Lipoprotein(a) and other lipids after oophorectomy and estrogen replacement therapy

Review of Hormone Replacement Therapy in Girls and Adolescents with Hypogonadism

Girls with either hypo- or hypergonadotropic hypogonadism need treatment with estrogens to initiate puberty and maintain a normal hormonal milieu. The focus of this review is hormone replacement treatment in girls with hypogonadism, to initiate and progress through puberty, and to maintain a healthy hormonal milieu in women. It also addresses what is known in the literature regarding estrogen levels in girls and women, instructive cases, practical tables for reference and application, and thoughts on future directions in this area. It represents a thorough literature review with author opinions and recommendations. Girls with normal ovarian function begin puberty on average at 10.5 years old, although there is variation according to ethnicity and degree of excess weight gain. The aim of estrogen therapy to initiate puberty is to mimic normal onset and rate of progression. On the basis of the currently available literature, when a diagnosis of hypogonadism is established, we recommend initiating treatment between age 11 and 12 years of age, with dose increases approximately every 6 months until adult levels are reached. In some situations, treatment may be delayed to allow time for diagnosis or permit more time for linear growth, or address unique risks found in girls treated for various cancers or blood disorders. When adult dosing is reached, progestins are also used to protect uterine health. This can be combined sequentially, allowing regular menstruation, or combined continuously when menstrual bleeding is not preferred. Treatment is continued until the average age of menopause, again with various considerations for longer or shorter duration on the basis of risk-benefit ratios. Transdermal estrogens are considered the most physiologic replacement and theoretically might have fewer associated risks. We review what is known about risks and outcomes and areas for future research.

Lipoprotein(a) in postmenopausal women: assessment of cardiovascular risk and therapeutic options

INTRODUCTION

Lipoprotein(a) [Lp(a)], a low-density lipoprotein (LDL)-like particle, has been independently associated with increased cardiovascular disease (CVD) risk in various populations, such as postmenopausal women. The purpose of this narrative review is to present current data on the role of Lp(a) in augmenting CVD risk in postmenopausal women and focus on the available therapeutic strategies.

METHODS

PubMed was searched for English language publications until November 2015 under the following terms: "therapy" OR "treatment" AND ["lipoprotein (a)" OR "Lp(a)"] AND ("postmenopausal women" OR "menopausal women" OR "menopause").

RESULTS

Only hormone replacement therapy (mainly oral estrogens) and tibolone have been specifically studied in postmenopausal women and can reduce Lp(a) concentrations by up to 44%, although evidence indicating a concomitant reduction in CVD risk associated with Lp(a) is lacking. As alternative treatments for women who cannot, or will not, take hormonal therapies, niacin and the upcoming proprotein convertase subtilisin / kexin type 9 (PCSK-9) inhibitors are effective in reducing Lp(a) concentrations by up to 30%. Statins have minimal or no effect on Lp(a). However, data for these and other promising Lp(a)-lowering therapies including mipomersen, lomitapide, cholesterol-ester-transfer protein inhibitors and eprotirome are derived from studies in the general, mainly high CVD risk, population, and include only subpopulations of postmenopausal women.

CONCLUSIONS

Past, present and emerging therapies can reduce Lp(a) concentrations to a varying extent. Overall, it remains to be proven whether the aforementioned reductions in Lp(a) by these therapeutic options are translated into CVD risk reduction in postmenopausal women.

The Metabolic Syndrome in Women

The clustering of metabolic risk factors, overweight and hypertension is of particular importance in postmenopausal women due to the negative effect of menopause on bodyweight, glucose metabolism and the development of hypertension. Menopause acts directly as a risk factor by reducing the direct beneficial effect of ovarian hormones on cardiovascular functions, and indirectly by negatively influencing traditional risk factors for coronary artery disease. All changes occurring after the menopause must be regarded under a unifying mechanism that induces unfavorable changes in cardiovascular risk factors and vascular functions, which interact with each other, amplifying the effect of ovarian hormone deficiency and aging.

Ovariectomy shortens the life span of female mice

This study shows that lack of ovarian activity has a negative impact on the life span of female mice. The extent to which this phenomenon could be associated with the anti-inflammatory effect of estrogens was analyzed in metabolic organs and aorta, by quantitative analysis of mRNAs encoding proteins in the inflammatory cascade. We demonstrate that the TNFα, IL-1β, MCP-1, MIP-2 and IL-6 mRNA contents are increased in the liver, adipose tissue and aorta 7 months after ovariectomy (ovx) and this increased basal inflammation is maintained as the mice aged. In contrast, the extent of inflammatory gene expression is directly proportional to age in sham-operated mice. As a consequence, at 22 months, most of the inflammatory parameters examined were higher in the sham-operated group compared with the ovx group. These observations led us to propose that the decreased longevity of ovx mice may be due to an acceleration of the basal state of inflammation in metabolic organs, which is likely driven by the combination of a lack of estrogen-mediated anti-inflammatory activity and the loss of gonadal control of energy metabolism.

Estrogen restores brain insulin sensitivity in ovariectomized non-obese rats, but not in ovariectomized obese rats

OBJECTIVE

We previously demonstrated that obesity caused the reduction of peripheral and brain insulin sensitivity and that estrogen therapy improved these defects. However, the beneficial effect of estrogen on brain insulin sensitivity and oxidative stress in either ovariectomy alone or ovariectomy with obesity models has not been determined. We hypothesized that ovariectomy alone or ovariectomy with obesity reduces brain insulin sensitivity and increases brain oxidative stress, which are reversed by estrogen treatment.

MATERIALS/METHODS

Thirty female rats were assigned as either sham-operated or ovariectomized. After the surgery, each group was fed either a normal diet or high-fat diet for 12 weeks. At week 13, rats in each group received either the vehicle or estradiol for 30 days. At week 16, blood and brain were collected for determining the peripheral and brain insulin sensitivity as well as brain oxidative stress.

RESULTS

We found that ovariectomized rats and high-fat diet fed rats incurred obesity, reduced peripheral and brain insulin sensitivity, and increased brain oxidative stress. Estrogen ameliorated peripheral insulin sensitivity in these rats. However, the beneficial effect of estrogen on brain insulin sensitivity and brain oxidative stress was observed only in ovariectomized normal diet-fed rats, but not in ovariectomized high fat diet-fed rats.

CONCLUSIONS

Our results suggested that reduced brain insulin sensitivity and increased brain oxidative stress occurred after either ovariectomy or obesity. However, the reduced brain insulin sensitivity and the increased brain oxidative stress in ovariectomy with obesity could not be ameliorated by estrogen treatment.

Flaxseed reverses atherosclerotic lesion formation and lowers lipoprotein(a) in ovarian hormone deficiency

OBJECTIVE

The incidence of cardiovascular disease dramatically increases during menopause, and postmenopausal women seek natural alternatives to hormone therapy. Flaxseed can slow the progression of atherosclerotic lesion formation; however, it is not known whether it can reverse formation that has already occurred.

METHODS

Seventy-two female Golden Syrian hamsters were randomly divided into six groups (n = 12), sham-operated (sham) or ovariectomized (ovx), and kept on the same diet for 120 days to allow for atherosclerotic lesion development. After this 120-day period, whole flaxseed was introduced to the diets of hamsters in three of the groups: group 1 (sham + casein); group 2 (ovx + casein); group 3 (ovx + 7.5% flaxseed); group 4 (ovx + 15% flaxseed); group 5 (ovx + 22.5% flaxseed); and group 6 (ovx + 17β-estradiol). This diet was maintained for an additional 120 days. Lesion regression was examined histologically, and serum was analyzed for total cholesterol, triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, Apo A, Apo B, and lipoprotein(a).

RESULTS

Results showed that 15% and 22.5% flaxseed, compared with ovx animals, significantly reduced lipoprotein(a) (4.4 mg/dL [ovx] vs 2.15 mg/dL [15% flaxseed] and 0.3 mg/dL [22.5% flaxseed]; P < 0.05) and Apo B (2.8 mg/dL [ovx] vs 2.4 mg/dL [15% flaxseed] and 2.5 mg/dL [22.5% flaxseed]). Flax reduced by 67% the number of animals with aortic arch lesions.

CONCLUSIONS

All three doses of flax reduce the severity of lesion formation compared with ovx controls. These results support the efficacy of flaxseed in reducing cardiovascular disease risk.

Hypocholesterolemic effects of microbial protease-resistant fraction of Katsuobushi in ovariectomized rats depend on the both oil and undigested protein

The purpose of this study was to examine which component in the microbial protease-resistant fraction of Katsuobushi (KBR), smoke-dried bonito, is hypocholesterolemic in ovariectomized rats (OVX-rats). KBR contains two major components: oil and protease-resistant protein. Oil extracted from KBR (EX) was rich in palmitic, oleic and docosahexaenoic acids. OVX-rats were fed one of the following diets for 28 d: diets containing casein as the protein source (C or C+EX diet), a diet containing KBR as the protein source (KBR diet) or diets containing degreased KBR as the protein source (DF/KBR or DF/KBR+EX diet). The C and DF/KBR diets contained soybean oil as the oil source. In the C+EX, KBR and DF/KBR+EX diets, soybean oil was replaced by oil extracted from KBR (EX). Plasma total- and low density lipoprotein-cholesterol concentrations in the C+EX, KBR and DF/KBR+EX groups, but not in the DF/KBR group, were significantly lower than that in the C group. Fecal bile acid excretion was significantly greater in the C+EX, KBR, DF/KBR and DF/KBR+EX groups in comparison to the C group, whereas excretion in the KBR and DF/KBR+EX groups was significantly greater than in the C+EX and DF/KBR groups. Cholesterol 7alpha-hydroxylase activity was higher in the C+EX, KBR, DF/KBR and DF/KBR+EX groups than the C group. In OVX-rats fed C, C+EX or KBR for 28 d, bile acid flux into the small intestine increased in KBR and C+EX groups in comparison to the C group. The hypocholesterolemic effect of KBR in OVX-rats reflected in increased fecal bile acid excretion may be mediated by increased bile acid flux caused by EX and the binding of bile acids by protease-resistant proteins.

Raloxifene has favourable effects on metabolic parameters but has no effect on left ventricular function in postmenopausal women

In this prospective randomized study, we investigated the effect of raloxifene on the echocardiographic parameters of left ventricular diastolic and systolic function and on blood levels of lipids, homocysteine, and lipoprotein (a) in postmenopausal osteoporotic patients and compared the results with those treated with risedronate. A total of 44 women were included in the study. Patients were randomized into two groups. Twenty-two patients received raloxifene 60 mg/day (group 1), and 22 patients received risedronate 5mg/day (group 2; the control group). All patients underwent quantitative two-dimensional pulsed wave Doppler and tissue Doppler echocardiography. Levels of fasting total-C, HDL-C, LDL-C, triglycerides, homocysteine, and lipoprotein (a) were measured. All echocardiographic and biochemical parameters were assessed at the beginning of the study and after the 6-month follow-up. Demographic characteristics and baseline metabolic and echocardiographic parameters were similar in the two groups. After 6 months of the therapy, serum levels of total-C, LDL-C, and homocysteine decreased significantly (P=.04, P=.02, P=.008, respectively) in the treated group when compared with the control group. All echocardiographic measurements except a wave from level of basal interventricular septum were similar in the two groups both before and after 6 month of therapy. In the control group, a wave from level of basal interventricular septum increased significantly (P=.019). In conclusions raloxifene may decrease serum levels of total-C, LDL-C, and homocysteine in postmenopausal osteoporotic patients and raloxifene therapy seems to have no significant effect on left ventricular systolic and diastolic function.

Effects of non-oral postmenopausal hormone therapy on markers of cardiovascular risk: a systematic review

OBJECTIVE

To review the effects of non-oral administration of postmenopausal hormone therapy (HT) on risk markers for atherosclerotic and venous thromboembolic disease.Non-oral postmenopausal HT appears not to increase venous thromboembolic risk, whereas the effect on coronary heart disease risk is less clear.

DESIGN

Systematic review of literature obtained from MEDLINE, EMBASE, and CENTRAL databases from 1980 until and including April 2006. Terms for "postmenopausal hormone therapy" and for "non-oral administration" were combined in the search.

SETTING

Randomized clinical trials.

PATIENT(S)

Postmenopausal women, both healthy and with established cardiovascular disease or specified cardiovascular risk factors

INTERVENTION(S)

Non-oral HT (e.g., transdermal or intranasal) compared with oral HT or no treatment/placebo.

MAIN OUTCOME MEASURE(S)

Lipoprotein(a), homocysteine, C-reactive protein (CRP), cell adhesion molecules, markers of endothelial dysfunction, coagulation, and fibrinolysis.

RESULT(S)

Seventy-two studies investigating either transdermal or intranasal administration were included. For non-oral HT, decreases in lipoprotein(a), cell adhesion molecules, and factor VII generally were significant, resistance to activated protein C (APCr) was slightly increased, and other markers including CRP and homocysteine did not change. Compared with oral HT, changes in CRP and APCr were smaller, changes in cell adhesion molecules and some fibrinolytic parameters tended to be smaller, whereas changes in other factors including lipoprotein(a) and homocysteine did not differ.

CONCLUSION(S)

Potentially unfavorable changes seen with oral HT on two important markers, CRP and APCr, are substantially smaller with non-oral HT. Non-oral HT has minor effects on the other cardiovascular risk markers studied. Therefore, compared with oral HT, non-oral HT appears be safer with respect to atherosclerotic and venous thromboembolic disease risk.

Hypocholesterolemic effect of katsuobushi, smoke-dried bonito, prevents ovarian hormone deficiency-induced hypercholesterolemia

The purpose of this study was to examine whether katsuobushi, smoked-dried bonito (KB), which is a traditional Japanese food, prevents ovarian hormone deficiency-induced hypercholesterolemia. In experiment 1, ovariectomized rats (OVX-rats) were fed a purified diet containing casein or KB. Compared with the casein diet, the KB diet reduced the plasma cholesterol concentration and apparent protein digestibility, and increased the fecal dry weight and fecal bile acid excretion. In experiment 2, OVX-rats were fed one of the following four diets: casein diet containing corn oil or fish oil (CA/CO or CA/FO), or a diet containing the digested or undigested fraction of KB after treatment with microbial protease (KBE or KBR). KBR contains mainly two components: oil and protease-undigested protein of KB origin. In comparison with the CA/CO diet, the KBE diet did not affect the plasma and liver lipids concentrations, apparent protein digestibility nor fecal bile acid excretion. However, the KBR and CA/FO diets reduced the plasma cholesterol and triacylglycerol (TAG) concentrations and the liver total lipid and TAG concentrations, but increased the liver total and esterified cholesterol concentrations. The KBR diet increased fecal bile acid excretion and fecal dry weight, whereas the CA/FO diet did not. Thus, the preventive effect of KB on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration appears to be mediated by an increase in bile acid excretion through a promoted secretion of bile acids by the binding of bile acids to resistant proteins.

Complex actions of sex steroids in adipose tissue, the cardiovascular system, and brain: Insights from basic science and clinical studies

Recent publications describing the results of the Women's Health Initiative (WHI) and other studies reporting the impact of hormone therapy on aging women have spurred reexamination of the broad use of estrogens and progestins during the postmenopausal years. Here, we review the complex pharmacology of these hormones, the diverse and sometimes opposite effects that result from the use of different estrogenic and progestinic compounds, given via different delivery routes in different concentrations and treatment sequence, and to women of different ages and health status. We examine our new and growing appreciation of the role of estrogens in the immune system and the inflammatory response, and we pose the concept that estrogen's interface with this system may be at the core of some of the effects on multiple physiological systems, such as the adipose/metabolic system, the cardiovascular system, and the central nervous system. We compare and contrast clinical and basic science studies as we focus on the actions of estrogens in these systems because the untoward effects of hormone therapy reported in the WHI were not expected. The broad interpretation and publicity of the results of the WHI have resulted in a general condemnation of all hormone replacement in postmenopausal women. In fact, careful review of the extensive literature suggests that data resulting from the WHI and other recent studies should be interpreted within the narrow context of the study design. We argue that these results should encourage us to perform new studies that take advantage of a dialogue between basic scientists and clinician scientists to ensure appropriate design, incorporation of current knowledge, and proper interpretation of results. Only then will we have a better understanding of what hormonal compounds should be used in which populations of women and at what stages of menopausal/postmenopausal life.

Retrograded Tapioca Starch Prevents Ovarian Hormone Deficiency-Induced Hypercholesterolemia

The purpose of this study was to examine whether retrograded tapioca starch (RS3-tapioca) prevents ovarian hormone deficiency-induced hypercholesterolemia. Six-month-old Wistar female rats were subjected to sham-operation or ovariectomy, and fed a cholesterol-free purified diet with or without RS3-tapioca (150 g/kg diet) instead of digestible cornstarch for 28 d. Body weight gain and food intake increased in ovariectomized rats (OVX-rats). Plasma total cholesterol concentration was lowered by RS3-tapioca in OVX rats, but not in sham-operated rats. Liver lipids increased in OVX-rats, but liver cholesterol concentration was not affected by ovariectomy and RS3-tapioca. CYP7A1 activity, small intestinal and cecal bile acid content, and fecal bile acid excretion were increased by RS3-tapioca. The ratio of cholic acid groups to chenodeoxycholic acid groups in the bile acid of the small intestine was increased by RS3-tapioca. Thus, the preventive effect of RS3-tapioca on the ovarian hormone deficiency-associated increase in plasma cholesterol concentration appears to be mediated by accelerated fecal excretion of bile acid and an increase in the intestinal pool of bile acid.

Effects of transdermal estrogen replacement therapy on plasma levels of nitric oxide and plasma lipids in postmenopausal women

OBJECTIVE

Our purpose was to assess the effects of transdermal estrogen replacement therapy (TERT) on plasma levels of nitric oxide (NO) and plasma lipids in postmenopausal women.

MATERIALS AND METHODS

The study designed as a randomized, double-blind, placebo-controlled trial, involved 43 postmenopausal healthy women who had previously undergone hysterectomy. Women received either transdermal 100 microg 17beta-estradiol (Climara forte TTS) or placebo once a week for 3 months. Plasma levels of NO metabolites, estradiol (E2), total cholesterol (TC), triglicerides (TG), low-density lipoproteins (LDL), high-density lipoproteins (HDL), HDL2 and HDL3 were measured in blood samples of all women which were collected before, after 24 h and after 3 months of therapy.

RESULTS

We found significantly increased NO levels 24 h after therapy in TERT group. Moreover significantly higher NO levels were determined at 3rd month of therapy. Serum HDL and HDL2 levels of ERT group were significantly increased at 3rd month of therapy. Alteration of serum levels of HDL3, LDL and TC were not significantly different in groups. TG levels were significantly decreased in TERT group.

DISCUSSION

NO-related mechanism may help to explain the cardio-protective effect of TERT in the postmenopausal period. TERT seems to have favorable effects on plasma lipids in surgical menopausal women.

The effects of 17β-oestradiol plus dydrogesterone compared with conjugated equine oestrogens plus medroxyprogesterone acetate on lipids, apolipoproteins and lipoprotein(a)

OBJECTIVE

To compare the effects of 17 beta-oestradiol plus dydrogesterone with conjugated equine oestrogens plus medroxyprogesterone acetate on serum lipids, apolipoproteins and lipoprotein(a) in postmenopausal women.

METHODS

A multi-centre, prospective, randomised, double-blind, comparative one-year study in 362 healthy postmenopausal women aged 39-74 years with an intact uterus. Fasting blood samples were taken at baseline and after 28 and 52 weeks of treatment. Participants received daily oral treatment with continuous combined 1 mg micronised 17 beta-oestradiol/5 mg dydrogesterone (E/D: n=180) or 0.625 mg conjugated equine oestrogens/5 mg medroxyprogesterone acetate (CEE/MPA: n=182).

RESULTS

Significant differences between the two groups after 52 weeks were observed for total cholesterol (E/D: -1.7%; CEE/MPA: -7.3%), LDL-cholesterol (E/D: -4.5%; CEE/MPA: -11.3%), HDL-cholesterol (E/D: +15.3%; CEE/MPA: +7.5%), triglycerides (E/D: +9.8%; CEE/MPA: +16.6%), VLDL-triglycerides (E/D: -3.3%; CEE/MPA: +10.0%), lipoprotein(a) (E/D: 0.0%; CEE/MPA: -25.2%) and for the ratio apolipoprotein B/LDL-cholesterol (E/D: +0.9%; CEE/MPA +5.9%).

CONCLUSIONS

E/D and CEE/MPA differ in their anti-atherogenic effects on lipids and lipoproteins. This however can not easily be translated to differences in clinical cardiovascular outcomes.

Surgical risk reduction: prophylactic salpingo-oophorectomy and prophylactic mastectomy

Investigators have used retrospective and prospective study designs to provide much needed data on the extent of risk reduction after prophylactic oophorectomy and mastectomy in women at increased risk for breast and ovarian cancer. In this publication we identify those women who may wish to consider prophylactic surgery, review data demonstrating the efficacy of prophylactic surgery, and discuss potential surgical complications. We also present data about the frequency of use and psychosocial impact of prophylactic surgery in this typically young group of women. Finally, we provide general treatment guidelines for the practicing clinician.

Modest protective effects of isoflavones from a red clover-derived dietary supplement on cardiovascular disease risk factors in perimenopausal women, and evidence of an interaction with ApoE genotype in 49-65 year-old women

Data suggest that soy protein, a source of isoflavones, may have favorable effects on cardiovascular risk factors. Women (n = 205), ages 49-65 y, were randomized into this double blind, placebo-controlled trial of 43.5 mg red clover-derived isoflavones/d. A total of 177 women completed the trial. There were no differences between treatments for changes from baseline to 12 mo in total cholesterol, LDL cholesterol, triglycerides, HDL cholesterol, systolic and diastolic blood pressures, fibrinogen, and plasminogen activator inhibitor type 1 (PAI-1) (P >/= 0.1). Interactions between treatment and menopausal status were significant for changes in triglycerides and PAI-1 (P = 0.02 and P = 0.01), and changes were significant among perimenopausal women. In the isoflavone and placebo groups, changes in triglycerides were -0.2 +/- 0.6 and 0.4 +/- 0.6 mmol/L, P = 0.02, and changes in PAI-1 were -3.06 +/- 5.88 and 4.95 +/- 6.25 IU/L, P = 0.004, respectively. Interactions between apolipoprotein E (apoE) genotype and treatment tended to be significant for changes in total and LDL cholesterol (P = 0.06 and P = 0.05), and differences between treatments were significant in E2/E3 women. In the isoflavone and placebo groups, changes in total cholesterol were -0.61 +/- 0.79 and 0.18 +/- 0.79 mmol/L, P = 0.03, and changes in LDL cholesterol were -0.84 +/- 0.79 and -0.04 +/- 0.69 mmol/L, P = 0.02, respectively. Although there were potentially beneficial changes in triglycerides and PAI-1 among perimenopausal women consuming isoflavones, this study suggests that isoflavones alone are not responsible for the well-documented effects of soy protein on blood lipids. A larger study is required to confirm the effect modification by apoE genotype.

Oral, more than transdermal, estrogen therapy improves lipids and lipoprotein(a) in postmenopausal women: a randomized, placebo-controlled study

OBJECTIVE

To assess the effects of low-dose oral and transdermal estrogen therapy on the lipid profile and lipoprotein(a) [Lp(a)] levels in healthy, postmenopausal women and to study the additional influence of gestodene administration.

DESIGN

In a multicenter, randomized, double-blind, placebo-controlled study, 152 healthy, hysterectomized, postmenopausal women received daily either placebo (n = 49), 50 microg transdermal 17beta-estradiol (tE2, n = 33), 1 mg oral 17beta-estradiol (oE2, n = 37), or 1 mg oE2 combined with 25 microg gestodene (oE2 + G, n = 33) for 13 cycles of 28 days, followed by 4 cycles of placebo in each group. Fasting serum concentrations of total, high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol, triglycerides, and Lp(a) were measured at baseline and in cycles 4, 13, and 17.

RESULTS

In cycle 13, a significant mean percentage decrease from baseline was found in all treatment groups compared with placebo in total cholesterol (tE2, -4.7%; oE2, -6.9%; oE2 + G, -10.5%) and LDL cholesterol (tE2, -5.8%; oE2, -12.6%; oE2 + G, -13.6%). For both oral groups, the reductions were already significant in cycle 4. None of the treatment groups showed a significant change in HDL cholesterol or triglycerides. In cycle 13, Lp(a) was decreased compared with placebo in the oE2 group (-6.6%) and the oE2 + G group (-8.2%). After washout, all observed changes had returned to baseline level, except for the decreases in total and LDL cholesterol in the oE2 + G group.

CONCLUSIONS

Oral E2 and E2 + G, and to a lesser extent transdermal E2, decreased total and LDL cholesterol. Lp(a) was lowered only by the oral treatments.

Taurine prevents hypercholesterolemia in ovariectomized rats fed corn oil but not in those fed coconut oil

We studied whether the type of dietary fatty acid influences the preventive effect of taurine on the ovarian hormone deficiency-induced increase in plasma cholesterol concentration in 6-mo-old ovariectomized rats. Rats were fed one of the following four diets for 28 d: purified diets based on corn oil, which is rich in linoleic acid, with or with out taurine (50 g/kg) or purified diets based on coconut oil, which is rich in lauric and myristic acids, with or without taurine. Body mass gain, food intake, liver weight and plasma apolipoprotein (apo) A-I, apo B, LDL and VLDL concentrations were not affected by the diets. On the other hand, taurine lowered the plasma total cholesterol concentration (P < 0.02) in rats fed corn oil, but not in those fed coconut oil. In rats fed both types of oils, taurine increased the LDL receptor mRNA level (P < 0.01), hepatic cholesterol 7alpha-hydroxylase activity (P < 0.01) and fecal bile acid excretion (P < 0.01). Taurine increased the HMG-CoA reductase mRNA level (P < 0.02) in the liver of rats fed coconut oil, but not in those fed corn oil. Taurine increased liver total lipid (P < 0.05) and triglyceride (P < 0.05) concentrations in rats fed corn oil, but not in those fed coconut oil. These results indicate that the effect of taurine on ovarian hormone deficiency-induced changes in cholesterol metabolism is influenced by the type of dietary fatty acids.

A 2-year, randomized, comparative, placebo-controlled study on the effects of raloxifene on lipoprotein(a) and homocysteine

OBJECTIVES

Lipoprotein(a) (Lp(a)) and homocysteine (Hcy) are independent cardiovascular risk factors, which have been shown to be lowered by hormone replacement therapy (HRT). In this 2-year study, the long-term effects of raloxifene (Rlx) in two doses, on Lp(a) and Hcy, were studied and compared with the effects of continuously combined hormone replacement therapy (ccHRT).

METHODS

In a prospective, randomized, double-blind, placebo-controlled 2-year study, 95 healthy, non-hysterectomized, early postmenopausal women, received daily either oral Rlx 60 mg (N=24) or 150 mg (N=23), ccHRT (conjugated equine estrogens 0.625 mg plus medroxyprogesterone acetate 2.5 mg; N=24) or placebo (N=24). Fasting serum Lp(a) and plasma Hcy concentrations were measured at baseline and at 6, 12 and 24 months.

RESULTS

The mean individual changes compared to baseline after 24 months were for Lp(a): Rlx 60: - 5%, Rlx 150: -7%, ccHRT: -34%, placebo: +1% and for Hcy: Rlx 60: -3%, Rlx 150: -4%, ccHRT: -4%, placebo: +6%. ANCOVA was significant for Lp(a) under ccHRT versus placebo (P=0.001) and for Lp(a) under ccHRT versus each of the two Rlx groups (P<0.05).

CONCLUSIONS

Long-term treatment with Rlx was not as effective as ccHRT in lowering Lp(a). Although not significant and without an obvious dose-related response, the Hcy values showed the same trend for each treatment arm, which is in line with data reported earlier.

Effects of postmenopausal hormone replacement therapy on lipid, lipoprotein, and apolipoprotein (a) concentrations: analysis of studies published from 1974-2000

OBJECTIVE

To establish reference estimates of the effects of different hormone replacement therapy (HRT) regimens on lipid and lipoprotein levels.

DESIGN

Review and pooled analysis of prospective studies published up until the year 2000.

SETTING

Clinical trials centers, hospitals, menopause clinics.

PATIENT(S)

Healthy postmenopausal women.

INTERVENTION(S)

Estrogen alone, estrogen plus progestogen, tibolone, or raloxifene in the treatment of menopausal symptoms.

MAIN OUTCOME MEASURE(S)

Serum high- and low-density lipoprotein (HDL and LDL) cholesterol, total cholesterol, triglycerides, and lipoprotein (a).

RESULT(S)

Two-hundred forty-eight studies provided information on the effects of 42 different HRT regimens. All estrogen alone regimens raised HDL cholesterol and lowered LDL and total cholesterol. Oral estrogens raised triglycerides. Transdermal estradiol 17-beta lowered triglycerides. Progestogens had little effect on estrogen-induced reductions in LDL and total cholesterol. Estrogen-induced increases in HDL and triglycerides were opposed according to type of progestogen, in the order from least to greatest effect: dydrogesterone and medrogestone, progesterone, cyproterone acetate, medroxyprogesterone acetate, transdermal norethindrone acetate, norgestrel, and oral norethindrone acetate. Tibolone decreased HDL cholesterol and triglyceride levels. Raloxifene reduced LDL cholesterol levels. In 41 studies of 20 different formulations, HRT generally lowered lipoprotein (a).

CONCLUSION(S)

Route of estrogen administration and type of progestogen determined differential effects of HRT on lipid and lipoprotein levels. Future work will focus on the interpretation of the clinical significance of these changes.

Ethanol-extracted soy protein isolate does not modulate serum cholesterol in golden Syrian hamsters: a model of postmenopausal hypercholesterolemia

Soy protein consumption has been linked to reduction in hypercholesterolemia, a risk for coronary heart disease. However, to what extent soy protein itself or its non-nutritive components, e.g., isoflavones and saponins, exert this cholesterol-lowering effect requires further investigation. To evaluate the effect of the protein component alone on lipid variables, ethanol-extracted, isoflavone-depleted soy protein isolate (SPe) was studied in ovarian hormone-deficient hamsters. Forty-eight 6-month-old female Golden Syrian hamsters were either sham-operated or ovariectomized and fed casein-based or SPe-based diets for 70 d. Ovariectomy, but not protein source, significantly (P < 0.05) increased serum phospholipids and total, non-high density lipoprotein, free and esterified cholesterol concentrations. Serum HDL cholesterol concentrations were not altered with either treatment. No significant differences were observed in liver total lipids or liver total cholesterol among the groups. Soy protein isolate, however, lowered serum triglyceride concentrations in both sham-operated and ovariectomized hamsters. These findings confirm the ovariectomized hamster as a model of postmenopausal hypercholesterolemia. The results are consistent with earlier observations that isoflavones or other nonprotein components, perhaps in combination with soy protein, play an important role in exerting this hypocholesterolemic effect. Further studies are needed to investigate whether isolated nonprotein components of soy would be able to prevent the ovarian hormone deficiency-associated rise in serum cholesterol regardless of dietary protein source.

Long-term chemotherapy-related cardiovascular morbidity

As a consequence of the successful use of chemotherapy in the treatment of curable neoplasms such as germ cell tumours and malignant lymphomas, and the increasing application of primary and adjuvant chemotherapy for various tumour types, the number of patients with a prolonged life expectancy after treatment is rising. Attention to long-term side-effects, including cardiovascular toxicity, is therefore of growing importance. In this review we evaluate the literature on long-term cardiovascular toxicity related to chemotherapy in adult patients. Two categories of patient with favourable life expectancy have been reviewed, namely patients cured of metastatic disease by chemotherapy and patients treated with adjuvant chemotherapy. In the first category, the literature on long-term cardiovascular morbidity in survivors of metastatic testicular cancer and lymphomas is discussed, while in the second category this is done for patients treated with adjuvant chemotherapy for breast and colon cancer. As well as the direct toxic effects of chemotherapy on the cardiovascular system, the indirect toxic effects such as chemotherapy-related metabolic changes that may cause cardiovascular morbidity are also discussed.

Effects of menopause and hormone replacement therapy on plasma lipids, lipoproteins and LDL-receptor activity

A cross-sectional study of ninety six women was conducted to examine the effect of menopause and hormone replacement therapy (HRT) on plasma lipids, lipoproteins and oxidation of low density lipoproteins. The sample consisted of 26 premenopausal women, 26 postmenopausal women taking no replacement hormones and 43 postmenopausal women on hormone replacement therapy. Postmenopausal women not taking replacement hormones had significantly higher plasma cholesterol, low density lipoprotein (LDL) cholesterol and lipoprotein[a] (Lp[a]) levels compared to premenopausal women or postmenopausal women on HRT [6.00 +/- 0.15, 5.36 +/- 0.17 (P < 0.01), 5.63 +/- 0.13 (P < 0.05) mmol/l, respectively for total cholesterol; 4.13 +/- 0.15, 3.64 +/- 0.15 (P < 0.05), 3.82 +/- 0.12 (P < 0.05) mmol/l, respectively for LDL-cholesterol; 48.19 +/- 9.90, 26.59 +/- 5.53 (P < 0.03), 25.12 +/- 4.62 (P < 0.03) mg/dl, respectively for Lp[a]]. The differences in LDL cholesterol concentrations were inversely related to changes in LDL receptor activity (r = -0.27, P < 0.01). HRT use was found to be associated with a significantly smaller LDL particle size. Plasma triglyceride was significantly higher in women on HRT (1.16 +/- 0.07 mmol/l) than in the premenopausal group (0.96 +/- 0.07) or postmenopausal group not using HRT (0.87 +/- 0.06). There were no differences in LDL oxidation between the groups when LDL was oxidised in the presence of copper. Nor was there any difference in the uptake of copper-oxidised or macrophage-modified LDL into J774 macrophages. These results confirm the effect of menopause and exogenous hormones on plasma lipids and lipoproteins, and suggest that HRT modifies the activity of the LDL receptor. Hormone replacement did not appear to protect LDL from oxidation.

Hormone replacement therapy and lipid-lipoprotein concentrations

OBJECTIVE

To evaluate the links between hormone replacement therapy and lipid-lipoprotein concentrations (total cholesterol [T.Ch] triglycerids, high density lipoprotein cholesterol [HDL-C], low density lipoprotein cholesterol [LDL-C] and very low density lipoprotein cholesterol [VLDL-C]) in a total of 6416 postmenopausal women.

STUDY DESIGN

Open prospective longitudinal study. Of the 2184 surgical postmenopausal women, 1102 received conjugated equine estrogen (CEE), and 1082 transdermal estradiol (TDE2). Of the 4232 natural postmenopausal women: 1073 received CEE+medroxyprogesterone acetate (MPA), 1068 CEE+dydrogesterone (DD), 1044 TDE2+MPA, 1047 TDE2+DD. Lipid-lipoprotein concentrations were evaluated by using a SPSS program at 1,2,3,4,5,6,7 years of therapy and cumulatively.

RESULTS

Cumulative evaluation of the data on estrogen only replacement therapy revealed a significant decrease in T.Ch, LDL-C and VLDL-C, and an increase in HDL-C; however, the increase in HDL-C and triglycerids was significantly higher in CEE than TDE2 (P<0.01). Cumulative evaluation of the data on estrogen progestin hormone replacement therapy revealed a significant decrease in T.Ch, LDL-C and an increase in HDL-C for all; however, triglycerides and VLDL levels decreased in TDE2+MPA and TDE2+DD groups (P<0.05).

CONCLUSION

Both the natural and surgical menopause patients were found to have more favorable lipid profiles after treatment with estrogen progesterone combined formulations and estrogen only replacement.

Comparison of the effects of conjugated estrogen treatment on blood lipid and lipoprotein levels when initiated in the first or fifth postmenopausal year

Although estrogen replacement therapy (ERT) is known to be protective against the development of cardiovascular disease in patients with surgical menopause, the effects of ERT on blood lipids when started late after the operation is not yet clear. In this prospective study, blood lipid and lipoprotein levels were measured within a 2 year period, in Group I (n = 28 patients) and in Group II (n = 21 patients), who had total abdominal hysterectomy and bilateral salphingo-oophorectomy 10-16 or 55-65 months ago, respectively. Each patient received 0.625 mg conjugated equine estrogen once daily. Blood levels of total cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL), high density lipoprotein (HDL) and very low density lipoprotein (VLDL) were measured at the beginning of the study as well as 12 and 24 months after ERT, was commenced. When the levels obtained after 12 and 24 months of ERT were compared to the baseline levels, LDL levels were decreased, whereas HDL levels were increased in Group I (p < 0.05); however, only the TC levels were significantly lower in Group II (p < 0.05). In conclusion, our results show that ERT is more effective on blood lipid changes when initiated within one year of oophorectomy compared with ERT initiated 5 years after the menopause.

Postmenopausal hormone replacement, risk estimators for coronary artery disease and cardiovascular protection

Menopause, regardless of age at onset, is associated with a marked increase in coronary artery disease (CAD) risk. A large body of observational clinical studies repeatedly demonstrated favorable associations between postmenopausal hormone replacement therapy (HRT) and cardiovascular morbidity, mortality, and risk factors. Estrogens may act in a gender-specific way on vascular endothelial cells and other components of the vessel wall, enhancing the synthesis and release of nitric oxide (NO) and other vasodilators, and by inhibiting the synthesis and release of vasoconstricting agents, thus favoring vasodilation. Menopause-related changes in metabolic cardiovascular risk factors are identifiable, as are HRT-related changes in these factors. The metabolic effects include changes in lipoprotein (a), coagulation and fibrinolysis as well as homocysteine metabolism. The various actions of estrogen alone and combined with progestogen on the vascular system are reviewed. Furthermore, the outcome of the recently published Heart and estrogen/progestin replacement study (HERS) data are put in perspective. In addition, we outline the present data on the effects of raloxifene, a new second generation selective estrogen receptor modulator (SERM), which has been shown to favorably alter several markers of cardiovascular risk in postmenopausal women.

Phyto-oestrogens: a potential role in the prevention of CHD?

CHD is a major cause of morbidity and mortality in women. The incidence of CHD in premenopausal women is low but increases substantially after the menopause, and this difference suggests that endogenous oestrogens are cardioprotective. Observational prospective studies have consistently shown that exogenous oestrogens also lower CHD risk. The biological mechanisms by which endogenous and exogenous oestrogens exert their protective effect are multifactorial, affecting lipids, carbohydrate metabolism, body fat distribution and blood pressure. The prevention of CHD with oestrogen therapy is therefore aimed both at correction of the traditional risk factors and at direct control of vessel structure and function. The wide international variation in rates of CHD together with the lower mortality in sub-groups of the population suggests that a considerable proportion of CHD may be prevented by dietary modification. Since phyto-oestrogens are structually similar to oestrogen, they have the potential to mimic its effects in vivo. The hypocholesterolaemic effects of soyabean protein (rich in phyto-oestrogen precursors) are well established, but the underlying mechanism and atherogenic potential of these changes are unknown. One isoflavone, genistein, has been shown in vitro to exert effects which may slow the development of atherosclerotic disease. However, further studies are required to determine the dose-related changes induced by phyto-oestrogens on serum lipoproteins, haemostasis and vascular function.

Oestrogen replacement therapy and coronary heart disease

This review highlights recent progress in our understanding of the beneficial effects of hormone replacement therapy (HRT) in cardiovascular disease (CVD). The fact that HRT is increasingly advocated has raised concern about possible adverse effects weighed against the potential benefits of HRT regimens. Both favourable and unfavourable effects of oestrogens and HRT regimens on CVD risk factors are increasingly recognized. Consequently, the picture on cardiovascular effects of oestrogen and HRT has become more complicated, and research in this field has extended to novel areas.

Hormone replacement therapy in postmenopausal women with specific risk factors for coronary artery disease

Hormone replacement therapy (HRT) in postmenopausal women is associated with a reduction in the risk of developing coronary artery disease (CAD) of about 50%. Women with an elevated risk for CAD appear to benefit most by HRT. The HRT-associated cardiovascular protection may be related to favourable changes in several important cardiovascular risk estimators, such as circulating blood concentrations of cholesterol, lipoprotein(a) (Lp(a)) and homocysteine. This paper reviews the literature presently available on the effects of HRT on cholesterol, Lp(a) and homocysteine concentrations, and special attention will be given to the effects on their elevated concentrations. The effect of HRT in women with hypertension is reviewed as well. From this overview it can be concluded that risk factors such as cholesterol, Lp(a), and homocysteine can be favourably modulated by HRT, and especially, that the strongest reductions can be achieved in those women with the highest concentrations. Although clinical trials still need to demonstrate the impact of lowering concentrations of Lp(a) and homocysteine, HRT appears to be a promising risk reduction strategy in this respect.

CI-1011 lowers lipoprotein(a) and plasma cholesterol concentrations in chow-fed cynomolgus monkeys

Lipoprotein(a) (Lp(a)), which is generated through the covalent association of apolipoprotein(a) (apo(a)) and apo B-100-LDL, is an independent risk factor for several vascular diseases. Therefore, there is interest in developing therapies for lowering Lp(a). This investigation was carried out to determine the effect of CI-1011, a potent lipid regulator in rodents, on Lp(a) and other lipid parameters in cynomolgus monkeys (Macaca fascicularis). Nine healthy male monkeys on a normal chow diet were orally treated with CI-1011 at 30 mg/kg per day for 3 weeks. Lp(a) and total cholesterol levels were significantly decreased after 1 week and maximally reduced to 68 and 73% of control levels, respectively, after 3 treatment weeks. The decreases in total cholesterol were mainly due to changes in low density lipoprotein (LDL). The LDL:HDL ratio decreased by 30%. Triglycerides were unaffected by treatment. Lp(a) and total cholesterol levels returned to pretreatment values after stopping treatment suggesting a direct effect of the compound on their inhibition. Further studies demonstrated that CI-1011 was effective at a low dose of 3 mg/kg per day after 1 week of administration. CI-1011 also decreased apo B-100 to 80% of control levels, but this change was not sufficient to account for the Lp(a) lowering. There was also no correlation between the changes in Lp(a) and apo B-100 levels. Treatment of cynomolgus monkey primary hepatocyte cultures with CI-1011 resulted in a dose-dependent inhibition of Lp(a) levels suggesting a direct hepatic effect of the compound. Western blot analysis of the samples showed that changes in Lp(a) were associated mainly with decreased apo(a) (47%), but not apo B-100 (17%). These results demonstrate that CI-1011 effectively decreases Lp(a) levels both in vivo and in vitro.