Oestrogen replacement therapy lowers plasma levels of asymmetrical dimethylarginine in healthy postmenopausal women.

Oestrogen replacement therapy (ERT) has been shown to lead to favourable changes in the cardiovascular risk profile of postmenopausal women. Part of this effect is ascribed to increased production or bioavailability of nitric oxide (NO). We have tested the hypothesis that ERT lowers plasma levels of asymmetrical dimethylarginine (ADMA), an endogenous inhibitor of NO synthase (NOS). In a randomized double-blind study design, 40 hysterectomized postmenopausal women received conjugated equine oestrogen (CEE; 0.625 mg/day; n =14), the selective oestrogen receptor modulator raloxifene (150 mg/day; n =13) or placebo ( n =13). At baseline and after 6, 12 and 24 months of treatment, plasma was analysed for levels of arginine, ADMA, and symmetrical dimethylarginine (SDMA), a stereoisomer of ADMA that does not inhibit NOS. An overall treatment effect on ADMA levels was observed in the CEE group ( P =0.004 compared with placebo), but not in the raloxifene group ( P =0.50). The decrease of ADMA levels by CEE treatment was consistent over the 2-year study period, without significant differences between the effects at 6, 12 and 24 months. The average post-baseline change in ADMA in the CEE group compared with placebo was -7.8% (95% confidence interval -12.8% to -2.9%; P =0.003). Arginine or SDMA levels did not change during treatment in any of the groups. Thus ERT with oral conjugated oestrogen, but not with raloxifene, significantly reduced plasma concentrations of the cardiovascular risk factor ADMA in healthy postmenopausal women.

Effect of 1 year of discontinuation of raloxifene or estrogen therapy on bone mineral density after 5 years of treatment in healthy postmenopausal women.

The beneficial effects of hormone replacement therapy (HRT), selective estrogen receptor modulators (SERMs), or bisphosphonates in the prevention and treatment of osteoporosis in postmenopausal women have been well established. However, little is known about the effects of discontinuation of treatment on bone mineral density. We investigated the effect of 1 year of discontinuation of the SERM raloxifene (Ral; 60 mg and 150 mg), conjugated equine estrogen (CEE; 0.625 mg), and placebo after 5 years of treatment in a double-blind, randomized study. Thirty-eight of 59 healthy and hysterectomized postmenopausal women (mean age 55 years) completed the treatment and 1 year follow-up period. Lumbar spine and femoral neck bone mineral density (BMD) were performed with dual-energy X-ray absorptiometry, before, during, and at the end of treatment, as well as after 1 year of discontinuation of therapy. One year of discontinuation significantly reduced the mean lumbar spine BMD in the raloxifene- and estrogen-treated women (p < 0.05), whereas mean femoral neck BMD was reduced significantly only in women treated with 60 mg Ral (p < 0.05). The mean percentage change (+/-SD) in lumbar spine BMD was: CEE, -6.2% (+/-3.7%); Ral 60 mg, -2.4% (+/-2.4%); Ral 150 mg, -2.6% (+/-3.1%); and placebo, -1.6% (+/-4.3%). Our results show that 5 years of treatment with either Ral or CEE did not protect against bone loss after 1 year of withdrawal of therapy, and that the rate of bone loss was not significantly different from that of placebo-treated women.

Raloxifene reduces impedance to flow within the uterine artery in early postmenopausal women: a 2-year randomized, placebo-controlled, comparative study.

OBJECTIVE: We sought to investigate the long-term effect of raloxifene and continuous combined hormone replacement therapy (ccHRT) on impedance to flow within the uterine artery in postmenopausal women. STUDY DESIGN: A prospective, randomized, double-blind, placebo-controlled 2-year study was performed in 95 postmenopausal women. They received either 60 mg of raloxifene daily (raloxifene 60 group), 150 mg of raloxifene daily (raloxifene 150 group), ccHRT, or placebo. At baseline and thereafter every 6 months, color Doppler ultrasonography was used to measure the pulsatility index (PI) of the uterine artery. RESULTS: After 24 months of treatment, compared with placebo, significant decreases were found in the PI in the raloxifene 150 group (P = .021) and in the ccHRT group (P = .007). In the raloxifene 150 group compared with the placebo group, after 6 and 24 months, decreases were observed in median PI of -5% and -15%, respectively, and in the ccHRT group decreases of -2% and -19%, respectively, were found. CONCLUSION: Long-term use of 150 mg of raloxifene daily or ccHRT reduces impedance to flow within the uterine artery. This indicates that high-dose raloxifene may exert cardiovascular protection.

Raloxifene affects brain activation patterns in postmenopausal women during visual encoding.

Recent brain imaging studies have shown that estrogens alter brain activation patterns upon working memory tasks in postmenopausal women. Estrogens, however, have many systemic side effects. We investigated the effect of the Selective estrogen receptor modulator (SERM) raloxifene on brain activation patterns during a memory task in postmenopausal women with functional magnetic resonance imaging (fMRI). Twenty postmenopausal and right handed women (mean age 65.7 years; SD 3.0) were included in this double blind, placebo controlled and randomized study. Whole brain fMRI was performed before and after three months of daily treatment with raloxifene 60 mg or placebo. Each scanning session consisted of a visual encoding task, a recognition test and a simple photic simulation test. Data analyses was performed with SPM99b software. Specific regions of interest for the tasks were defined based in previous experiments. Visual encoding activated the ventral route, posterior medial temporal lobe and frontal cortex in both groups. Treatment interactions for raloxifene compared to placebo were a decrease in activation in the left parahippocampal gyrus and left lingual gyrus, an increase in activation in the right superior frontal gyrus. The mean recognition test and the simple photic stimulation test showed no treatment interactions. Our results show that raloxifene affects brain activation patterns upon visual encoding in postmenopausal women.

Effect of estrogen on intestinal strontium absorption in postmenopausal women.

OBJECTIVES: there is considerable uncertainty about the underlying cause of decreased intestinal calcium absorption that occurs in postmenopausal women. In a previous study, estrogen treatment did not result in an increased intestinal calcium absorption using strontium as a marker. A possible explanation could be that the calcium/strontium load given to the women was too high ( approximately 600 mg Ca), which might result in an insensitive test with respect to the possible stimulation of active strontium transport by estrogen. Therefore, the purpose of this study was to reinvestigate the effect of estrogen on active intestinal strontium absorption using a load of 2.5 mmol of strontium only. METHODS: the effect of estrogen on intestinal strontium absorption was measured in eight normal postmenopausal women. The study included two baseline strontium absorption tests, which were performed with an interval of 10 days for calculating the within subject variation (SER). Thereafter the effect of 2 months of estrogen treatment on intestinal strontium absorption was assessed. Fractional absorption (FC(240)) and the area under the concentration time curve (AUC) 4 h after an oral strontium load of 2.5 mmol were calculated. RESULTS: the within subject SER of FC(240) and AUC(0-240) were 2.3+/-0.76 and 1.2+/-0.41, respectively. FC(240) and AUC(0-240) of strontium were unchanged after treatment with estrogen. CONCLUSIONS: in normal postmenopausal women, we did not find a modulating effect of short-term treatment with a (supra) physiological dose of estrogen on intestinal calcium absorption as measured by the strontium absorption test.

Ultrasound assessment of the endometrium in healthy, asymptomatic early post-menopausal women: saline infusion sonohysterography versus transvaginal ultrasound.

OBJECTIVE: To exclude pre-existing endometrial pathology in asymptomatic early post-menopausal women before starting hormone replacement therapy by transvaginal ultrasound (TVS) and saline infusion sonohysterography (SIS). METHODS: In a cross-sectional study, 148 healthy women (mean age, 51.1 years; range, 46-59 years) underwent ultrasound evaluation of the endometrium before participation in a clinical trial. TVS was used to measure double-layer endometrial thickness. SIS was performed at the same visit to measure anterior and posterior single-layer endometrial thickness, and to identify endometrial abnormalities when present. Ultrasound results were defined as informative if the endometrium could be adequately visualized. Findings on TVSs were defined as abnormal if a double-layer endometrial measurement > 5.0 mm was obtained. Findings on SIS were defined as abnormal if one or both single layers of the endometrium measured > 2.5 mm, or if focal endometrial thickening or a polyp was present. RESULTS: Of the 148 eligible women, informative TVS results were obtained from 134 women, SIS results from 133 women and both procedures combined from 119 women. TVS scans gave abnormal results in 8.2% of women (11 of 134) and SIS gave abnormal results in 36.8% of women (49 of 133). Of the 14 women with a non-informative TVS, eight had abnormal SIS results. Of the 15 women with a non-informative SIS, three had abnormal TVS results. In the 119 women with both informative TVS and SIS, abnormal TVS scans were found in 6.7% of women (eight of 119) and abnormal SIS in 34.5% of women (41 of 119). All eight women with abnormal TVS had an abnormal SIS, whereas 29.7% (33 of 111) of the women with a normal TVS had an abnormal SIS. CONCLUSIONS: Ultrasound evaluation demonstrated endometrial abnormalities in 34.5% (41 of 119) of asymptomatic post-menopausal women. SIS is more accurate than TVS in the detection of endometrial abnormalities.