Neuroprotective effects of a novel non-receptor-binding estrogen analogue: in vitro and in vivo analysis

BACKGROUND AND PURPOSE

Although estrogens are neuroprotective, hormonal effects limit their clinical application. Estrogen analogues with neuroprotective function but lacking hormonal properties would be more attractive. The present study was undertaken to determine the neuroprotective effects of a novel 2-adamantyl estrogen analogue, ZYC3.

METHODS

Cytotoxicity was induced in HT-22 cells by 10 mmol/L glutamate. 17beta-Estradiol (E2) or ZYC3 was added immediately before the exposure to glutamate. Cell viability was determined by calcein assay. The binding of E2 and ZYC3 to human alpha (ERalpha) and beta (ERbeta) estrogen receptors was determined by ligand competition binding assay. Ischemia/reperfusion injury was induced by temporary middle cerebral artery occlusion (MCAO). E2 or ZYC3 (100 microg/kg) was administered 2 hours or immediately before MCAO, respectively. Infarct volume was determined by 2,3,5-triphenyltetrazolium chloride staining. Cerebral blood flow was recorded during and within 30 minutes after MCAO by a hydrogen clearance method.

RESULTS

ZYC3 significantly decreased toxicity of glutamate with a potency 10-fold that of E2. ZYC3 did not bind to either ERalpha or ERbeta. Infarct volume was significantly reduced to 122.4+/-17.6 and 83.1+/-19.3 mm(3) in E2 and ZYC3 groups, respectively, compared with 252.6+/-15.6 mm(3) in the ovariectomized group. During MCAO, both E2 and ZYC3 significantly increased cerebral blood flow in the nonischemic side, while no significant differences were found in the ischemic side. However, E2 and ZYC3 significantly increased cerebral blood flow in both sides within 30 minutes after reperfusion.

CONCLUSIONS

Our study shows that ZYC3, a non-receptor-binding estrogen analogue, possesses both neuroprotective and vasoactive effects, which offers the possibility of clinical application for stroke without the side effects of estrogens. It also suggests that both the neuroprotective and vasoactive effects of estrogen are receptor independent.

Dietary phytoestrogens and their synthetic structural analogues as calcium channel blockers in human platelets

Phytoestrogens have been shown to inhibit platelet activation by blocking platelet calcium channels. This study examined the effect of several synthetic derivatives of trans-resveratrol, genistein, and daidzein on platelet free intracellular calcium ([Ca2+]i) elevation in thrombin-activated platelets and the possible mechanisms of this inhibitory effect. Studies were conducted on fresh human platelets from healthy volunteers. The fluorescent dye fura-2 was used to monitor [Ca2+]i in platelets. At 10 microM-resveratrol, triacetyl-trans-resveratrol, and trimethoxy-trans-resveratrol produced, respectively, 57 +/- 4%, 40 +/- 4%, and 21 +/- 1% inhibition; genistein, acetylgenistein, and dihydrogenistein produced 51 +/- 10%, 26 +/- 7%, and 16 +/- 2% inhibition, respectively; daidzein and diacetyldaidzein produced 56 +/- 5% and 45 +/- 10% inhibition of thrombin-induced [Ca2+]i elevation. The inhibitory effect was immediate and appeared to directly affect the calcium influx channels. Phytoestrogen action on [Ca2+]i did not cause alteration in nitric oxide signaling. Tyrosine phosphorylation was not involved in the inhibition of [Ca2+]i elevation by phytoestrogens, because the percent inhibition produced by the tyrosine kinase inhibitor genistein and its inactive analogue daidzein on thrombin-induced and thapsigargin-induced [Ca2+]i elevation was not significantly different for either compound at any concentration tested. Structure-activity relationship studies on this limited set of compounds reveal the requirements for the stilbene pharmacophore for the calcium-blocking activity.

Combining xenoestrogens at levels below individual no-observed-effect concentrations dramatically enhances steroid hormone action

The low potency of many man-made estrogenic chemicals, so-called xenoestrogens, has been used to suggest that risks arising from exposure to individual chemicals are negligible. Another argument used to dismiss concerns of health effects is that endogenous steroidal estrogens are too potent for xenoestrogens to contribute significantly to estrogenic effects. Using a yeast reporter gene assay with the human estrogen receptoralpha, we tested these ideas experimentally by assessing the ability of a combination of 11 xenoestrogens to affect the actions of 17ss-estradiol. Significantly, each xenoestrogen was present at a level well below its no-observed-effect concentration (NOEC). To derive accurate descriptions of low effects, we recorded concentration-response relationships for each xenoestrogen and for 17ss-estradiol. We used these data to predict entire concentration-response curves of mixtures of xenoestrogens with 17ss-estradiol, assuming additive combination effects. Over a large range of concentrations, the experimentally observed responses decisively confirmed the model predictions. The combined additive effect of the 11 xenoestrogens led to a dramatic enhancement of the hormone's action, even when each single agent was present below its NOEC. Our results show that not even sub-NOEC levels of xenoestrogens can be considered to be without effect on potent steroidal estrogens when they act in concert with a large number of similarly acting chemicals. It remains to be seen to what degree these effects can be neutralized by environmental chemicals with antiestrogenic activity. Nevertheless, potential human and wildlife responses induced by additive combination effects of xenoestrogens deserve serious consideration.

Metabolism of the endocrine disruptor pesticide-methoxychlor by human P450s: pathways involving a novel catechol metabolite

The metabolism of methoxychlor, a proestrogenic pesticide (endocrine disruptor), was investigated with cDNA expressed human cytochrome P450s and liver microsomes (HLM). In addition to 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(4-methoxyphenyl)ethane (mono-OH-M), 1,1,1-trichloro-2, 2-bis(4-hydroxyphenyl)ethane (bis-OH-M), and 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(3, 4-dihydroxyphenyl)ethane (tris-OH-M), a new metabolite was identified as 1,1,1-trichloro-2-(4-methoxyphenyl)-2-(3, 4-dihydroxyphenyl)ethane (catechol-M; previously assumed to be ring-OH-M) and as a key metabolic intermediate. A novel metabolic route was proposed involving methoxychlor O-demethylation to mono-OH-M, followed by bifurcation of the pathway, both leading to the same final product tris-OH-M: pathway a, mono-OH-M is demethylated to bis-OH-M, followed by ortho-hydroxylation forming tris-OH-M and pathway b, mono-OH-M is ortho-hydroxylated forming catechol-M that is O-demethylated forming tris-OH-M. Among the human cDNA-expressed P450s examined, CYP1A2, 2A6, 2C8, 2C9, 2C19, and 2D6 exhibited mainly O-demethylation, with CYP2C19 being the most catalytically competent. CYP3A4, 3A5, and rat 2B1 catalyzed primarily ortho-hydroxylation of mono-OH-M (CYP3A4 being catalytically the most active) but were weak in O-demethylation. CYP1A1, 1B1, 2E1, and 4A11 demonstrated little or no catalytic activity. CYP2B6 appeared unique, catalyzing effectively both O-demethylation and ortho-hydroxylation. Thus, CYP2B6 demethylated methoxychlor to mono-OH-M and ortho-hydroxylated the mono-OH-M forming catechol-M; however, 2B6 did not appreciably demethylate mono-OH-M or ortho-hydroxylate bis-OH-M, suggesting a narrow substrate specificity. CYP2C19-catalyzed demethylation of methoxychlor, mono-OH-M and catechol-M, demonstrating relatively good substrate affinity (K(m) = 0.23 - 0.41 microM). However, the 3A4 ortho-hydroxylation of mono-OH-M and bis-OH-M exhibited lower affinity, K(m) = 12 and 25 microM, respectively. Thus, a phenolic group seems essential for efficient ortho-hydroxylation, forming catechol-M and tris-OH-M. Inhibition studies with HLM and P450s indicate that CYP2C9 and likely 2C19 are catalysts of methoxychlor-mono-demethylation.

Estradiol, but not raloxifene, improves aspects of spatial working memory in aged ovariectomized rhesus monkeys

Estrogen replacement therapy (ERT) alleviates many postmenopausal symptoms but whether it also benefits cognitive function remains controversial. Further, since estrogen increases the risk of breast and uterine cancers, a new class of compounds, called selective estrogen receptor modulators (SERMs) is being considered as possible alternative to ERT. The SERM raloxifene is particularly interesting because, like estrogen, it improves lipid metabolism and reduces bone loss, without adverse effects on the breast or uterus. Little is known, however, about its effect upon cognitive function. We used a rhesus monkey model of human menopause to examine the effects of ERT and raloxifene on cognitive function. We tested 5 aged females (21-24 years old) ovariectomized long-term (10-16 years) on a battery of age-sensitive tasks, including the Delayed Response (DR), the Delayed Non-Matching-to-Sample-10 min (DNMS-10 min) and the spatial-Delayed Recognition Span Test (DRST). Monkeys were tested 5 days a week on each task for 9 consecutive months, while undergoing treatments with placebo, ethinyl estradiol (EE(2)), and raloxifene in alternating 28-days blocks. EE(2) transiently enhanced the working memory component of the spatial-DRST, but did not affect performance on the other tasks of the battery. Raloxifene had no effect on cognitive performance. These findings indicate that estradiol is able to enhance some aspects of spatial working memory in aged monkeys despite many years of estrogenic deprivation. Further, they suggest that raloxifene does not affect cognitive function after long-term ovarian hormone deprivation.

Estrogen receptor alpha inhibits IL-1beta induction of gene expression in the mouse liver

Estrogens have been suggested to modulate several inflammatory processes. Here, we show that IL-1beta treatment induced the expression of approximately 75 genes in the liver of ovariectomized mice. 17alpha-Ethinyl estradiol (EE) pretreatment reduced the IL-1beta induction of approximately one third of these genes. Estrogen receptor alpha (ERalpha) was required for this inhibitory activity, because EE inhibition of IL-1beta-stimulated gene expression occurred in ERbeta knockout mice, but not in ERalpha knockout mice. EE treatment induced expression of 40 genes, including the transcriptional repressor short heterodimer partner and prostaglandin D synthase, known modulators of nuclear factor-kappaB signaling. However, the ER agonists genistein and raloxifene both inhibited IL-1beta gene induction without stimulating the expression of prostaglandin D synthase, short heterodimer partner, or other ER-inducible genes, indicating that induction of gene expression was not required for ER inhibition of IL-1beta signaling. Finally, the ability of EE to repress IL-1beta gene induction varied among tissues. For example, EE inhibited IL-1beta induction of lipopolysaccharide-induced c-x-c chemokine (LIX) in the liver, but not in the spleen or lung. The degree of EE repression did not correlate with ER expression. cAMP response element binding protein-binding protein (CBP)/p300 levels also varied between tissues. Together, these results are consistent with a model of in vivo ER interference with IL-1beta signaling through a coactivator-based mechanism.

[Low-dose combination oral contraceptives use in women with uterine leiomyomas]

BACKGROUND

To evaluate the effects of the last generation of oral contraceptives (OC) on uterine leiomyomas.

METHODS

DESIGN

non-randomized perspective study on the effects of the last generation of oral contraceptives on uterine myomas during 24 months follow-up.

SETTING

III Unit of Obstetrics and Gynecology, University of Bari.

PARTICIPANTS

between 1999 and 2000 a total of 121 asymptomatic women with only one subserous and/or intramural uterine myoma, having diameter pound 25 mm have been recruited. These patients were divided into two groups: the treatment group was composed of 53 women and was treated with last generation pill containing 20 microgram of ethynilestradiol and 150 microgram of desogestrel or 20 microgram of ethynilestradiol and 75 microgram of gestodene, while the control group was composed of 68 women having no hormonal therapy. In both groups the uterine myoma size (evaluated by transvaginal ultrasonography), the duration of menstrual flow and the hematocrit at the time of recruitment, after 12 months and after 24 months were examined.

RESULTS

Forty-eight (90.6%) women belonging to the study group completed 2 years of OC use; only sixty women (88.2%) belonging to the control group completed the study. The use of the last generation oral contraceptives for 2 years didn't increase significantly uterine myomas size; besides after 24 months there was a significant reduction of more than two days of menstrual flow, and a significant increase of two and a half points of hematocrit. On the contrary, in the control group, we found a significant increase of uterine myoma volume, a not significant increase of menses duration and a not significant reduction of hematocrit.

CONCLUSIONS

The prolonged use of the last generation of oral contraceptives does not affect the uterine myomas volume increase and furthermore it produces a significant reduction in the duration of menstrual flow with a significant increase in hematocrit.

Estrogen promotes early osteoblast differentiation and inhibits adipocyte differentiation in mouse bone marrow stromal cell lines that express estrogen receptor (ER) alpha or beta

Although cells of the osteoblast lineage express functional ERs, direct effects of estrogen on bone formation remain obscure. In the present study, we have investigated estrogen effects on osteoblastic and adipocytic differentiation from a mouse bone marrow stromal cell line, ST-2, which had been manipulated to overexpress either human ER alpha (ST2ER alpha) or ER beta (ST2ER beta). Treatment with bone morphogenetic protein-2 increased alkaline phosphatase activity as well as the number of Oil Red O-positive adipocytes, indicating that bone morphogenetic protein-2 stimulated both osteoblastic and adipocytic differentiation from these bipotential cells. In both ST2ER alpha and ST2ER beta cells, cotreatment with E2 caused enhancement of alkaline phosphatase activity and suppression of lipid accumulation. These effects were completely reversed by an ER antagonist, ICI182780. Therefore, the estrogen regulation occurred in an ER-specific manner but without ER subtype specificity. Moreover, dose response curves of the opposing effects of estrogen on osteoblastogenesis and adipogenesis formed an apparent mirror image, consistent with a reciprocal regulation of differentiation into the two cell lineages. These results demonstrate that estrogen directly modulates differentiation of bipotential stromal cells into the osteoblast and adipocyte lineages, causing a lineage shift toward the osteoblast. Such effects would lead to direct stimulation of bone formation and thereby contribute to the protective effects of estrogen on bone.

Estrogenic activity of the phytoestrogens naringenin, 6-(1,1-dimethylallyl)naringenin and 8-prenylnaringenin

Chemically synthesized naringenin derivatives, identical to natural occurring compounds, were tested for their estrogenic activity using two independent estrogen screening assays. Using a yeast based estrogen receptor assay, strong estrogenic activities were demonstrated for 6-(1,1-dimethylallyl)naringenin and 8-prenylnaringenin, while the parent compound naringenin did not show recognizable estrogenic activity. In MVLN cells, a bioluminescent MCF-7-derived cell line, the estrogenic activity of 8-prenylnaringenin and 6-(1,1-dimethylallyl)naringenin was detected at concentrations of 10(-6) M and 5 x 10(-6) M respectively. Naringenin demonstrated estrogenic activity but only at a concentration of 10(-5) M. These estrogenic effects are mediated by the ER, as the antiestrogen 4-hydroxytamoxifen inhibited these activities. In summary, this study provides the further confirmation that 8-prenylnaringenin demonstrates high estrogenic activity, and demonstrated for the first time for 6-(1,1-dimethylallyl)naringenin a reasonable high estrogenic activity, while naringenin exhibit low or no estrogenic activity.

Detection of MDM2 alterations in cultured human hepatocytes treated with 17beta-estradiol or 17alpha-ethinylestradiol

BACKGROUND

Preneoplastic and neoplastic lesions of the liver are suspected to arise as a result of estrogen treatment. Here we present the first report on the modulational effects of the steroids 17beta-estradiol (E2) and 17alpha-ethinylestradiol (EE2) on oncogene MDM2 in human hepatocytes.

MATERIALS AND METHODS

Collagen-embedded cultures of hepatocytes stimulated with different E2/EE2 concentrations were analyzed by immunocytochemistry, RT-PCR and sequencing for MDM2 protein/mRNA expression, MDM2 mRNA splicing and MDM2 gene mutation.

RESULTS

The hepatocytes responded to stimulation with steroid E2/EE2 concentrations from 1-100 nmol/l with the overexpression of MDM2 protein while non-stimulated cells were negative. Stimulation with 1 nmol/l E2 and 10-100 nmol/l EE2 induced MDM2 splicing variants. Hepatocytes treated with 100 nmol/l E2 contained full-length MDM2 mRNA carrying a new type of MDM2 gene mutation. Unstimulated hepatocytes revealed neither mRNA splicing nor alteration of the MDM2 genes.

CONCLUSION

The data show that steroid hormones are involved in the induction of MDM2 alterations in benign human hepatocytes. We speculate that some of the alterations may influence MDM2 function, thus possibly favouring genesis of liver changes.

Impaired estrogen-induced negative feedback on gonadotropin secretion in patients with gonadotropin-secreting and nonfunctioning pituitary adenomas

BACKGROUND

Several in vitro studies suggest that gonadotropin-secreting pituitary adenomas (Gn-omas) and non functioning pituitary adenomas (NFPA) originate from gonadotroph cells. Patients with Gn-oma and NFPA frequently show abnormal gonadotropin response to TRH. The aim of the study was to investigate whether the estrogen-induced negative feedback is operating in either patients with Gn-oma or NFPA.

MATERIALS AND METHODS

Serum gonadotropin levels were evaluated at 24 h after ethinylestradiol administration (1 mg per os; EE2 test) in seven patients with a diagnosis of Gn-oma, based on the presence of high follicle-stimulating hormone (FSH) and/or lutenising hormone (LH) levels with normal or high levels of sex steroids, in 22 patients with NFPA with normal or low levels of gonadotropin and sex steroids, and 30 sex- and age-matched healthy subjects. A normal response to EE2 test was arbitrarily defined as a serum LH and FSH decrease of at least 40 and 30% below basal levels.

RESULTS

Among patients with Gn-oma, only one had a normal FSH inhibition and another, a normal LH inhibition. Among the 22 patients with NFPA, the EE2 test caused a normal FSH or LH reduction in 10 and 15, respectively, while a normal reduction of both FSH and LH was observed in nine.

CONCLUSIONS

The study demonstrates that estrogen-induced negative feedback of gonadotropin secretion is disrupted in almost all patients with Gn-oma and in half of those with NFPA. This defective feedback is reminiscent of the resistance to thyroid hormones and glucocorticoids observed in patients with thyroid-stimulating hormone- (TSH-) and adrenocorticotropic hormone- (ACTH-)secreting adenomas, respectively.

Synthesis and cytotoxic activity of new 2,4-diaryl-4H,5H-pyrano[3,2-c]benzopyran-5-ones on MCF-7 cells

A series of eight halogenated 2,4-diaryl-4H,5H-pyrano[3,2-c]benzopyran-5-ones have been synthesized, characterized and their stereochemistry determined. In a second stage of our work, the reported molecules were tested for their antiproliferative activity on MCF-7 breast carcinoma cells. Pharmacological results were compared with those of diethylstilbestrol (DES), an estrogen, as well as ICI 182,780, a pure antiestrogen. Then, these derivatives were evaluated for their capacity to activate the transcription of a reporter gene and for their affinity for human recombinant estrogen receptors alpha (hER alpha). These results were compared with those of coumestrol, a phytoestrogen structurally close to 2,4-diaryl-4H,5H-pyrano[3,2-c]benzopyran-5-ones, and with RU 58668, a pure antiestrogen. Although these derivatives exhibit a significant antiproliferative activity higher than that of ICI 182,780, neither of them displayed a significant estrogenicity or an affinity for hER alpha. Such results may suggest that their antiproliferative activity is not dependent of an antiestrogenic response.

Effect of two oral contraceptives containing ethinylestradiol and levonorgestrel on serum and urinary surrogate markers of endothelial function

OBJECTIVE

To investigate the effect of two oral contraceptives containing 0.02 mg ethinylestradiol and 0.1 mg levonorgestrel (Formulation A, Leios), and the other containing 0.03 mg ethinylestradiol and 0.15 mg levonorgestrel (Formulation B, Stediril 30) on the serum and urinary concentrations of various markers reflecting the status of vascular tone and development of atherosclerosis. The adhesion molecules E-selectin, inter-cellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and homocysteine were included as serum markers and cGMP, prostacyclin and its antagonist thromboxane as urinary markers.

METHODS

In a comparative, double-blind, randomized, parallel group study, 34 women received formulation A and 33 women formulation B. Serum samples were collected before treatment and after 3, 6 and 12 cycles. Nocturnal urine was collected before treatment and during cyclic treatment after 3 and 12 cycles. Serum and urinary markers were measured by enzyme immunoassays.

RESULTS

E-selectin levels were significantly reduced by both contraceptives after 3, 6 and 12 months compared to pretreatment levels. A slight increase in ICAM concentrations was observed for both contraceptives after 6 cycles, but this fell to pretreatment levels after 12 cycles. VCAM values were significantly lowered after 3, 6 and 12 months by both contraceptives. No significant changes were found in serum levels of homocysteine. No significant differences were found between treatment groups for the serum markers. Both contraceptives significantly enhanced urinary cGMP excretion after 12 cycles. The prostacyclin metabolite remained unchanged in the case of both formulations, but the excretion of the thromboxane metabolite was significantly decreased after 12 cycles. Thus, the ratio of prostacyclin to thromboxane, decisive for the resulting effect on vascular tone, increased significantly.

CONCLUSION

These results indicate that the low-dose oral contraceptives can reduce the production of adhesion molecules which play a crucial role in the early stages of atherosclerosis. In addition, these contraceptives can shift the balance of vascular tone towards dominance of vasodilatory substances after 12 cycles of treatment. Thus, the positive influence of these contraceptives on the various markers investigated may improve vascular tone and impede development of atherosclerosis.

Antioxidant effects of phyto-and synthetic-estrogens on cupric ion-induced oxidation of human low-density lipoproteins in vitro

Oxidation of low-density lipoproteins (LDL) promotes the formation of atherosclerotic plaques. Estrogenic compounds (EC) from foods and other natural products, and synthetic estrogenic compounds (SECs) may prevent heart disease by inhibiting LDL oxidation. In the present study, we tested the antioxidant capacities of two phytoestrogens, daidzein (DAI) and genistein (GEN), and four SECs, (+)- and (-)-Z-bisdehydrodoisynolic acid (ZBDDA), and (+)- and (-)-hydroxy-allenoic acid (HAA), on isolated human LDL subjected to oxidation by cupric sulfate. The effects of these estrogenic compounds on the kinetics of conjugated diene formation in LDL undergoing oxidation were evaluated with a lag-time assay with continuous monitoring of absorbance at 234 nm. Lag-time data revealed that (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA had similarly stronger antioxidant activities than either GEN or DAI. We also found that (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA strongly inhibited the formation of Cu+-induced thiobarbituric acid reactive substances (TBARS) in LDL, and that GEN and DAI were less effective for inhibiting LDL lipid peroxidation. Finally, electrophoretic evaluation suggested that (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA protected the apolipoprotein B-100 of LDL against oxidation better than did GEN or DAI. In summary, the four SECs, (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA, were more potent antioxidants than the phytoestrogens, DAI and GEN.

Short-term effects of new synthetic conjugated estrogens on biochemical markers of bone turnover

Fifty early postmenopausal women completed a double-blind, placebo-controlled study evaluating the short-term effect of a new synthetic conjugated estrogens formulation (Cenestin) on bone turnover. Subjects were randomized to either 0.625 mg/day synthetic conjugated estrogens (n = 35) or placebo (n = 15) for 3 months. Biochemical markers were evaluated at baseline (three measurements at Days -2, -1, and 0) and Days 30, 60, and 90. Bone resorption assessed by urinary NTX (-31.4%) and serum CTX (-34.2%) was significantly (p < 0.01) decreased in the estrogen-treated group compared to the placebo group within 1 month of treatment. The mean percent decreases for urinary NTX from baseline during estrogen treatment were -58.0% (p < 0.01 vs. placebo) and -34.1% (ns) after 2 and 3 months, respectively. For serum CTX, the percent changes from baseline were -17.6% (p < 0.01) and -16.9% (p < 0.01) at 2 and 3 months, respectively. As expected, the decrease of both bone formation markers (bone ALP and PINP) was delayed compared to that of bone resorption and significant (p < 0.05-0.01) only after 2 months of treatment in the estrogen-treated group compared to the placebo group. Synthetic conjugated estrogens significantly decreased bone resorption and bone formation comparable to that previously reported for estrogen treatments proven efficacious in preventing postmenopausal bone loss.

Oestrogens and puberty

Oestrogens induce the development of female reproductive tissues. Endogenous human oestrogens include oestradiol, oestrone and oestriol. Oestrogen signalling in target tissues is dependent on the tissue concentration of oestrogen and the interaction of oestrogen receptors with an array of cell-specific co-regulator proteins. The diverse mechanisms of oestrogen signalling are complex and incompletely understood. In puberty, oestrogen is derived from both gonadal and peripheral sources. Originally, oestrogen was only thought to drive feminization in females; now, oestrogen is known to be important for pubertal development of males as well. Oestrogen is required for normal maturation of the neuroendocrine-gonadal axis and bone in both sexes, and a variety of other tissues are also responsive to oestrogen. Abnormal puberty can be associated with either excessive or inadequate oestrogen production. Girls deficient in oestrogen should receive replacement in physiological doses. Aromatase inhibitors and anti-oestrogens may prove to be useful therapeutic tools in some types of abnormal puberty.

Comparison of cycle control with a combined contraceptive vaginal ring and oral levonorgestrel/ethinyl estradiol

OBJECTIVE

The purpose of this study was to compare cycle control and tolerability of the NuvaRing (NV Organon, Oss, The Netherlands), a novel combined contraceptive vaginal ring, with a standard combined oral contraceptive pill.

STUDY DESIGN

Healthy women aged 18 to 40 years who requested contraception received either NuvaRing or a combined oral contraceptive containing 30 microg ethinyl estradiol and 150 microg levonorgestrel for 6 cycles in 3 similarly designed studies. Each cycle comprised 3 weeks of ring or pill use, followed by 1 ring- or pill-free week.

RESULTS

Two hundred forty-seven women began the studies, 121 women with NuvaRing and 126 women with the combined oral contraceptive. Withdrawal bleeding occurred in virtually all cycles in both groups. In the NuvaRing groups, the incidence of irregular bleeding was < or =5% in all cycles; this was lower than the combined oral contraceptive groups (5.4%-38.8%). Furthermore, the incidence of a normal intended bleeding pattern was significantly higher in the NuvaRing groups than in the combined oral contraceptive groups (P <.01). Both contraceptives were well tolerated.

CONCLUSION

NuvaRing has excellent cycle control and is well tolerated.

Effects of 3-phenyl-4-[[4-[2-(1-piperidinyl)ethoxy]phenyl]methyl]- 2H-1-benzopyran-7-ol (CHF 4056), a novel nonsteroidal estrogen agonist/antagonist, on reproductive and nonreproductive tissue

We have discovered a new, nonsteroidal, estrogen agonist/antagonist, 3-phenyl-4-[[4-[2-(1-piperidinyl)ethoxy]phenyl] methyl]-2H-1-benzopyran-7-ol (CHF 4056). The aim of this study was to determine the effects of CHF 4056 on a series of parameters (body weight, uteri, serum cholesterol, and bones) that were previously shown to be sensitive to estrogens and to selective estrogen receptor modulators (SERMs). CHF 4056 is a benzopyran derivative that binds with high affinity to the human estrogen receptors alpha and beta (dissociation constant K(i) of 0.041 and 0.157 nM, respectively). In immature rats, CHF 4056 induced a full estrogen antagonism (half-maximal efficacious dose = 0.33 mg/kg x day p.o.) coupled with a lack of uterine stimulatory activity, whereas the structurally related SERM levormeloxifene demonstrated a maximal partial agonist effect of approximately 65% that of 17alpha-ethynyl estradiol (EE2). In ovariectomized (OVX) rats, CHF 4056 (0.1-1 mg/kg x day p.o. for 4 weeks) significantly reduced OVX-induced bone loss in the lumbar spine L1-4 and OVX-induced increase in serum osteocalcin. These protective effects on bone tissue were comparable with those of 0.1 mg/kg x day EE2. In the same experimental conditions, serum cholesterol was significantly lower in the CHF 4056-treated animals, compared with vehicle-treated OVX rats. In line with the results observed in immature rats, also in OVX rats CHF 4056 diverged dramatically from EE2 and levormeloxifene in its lack of significant estrogenic effects on uterine tissue. In conclusion, CHF 4056 is a new SERM that produces beneficial effects on bone and cholesterol levels, while maintaining antagonist effects on the uterus.

Transdermal contraception: evaluation of three transdermal norelgestromin/ethinyl estradiol doses in a randomized, multicenter, dose-response study

OBJECTIVE

The objective of this study was to identify the dose for a contraceptive patch that provides a predetermined level of ovulation suppression and cycle control and that is well tolerated.

STUDY DESIGN

In this randomized study, 610 subjects received 10-, 15-, or 20-cm(2) patch dose sizes (20-cm(2), Ortho Evra/Evra) (Janssen Pharmaceutica, NV Belgium) or Ortho-Cyclen/Cilest (Janssen Pharmaceutica, NV Belgium) for up to 4 cycles. As with Ortho-Cyclen, patch regimens included 21 dosing days (3 consecutive 7-day patches) followed by 1 dose-free week.

RESULTS

The patch regimens demonstrated a dose-response for ovulation suppression and cycle control. Presumed ovulation, determined on the basis of serum progesterone concentrations > or = 3 ng/mL in cycles 1 and 3, occurred in 6.2% (Ortho Evra) and 7.2% (Ortho-Cyclen) of subjects. At cycle 3, breakthrough bleeding/spotting was reported by 10.5% and 15.0% of subjects, respectively. Compliance with each patch was superior to that with Ortho-Cyclen (all P <.001). All regimens had safety profiles typical of oral contraceptives.

CONCLUSION

The 20-cm(2) patch (Ortho Evra) provided ovulation suppression, cycle control, and safety similar to that of Ortho-Cyclen, with significantly better compliance.

Different effects of oral contraceptives containing levonorgestrel or desogestrel on plasma lipoproteins and coagulation factor VII

OBJECTIVE

The objective of the study was to compare the effects of two different combined oral contraceptives on levels of plasma lipoproteins and coagulation factor VII.

STUDY DESIGN

A prospective randomized crossover study was undertaken. Thirty-five women were treated with combined oral contraceptives containing the same amount of ethinyl estradiol and either levonorgestrel or desogestrel. Levels of plasma lipoproteins and factor VII were determined before and after 2 months of treatment with each preparation.

RESULTS

Levels of high-density lipoprotein cholesterol were increased significantly with treatment with ethinyl estradiol/desogestrel when compared with baseline and treatment with ethinyl estradiol/levonorgestrel. A significant rise in plasma triglyceride levels was obtained with both preparations, although the increase was more pronounced with ethinyl estradiol/desogestrel. Plasma concentrations of factor VII mass concentration and activated factor VII were increased significantly only with ethinyl estradiol/desogestrel.

CONCLUSION

The rise in concentrations of high-density lipoprotein cholesterol may be advantageous, whereas the combined elevations of plasma triglyceride and factor VII levels obtained with ethinyl estradiol/desogestrel may reflect a hypercoagulable state.

Phytosterols act as endocrine and metabolic disruptors in the European polecat (Mustela putorius)

Phytosterols or plant sterols (PS) are consumed as natural remedies and margarines by the general population in developed countries to lower elevated serum cholesterol levels. They are also present in high concentrations in pulp mill effluents. The aim of the study was to screen the endocrine and metabolic parameters of the European polecat (Mustela putorius) for the effects of PS. The results showed an increase in the plasma estradiol and TH levels with no effects on the hypophyseal regulatory hormones. The plasma ghrelin levels decreased. PS also affected intermediary metabolism. The liver glycogen content increased as did the kidney glucose-6-phosphatase activity. The liver lipase esterase activity, on the other hand, decreased due to PS. In serum lipids the total cholesterol did not change, but the low-density lipoprotein levels increased and the high-density lipoprotein-cholesterol ratio decreased. PS had widespread previously unreported effects on the physiology of the polecat. The multiple effects indicate the need of a thorough risk assessment of the effects and interactions of PS.

Arzoxifene, a new selective estrogen receptor modulator for chemoprevention of experimental breast cancer

Arzoxifene ([6-hydroxy-3-[4-[2-(1-piperidinyl)-ethoxy]phenoxy]-2-(4-methoxyphenyl)]benzo[b]thiophene) is a selective estrogen receptor modulator (SERM) that is a potent estrogen antagonist in mammary and uterine tissue while acting as an estrogen agonist to maintain bone density and lower serum cholesterol. Arzoxifene is a highly effective agent for prevention of mammary cancer induced in the rat by the carcinogen nitrosomethylurea and is significantly more potent than raloxifene in this regard. Arzoxifene is devoid of the uterotrophic effects of tamoxifen, suggesting that, in contrast to tamoxifen, it is unlikely that the clinical use of arzoxifene will increase the risk of developing endometrial carcinoma.