Effect of estradiol and selected antiestrogens on pro- and antioxidant pathways in mammalian uterus

The involvement of estrogen receptors α and β in the in vitro effects of 17β-estradiol on secretory profile of peritoneal macrophages from naturally menopausal female and middle-aged male rats

The systemic and extra- gonadal levels of 17β-estradiol (E2) change during aging, and affect the expression of estrogen receptors (ERs) in the immune cells of both females and males. The age-related cessation of ovarian function in females, as well as the tissue-specific expression of enzyme aromatase (estrogen synthase which significantly rises with the advancing age) in both males and females, both determine the concentration of E2 to which immune cells may be exposed. The present study was set up to investigate the direct influence of E2 in vitro on the secretory profile of peritoneal macrophages from young and naturally menopausal female rats, and from young and middle-aged male rats. The involvement of receptor(s) responsible for mediating the effects of E2 in vitro was examined by use of antagonists specific for ERα or ERβ. Whereas in macrophages from young female rats E2 treatment diminished interleukin (IL)-1β secretion, it increased it in young males, and the middle-aged females. The in vitro E2 treatment increased tumor necrosis factor (TNF)-α release by macrophages from young rats of both sexes, while it increased macrophage IL-6 release independently of both sex and age. At the same time, E2 decreased hydrogen peroxide (H₂O₂) production in macrophages from females, and increased it in male rats of both ages, whereas it diminished nitric oxide (NO) release in all experimental groups. Inspite of the sex- and age-specific effects of E2 on macrophage urea release, E2 did not affect the NO/urea ratio in macrophages from female rats, and diminished it in macrophages from both young and middle-aged male rats. Independently of the sex and age, E2 stimulated the release of inflammatory cytokines predominantly via macrophage ERα, and inhibited the IL-1β release in young females via ERβ. In contrast, E2 increased macrophage H₂O₂ and urea production by activating ERβ, but diminished their release via ERα. Our study may contribute to better understanding of the complex role(s) that E2 may play in innate immunity during aging, and that are dependent of sex.

Anti-inflammatory, Anti-estrogenic, and Anti-implantation Activity of Bergia suffruticosa (Delile) Fenzl

BACKGROUND

Bergia suffruticosa (Delile) Fenzl (Syn. Bergia odorata Edgew) (Elatinaceae family) is used traditionally to repair bones and is applied as a poultice on sores. It is also used for stomach troubles and as an antidote to scorpion stings. So far, very little scientific work has been reported to validate its ethnomedical uses in the alleviation of pain, bone repair, etc.

OBJECTIVE

This study was designed to explore the anti-inflammatory and anti-implantation potential of n-hexane extract of B. suffruticosa whole plant in mice along with identification of its chemical constituents.

MATERIALS AND METHODS

n-Hexane extract of B. suffruticosa whole plant was screened for acute and chronic anti-inflammatory activity followed by an anti-estrogenic activity. Eventually, n-hexane extract was tested for anti-implantation activity by exploiting markers of uterine receptivity, lipid peroxidation, and superoxide enzyme activity. The extract was administered orally at a dose of 100 mg/kg body weight in each study.

RESULTS

Thin layer chromatography fingerprint profile of n-hexane extract revealed the presence of lupeol and β-sitosterol. The n-hexane extract reduced the edema by 80% in acute inflammation, whereas it reduced edema to 75% on the 5(th) day in chronic inflammation. The n-hexane extract reduced elevated malonaldehyde level from 6 to 2.5 nmol/g × 10(-5) and increased superoxide dismutase enzyme activity from 0 to 350 units/g in treated animals on the 5(th) day of pregnancy. Moreover, extract decreased uterine weight from 0.33 to 0.2 g in estradiol treated animals.

CONCLUSION

These results indicate that n-hexane extract of B. suffruticosa is having potent anti-inflammatory, anti-estrogenic, and anti-implantation activity. This is the first report of all the pharmacological activities of B. suffruticosa mentioned above.

SUMMARY

TLC fingerprint profile of n-hexane extract of Bergia suffruticosa whole plant revealed the presence of lupeol and β-sitosteroln-Hexane extract showed in vivo anti-inflammatory activity in both acute and chronic model of inflammation in ratsn-Hexane extract possess significant anti-estrogenic activityn-Hexane extract altered the levels superoxide anion radical and superoxide dismutase enzyme activity during the blastocyst implantationAnti-implantation activity of n-hexane extract is attributed to its anti-inflammatory and anti-estrogenic potential. Abbreviations used: TLC: Thin layer chromatography; LPO: Lipid peroxidation; SOD: Superoxide dismutase; B. suffruticosa: Bergia suffruticosa; TNF-α: Tumor necrosis factor-α; NO: Nitric oxide; IL-1: Interleukin-1; LIF: Leukemia inhibitory factor; CSF-1: Colony-stimulating factor; COX: Cyclooxygenase; SDS: Sodium dodecyl sulfate; IAEC: Animal House Ethics Committee; CPCSEA: Committee for the Purpose of Control and Supervision of Experiments on Animals; HBSS: Hank's balanced salt solution; MDA: Malonaldehyde; and TBA: Thiobarbituric acid.

The periovulatory endocrine milieu affects the uterine redox environment in beef cows

BACKGROUND

In cattle, recent studies have shown positive associations between pre-ovulatory concentrations of estradiol (E2), progesterone (P4) at early diestrus and fertility. However, information on cellular and molecular mechanisms through which sex steroids regulate uterine function to support early pregnancy is lacking. Based on endometrial transcriptome data, objective was to compare function of the redox system in the bovine uterus in response to different periovulatory endocrine milieus.

METHODS

We employed an animal model to control growth of the pre-ovulatory follicle and subsequent corpus luteum (CL). The large follicle-large CL group (LF-LCL, N=42) presented greater levels of E2 on the day of GnRH treatment (D0; 2.94 vs. 1.27 pg/mL; P=0.0007) and P4 at slaughter on D7 (3.71 vs. 2.62 ng/mL, P=0.01), compared with the small follicle-small CL group (SF-SCL, N=41). Endometrium and uterine washings (N=9, per group) were collected for analyses of variables associated with the uterine redox system.

RESULTS

The SF-SCL group had lower endometrial catalase (0.5 vs. 0.79 U/mg protein, P<0.001) and glutathione peroxidase (GPx; 2.0 vs. 2.43 nmol β-nicotinamide adenine dinucleotide phosphate reduced/min/mg protein, P=0.04) activity, as well as higher lipid peroxidation (28.5 vs. 17.43 nmol malondialdehyde/mg of protein, P<0.001) and superoxide dismutase (SOD) activity (44.77 vs. 37.76 U; P=0.04). There were no differences in the endometrial reactive species (RS) or glutathione (GSH) concentrations between the groups. The uterine washing samples showed no differences in the concentrations of RS or GSH or in total SOD activity (P>0.1). Additionally, catalase, GPx4, SOD1 and SOD2 gene expression was lower in the SF-SCL group than in the LF-LCL group.

CONCLUSIONS

We concluded that the intrauterine environment of cows from the LF-LCL group exhibited higher antioxidant activity than that of the cows from the SF-SCL group. We speculate that uterine receptivity and fertility are associated with an optimal redox environment, such as that present in the animals in the LF-LCL group.

Antiestrogenic and Anti-Inflammatory Potential of n-Hexane Fraction of Vitex negundo Linn Leaf Extract: A Probable Mechanism for Blastocyst Implantation Failure in Mus musculus

The anti-implantation potential of different fractions of Vitex negundo Linn leaf extract was evaluated in female Swiss Albino mice. Animals from different groups were dosed orally either with 0.2% agar (vehicle) or with fractions of V. negundo leaf extract (n-hexane, chloroform, n-butanol, and remnant fractions) at 10:00 a.m., from day 1 to day 6 of pregnancy. The pregnant females from each group were sacrificed on different days of pregnancy (n = 6), and uterus was excised and used for estimation of lipid peroxidation and assay of superoxide dismutase activity as a marker for blastocyst implantation. Animals treated with n-hexane fraction showed altered level of superoxide anion radical and superoxide dismutase activity as compared to control animals. The probable mechanism by which this extract exhibits inhibition of blastocyst implantation is through the anti-inflammatory and antiestrogenic potential.

Thioredoxin-mediated redox regulation of resistance to endocrine therapy in breast cancer

Resistance to endocrine therapy in breast carcinogenesis due to the redox regulation of the signal transduction system by reactive oxygen species (ROS) is the subject of this review article. Both antiestrogens and aromatase inhibitors are thought to prevent cancer through modulating the estrogen receptor function, but other mechanisms cannot be ruled out as these compounds also block metabolism and redox cycling of estrogen and are free radical scavengers. Endocrine therapeutic agents, such as, tamoxifen and other antiestrogens, and the aromatase inhibitor, exemestane, are capable of producing ROS. Aggressive breast cancer cells have high oxidative stress and chronic treatment with exemestane, fulvestrant or tamoxifen may add additional ROS stress. Breast cancer cells receiving long-term antiestrogen treatment appear to adapt to this increased persistent level of ROS. This, in turn, may lead to the disruption of reversible redox signaling that involves redox-sensitive phosphatases, protein kinases, such as, ERK and AKT, and transcription factors, such as, AP-1, NRF-1 and NF-κB. Thioredoxin modulates the expression of estrogen responsive genes through modulating the production of H2O2 in breast cancer cells. Overexpressing thioredoxine reductase 2 and reducing oxidized thioredoxin restores tamoxifen sensitivity to previously resistant breast cancer cells. In summary, it appears that resistance to endocrine therapy may be mediated, in part, by ROS-mediated dysregulation of both estrogen-dependent and estrogen-independent redox-sensitive signaling pathways. Further studies are needed to define the mechanism of action of thioredoxin modifiers, and their effect on the redox regulation that contributes to restoring the antiestrogen-mediated signal transduction system and growth inhibitory action.

Lactational hexavalent chromium exposure-induced oxidative stress in rat uterus is associated with delayed puberty and impaired gonadotropin levels

Hexavalent chromium (CrVI) is a transition element utilized in many fields of modern industries. CrVI is a reproductive metal toxicant that can traverse the placental barrier and cause a wide range of fetal effects. Therefore, the present study was carried out to determine the CrVI-induced utero-toxicity. In the present study, lactating rats received drinking water containing CrVI (50 mg/L and 200 mg/L) from postnatal days (PND) 1-21. During PND 1-21, the pups received CrVI via the mother's milk. Pups from both control and treatment groups were continued on regular diet and water from PND-21 onwards and euthanized on PND-45 and -65. Specific activities antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) were estimated. Hydrogen peroxide (H₂O₂), lipid peroxidation (LPO) and serum gonadotropins viz. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) were also assayed. Specific activities of SOD, CAT, GPX, GR and GST and serum testosterone and progesterone were significantly decreased, while H₂O₂, LPO and serum FSH was increased in 50-parts per million (ppm) and 200 ppm-treated rats in an age-dependent manner. These results suggest that lactational CrVI exposure induces oxidative stress in rat uterus by decreasing antioxidant enzymes, which were associated with delayed puberty and altered steroids and gonadotrophin levels.

Regulation of key antioxidant enzymatic systems in the sheep endometrium by ovarian steroids

Reactive oxygen species (ROS) and their control by antioxidant enzymes are involved in the physiology of the female reproductive system. Thus, it is important to understand the regulation of key antioxidant enzymatic pathways. The roles of estrogen and progesterone in regulating the physiological functions of the endometrium have become central dogma. We examined the effects of ovarian steroids on superoxide dismutases (SOD1 and SOD2), catalase (CAT), glutathione peroxidase (GPX), and glutathione reductase (GSR) activities in the aglandular caruncular and glandular inter-caruncular endometrial tissues of ovariectomized (OVX) ewes and in OVX ewes treated with estradiol (E2), progesterone (P4), or both hormones according to schedules designed to produce physiological changes of these hormones during the estrous cycle. The activities SOD2, CAT, GPX and GSR in both endometrial tissues were unaffected by P4 treatment. The activity of SOD1 in the aglandular tissue was unaffected by P4 treatment, however this treatment decreased SOD1 activity in the glandular tissue (P < 0.01). Treatment with E2, either alone or in combination with P4, decreased SOD1 (P < 0.01), CAT (P < 0.01) and GPX (P < 0.05) activities in both endometrial tissues. The activity of GSR decreased only in the glandular tissue (P < 0.05) after E2 treatment, either alone or in combination with P4. No change in SOD2 activity was detected in both endometrial tissues after administration of E2, P4 or both hormones. This study provides the first firm evidence for the role of ovarian steroid hormones in the regulation of the activities of key antioxidant enzyme in the endometrium of female mammals.

Estrogen-induced generation of reactive oxygen and nitrogen species, gene damage, and estrogen-dependent cancers

In addition to the direct effect of estrogen on mitochondria and the redox cycling of catechol estrogen, estrogen-induced proinflammatory cytokines, such as interleukin-1 beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha), also generate reactive oxygen and nitrogen species (RO/NS). Different cellular signaling pathways may operate in response to varying levels of estrogen-induced RO/NS, leading to genotoxic damage, cell apoptosis, or cell growth. At high levels of RO/NS, cells receiving genotoxic insults, if not repaired, may engage the apoptotic pathways. There is increasing evidence supporting that estrogen-induced alterations in the genome of cells is produced by oxidative attack. Furthermore, ROS generated by estrogen exposure and/or active metabolites of estrogen in combination with receptor-mediated proliferation of genetically damaged cells may be involved in tumor development. This view is supported by the findings of DNA modifications produced in vitro or in vivo by natural and synthetic estrogens in the target organs of cancer both in experimental models and in humans. Interaction of estrogen-induced oxidants and estrogen metabolites with DNA was shown to generate mutations in genes. Cotreatment with an inhibitor of IL-1beta and TNF-alpha synthesis, pentoxifylline, decreased stilbene estrogen-induced levels of myeloperoxidase (MPO), 8-hydroxydeoxyguanosine formation, and gene mutations, and prevented stilbene estrogen-induced lesions. Stable MCF-7 clones overexpressing IL-1beta resulted in a high level of IL-1beta peptide secretion undergoing cell apoptosis, and an elevated level of p53 protein in response to high oxidative stress when compared to nontransfected cells, whereas MCF-7 clones overexpressing IL-1beta that resulted in a moderate level of IL-1beta secretion stimulated the clonal expansion of MCF-7 and TM3 cells. Estrogen-induced MCF-7 cell growth and cyclin D1 expression were suppressed by antioxidants and mitochondrial blockers. These studies support that in addition to ovarian estrogen-mediated ER signaling, mitogenic signals may also come from estrogen-induced RO/NS. Further validation of this concept that the concentration of the RO/NS within the cellular microenvironment determines its stimulatory or inhibitory growth signals as well as its genotoxic effects regulating the growth of estrogen-dependent tumors may result in novel preventive strategies.

Comparison of estrogen-derived ortho-quinone and para-quinol concerning induction of oxidative stress

Ortho-quinones formed from catechol estrogens are considered prooxidants due to the production of superoxide radical anions through redox cycling via semiquinones. Para-quinols have been identified as novel metabolites of and as the major products of hydroxyl-radical scavenging by estrogens. Cycling of these compounds has also been discovered, because they are converted back to the parent estrogen via reductive aromatization in vitro and in vivo. We hypothesized that, unlike ortho-quinones, para-quinols do not induce oxidative stress due to this cycling. Like the estrogen itself, the 17beta-estradiol-derived para-quinol (10beta,17beta-dihydroxyestra-1,4-diene-3-one) did not induce oxidative stress, as the rate of hydrogen peroxide production during the incubations of the compounds in various tissue homogenates was not significantly different from that of the control experiments performed without the addition of a test compound. We also confirmed that the estrogen metabolite estra-1,5(10)-dien-3,4,17-trione (estrone 3,4-quinone) was a profound prooxidant due to redox cycling, especially in uterine tissue. Therefore, we concluded that para-quinols do not induce oxidative stress.

Antioxidant agents transiently inhibit aneuploidy progression in Li-Fraumeni cell strains

Cultured human fibroblasts from patients with the Li-Fraumeni syndrome (LFS) containing heterozygous germline p53 mutations develop genomic instability, loss of the wild-type p53 allele, and immortalize at a low frequency. Since genomic instability and phenotypic change are observed in presenescent cells without specific exposure to mutagens, we hypothesized that reactive oxygen species (ROS) produced during normal cell metabolism coupled with deficient p53 dependent DNA damage repair pathways make a significant contribution to immortalization related parameters. To test this hypothesis, three LFS cell strains (MDAH087, MDAH041, and MDAH172) were exposed to five compounds with demonstrated antioxidant properties for > or =85% of their proliferative lifetimes. Agent effectiveness was evaluated every five passages during subculturing by analyzing aberrant chromosome number, anchorage independent growth (AIG), and p16 expression. Cytogenetic analysis revealed that of the five antioxidants tested, only oltipraz was significantly effective in transiently delaying a shift to hyperdiploidy in all three cell strains. However, treated populations were not different from untreated controls when measured in the last 10% of their lifetimes. Additionally, no differences were observed in AIG and p16 expression in antioxidant treated or untreated control populations. Epidemiological studies, in vitro and in vivo experimentation and some clinical trials have suggested that antioxidants may inhibit the progression of cancer and other mutation related diseases. This data, however, does not support the hypothesis that the antioxidants tested have chemopreventive potential in cancers that develop genomic instability due to loss of p53.

Male genital tract antioxidant enzymes--their ability to preserve sperm DNA integrity

Male germ cells are unique because they lose a bulk of their cytoplasm as cytoplasmic droplets when they develop, leading to a decrease in endogenous antioxidant and hence a dependence on extracellular antioxidant system to overcome oxidative stress. Spermatozoa are particularly vulnerable to oxidative stress because their plasma membrane is rich in polyunsaturated fatty acids and membrane-bound NADPH oxidase. To protect spermatozoa from oxidative attack, an optimal amount of reactive oxygen species is maintained by balancing the reactive oxygen species generated during sperm maturation in the epididymidis and antioxidants in secretions of the male reproductive tract. The male accessory sex glands secretions have been shown to be the major source of antioxidant enzymes in the ejaculate and have the important function of preserving sperm DNA integrity from oxidative stress experienced in the uterine environment. In our in vivo golden hamster model, ablation of the five major male accessory sex glands, namely the ampullary glands, coagulating glands, dorsolateral prostate, ventral prostate and seminal vesicle, was found to cause higher incidence and greater degree of DNA damage in spermatozoa. These damaged sperm are able to undergo fertilization at the same rate as intact ones; however, the outcome of embryos sired is seriously affected.

Bridging advanced glycation end product, receptor for advanced glycation end product and nitric oxide with hormonal replacement/estrogen therapy in healthy versus diabetic postmenopausal women: A perspective

Cardiovascular diseases (CVD) are the most significant cause of death in postmenopausal women. The loss of estrogen biosynthesis with advanced age is suggested as one of the major causes of higher CVD in postmenopausal women. While some studies show beneficial effects of estrogen therapy (ET)/hormonal replacement therapy (HRT) in the cardiovascular system of healthy postmenopausal women, similar studies in diabetic counterparts contradict these findings. In particular, ET/HRT in diabetic postmenopausal women results in a seemingly detrimental effect on the cardiovascular system. In this review, the comparative role of estrogens is discussed in the context of CVD in both healthy and diabetic postmenopausal women in regard to the synthesis or expression of proinflammatory molecules like advanced glycation end products (AGEs), receptor for advanced glycation end products (RAGEs), inducible nitric oxide synthases (iNOS) and the anti-inflammatory endothelial nitric oxide synthases (eNOS). The interaction of AGE-RAGE signaling with molecular nitric oxide (NO) may determine the level of reactive oxygen species (ROS) and influence the overall redox status of the vascular microenvironment that may further determine the ultimate outcome of the effects of estrogens on the CVD in healthy versus diabetic women.

Angiotensin II (AT1) receptors and NADPH oxidase regulate Cl- current elicited by beta1 integrin stretch in rabbit ventricular myocytes

Direct stretch of β1 integrin activates an outwardly rectifying, tamoxifen-sensitive Cl⁻ current (Cl⁻ SAC) via focal adhesion kinase (FAK) and/or Src. The characteristics of Cl⁻ SAC resemble those of the volume-sensitive Cl⁻ current, I_Cl,swell. Because myocyte stretch releases angiotensin II (AngII), which binds AT1 receptors (AT1R) and stimulates FAK and Src in an autocrine-paracrine loop, we tested whether AT1R and their downstream signaling cascade participate in mechanotransduction. Paramagnetic beads coated with mAb for β1-integrin were applied to myocytes and pulled upward with an electromagnet while recording whole-cell anion current. Losartan (5 μM), an AT1R competitive antagonist, blocked Cl⁻ SAC but did not significantly alter the background Cl⁻ current in the absence of integrin stretch. AT1R signaling is mediated largely by H₂O₂ produced from superoxide generated by sarcolemmal NADPH oxidase. Diphenyleneiodonium (DPI, 60 μM), a potent NADPH oxidase inhibitor, rapidly and completely blocked both Cl⁻ SAC elicited by stretch and the background Cl⁻ current. A structurally unrelated NADPH oxidase inhibitor, 4-(2-aminoethyl) benzenesulfonyl fluoride (AEBSF, 0.5 and 2 mM), also rapidly and completely blocked Cl⁻ SAC as well as a large fraction of the background Cl⁻ current. With continuing integrin stretch, Cl⁻ SAC recovered upon washout of AEBSF (2 mM). In the absence of stretch, exogenous AngII (5 nM) activated an outwardly rectifying Cl⁻ current that was rapidly and completely blocked by DPI (60 μM). Moreover, exogenous H₂O₂ (10, 100, and 500 μM), the eventual product of NADPH oxidase activity, also activated Cl⁻ SAC in the absence of stretch, whereas catalase (1,000 U/ml), an H₂O₂ scavenger, attenuated the response to stretch. Application of H₂O₂ during NADPH oxidase inhibition by either DPI (60 μM) or AEBSF (0.5 mM) did not fully reactivate Cl⁻ SAC, however. These results suggest that stretch of β1-integrin in cardiac myocytes elicits Cl⁻ SAC by activating AT1R and NADPH oxidase and, thereby, producing reactive oxygen species. In addition, NADPH oxidase may be intimately coupled to the channel responsible for Cl⁻ SAC, providing a second regulatory pathway.

Small nuclear RING finger protein expression during gonad development: regulation by gonadotropins and estrogen in the postnatal ovary

Small nuclear RING finger protein (SNURF/RNF4) is a steroid receptor coregulator that is down-regulated in testicular germ cell cancer. In this work, we examined SNURF expression during murine fetal gonad development and postnatal ovarian folliculogenesis by in situ hybridization and immunohistochemical staining. SNURF mRNA was detectable in gonads of both sexes from embryonic 10.5 days post conception onward. SNURF protein localized to gonocytes and somatic Leydig and Sertoli cells of fetal testis and in oogonia and supporting cells of fetal ovary. In murine postnatal ovary, SNURF mRNA and protein were expressed throughout folliculogenesis, peaking in the oocytes of preantral follicles. Lower amounts of SNURF mRNA and protein were also present in granulosa cells of secondary, antral, and preovulatory follicles and in luteal glands. Exposure of immature female mice and rats to gonadotropin from pregnant mare serum and human chorionic gonadotropin did not change dramatically SNURF mRNA levels in ovary. SNURF mRNA expression was increased in ovaries of immature mice treated with diethylstilbestrol, an effect that was blocked by the pure antiestrogen ICI 182,780. SNURF protein was constitutively expressed in oocytes of hypophysectomized rats, and its content was augmented by estradiol in granulosa cells. In granulosa cell culture, SNURF mRNA accumulation was transiently increased by treatment with the LH agonists phorbol myristate and forskolin at 4 h after treatment and at 48 h in differentiated cells expressing markers of the preovulatory phenotype. These results suggest a role for SNURF in fetal germ cell development as well as in oocyte and granulosa cell maturation in an estrogen- and gonadotropin-regulated fashion.

Male genital tract antioxidant enzymes: their source, function in the female, and ability to preserve sperm DNA integrity in the golden hamster

Recently, we reported that male accessory sex gland (ASG) secretions protect sperm genomic integrity by demonstrating that DNA damage was more extensive in sperm not exposed to the secretions. The present study was conducted to find out if ASGs secrete the main antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx or GSH-Px), and catalase (CAT) and if the most abundant one, SOD, can protect those sperm that were not exposed to ASG secretions against NADPH-induced oxidative stress. Four experimental groups of male golden hamsters were used: intact animals with proven fertility, animals with all major ASGs removed (TX), animals that were bilaterally vasectomized, and sham-operated controls. SOD, CAT, and GPx activities were measured in secretions from all 5 ASGs and sperm-free uterine flushing from virgin females and those mated with the experimental males. The alkaline comet assay was used to analyze DNA integrity of the TX group sperm after incubation in a medium containing 50 U/mL of SOD along with 0 to 20 mmol/L NADPH. The main antioxidant enzyme in ASGs was SOD from coagulating glands (P <.05) and GPx together with CAT from ampullary glands (P <.05). Uterine flushing of ejaculates that contained ASG secretions had more SOD and CAT activities than those with epididymal secretions alone (P <.05 and P <.001, respectively), whereas activity of GPx was the same (P >.05). Addition of SOD in vitro dose dependently decreased the incidence of single-strand DNA damage in sperm not exposed to ASG secretions incubated in the presence of 0 to 20 mmol/L NADPH (P <.001). These results indicated that, in terms of abundance, SOD was the main antioxidant enzyme secreted by male ASGs, whereas CAT was the second one. The GPx activity came from both epididymis and ASGs. We conclude that ASG secretions play a significant role in protecting sperm against oxidative stress.

Functional implications of antiestrogen induction of quinone reductase: inhibition of estrogen-induced deoxyribonucleic acid damage

Recent studies have shown that the antiestrogens tamoxifen and raloxifene may protect against breast cancer, presumably because of a blockade of estrogen receptor (ER)-mediated transcription. Another possible explanation is that antiestrogen-liganded ER transcriptionally induces genes that are protective against cancer. We previously reported that antiestrogen-liganded ERbeta transcriptionally activates the major detoxifying enzyme quinone reductase (QR) [NAD(P)H:quinone oxidoreductase]. It has been established that metabolites of estrogen, termed catecholestrogens, can form DNA adducts and cause oxidative DNA damage. We hypothesize that QR inhibits estrogen-induced DNA damage by detoxification of reactive catecholestrogens. We report here that physiological concentrations of 17beta-estradiol cause oxidative DNA damage, as measured by levels of 8- hydroxydeoxyguanine, in ER-positive MCF7 breast cancer cells, MDA-MB-231 breast cancer cells (ERalpha negative/ERbeta positive) and nontumorigenic MCF10A breast epithelial cells (very low ER), which is dependent on estrogen metabolism. Estrogen-induced 8-hydroxydeoxyguanine was inversely correlated to QR and ERbeta levels and was followed by downstream induction of the DNA repair enzyme XPA. Trans-hydroxytamoxifen, raloxifene, and the pure antiestrogen ICI-182,780 protected against estradiol-mediated damage in breast cancer cells containing ERbeta. This is most likely due to the ability of these antiestrogens to activate expression of QR via ERbeta. We conclude that up-regulation of QR, either by overexpression or induction by tamoxifen, can protect breast cells against oxidative DNA damage caused by estrogen metabolites, representing a possible novel mechanism of tamoxifen prevention against breast cancer.

The effects of estrogen and raloxifene treatment on antioxidant enzymes in brain and liver of ovarectomized female rats

Recent studies documented that estrogen have antioxidant properties in-vitro, there are conflicting results on the effect of estrogen in vivo. We aimed to investigate the effects of estradiol and Raloxifene on the antioxidant enzyme [superoxide dismutase (SOD) and catalase (CAT)] activities and MDA levels in brain and liver homogenates of ovariectomized female rats. Twelve weeks after ovariectomy, female Sprague-Dawley rats (n = 26) were divided into three groups: (1) Ovariectomized placebo group (n = 6) was given physiologic saline. (2) Estrogen group (n = 10) was given Ethynyl estradiol, 0.1 mg/kg sc. (3) Raloxifene group (n = 10) was given raloxifene, 1 mg/kg sc during 8 weeks. Ten rats were used as naive controls without any treatment (Sham operated group, n = 10). Ovariectomy lead to an increase in the CAT activities in liver tissue samples compared to the sham group (p = 0.056, Mann-Whitney test). While estrogen treatment reversed to normal levels of CAT activities, raloxifene remained as ineffective. Superoxide dismutase activities and MDA levels in liver were remained unchanged in all groups. There was no significant change in the brain tissue SOD and CAT activities between the control ovariectomy, estrogen treated, and raloxifen treated groups. We determined an increase in MDA levels in brain of ovariectmised rat (p = 0.02). While raloxifene treatment reversed to normal levels of MDA (p = estrogen treatment failed. Our data showed that estrogen may play a role in regulation of CAT and SOD activities in liver due to its antioxidative effects. We can suggest estrogen and raloxifene exert their antioxidative effects in brain rather than liver. Since Raloxifene's effect is more clear than estradiol, raloxifene may be suggested primarily for treatment and/or prevention of diseases which can be resulted from oxidative stress in postmenopausal women.

Inhibition of low-density lipoprotein oxidation by the pure antiestrogens ICI 182780 and EM-652 (SCH 57068)

OBJECTIVE

The use of modulators of estrogen receptors activation is receiving increasing interest in menopausal medicine. Pure antiestrogens define a group of compounds exhibiting universal antagonistic properties. Nevertheless, we cannot disregard the possibility that they may still have some agonistic actions. Because estradiol (E2) has antioxidant properties, we tested the antioxidant capacity of two pure antiestrogens, ICI 182780 and EM-652 (SCH 57068).

DESIGN

The ability of both compounds to protect isolated low-density lipoproteins against copper-induced oxidation in vitro was used as an index of their antioxidant properties.

RESULTS

When compared with control (vehicle alone), ICI 182780 and EM-652 significantly increased the lag time of low-density lipoprotein oxidation when present at concentrations of 10 and 0.5 microM or greater, respectively. When compared with estrogens, ICI 182780 was as effective as E2 at the lower concentrations tested (0.1 and 1 microM) but less effective at higher concentrations. EM-652 had similar antioxidant potency as E2 but exerted maximal effects at lower concentration. Combined exposure to E2 and each of the antiestrogens resulted in a higher antioxidant effect than that of antiestrogen alone. Another estrogen (estrone), and selective estrogen-receptor modulators, such as tamoxifen and hydroxytamoxifen, displayed an antioxidant potency that was close to ICI 182780 but lower than EM-652. Progestogens, such as progesterone or medroxyprogesterone acetate, had no antioxidant effect.

CONCLUSIONS

Both ICI 182780 and EM-652 exhibited potent antioxidant activity, which could have important biological implications.

Effects of hormonal replacement therapy on oxidative stress and total antioxidant capacity in postmenopausal hemodialysis patients

BACKGROUND

Oxidative stress is known to be implicated in the pathogenesis of atherosclerotic cardiovascular disease. Many studies have demonstrated that hormone replacement therapy (HRT) has beneficial effects on oxidation injury in postmenopausal women with normal renal function. In this study, we examined the effects of HRT on plasma malondialdehyde (MDA) level and total antioxidant capacity (TAC) in postmenopausal hemodialysis women.

METHODS

We randomly assigned 70 postmenopausal women on maintenance hemodialysis into either a HRT group or a control group. Oral conjugated estrogen (0.625 mg) combined with medroxyprogesterone acetate (2.5 mg) was given daily for 12 weeks in HRT group. Plasma MDA, TAC, albumin, uric acid and C-reactive protein (CRP) were measured before, 4 and 12 weeks after the start of medication in the HRT group. In the control group, the same parameters were measured without HRT.

RESULTS

There was no difference in baseline values between the two groups. In the control group (n = 32), all these parameters showed no change at 4 and 12 weeks. HRT decreased MDA from 1.32 (0.55-1.88) microM to 1.08 (0.44-1.50) microM (p < 0.001) at 4 weeks and to 1.11 (0.50-1.37) microM (p < 0.001) at 12 weeks (n = 33). TAC was not changed at 4 weeks, however, it decreased from 1.59 (1.27-2.00) mM to 1.45 (1.08-1.65) mM (p < 0.05) at 12 weeks. The albumin, uric acid and CRP levels were not changed significantly after HRT.

CONCLUSIONS

These results suggest that HRT has a favorable effect on oxidative stress in postmenopausal women with ESRD as in the general population.

The first product of phospholipid N-methylation, phosphatidylmonomethylethanolamine, is a lipid mediator for progesterone action at the amphibian oocyte plasma membrane

Progesterone has been shown to act at plasma membrane receptors on the amphibian oocyte to trigger a cascade of changes in membrane phospholipids and to initiate the G(2)/M transition of the first meiotic division. The earliest event (0-1 min) is the transient N-methylation of phosphatidylethanolamine (PE) to form phosphatidylmonomethylethanolamine (PME), demonstrated using [(3)H]glycerol to prelabel oocyte plasma membrane PE. [(3)H]Glycerol-labeled PME rises 10-fold within the 1-2 min after exposure to progesterone and accounts for conversion of about 50% of the [3H]Glycerol-labeled PE. [(3)H]PME levels slowly decline over the following 10-30 min. [(3)H] or [(14)C] labeled fatty acid experiments showed that newly formed PME is enriched in linoleic or palmitic, but not in arachidonic acid, indicating that specific PE pools undergo progesterone-induced N-methylation. Two plasma membrane changes: activation of serine protease, and Ca(2+) release from the oocyte surface coincide with PME formation; both are prevented by pretreatment of oocytes with the N-methylation inhibitor, 2-methylaminoethane. Media containing PME micelles release both protease and Ca(2+) from intact oocytes within the first 1-2 min. The immediate downstream metabolites of PME, PDE and PC, do not induce serine protease activity or Ca(2+) release. We conclude that progesterone initially activates N-methyltransferase in the oocyte plasma membrane, and that the first product, PME, is responsible for activation of serine protease in the plasma membrane and the release of Ca(2+) from the oocyte surface.