on cardiovascular diseases: the haemostatic system.

The effect of progestin-only therapy on the haemostatic system has mainly been studied in premenopausal women. Although these studies are difficult to compare, most authors agree that there is no consistent pattern of effects on haemostasis. Oestrogen-progestin combinations have been extensively studied in pre- (combined oral contraceptives) and postmenopausal women (sequential and continuous combined hormone replacement therapy), but mostly with emphasis on the effects of oestrogens. Comparative studies into the differential effects of progestins in combined preparations are scarce. Based on these studies, there is evidence for modifying effects of progestins on oestrogen-induced changes, particularly on fibrinogen, factor VII and the fibrinolytic system. The modifying effects appear to vary among certain progestins, the variation being most likely due to differential effects on lipid metabolism. The clinical interpretation of steroid-induced effects on the haemostatic system is difficult. Retrospective analyses linking certain patterns of haemostatic regulation to the risk of venous or arterial vascular diseases are subject to bias, and no interventional studies are yet available. In the absence of such prospective studies and well-designed comparative studies, the available data do not support the notion of a superiority of certain progestins with regard to cardiovascular risks of combined preparations.     

Differential effects of medroxyprogesterone acetate on thrombosis and atherosclerosis in mice

Background and purpose:

The risk for cardiovascular events including venous and arterial disease and stroke is elevated after treatment with estrogen and medroxyprogesterone acetate (MPA) in postmenopausal women. Here, we have investigated the effect of MPA on arterial thrombosis and atherosclerosis in a murine model of atherosclerosis.

Experimental approach:

Apolipoprotein E (ApoE)^−/− mice were bilaterally ovariectomized and treated with placebo, MPA (27.7 µg·day⁻¹) and MPA + 17-β-oestradiol (E₂; 1.1 µg·day⁻¹) for 90 days, on a Western-type diet. Thrombotic response was measured in a photothrombosis model, platelet activation by fluorescence activated cell sorting (FACS) analysis (CD62P) and thrombin generation by the endogenous thrombin potential (ETP). Furthermore, aortic plaque burden and aortic root plaque composition were determined.

Key results:

MPA and MPA + E₂-treated animals showed an aggravated thrombotic response shown by significantly reduced time to stable occlusion. The pro-thrombotic effect of MPA was paralleled by increased ETP whereas platelet activation was not affected. Furthermore, MPA + E₂ reduced the number of cells positive for α-smooth muscle actin and increased hyaluronan in the plaque matrix. Interestingly, total plaque burden was reduced by MPA but unchanged by MPA + E₂.

Conclusion and implications:

Long-term treatment with MPA and MPA + E₂ increased arterial thrombosis despite inhibitory effects of MPA on atherosclerosis in ApoE-deficient mice. Increased thrombin formation, reduced smooth muscle content and remodelling of non-collagenous plaque matrix may be involved in the pro-thrombotic effects. Thus, MPA exhibits differential effects on arterial thrombosis and on atherosclerosis.