Conjugated estrogen/progestagen versus tibolone hormone replacement therapy in postmenopausal women: Effects on carbohydrate metabolism and serum sex hormone-binding globulin

OBJECTIVE: To study the effects of different types of continuous hormone replacement therapy on carbohydrate metabolism. METHOD: Postmenopausal women were treated with conjugated estrogens, 0.625 mg/medroxyprogesterone acetate, 2.5 or 5 mg (CEE/MPA) or tibolone 2.5 mg daily for 13 28-day cycles. Serum glucose and insulin were measured before and during a 75 g oral glucose tolerance test (OGTT) at baseline and after 3, 6 and 13 cycles and areas under the curve (AUC) were calculated. Sex hormone-binding globulin (SHBG) was measured as an additional marker of nutritional and insulin status. RESULTS: Neither CEE/MPA 2.5mg nor tibolone had any effects on carbohydrate metabolism while AUC(insulin), AUC(glucose) and also body mass index (BMI) increased after 13 cycles of treatment in the CEE/MPA 5 mg group. SHBG increased significantly during CEE/MPA treatment and decreased significantly during treatment with tibolone. The effects on SHBG were less pronounced in the CEE/MPA 5mg group. Pretreatment SHBG showed significant negative correlations to BMI and to variables that may reflect a certain degree of insulin resistance, the most pronounced being fasting glucose. Changes in SHBG during treatment with tibolone were negatively correlated to pretreatment SHBG and positively to BMI, AUC(insulin) and fasting insulin resistance index, while no such correlations were found in the CEE/MPA groups. There were no correlations between changes in AUC(insulin) and AUC(glucose) on one hand and basal variables or treatment SHBG on the other in the CEE/MPA groups. CONCLUSION: The effects of tibolone and CEE/MPA on carbohydrate metabolism were considered to have clinical significance only for CEE/MPA 5mg, indicating a less favourable role of the higher progestagen dose. The results further support the important role of metabolic and insulin status in the physiological regulation of SHBG and also indicate that the suppressive effect of tibolone on circulating SHBG is mainly depends on pretreatment SHBG levels. SHBG does not reflect changes in carbohydrate metabolism during CEE/MPA treatment.     

A comparative study of two hormone replacement therapy regimens on safety and efficacy variables

Objective: To assess the effect of tibolone on endometrial safety, plasma estradiol concentrations, lipid metabolism and climacteric symptoms in comparison to sequential conjugated equine estrogens and medroxyprogesterone acetate in postmenopausal women. Methods: In a randomised, open-label, 6-cycle, group-comparative study, the effects on the aforementioned parameters were studied with tibolone 2.5 mg/day (N = 13) continuously, and with conjugated equine estrogens 0.625 mg/day continuously, combined with medroxyprogesterone acetate 5 mg/day (N = 11) (CEE/MPA) sequentially, during 12 days of each 28-day cycle. Within-group statistical analysis was performed with Student's t-test for paired samples, whereas between-group statistics were performed using the Student's t-test for independent groups. Results: Cytological evaluation revealed no endometrial stimulation in either group. In the tibolone group, there were no effects on estradiol levels, whereas in the CEE/MPA group, an increase in total and non-SHBG-bound estradiol plasma levels was reported. In the tibolone group, there were significant decreases in plasma total cholesterol, triglycerides, HDL-cholesterol and VLDL-cholesterol, whereas no significant changes in LDL-cholesterol and IDL-cholesterol were reported. In the CEE/MPA group there were significant decreases in plasma total cholesterol, HDL-cholesterol and LDL-cholesterol, whereas there were no significant changes in triglycerides, IDL-cholesterol and VLDL-cholesterol. Climacteric symptoms, particularly vasomotor episodes, decreased similarly in both groups. Conclusions: Both tibolone and CEE/MPA were safe with respect to effects on the endometrium and both treatments induced changes in the plasma profiles of certain lipid and lipoprotein parameters. However, the overall clinical implications of these changes are unknown. Finally, both regimens were equally effective in the treatment of climacteric symptoms     

Effects of tibolone on bone quality in ovariectomized monkeys

OBJECTIVE: The purpose of this report is to examine the effects of two doses of tibolone on bone quality (bone biomarkers, bone density, and bone strength) in ovariectomized cynomolgus monkeys fed high-fat diets. DESIGN: Ovariectomized cynomolgus monkeys were randomized into one of five treatment groups: placebo-treated control, tibolone (0.2 mg/kg/day), tibolone (0.05 mg/kg/day), conjugated equine estrogens (Premarin, 0.042 mg/kg/day), and conjugated equine estrogens plus medroxyprogesterone acetate (0.042 and 0.167 mg/kg/day, respectively). Bone quality was assessed by determining bone strength and density in vertebrae and femora collected after 24 months of treatment. RESULTS: Monkeys treated for 24 months with tibolone had increased bone mineral density in the distal femur and improved biomechanical properties in the midshaft femur compared with placebo-treated ovariectomized monkeys, as did monkeys treated with conjugated equine estrogens with or without medroxyprogesterone acetate. No treatment effects were seen in lumbar vertebra bone density or strength. There was no significant difference between tibolone and estrogen on biomechanical properties of the femur. CONCLUSION: These data show that tibolone is comparable to conjugated equine estrogens with or without medroxyprogesterone acetate in decreasing bone turnover and increasing bone strength in ovariectomized monkeys.     

Blood flow in the internal carotid and middle cerebral arteries: effects of continuous oral conjugated equine estrogens administration with monthly progestogen supplementation on postmenopausal women.

OBJECTIVE: This study was designed in order to evaluate the effect of conjugated equine estrogens (CEE) on internal carotid and middle cerebral artery blood flow in postmenopausal women. DESIGN: Thirty-four healthy postmenopausal women with intact uteri were randomly divided into two groups of 17 subjects each. The first group was treated for 24 weeks with continuous CEE medication (0.625 mg daily) and cyclical supplementations of 5 mg/day of medrogestone acetate, given on the last 12 days of every 4-week period (Prempak, Wyeth, Italy). The second group received no treatment. The pulsatility indices (PI) of both the internal carotid artery and middle cerebral artery were measured. RESULTS: In the treated group, the PI of the interior carotid artery and MCA was reduced from respectively 0.736 (0.016) and 0.745 (0.009) at baseline, to 0.669 (0.021) and 0.670 (0.011) after 24 weeks (p = 0.01); in the control group, the PI values remained unchanged. The between-group difference for both arteries was significant (p < 0.01). CONCLUSIONS: The administration of CEE with cyclical medrogestone supplementation to postmenopausal women induces a statistically significant reduction in the PI of cerebral arteries.     

Tibolone versus conjugated estrogens and sequential progestogen in the treatment of climacteric complaints

Objective: Tibolone has been shown to alleviate climacteric symptoms. This study was designed to compare the effect of tibolone (Livial®, 2.5 mg daily) on different climacteric complaints and its impact on the endometrium, determined by vaginal ultrasound, with that of conjugated estrogens (Premarin®, 0.625 mg daily) continuously for 6 months in combination with the progestogen medrogestone (Colpron®, 2 × 5 mg daily for 12 days each month). Methods: One hundred and twenty-nine postmenopausal women were recruited and the severity of climacteric symptoms as well as endometrial thickness were recorded at the pre-trial examination and after 1, 3, and 6 months. Results: With the exception of vertigo, mood depression, mood disorder, loss of libido, and dryness of skin, where tibolone was found to be more effective than conjugated estrogens/medrogestone, climacteric symptoms improved significantly in both groups over the 6-month study period. Endometrial thickness did not increase significantly in the tibolone group, whereas in the conjugated estrogens/medrogestone group there was a highly significant increase after 1 month and still a trend towards significance after 6 months. Recurrence of vaginal bleeding occurred significantly less frequently in the tibolone group than in the comparison group. Conclusion: Tibolone seems to offer a complete treatment of the climacteric complaints whilst avoiding some of the problems associated with classical hormone replacement therapy.     

Effects of two continuous hormone therapy regimens on C-reactive protein and homocysteine

OBJECTIVE: To compare the effects of two continuous hormone therapy (HT) regimens on the cardiovascular risk markers, C-reactive protein (CRP) and homocysteine. DESIGN: A prospective study in which 43 postmenopausal women were randomly assigned to either tibolone 2.5 mg/day (n = 20) or 0.625 mg/day conjugated equine estrogens (CEE) plus continuous medroxyprogesterone acetate (MPA) 5 mg/day (n = 23). Serum levels of CRP, homocysteine, vitamin B12, and folate were determined before and during 12 weeks of therapy. RESULTS: C-reactive protein levels were increased by tibolone (76%; P < 0.001) and CEE+MPA (81%; P < 0.001). Neither tibolone nor CEE+MPA had any significant effect on homocysteine levels, but there was a significant difference between the effects of treatment over time (P = 0.046). Both tibolone and CEE+MPA reduced vitamin B12 levels (11%; P < 0.001, and 8%; P < 0.01, respectively), but had no statistically significant effect on folate levels. Individual changes in homocysteine levels were negatively associated with changes in vitamin B12 levels (r = -0.68; P < 0.01) after tibolone therapy. CONCLUSION: Both tibolone and CEE plus MPA increased CRP levels and reduced levels of vitamin B12. Neither therapy had any significant effect on homocysteine levels. Further long-term studies into the effect of HRT on these markers, and the relationship to cardiovascular disease risk, are required.     

A comparison of tibolone and hormone replacement therapy on coronary artery and myocardial function in ovariectomized atherosclerotic monkeys.

OBJECTIVE: Tibolone is used to prevent osteoporosis and to treat climacteric symptoms. The objectives of these studies were to measure and compare the effects of tibolone with hormone replacement therapy on coronary artery vascular reactivity and myocardial function and to relate these outcomes to treatment-induced plasma lipid/lipoprotein concentrations and atherosclerosis. DESIGN: One hundred forty-eight adult ovariectomized cynomolgus monkeys were fed an atherogenic diet for 24 months while receiving one of five oral treatments: no treatment (control, n = 31); conjugated equine estrogens (CEE), given at the equivalent of 0.625 mg/day ( n = 27); CEE (same dose) plus medroxyprogesterone acetate (MPA), given at the equivalent of 2.5 mg/day ( n = 29); low-dose tibolone (LoTib; 0.625 mg/day equivalent, n = 30); or high-dose tibolone (HiTib; 2.5 mg/day equivalent, n = 31). RESULTS: Quantitative coronary angiography showed that endothelium-mediated dilation was enhanced (17.5 +/- 5%, p = 0.002) in the CEE-treated group (but not other treatment groups) compared with the control. Both doses of tibolone and CEE reduced the incidence of dobutamine-induced ST-segment depression (LoTib: 33%, HiTib 25%, and CEE: 23%) compared to the control (79%) ( p = <0.05). Neither vascular reactivity nor dobutamine-induced myocardial ischemia were associated with treatment-induced changes in atherosclerosis or plasma lipid/lipoprotein concentrations. CONCLUSIONS: Tibolone, unlike CEE, has no benefit for endothelium-mediated dilation. Despite these differences, both tibolone and CEE reduced the incidence of myocardial ischemia, whereas CEE+MPA had no effect. It is speculated that tibolone may have direct effects on the myocardium that protect against myocardial ischemia.     

Serum androgen levels and insulin resistance in postmenopausal women: association with hormone therapy, tibolone and raloxifene

OBJECTIVE: To assess endogenous androgen and insulin resistance status in postmenopausal women receiving continuous combined hormone therapy (HT), tibolone, raloxifene or no therapy. METHODS: A total of 427 postmenopausal women aged 42-71 years were studied in a cross-sectional design. Among them 84 were taking HT (46 women conjugated equine estrogens 0.625 mg; medroxyprogesterone acetate, 5 mg, CEE/MPA; and 38 women 17beta-estradiol 2 mg; norethisterone acetate 1 mg, E2/NETA); 83 were taking tibolone 2.5 mg; 50 were taking raloxifene HCl 60 mg; and 210 women were not receiving any therapy. Main outcome measures were FSH, LH, estradiol, total testosterone, SHBG, free androgen index (FAI), Delta4-Androstendione (Delta4-A), Dehydroepiandrosterone sulphate (DHEAS) and HOMA insulin resistance index (HOMA-IR). RESULTS: In women not on hormone therapy smoking and older age was associated with lower DHEAS levels. FAI values increased linearly with increasing BMI. Age and BMI were positive determinants of HOMA-IR, while no association was identified between endogenous sex steroids and insulin resistance. CEE/MPA therapy was associated with higher SHBG, lower FAI and lower HOMA-IR values compared to women not on therapy (age and BMI-adjusted SHBG: CEE/MPA 148.8 nmol/l, controls 58.7 nmol/l, p < 0.01; age-adjusted FAI: CEE/MPA 0.8, controls 3.2, p < 0.05; age-adjusted HOMA-IR: CEE/MPA 1.3, controls 2.6, p < 0.05). On the contrary, E2/NETA treatment had no effect on these parameters. Women on tibolone had lower SHBG, higher FAI and similar HOMA-IR values compared to controls (age and BMI-adjusted SHBG: 24.1 nmol/l, p < 0.01; FAI: 6.0, p < 0.05; HOMA-IR: 2.3, p = NS). Raloxifene users did not exhibit any difference with respect to sex steroids and HOMA-IR levels. CONCLUSIONS: CEE/MPA users had lower free testosterone and improved insulin sensitivity. Tibolone on the other hand associated with higher free testosterone, while raloxifene did not relate to any of these parameters.     

Influence of different HRT regimens on mammographic density

OBJECTIVES: A prospective, randomized, open-label study was conducted to evaluate effects on mammographic density in postmenopausal and late perimenopausal women receiving continuous combined or sequential combined hormone replacement therapy (HRT). METHODS: The subjects were randomized to treatment with low-dose continuous combined HRT containing 1 mg 17beta-estradiol plus 0.5 mg norethisterone acetate (Activelle) or a sequential combined HRT regimen consisting of 0.625 mg conjugated equine estrogens for 28 days plus 5 mg medrogestone for 14 days (Presomen). Mammograms were obtained at baseline and after 9 cycles (each 28 days) of treatment. RESULTS: The majority of women (approximately two-thirds in each treatment group) had no changes in mammographic breast density between baseline and the final study visit. There were no marked differences between treatment groups. Approximately 20% of women in both groups had a slight increase in mammographic density. Only 10-14% of women in both groups had a pronounced increase in mammographic density. The analyses of the degree of change showed no remarkable differences between treatments. CONCLUSION: These results indicate that the increase in mammographic density with a low-dose continuous combined HRT regimen is no greater than that with a sequential combined HRT regimen. The type of progestogen does not have an impact on the extent of mammographic density changes.     

Effects of tibolone and hormone replacement therapy on the breast of cynomolgus monkeys

OBJECTIVE: To measure the effects of 2 years of treatment with tibolone on the breasts of cynomolgus macaques (Macaca fascicularis) in comparison with conventional hormone replacement therapy. DESIGN: Ovariectomized cynomolgus macaques were randomized into five groups and treated for 2 years. Groups included controls (n = 31) and four drug treatments, including tibolone at 0.05 mg/kg (LoTIB, n = 30) or 0.2 mg/kg (HiTIB, n = 31), conjugated equine estrogens at 0.042 mg/kg (CEE, n = 28), or CEE + medroxyprogesterone acetate (MPA) at 0.167 mg/kg (CEE + MPA, n = 29). Endpoints included histologic, histomorphometric, and immunohistochemical assessment of the mammary gland. RESULTS: Tibolone did not cause stimulation of the breast in contrast to distinct proliferative responses of the breast to CEE and CEE + MPA, as measured by increases in breast epithelial tissue area and expression of the proliferation marker Ki67 in breast epithelial cells. Tibolone at the higher dose increased progesterone receptor expression in the breast relative to controls, indicating partial estrogen-agonist activity, but without induction of proliferation. Progesterone receptor expression was also induced by CEE. CONCLUSIONS: Tibolone may have an advantage over conventional hormone replacement therapy because it does not stimulate proliferation in the breast. This lack of mammotrophic effect may reflect a lower risk for promotion of breast cancer.     

Comparative effects of tibolone and conjugated equine estrogens with and without medroxyprogesterone acetate on the reproductive tract of female cynomolgus monkeys

OBJECTIVE: To measure the effects of 2 years' treatment with tibolone on the reproductive tract of female monkeys (Macaca fascicularis) in comparison with conventional hormone replacement therapy. DESIGN: Ovariectomized adult female monkeys were randomized for 2 years of treatment into five groups: controls (n = 31); tibolone at 0.05 mg/kg (LoTIB group; n = 30); tibolone at 0.2 mg/kg (HiTIB group; n = 31); conjugated equine estrogens (CEE) at 0.042 mg/kg (CEE group; n = 28); or CEE + medroxyprogesterone acetate (MPA) at 0.167 mg/kg (CEE + MPA group; n = 29). Endpoints included vaginal cytology; uterine weight; histopathologic evaluation of the uterus, vagina, and cervix; histomorphometry of the endometrium; and immunohistochemical detection of the proliferation marker Ki67 and progesterone receptor in endometrial tissue. RESULTS: Endometrial atrophy was found in 29 of 30 and 23 of 31 animals in the LoTIB and HiTIB groups, respectively, compared with 0 of 28 and 11 of 29 in the CEE and CEE + MPA groups, respectively. All ovariectomized control animals had atrophic endometria. No complex or atypical hyperplasia was seen. Simple endometrial hyperplasia of a significant degree was seen in 3 of 31 HiTIB-treated animals, 1 of 30 LoTIB-treated animals, 26 of 28 CEE-treated animals, and 16 of 29 CEE + MPA-treated animals, and in none of the control animals. Marked simple endometrial hyperplasia and Ki-67 expression was induced by CEE and partially antagonized by MPA. LoTIB and HiTIB slightly increased endometrial thickness, whereas CEE and CEE + MPA induced a marked increase of 350% and 200%, respectively. Neither LoTIB nor HiTIB increased endometrial proliferation (Ki67 labeling) or induced vaginal keratinization. Endometrial bleeding was not seen in tibolone-treated animals but was present in 10 of 29 animals given CEE + MPA. CONCLUSIONS: The effect of tibolone on the uterus and lower reproductive tract was minimal. The lack of a proliferative response of the endometrium to tibolone, coupled with the lower incidence of endometrial bleeding, suggests that tibolone may have advantages over CEE and CEE + MPA regarding endometrial safety and efficacy.     

Effects of tibolone and conventional hormone replacement therapies on arterial and hepatic cholesterol accumulation and on circulating endothelin-1, vascular cell adhesion molecule-1, and E-selectin in surgically menopausal monkeys

OBJECTIVE: Menopause and aging are associated with a marked increase in the incidence of coronary heart disease as well as reductions in circulating estrogen, progestogen, and androgen levels. The synthetic compound tibolone and its metabolites have estrogenic, progestogenic, and androgenic characteristics. In the present study, we compared the effects of tibolone, estrogen replacement therapy, and estrogen plus progestogen replacement therapy on arterial and hepatic lipid accumulation and on circulating soluble adhesion molecule and endothelin-1 concentrations in surgically postmenopausal cynomolgus monkeys. DESIGN: Animals were fed an atherogenic diet for 2 years while receiving either no hormone treatment (control, n = 31) or the following treatments at doses designed to mimic the human dose on a daily caloric intake basis: tibolone at 2.5 mg/day (HiTib, n = 31), tibolone at 0.625 mg/day (LoTib, n = 29), conjugated equine estrogens (CEE) alone at 0.625 mg/day (CEE, n = 29), or CEE plus continuous medroxyprogesterone acetate (MPA) at 2.5 mg MPA/day (CEE + MPA, n = 30). RESULTS: Relative to the control group, iliac artery total cholesterol content was not different in the HiTib, LoTib, and CEE + MPA groups but was significantly lower in the group receiving CEE only (P < 0.05). In contrast, hepatic free cholesterol content was reduced in all treatment groups [HiTib (P < 0.01), LoTib (P < 0.05), CEE (P < 0.01), and CEE + MPA (P < 0.05)], whereas hepatic total and esterified cholesterol content were reduced in the HiTib, CEE, and CEE + MPA groups (all P < 0.05). HiTib and CEE groups had lower hepatic triglyceride levels per milligram of protein (P < 0.05). Iliac arterial cholesterol content was highly correlated with hepatic cholesterol content and with previously published histomorphometrically determined coronary artery atherosclerosis, supporting the use of the iliac artery as a surrogate for the coronary artery in the monkey. Circulating levels of soluble vascular cell adhesion molecule-1 were significantly reduced in the HiTib (P < 0.02) and CEE (P < 0.05) groups, whereas soluble E-selectin was reduced in the CEE group only (P < 0.01). Plasma endothelin-1 was significantly reduced in the LoTib (P < 0.05), CEE (P < 0.01), and CEE + MPA (P < 0.01) groups. CONCLUSIONS: These results suggest that while tibolone caused marked depression of high-density lipoprotein cholesterol and a resultant twofold increase in the total plasma cholesterol/high-density lipoprotein cholesterol ratio, those effects did not result in exacerbation of iliac artery atherosclerosis, perhaps because of beneficial effects on vascular biology or hepatic metabolism.     

A comparative study of the effect of continuous combined conjugated equine estrogen plus medroxyprogesterone acetate and tibolone on blood coagulability

BACKGROUND: Hormone therapy (HT) after the menopause is associated with increased risk of venous thromboembolism (VTE). Tibolone has pharmacodynamic properties different from other hormone preparations. We compared the effect of a combined HT and tibolone on the inhibition of haemostasis. METHODS: Thirty-eight post-menopausal women were randomly assigned to 1.25 or 2.5 mg per day of tibolone or oral continuous combined conjugated equine estrogen plus medroxyprogesterone acetate (CEE/MPA). Inhibitors of haemostasis were measured at baseline and after 12 months. RESULTS: Results from the two groups of women receiving tibolone were not significantly different and, to improve the power of the study, the two groups were merged. Higher concentration of protein S (1.16 versus 1.00 IU ml(-1); P = 0.005) and higher activated protein C resistance ratio (APC-R) (4.2 versus 3.65; P = 0.04) were observed in the tibolone group than in the CEE/MPA group. Both doses of tibolone increased APC-R significantly (P < 0.01). Tissue factor pathway inhibitor (TFPI) was lower in the CEE/MPA group than in the tibolone group (67.8 versus 79.9 ng ml(-1); P = 0.03). CEE/MPA reduced the concentration of antithrombin (P = 0.002), protein S (P < 0.001) and TFPI (P < 0.001). Both preparations reduced the concentration of plasminogen activator inhibitor 1 (P < 0.05). CONCLUSIONS: Tibolone induces fewer pharmacological alterations on blood coagulability than CEE/MPA and has a potentially favourable effect on APC-R. This may translate into a corresponding low risk of VTE, as also indicated from the existing clinical data.     

Effects of tibolone on estrogen biosynthesis in the mammary tissue of postmenopausal monkeys

OBJECTIVE: To evaluate the long-term effects of tibolone on estrone sulfate (E1S)-sulfatase activity in breast tissue in a primate model (Macaca fascicularis) in comparison with conventional hormone therapies. DESIGN: Ovariectomized female animals (n = 112) were randomized into five groups and treated for 2 years. Treatment included tibolone at 0.05 mg/kg (LoTib, n = 23) or 0.2 mg/kg (HiTib, n = 23), conjugated equine estrogens at 0.042 mg/kg (CEE, n = 24), CEE + medroxyprogesterone acetate at 0.167 mg/kg (CEE+MPA, n = 21), or placebo (controls, n = 21). E1S-sulfatase activity was evaluated by incubating homogenized breast tissue with [H]-E1S. Thin-layer chromatography was performed to separate the products estrone (E1) and estradiol (E2). Histomorphometry was performed to measure the amount of epithelial and fat tissue in the mammary gland. RESULTS: Significantly more E2 than E1 was produced in all groups. E1S-sulfatase activity did not differ among the groups. E1S-sulfatase activity was highest in HiTib animals with less fatty breasts (5.9 fmol total estrogen/mg of protein/min; P < or =0.05) and lowest in HiTib animals with more fatty breasts (2.8 fmol total estrogen/mg of protein/min; P = 0.004 relative to less fatty breasts). CONCLUSIONS: We conclude that tibolone had a differential effect on local estrogen biosynthesis in animals with high and low breast fat content. Therefore, breast tissue composition affects the steroidogenic response to hormonal treatment.     

Antioxidant effect of short-term hormonal treatment in postmenopausal women

OBJECTIVES: Recent studies have shown that estrogens alone or in association with progestins can exert an antioxidant effect on Low-Density Lipoprotein (LDL) and lipids of platelet membranes. It has been demonstrated that the oxidative modification of LDLs also involving the formation of lipid peroxides, exerts several biological effects that may contribute to the onset and progression of cardiovascular diseases. Therefore, the aim of our study was to evaluate the effect of short-term treatment with oral estrogens alone and estrogens plus progestin on endogenous and copper-induced serum levels of lipid peroxides in postmenopausal women. METHODS: Thirty-nine postmenopausal women were randomly divided into three groups: group I was treated with oral conjugated equine estrogens (CEE) for 21 days; group II received oral CEE for 21 days and, after 14 days of this treatment, 5 mg/day of medrogestone was added for 7 days; group III did not receive any therapy (controls). Endogenous and copper-induced serum levels of lipid peroxides were determined before and after 21 days of treatment in the two treated groups and in the control group. RESULTS: The serum endogenous levels of lipid peroxides in postmenopausal women did not change after short-term treatment with hormone replacement therapy. Moreover, copper-induced serum levels of lipid peroxides significantly decreased after therapy in both groups I and II. CONCLUSIONS: Our data show that hormone replacement therapy (HRT) inhibits lipid peroxidation and may play a role in preventing cardiovascular diseases.     

Assessment of DNA damage in postmenopausal women under hormone replacement therapy

OBJECTIVE: To evaluate the possible DNA damage in peripheral blood leukocytes of postmenopausal women under different hormone replacement therapies (HRT), comet assay, a standard method for assessing genotoxicity has been used. METHOD: 46 women were categorized in three groups-Group A: 15 surgical menopausal women who underwent surgery for benign conditions, receiving conjugated equine estrogen, 0.625 mg/day (CEE) for 2.3 +/- 1.5 years, Group B: 16 spontaneous menopausal women receiving conjugated equine estrogen, 0.625 mg/day plus medroxyprogesteron acetate, 5mg/day (CEE + MPA) for 2.4 +/- 1.0 years and Group C: 15 spontaneous menopausal women receiving tibolone, 2.5mg/day for 2.4 +/- 1.3 years. Control group consisted of 15 spontaneous menopausal women who never had HRT. RESULTS: Significant differences in terms of DNA damage were observed between Group A and B with controls as mean total comet scores 23.93 +/- 5.84, 19.44 +/- 6.19 and 10.07 +/- 2.40, but no significance (P > 0.05) were detected between Group C and controls as mean total comet scores 12.07 +/- 3.65 and 10.07 +/- 2.40, respectively. CONCLUSION: Reduced DNA damage were observed with tibolone compared to CEE or CEE + MPA therapy. Studies of this approach are needed.     

Increased serum levels of growth hormone and insulin-like growth factor-I associated with simultaneous decrease of circulating insulin in postmenopausal women receiving hormone replacement therapy

OBJECTIVE: Decreases in circulating growth hormone (GH) and its main biological messenger insulin-like growth factor-I (IGF-I) have been interpreted as part of the aging process. Because estrogens participate in modulating GH synthesis and secretion, hypoestrogenism in menopausal women may lead to GH deficiency. The aim of the present study was to determine the effect of hormone replacement therapy (HRT) on both GH and IGF-I levels as well as insulin concentrations in 50 menopausal women. DESIGN: Patients were assigned randomly into two treatment groups of 25 each; one group received three cycles of conjugated equine estrogen (CEE) 0.625 mg/day for 21 days, and the other, 1.25 mg/day during 21 days. Each also received chlormadinone acetate for 5 days. There was a control group consisting of regularly menstruating women. RESULTS: In the menopausal women, HRT increased significantly (p < 0.001) the low levels of GH and IGF-I; on the contrary the baseline insulin levels declined (p < 0.001) with HRT. A significant linear correlation (r = 0.90) was found between GH and IGF-I as well as with estradiol levels (r = 0.74) in the group of menopausal women receiving CEE 0.625 mg/day. This group of patients had a significant correlation (r = -0.63) between insulin and estradiol levels. No correlation was observed in the group receiving CEE 1.25 mg/day. CONCLUSIONS: HRT restored GH, IGF-I, and insulin levels to normal values in all women. Further research needs to be done to establish the beneficial effect of HRT regarding the prevention of the metabolic effects presumably caused by derangement in the somatotropic axis associated with aging.     

Multisystem evaluations of the long-term effects of tibolone on postmenopausal monkeys

This long-term study (2 years) was designed to compare the effects of tibolone (LoTib at 0.05 mg/kg and HiTib at 0.2 mg/kg) with those of conjugated equine oestrogens (CEE) alone (0.042 mg/kg) and CEE continuously combined with medroxyprogesterone acetate (MPA) (0.167 mg/kg) on coronary artery atherosclerosis, bone, mammary gland and uterus in ovariectomised cynomolgus monkeys fed a moderately atherogenic diet. Despite reductions in plasma concentrations of high density lipoprotein cholesterol in tibolone-treated monkeys, there was no exacerbation of coronary artery atherosclerosis. Tibolone was equivalent to, or slightly better than, CEE and CEE + MPA in protecting against postmenopausal bone loss and loss of bone strength. Tibolone also resulted in less stimulation of breast and endometrial tissue compared with CEE and CEE + MPA. In conclusion, the results suggest that tibolone is a cardiovascular-safe treatment that is effective for the prevention of osteoporosis and that may have advantages over CEE or CEE + MPA with regard to endometrial and breast safety.     

Does the beneficial effect of HRT on endothelial function depend on lipid changes

OBJECTIVES: To determine whether improvement in endothelial function of the brachial artery observed in women treated with hormone replacement therapy (HRT) may be explained by changes in lipid profile or blood pressure, information was used obtained in a single-centre, randomised, double blind, placebo-controlled trial. METHODS: Hundred-and-five healthy postmenopausal women, aged 50-65 years, were treated with 0.625 mg conjugated equine estrogens (CEE) combined with 2.5 mg medroxyprogesterone acetate (MPA) (CEE+MPA), 2.5 mg tibolone or placebo for 3 months. At baseline and after 3 months, endothelial function was assessed using flow-mediated dilatation (FMD) and nitro glycerine-mediated dilatation (NMD). Furthermore, lipids were measured. Multivariate linear regression analysis was applied to address the research question. RESULTS: Treatment with CEE+MPA resulted in an improvement in FMD of 2.0% (95% CI: -0.1; 4.1). CEE/MPA reduced total cholesterol with 13% (95% CI: -18%; -7%), LDL-cholesterol with 23% (95% CI: -30%; -15%) and lipoprotein(a) (Lp(a)) with 14% (95% CI: -26%; -2%). The magnitude of the relation of CEE/MPA with endothelial function was attenuated to from 2.0 to 1.6% when change in Lp(a) was taken into account. Adjustments for other lipids or blood pressure did not attenuate the association. CONCLUSIONS: The improvement in endothelial function in postmenopausal women treated with CEE+MPA appears to be partially mediated by change in Lp(a), and apparently not by changes in other lipids.     

The effects of 17 beta-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.