The effects of hormone replacement therapy on lipid peroxidation and antioxidant status

Vascular dysfunction across the stages of the menopausal transition is associated with menopausal symptoms and quality of life

OBJECTIVE

The menopausal transition is associated with somatic symptoms and increased rates of depression, which can impair quality of life (QOL) and increase cardiovascular disease (CVD) risk. This period is also associated with accelerated vascular aging (arterial stiffening and endothelial dysfunction), an antecedent to CVD. This secondary analysis sought to explore associations between depression, menopausal symptoms and QOL, and vascular aging across menopause stages.

METHODS

Arterial stiffness (carotid artery compliance), endothelial function (brachial artery flow-mediated dilation [FMD]), menopausal symptoms (Menopausal Symptom List [MSL]), depression (Center for Epidemiologic Studies Depression Scale [CES-D]), and QOL (Utian QOL Scale [UQOL]) were measured in 138 women (19-70 years) classified as premenopausal (n = 41, 34 ± 8 years; mean ± SD), early (n = 25, 49 ± 3 years), or late perimenopausal (n = 26, 50 ± 4 years), or early (n = 22, 55 ± 4 years) or late postmenopausal (n = 24, 61 ± 5 years). Differences across menopause stages were determined using one-way analysis of variance; associations between vascular measures and MSL, CES-D, and UQOL were tested using Pearson's correlation analyses.

RESULTS

Menopausal symptoms, depression, and QOL worsened across menopause stages, particularly in late perimenopausal women. Vasosomatic symptom frequency, and general somatic symptom frequency and severity were inversely correlated with carotid artery compliance and FMD (r = -0.27 to -0.18, all P < 0.05). Only correlations with general somatic symptoms were significant after adjusting for multiple comparisons. Total QOL was positively correlated with carotid artery compliance (r = 0.23, P = 0.01). CES-D scores were not correlated with carotid artery compliance or FMD (r = -0.08, -0.03, P = 0.35).

CONCLUSIONS

Vascular dysfunction across the stages of menopause was associated with greater frequency and severity of menopausal symptoms, and lower QOL, but not depression. Mechanisms underlying these associations (eg, inflammation, oxidative stress) should be explored.

Hormone replacement therapy reduces lipid oxidation directly at the arterial wall: A possible link to estrogens' cardioprotective effect through atherosclerosis prevention

Background:

The first step in atherosclerosis formation is the ingurgitation of an oxidized low-density lipid (LDL) molecule by a macrophage which then turns into a foam cell within the vascular wall and initiates a cascade of inflammatory responses. Could it be that the potential cardioprotective effect observed in women receiving hormone replacement therapy (HRT) is modulated by estrogen's capacity to decrease LDL oxidation in the vascular wall and thus decrease atherosclerotic foam cells?

Materials and Methods:

Thirty-four adult female Wistar rats were divided into three groups. All were double oophorectomized. After recovery, Group 1 received Estradiol Valerate subcutaneous (SC) (2.5 mg/kg/week), Group 2 Estradiol Valerate SC (2.5 mg/kg/week) + Progesterone SC (10 mg/kg/48 h), and Group 3 Placebo SC. After 10 weeks, all rats were sacrificed and a vascular dissection performed. Malondialdehyde (MDA) was measured directly on the vascular extract to determine lipid oxidative levels and HRTs' effect. Renal and hepatic tissue was also studied. Total antioxidant status (TAS) was measured to determine overall oxidative behavior.

Results:

Vascular MDA levels for Group 1 = 80.80 (±16.8) μmol/ml/g, Group 2 = 107.69 (±24.9) μmol/ml/g, and Group 3 = 140.96 (±32.4) μmol/ml/g. ANOVA (P < 0.05), with a post hoc Bonferroni corrective t-test, showed that both Group 1 and 2 have statistically significant lower levels of MDA than Group 3. Renal tissue showed less oxidative damage in the HRT groups, while hepatic tissue showed an inverse behavior with less lipid oxidation in the placebo group. TAS decreased with oophorectomy in all groups but decreased less in both groups that received HRT compared to placebo (P < 0.05).

Conclusion:

HRT significantly reduces lipid oxidation directly in the arterial wall.

Oxidative stress contributes to large elastic arterial stiffening across the stages of the menopausal transition

OBJECTIVE

It is unclear how changes in ovarian hormones during the menopausal transition contribute to age-associated arterial stiffening. We sought to evaluate differences in arterial stiffness and the role of oxidative stress across the stages of the menopausal transition in healthy women.

METHODS

Arterial stiffness (carotid artery compliance and ultrasound) was measured during immediate infusions of saline (control) and ascorbic acid (experimental model to immediately decrease oxidative stress) in 97 healthy women (22-70 y) classified as premenopausal (n = 24; mean [SD] age, 33 [7] y), early perimenopausal (n = 21; 49 [3] y) or late perimenopausal (n = 21; 50 [4] y), or postmenopausal (n = 31; 57 [5] y).

RESULTS

Basal carotid artery compliance was different among the groups (P < 0.001). Mean [SD] compliance was highest in premenopausal women (1.31 [0.25] mm/mm Hg × 10), with progressive decrements in perimenopausal (early perimenopausal, 0.98 [0.31] mm/mm Hg × 10; late perimenopausal, 0.90 [0.25] mm/mm Hg × 10) and postmenopausal (0.75 [0.24] mm/mm Hg × 10) women. Ascorbic acid infusion improved compliance in late perimenopausal (15% [18%] increase, P = 0.001) and postmenopausal (17% [26%] increase, P = 0.002) women but not in early perimenopausal or premenopausal women.

CONCLUSIONS

Arterial stiffening worsens across the stages of the menopausal transition in healthy women. This seems to be mediated, in part, by oxidative stress, particularly during the late perimenopausal and postmenopausal periods. It remains uncertain whether this is specifically caused by loss of ovarian function or aging.

Estrogen plus progestin increase superoxide dismutase and total antioxidant capacity in postmenopausal women

OBJECTIVE

This cross-sectional study aimed to evaluate the behavior of blood antioxidant enzymes (superoxide dismutase (SOD), catalase and glutathione peroxidase), plasma total antioxidant capacity and oxidative damage (lipid oxidation and protein carbonyl levels) and their relationship with the serum levels of steroid hormones in premenopausal and postmenopausal women without and with estrogen alone (ET) or estrogen plus progestin therapy (EPT).

METHODS

Blood was collected from four groups of subjects: premenopausal women (n = 24), postmenopausal women without hormone therapy (n = 31), postmenopausal women with ET (n = 12) and postmenopausal women with EPT (n = 16).

RESULTS

The activities of the different SOD isoforms (CuZnSOD and MnSOD) and the plasma total antioxidant power were significantly higher in the postmenopausal women under EPT than in the postmenopausal women without hormone replacement therapy (HRT). Only CuZnSOD activity was increased in women receiving ET compared to the postmenopausal women without HRT. However, no differences were observed in the levels of lipid or protein oxidation or in the non-enzymatic plasma antioxidants (uric acid and albumin) among the groups. The duration of HRT and serum estrogen levels were positively correlated to the blood CuZnSOD activity and to plasma total antioxidant power, whereas the serum progesterone levels were positively correlated to CuZnSOD activity and negatively correlated to protein carbonyl groups. Interestingly, the total antioxidant power of plasma was positively correlated to CuZnSOD and glutathione peroxidase activities.

CONCLUSION

We conclude that EPT increases blood MnSOD and CuZnSOD activity in postmenopausal women, leading to an increased plasma total antioxidant capacity. This finding may be relevant to the prevention of oxidative stress-related disorders in postmenopausal women.

NAD(P)H:quinone oxidoreductase 1 is induced by progesterone in cardiomyocytes

NAD(P)H: quinone oxidoreductase 1 (NQO1) is a ubiquitous flavoenzyme that catalyzes two-electron reduction of various quinones by utilizing NAD(P)H as an electron donor. Our previous study found that progesterone (PG) can protect cardiomyocytes from apoptosis induced by doxorubicin (Dox). Microarray analyses of genes induced by PG had led to the discovery of induction of NQO1 mRNA. We report here that PG induces NQO1 protein and its activity in a dose-dependent manner. Whereas NQO1 is well known as a target gene of Nrf2 transcription factor due to the presence of antioxidant response element (ARE) in the promoter, PG did not activate the ARE, suggesting Nrf2-independent induction of NQO1. To address the role of NQO1 induction in PG-induced cytoprotection, we tested the effect of NQO1 inducer β-naphthoflavone and inhibitor dicoumarol. Induction of NQO1 by β-naphthoflavone decreased Dox-induced apoptosis and potentiated the protective effect of PG as measured by caspase-3 activity. PG-induced NQO1 activity was inhibited with dicoumarol, which did not affect PG-induced cytoprotection. Dicoumarol treatment alone potentiated Dox-induced caspase-3 activity. These data suggest that while NQO1 plays a role in PG-induced cytoprotection, there are additional components contributing to PG-induced cytoprotection.

Impact of Serum Estradiol on Biomarkers of Oxidative Stress in Polycystic Ovary Syndrome and Ovulatory Women

Background

Estrogens are thought to possess antioxidant properties in vivo, with estradiol being the most biologically active and available. Unlike ovulatory women, those with polycystic ovary syndrome (PCOS) have a relative steady-state serum estradiol concentration across a typical month. To better understand the antioxidant role of serum estradiol in premenopausal women, we evaluated biomarkers of oxidative stress at two time points in both ovulatory and anovulatory cycles (ie, women with PCOS).

Methods

A total of 16 women (7 PCOS, 9 ovulatory) completed this study. Ovulatory women were tested on cycle day 3, and again on cycle day 21. Women with PCOS were tested at a random time and returned to the clinic 14 days later. At each visit, blood was collected for determination of malondialdehyde (MDA), hydrogen peroxide (H2O2) and Trolox Equivalent Antioxidant Capacity (TEAC). Estradiol, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were also measured.

Results

There were no significant differences observed in any oxidative stress biomarker between ovulatory and PCOS women. Estradiol levels were positively correlated with TEAC in women with PCOS (r = 0.57; P = 0.03), but not in ovulatory women. While not statistically significant, negative correlations were noted between estradiol and MDA and estradiol and H2O2 in women with PCOS but not in ovulatory subjects.

Conclusions

Our data indicate that oxidative stress biomarkers do not differ between PCOS and ovulatory women. The changing estrogen level that occurs throughout ovulatory cycles does not appear to impact overall oxidative status when compared to the relative steady-state estradiol levels in PCOS subjects in our study. Furthermore, estradiol may be associated with antioxidant status and biomarkers of oxidative stress in women with PCOS but not in those with regular menstrual cycles.

Post-menopausal hormone therapy reduces autoantibodies to oxidized apolipoprotein B100

The aim of the study was to verify whether post-menopausal hormone replacement therapy (HRT) modifies autoantibody titers against oxidized low-density lipoprotein (LDL) (anti-LDLoxi), against epitopes of oxidized apolipoprotein B100 and common carotid intima-media thickness (IMT) in these women. Sixty-eight women in pre-menopause (PMW) and 216 in post-menopause (POMW) were recruited; eighty-three had undergone HRT for at least 12 months, where 48 received conjugated estrogens alone (EHRT) and 35 received conjugated estrogen and medroxyprogesterone acetate (CHRT). ELISA was used to determine autoantibodies. Lipoprotein lipase (LPL), hepatic lipase (HL), cholesterol ester transfer protein (CETP) and phospholipid transfer protein (PLTP) activities were assayed by radiometric methods. IMT was measured using Doppler ultrasound. Anti-oxidized LDL and anti-D antibodies increased by 40% (p ≤ 0.003) and 42% (p ≤ 0.006), respectively, with menopause. There was a surprising and significant 7% reduction in anti-D2 antibody titers with HRT (p ≤ 0.050), indicating a positive effect of treatment on the immune response to oxidized LDL. Combined HRT decreased activities of HL and LPL. HRT did not change common carotid IMT, which was increased by 32% as expected after menopause (p ≤ 0.030). This study describes, for the first time, the protective effect of HRT on decreasing autoantibody titers against oxidized apolipoprotein B in LDL.

Effect of hormone replacement therapy on total serum anti-oxidant potential and oxidized LDL/β2-glycoprotein I complexes in postmenopausal women

Oxidative stress and consequent oxidized lipoprotein production is thought to play a central role in both the initiation and progression of atherosclerosis. Oxidized low-density lipoprotein (oxLDL)/β2-glycoprotein I (β2GPI) complexes are etiologically important in the development of atherosclerosis. The aim of the present study was to investigate whether long-term treatment with conventional hormone replacement therapy (HRT) in postmenopausal women could affect total serum antioxidant capacity (TAC) and serum levels of oxLDL/β2GPI complexes. A total of 60 normolipidemic postmenopausal women treated with oral estrogen together with progestin therapy for 3 months were selected. TAC and serum levels of oxLDL/β2GPI complexes were measured at the beginning and end of the HRT. HRT led to a significant increase in TAC (15%, P=0.02) and a minor but statistically nonsignificant decrease of oxLDL/β2GPI complexes (3%, P=0.30) when compared with the baseline control levels. There was also no significant association between TAC and oxLDL/β2GPI complexes changes related to HRT. This study indicates that, HRT in postmenopausal women leads to an increase in TAC without an equivalent change in serum levels of oxLDL/β2GPI complexes. It is concluded that beneficial effects of HRT could be explained, at least in part, by improving antioxidant status, but may not be directly associated with a change in oxidized lipoprotein production.

Plasma protein carbonyls and breast cancer risk in sisters discordant for breast cancer from the New York site of the Breast Cancer Family Registry

Reactive oxygen species are important in the pathogenesis of many diseases, including breast cancer. Several population-based case-control studies have shown that various biomarkers of oxidative stress are associated with an increase in breast cancer risk. We selected sisters discordant for breast cancer (n=645) from the New York site of the Breast Cancer Family Registry to explore factors that contribute to variation in plasma protein carbonyls, and to determine whether this biomarker is associated with an increase in breast cancer risk among those with a family history. Late age at menarche, hormone replacement therapy use, and Hispanic race were significantly associated with lower plasma protein carbonyl levels in unaffected sisters. Plasma protein carbonyls were associated with an increase in breast cancer risk [Q2 odds ratio (OR), 1.4; 95% confidence interval (CI), 0.8-2.7; Q3 OR, 2.4; 95% CI, 1.1-4.9; Q4 OR, 1.9; 95% CI, 0.8-4.2], although not in a dose-dependent manner. These data suggest that oxidative damage is a risk factor for breast cancer in high-risk women.

Effects of oral contraception with ethinylestradiol and drospirenone on oxidative stress in women 18-35 years old

BACKGROUND

Oral contraceptives (OCs) with estrogens and progestins may affect oxidative stress (OS) status.

STUDY DESIGN

A group of 32 women using oral contraceptives (OCU) containing 0.03 mg ethinylestradiol and 3 mg drospirenone have been compared to a matched control group of 30 noncontraception users (NCU). Blood levels of antioxidants, trace elements and markers of lipid peroxidation were assessed by biochemical methods. A microarray analysis of whole blood mRNA levels of 200 genes involved in OS-dependant pathway was also performed.

RESULTS

Levels of zinc, vitamin E and antibodies to oxidized low-density lipoproteins (LDLs) were not significantly different between the two groups. On the other hand, significant increases in the mean levels of lipid peroxides (+176%, p<.001), oxidized LDLs (+145%, p<.002), copper (+103%, p<.001), Cu/Zn ratio (+100%, p<.001) and a significant decrease in the mean level of beta-carotene (-41%, p<.01) were observed in the OCU compared to NCU. There was a highly significant positive correlation between the lipid peroxide levels and the copper-to-zinc ratio. From the 200 genes tested by microarray, one coding for HSP70 was significantly up-regulated (log(2) fold change=+ 0.45, p<.02) and one coding for inducible nitric oxide synthase significantly down-regulated (log(2) fold change=-0.24, p<.05) in the OCU compared to the NCU.

CONCLUSIONS

The recently introduced combination of ethinylestradiol and drospirenone induced the heightening of lipid peroxidation correlated with high levels of copper, a situation that could be associated with increased cardiovascular risk.

Proteasome activity as a target of hormone replacement therapy-dependent plaque stabilization in postmenopausal women

The molecular mechanisms of the atheroprotective effect evoked by hormone replacement therapy in postmenopausal women is not well known. Recently, we have demonstrated enhanced activity of the ubiquitin-proteasome system in human atherosclerotic plaques and evidenced that it is associated with inflammatory-induced plaque rupture. Therefore, we hypothesized that hormone replacement therapy may exert the cardioprotective effects modulating the ubiquitin-proteasome activity. To investigate this possibility, this study examined the differences in inflammatory infiltration, as well as ubiquitin-proteasome activity, between asymptomatic carotid plaques of postmenopausal women with and without concomitant hormone replacement therapy. Plaques were obtained from 20 postmenopausal women treated with hormone replacement therapy (current users) and 32 nontreated women (never-users) enlisted to undergo carotid endarterectomy for extracranial high-grade (>70%) internal carotid artery stenosis. Plaques were analyzed for macrophages, T lymphocytes, human leukocyte antigen-DR+ cells, ubiquitin-proteasome system, nuclear factor kappaB, inhibitor of nuclear factor kappaBbeta, tumor necrosis factor-alpha, nitrotyrosine, matrix metalloproteinase-9, and collagen content (immunohistochemistry and ELISA). Compared with plaques from current users, plaques from never-users had more macrophages, T lymphocytes, and human leukocyte antigen-DR+ cells (P<0.001); more ubiquitin-proteasome activity, tumor necrosis factor-alpha, and nuclear factor kappaB (P<0.001); and more nitrotyrosine and matrix metalloproteinase-9 (P<0.001), along with a lesser collagen content and inhibitor of nuclear factor kappaBbeta levels (P<0.001). This study supports the hypothesis that hormone replacement therapy inhibits plaque ubiquitin-proteasome activity by decreasing oxidative stress generation in postmenopausal women. This effect, in turn, might contribute to plaque stabilization by inhibiting the activation of nuclear factor kappaB-dependent inflammation, responsible for plaque rupture.

Hormone replacement therapy and cataract: a population-based case-control study

PURPOSE

Laboratory studies have suggested that hormone replacement therapy (HRT) may protect against the development of cataract, but epidemiological studies in humans have thus far been inconclusive. The aim of this study was to assess the association between hormone replacement therapy and cataract.

METHODS

Population-based case-control study using data from the General Practice Research Database in the UK. Participants were 10 000 women aged 45 years and over with diagnosed cataract and 10 000 controls matched on age, general practice, and calendar period.

RESULTS

The crude odds ratio for the association between cataract and ever-use of oestrogen-only hormone replacement therapy was 1.13 (95% CI 0.99-1.29). This reduced to 0.81 (95% CI 0.71-0.94) after adjustment for consultation rate. Similarly, the crude odds ratio for the association between cataract and ever-use of a formulation containing oestrogen and progestogen was 1.18 (95% CI 1.01-1.39), reducing to 0.86 (95% CI 0.72-1.02) after adjustment for consultation rate.

CONCLUSIONS

Oestrogen-only and oestrogen-progestogen hormone replacement therapies are associated with a small reduced risk of cataract. This data adds to the growing body of evidence on the effects of HRT on health. All potential benefits and risks of this therapy should be taken into account when considering its use.

The effect of oestrogen on cytokine and antioxidant levels in male to female transsexual patients

OBJECTIVE

Whilst hormone replacement therapy (HRT) can be beneficial, it can be associated with deep venous thrombosis (DVT) and stroke. As male to female transsexuals take much higher doses of oestrogen than women on HRT, they provide a unique opportunity to study the long-term effects of oestrogen in a group of relatively young individuals who are largely free of established vascular disease.

METHODS

Thirty-eight male to female gender patients were enrolled into the study. Of these, 25 were receiving oestrogen treatment and 13 who were not on treatment served as a control group. Serum levels of cholesterol, HDL, triglycerides, Interleukin 6 (IL-6), nitric oxide (NO), glutathione, and superoxide dismutase (SOD) were measured in all patients.

RESULTS

The results showed that compared to the control group, patients on oestrogen had significantly raised levels of NO (32.1+/-14.3 versus 20.3+/-10.0, P<0.05) and reduced levels of IL-6 (0.75+/-0.6 versus 1.37+/-0.7, P<0.05) and SOD (13.2+/-3.0 versus 24.0+/-10.0, P<0.05). These changes were not accompanied by any significant change in plasma lipid levels.

CONCLUSION

It would appear that the very high levels of oestrogen taken by the gender patients produce similar beneficial effects to those seen in women on HRT. However, in this patient group it appears that these changes are independent of changes in cholesterol, triglyceride, and HLD.

Effects of oestradiol and oestroprogestin on erythrocyte antioxidative enzyme system activity in postmenopausal women

OBJECTIVE

Data concerning the relationship between sex steroid hormones and the cellular antioxidative enzyme system are controversial. We investigated the effects of oestradiol deficiency after menopause and the influence of transdermal oestradiol therapy (ET) and hormonal (oestradiol plus medroxyprogesterone) replacement therapy (HT) on erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT). GSH and selenium (Se) concentrations were also estimated. Serum lipid peroxide (LPO) levels were measured as an indicator of free-radical production and lipid peroxidation.

PATIENTS

The study group consisted of 80 postmenopausal women, divided into two subgroups: 26 women with surgically induced menopause (ET1) and 54 women with physiological menopause (HT1). Forty premenopausal healthy volunteers were controls (C group).

RESULTS

LPO was higher in postmenopausal women and decreased after both ET and HT. GSH-Px and GSH were lower in the postmenopausal groups but increased significantly after both types of therapy. Se concentrations did not differ significantly among the groups. CAT activities were similar in all groups and decreased after ET and HT. SOD activities in postmenopausal women were similar to those in the C group and did not change significantly after treatment.

CONCLUSIONS

The administration of natural oestrogens to postmenopausal women diminishes oxidative stress and increases antioxidative cell potency.

Influence of hormone replacement therapy on blood antioxidant enzymes in menopausal women

BACKGROUND

Natural loss of estrogen occurring in menopausal process may contribute to various health problems many of them possibly related to oxidative stress. Hormone replacement therapy (HRT) is the most common treatment to attenuate menopausal disturbances. This study was aimed at evaluating the influence of HRT on the activity of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and glutathione peroxidase, GPx) and lipid peroxidation (thiobarbituric acid reactive substances, TBARS) in menopausal women.

METHODS

Blood antioxidant enzyme activities were determined in premenopausal (n=18) and in postmenopausal healthy women without (n=21) or with (n=19) HRT (mean ages: 47, 59, and 57 years, respectively).

RESULTS

TBARS, CAT, and GPx activity were not significantly different among the groups of study. However, SOD activity was significantly lower in postmenopausal women without HRT (0.68+/-0.04 U/mg Hb) when compared both to premenopausal women (0.91+/-0.04 U/mg Hb) and to postmenopausal women with HRT (0.89+/-0.07 U/mg Hb). SOD activity was positively correlated to the duration of HRT in the postmenopausal groups (r=0.33, p<0.05).

CONCLUSIONS

HRT antagonizes the decrease of SOD activity that occurs after menopause, suggesting that HRT may play a beneficial role in the protection against oxidative stress.

Role of Lipid Peroxidation in the Epidemiology and Prevention of Breast Cancer

We have recently proposed a common mechanistic pathway by which obesity and hypertension lead to increased renal cell cancer risk. Our hypothesis posits lipid peroxidation, which is a principal mechanism in rodent renal carcinogenesis, as an intermediate step that leads to a final common pathway shared by numerous observed risks (including obesity, hypertension, smoking, oophorectomy/hysterectomy, parity, preeclampsia, diabetes, and analgesics) or protective factors (including oral contraceptive use and alcohol) for renal cell cancer [Cancer Causes Control 2002;13:287-93]. During this exercise, we have noticed how certain risk factors for renal cell carcinoma are protective for breast cancer and how certain protective factors for renal cell carcinoma increase risk for breast cancer. Parity and oophorectomy, for example, are positively associated with renal cell carcinoma but are negatively associated with breast cancer. Similarly, obesity and hypertension are positively associated with renal cell carcinoma, but obesity is negatively associated with breast cancer in premenopausal women and hypertension during pregnancy is negatively associated with breast cancer. Furthermore, alcohol intake, negatively associated with renal cell carcinoma, is also positively associated with breast cancer. We propose here the possibility that lipid peroxidation may represent a protective mechanism in breast cancer. Although this runs counter to the conventional view that lipid peroxidation is a process that is harmful and carcinogenic, we present here the chemical and biological rationale, based on epidemiologic and biochemical data, which may deserve further consideration and investigation.

Ascorbic acid selectively improves large elastic artery compliance in postmenopausal women

The compliance of large elastic arteries in the cardiothoracic region decreases with advancing age/menopause and plays an important role in the increased prevalence of cardiovascular diseases in postmenopausal women. We determined whether oxidative stress contributes to the reduced large elastic artery compliance of postmenopausal women. Carotid artery compliance was measured during acute intravenous infusions of saline (baseline control) and supraphysiological doses of the potent antioxidant ascorbic acid in premenopausal (n=10; 23+/-1; mean+/-SE) and estrogen-deficient postmenopausal (n=21; 55+/-1 years) healthy sedentary women. Carotid artery compliance was 56% lower in postmenopausal compared with premenopausal women during baseline control (P<0.0001). Ascorbic acid infusion increased carotid artery compliance by 26% in postmenopausal women (1.11+/-0.07 to 1.38+/-0.08 mm2/mm Hgx10(-1); P<0.001) but had no effect in premenopausal women (2.50+/-0.25 versus 2.43+/-0.20 mm2/mm Hgx10(-1)). Carotid artery diameter, blood pressure, and heart rate were unaffected by ascorbic acid. In the pooled population, the change in arterial compliance with ascorbic acid correlated with baseline waist-to-hip ratio (r=0.56; P=0.001), plasma norepinephrine (r=0.58; P=0.001), and LDL cholesterol (r=0.54; P=0.001). These results suggest that oxidative stress may be an important mechanism contributing to the reduced large elastic artery compliance of sedentary, estrogen-deficient postmenopausal women. Increased abdominal fat storage, sympathetic nervous system activity, and LDL cholesterol may be mechanistically involved in oxidative stress-associated suppression of arterial compliance in postmenopausal women.

Effects of Surgical Menopause and Estrogen Replacement Therapy on Serum Paraoxonase Activity and Plasma Malondialdehyde Concentration

BACKGROUND

We have investigated the effects of surgical menopause and estrogen replacement therapy (ERT) on serum paraoxonase 1 (PON1) activity and plasma malondialdehyde (MDA) levels in surgically postmenopausal women.

METHODS

Thirty-six healthy perimenopausal women who underwent total abdominal hysterectomy and bilateral salpingo-oopherectomy for uterine myoma were enrolled in this study. Blood samples were taken from the subjects 1 day before surgery, 1 day before starting ERT (30 days after the operation) and on the 30th day after the start of therapy.

RESULTS

After surgical menopause, there were significant increases in plasma MDA levels (p < 0.05) and a decrease in serum PON1 activity (p < 0.05). ERT significantly increased the PON1 activity (p < 0.05) and reduced MDA levels (p < 0.05). There was a positive correlation between serum high-density lipoprotein cholesterol and PON1 activity (r = 0.7, p < 0.001, n = 36) and a negative correlation between serum PON1 activity and plasma MDA levels (r = -0.63, p < 0.006, n = 36).

CONCLUSIONS

The present study suggests that postmenopausal women tend to have high levels of plasma MDA and reduced PON1 activity, and ERT reverses these effects. The effect of ERT on lipid peroxidation seems to be associated with serum PON1 activity.

Effects of menopause and hormone replacement therapy on serum levels of coenzyme Q10 and other lipid-soluble antioxidants

The present study examines the influence of menopause and hormone replacement therapy (HRT) on serum levels of coenzyme Q(10) and other lipid-soluble antioxidants in normal women. Serum levels of coenzyme Q(10), alpha-tocopherol, gamma-tocopherol, beta-carotene and lycopene in 50 premenopausal women (not using oral contraceptives), 33 healthy postmenopausal and 15 postmenopausal women on HRT ("Prempo"; combination of 0.625 mg conjugated estrogen and 2.5 mg medroxyprogesterone acetate) were measured by high-pressure liquid chromatography. Lipid profiles were also analyzed. Significantly higher serum coenzyme Q(10) and alpha-tocopherol levels were detected in postmenopausal compared with premenopausal women (P < 0.05, and < 0.001); whereas, in postmenopausal subjects on HRT, we detected a significant decrease in coenzyme Q(10) and gamma-tocopherol levels (P < 0.001, and < 0.05) and increased alpha-tocopherol levels (P < 0.05). Serum levels of beta-carotene, lycopene, LDL, HDL, cholesterol and triglyceride were comparable among the study groups. Coenzyme Q(10) is postulated to be involved in preventing cardiovascular disease (CVD) because of its bioenergetics role in the mitochondrial respiratory chain and its antioxidant properties at the mitochondrial and extramitochondrial levels. The decrease in serum concentrations of coenzyme Q(10), produced by HRT, may promote oxygen free radical-induced membrane damage and may, thus alter cardiovascular risk in postmenopausal women. HRT-induced reductions in lipid-soluble antioxidant(s) levels, and its potential consequences on CVD, needs to be further investigated.

Serum lipid peroxides and total antioxidant status in postmenopausal women on hormone replacement therapy

Estradiol (E2) has antioxidant properties. The role of progestins in antioxidant defense is still unknown. We have evaluated the influence of E2 and E2 plus medroxyprogesterone acetate (MPA) on serum lipid peroxide (LPO) levels, a marker of free radical reactions, and serum total antioxidant status (TAS) in postmenopausal women. Subjects consisted of 26 women with surgical menopause, before and after 4 months of estrogen replacement therapy (ERT; E2), and 54 women with natural menopause on hormone replacement therapy (HRT; E2 plus MPA). Forty premenopausal women served as a control group. Serum E2 was estimated by radioimmunoassay, follicle-stimulating hormone by IRMA methods, LPO and TAS by colorimetric methods. Before therapy, LPO levels in the postmenopausal women were significantly higher (p < 0.001) than in the control group. After both ERT and HRT, LPO decreased significantly and did not differ between both groups and the control group. TAS was significantly lower in postmenopausal women (p < 0.001) than in the control group before therapy. After both ERT and HRT, TAS increased significantly and did not differ between both groups and the control group. We conclude that oxidative stress is increased after menopause. ERT and HRT inhibit the generation of free radicals and raise antioxidant potential to the levels found in premenopausal women. MPA did not influence the antioxidant action of E2.

Antioxidants as treatment for neurodegenerative disorders

Oxidative stress is a ubiquitously observed hallmark of neurodegenerative disorders. Neuronal cell dysfunction and cell death due to oxidative stress may causally contribute to the pathogenesis of progressive neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease, as well as acute syndromes of neurodegeneration, such as ischaemic and haemorrhagic stroke. Neuroprotective antioxidants are considered a promising approach to slowing the progression and limiting the extent of neuronal cell loss in these disorders. The clinical evidence demonstrating that antioxidant compounds can act as protective drugs in neurodegenerative disease, however, is still relatively scarce. In the following review, the available data from clinical, animal and cell biological studies regarding the role of antioxidant neuroprotection in progressive neurodegenerative disease will be summarised, focussing particularly on Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. The general complications in developing potent neuroprotective antioxidant drugs directed against these long-term degenerative conditions will also be discussed. The major challenges for drug development are the slow kinetics of disease progression, the unsolved mechanistic questions concerning the final causalities of cell death, the necessity to attain an effective permeation of the blood-brain barrier and the need to reduce the high concentrations currently required to evoke protective effects in cellular and animal model systems. Finally, an outlook as to which direction antioxidant drug development and clinical practice may be leading to in the near future will be provided.