Plasma Estrogen Levels Research Articles

Immunohistochemical expression of estrogen and progesterone receptors in endometrial polyps and its relationship to clinical parameters

To investigate the differences in steroid receptor expression patterns between glandular and stromal portions in endometrial polyps among premenopausal and postmenopausal patients and the relationship between the receptor expression in endometrial polyps and clinical parameters. A total of 25 postmenopausal and 25 premenopausal patients with solitary endometrial polyp detected by office hysteroscopy were involved in the study. All patients underwent hysteroscopic polypectomy under general anesthesia or spinal anesthesia. Estrogen and progesterone expression patterns were investigated in the polyps using immunohistochemistry. The mean age was 57.6 years in postmenopausal patients and 36.9 in premenopausal patients. Average gravida, body mass index (BMI), and frequency of smokers did not differ between groups. However, the patient's age and their concomitant diseases were significantly different between premenopausal and postmenopausal patients (P = 0.01). Comparison in postmenopausal patients showed that glandular estrogen and progesterone receptor expression were both significantly greater than stromal estrogen and progesterone receptor expression (P = 0.037 and <0.001, respectively). Proliferative phase endometrial polyps also demonstrated significantly greater expression of progesterone receptors in glandular epithelium compared with stroma (P = 0.019). However, stromal and glandular estrogen receptor expression did not differ among premenopausal patients. There was a statistically significant correlation among stromal progesterone receptor expression, plasma estrogen and FSH level (P = 0.01). A negative correlation was found between stromal progesterone receptor expression and patient's age (P = 0. 01). Estrogen and progesterone receptor expression were lower in the stromal portion of the endometrial polyp than in the glandular portion in postmenopausal patients. Stromal progesterone receptor expression was lower in older patients and there was a relation between low estrogen hormone levels and lower stromal progesterone receptor expression.

Chronic 17β-estradiol treatment improves skeletal muscle insulin signaling pathway components in insulin resistance associated with aging

Insulin resistance is a common feature of aging in both humans and rats. In the case of females, it seems to be related to loss of gonadal function, due mainly due to a decrease in plasma estrogen levels. Several causes have been postulated for this insulin resistance, among them changes in several steps of the insulin pathway. In view of these findings, the purpose of the present study was to examine the role of chronic 17beta-estradiol treatment on insulin sensitivity during the aging process, and its effects on levels of the insulin-sensitive glucose transporter Glut4 (both total and plasma membrane localized), the interaction between p85alpha subunit of PI3-k and IRS-1, Tyr- and Ser-612 phosphorylation of IRS-1 levels, and Ser-473 phosphorylation of Akt. The present findings indicate that 17beta-estradiol treatment is able to minimize the deleterious effect of aging on insulin sensitivity, at least at the level of plasma membrane localized Glut4. Nevertheless further research is needed to determine this conclusively.

Sex differences in stress responses: Focus on ovarian hormones

Women in the reproductive age are more vulnerable to develop affective disorders than men. This difference may attribute to anatomical differences, hormonal influences and environmental factors such as stress. However, the higher prevalence in women normalizes once menopause is established, suggesting that ovarian hormones may play an important role in the development of depression in women. Ovarian hormones such as estrogen can pass the brain-blood barrier and bind to cytoplasmatic estrogen receptor (ER)-alpha and ER-beta in different areas of the limbic system. During stress, estrogen can modulate the behavioral and neurobiological response depending on the concentrations of estrogen. In this review we present evidence for disparate effects of chronic stress on neuroplasticity and brain activity in male and female rats. Furthermore, we will demonstrate that effects of social support on coping with stress can be mimicked by social housing of rats and that this model can be used for identification of underlying neurobiological mechanisms, including behavior, phosphorylation of CREB and ERK1/2, and brain activity changes as measured with fos expression. Using cyclic administration of estrogen in ovariectomized female rats we could specifically address effects of different plasma estrogen levels and antidepressants on stress-induced neuroplasticity and activity changes. In this model we also studied effects of estrogen on recovery after chronic stress. We conclude that the female brain has a different innate strategy to handle stress than the male brain and that female animal models are necessary for studying the underlying mechanisms and options for treatment.

Physical Activity and Endogenous Sex Hormone Levels in Postmenopausal Women: a Cross-Sectional Study in the Prospect-EPIC Cohort

The protective effect of physical activity on breast cancer risk might be mediated by sex hormone levels. In this study, we examined the association between usual physical activity and plasma levels of estrogens, androgens, dehydroepiandrosterone sulphate (DHEAS), and sex hormone binding globulin (SHBG) in postmenopausal women. We conducted a cross-sectional study among 806 postmenopausal women participating in the Prospect-EPIC study. Usual physical activity was assessed using a short questionnaire and summarized into a simple, validated four-level index. This index combines occupational physical activity with time spent on cycling and sporting. Levels of estrone, estradiol, androstenedione, DHEAS, testosterone, and SHBG were measured in plasma. General linear models were used to examine the association between usual physical activity and sex hormone levels, adjusted for confounders. We observed an inverse association between physical activity and estradiol levels (free: inactive, 0.26 pg/mL; active, 0.23 pg/mL; P-trend = 0.045; total: inactive, 8.8 pg/mL; active, 8.0 pg/mL; P-trend = 0.08) and a positive association between physical activity and SHBG (inactive, 15.1 nmol/L; active, 19.3 nmol/L; P-trend = 0.05). These associations could largely be explained by the effects of sporting. We also observed a positive association between physical activity and DHEAS (inactive, 352.4 ng/mL; active, 460.3 ng/mL; P-trend = 0.01). Our results are in accordance with the hypothesis that usual physical activity decreases estradiol levels and increases SHBG. We also found that high levels of physical activity are associated with high levels of DHEAS. Furthermore, our results suggest that vigorous forms of physical activity influence sex hormone levels most.

Do stress hormones suppress helper reproduction in the cooperatively breeding red-cockaded woodpecker (Picoides borealis)?

In the cooperatively breeding red-cockaded woodpecker (Picoides borealis), male helpers are subordinate to male breeders and do not mate with females, even when unrelated to the breeding female within their group or through extra-group matings, yet exhibit reproductive hormone profiles similar to those of breeders. We investigated whether reproduction might be suppressed in helper males via high levels of the stress hormone corticosterone. We also examined effects of group size and season on corticosterone levels by comparing baseline and maximal plasma levels of corticosterone between helper males and breeding males, and among helper males and breeders of both sexes living in groups of different sizes throughout the reproductive cycle. We also measured plasma levels of estrogen, progesterone, and testosterone to examine other potential hormonal differences between helpers and breeders. Male status did not explain variation in any hormones; therefore, our data do not support the hypothesis that helper males are reproductively suppressed via corticosterone or the other hormones investigated. However, the presence of two or more helper males in a group tended to reduce baseline corticosterone in breeding and helper males, but not breeding females, suggesting that helper males reduce parental effort of other male group members. Seasonally, maximal corticosterone peaked during the nestling provisioning phase for breeding and helper males, but not breeder females, suggesting that males show an increased response to stressors posing a potential threat to survival of offspring.

Interaction of reproduction rhythm, suckling and parity on mating incidence, ovarian dynamics and estrogensecretion in the rabbit doe

The effects of suckling and remating interval (11 or 21 d post partum) were studied in primiparous (P=25) and multiparous (M=23) hybrid rabbits. In P rabbits, suckling had no significant effect on mating incidence; however, a higher percentage of females accepted the male on d 11 than on d 21 (P<0.01). In M rabbits, no significant differences in mating performance due to either day, suckling or their interaction were found. A higher proportion of nonsuckled than suckled P rabbits ovulated (P<0.01). Ovulation incidence was not affected significantly by day of mating, suckling or their interaction in M rabbits. A comparison of the day influence in P and M rabbits on mating incidence showed a greater effect in the P (P<0.05) while the suckling effect on ovulation performance showed an insignificant difference in the two parity groups. Ovulation rate, as assessed by ultrasound, was not influenced significantly by day or suckling in either P or M rabbits. The follicle distribution was marked by fewer large follicles and lower plasma estrogen levels were detected in suckled than in nonsuckled P and M rabbits (P<0.05). Further research is needed to elucidate these phenomena also when AI is performed.

Effect of Handgrip Exercise on QTc Interval During Different Phases of Menstrual Cycle

Women have a slower cardiac repolarization than men, which manifests as longer heart rate corrected QT in- terval (QTc) on the ECG. This study was undertaken to identify cyclical variations of QTc and to detect whether it can further be modulated by handgrip exercise. ECG changes were recorded before and after handgrip exercise during different phases of menstrual cycle in 30 healthy women (25-40 yrs) with a regular menstrual cycle. The different menstrual cycle phases were assigned on the basis of dates and confirmed by plasma levels of estrogen and progesterone. Daily basal body temperature was recorded to con- firm the ovulatory phase. ECG parameters (in lead II) were recorded before and immediately after release of handgrip. During the menstrual phase, the basal RR interval was 0.765 ± 0.03 sec and after handgrip exercise, it increased to 0.829 ± 0.02 sec (p<0.05). The QTc interval was maximal in the menstrual phase (0.44 ± 0.007). There was a significant decrease in QTc interval in the menstrual phase (0.41 ± 0.009 sec, p<0.05) after handgrip exercise. This study confirms the cyclic variation of the QTc interval. The prolonged QTc interval during the menstrual phase is likely to produce arrhythmias if women are exposed to agents which further prolong the refractory period. A fall in the QTc interval was seen after handgrip exercise during the menstrual phase, females may be advised to engage themselves in isometric activities so as to decrease their susceptibility to arrhythmias.

Letrozole is Superior to Anastrozole in Suppressing Breast Cancer Tissue and Plasma Estrogen Levels

To evaluate the influence of the third-generation aromatase inhibitor letrozole (Femara) on breast cancer tissue levels of estrone (E(1)), estradiol (E(2)), and estrone sulfate (E(1)S) in postmenopausal women undergoing primary treatment for locally advanced estrogen receptor/progesterone receptor-positive breast cancers. Breast cancer tissue samples were collected before and following 4 months of neoadjuvant therapy with letrozole (2.5 mg o.d.), and tissue estrogen levels measured using a highly sensitive RIA after high-pressure liquid chromatography purification. Letrozole suppressed pretreatment tumor levels of E(2), E(1), and E(1)S by 97.6%, 90.7%, and 90.1%, respectively. These data reveal that letrozole suppresses tissue estrogen levels significantly below what has previously been recorded with anastrozole (89.0%, 83.4%, and 72.9% suppression, respectively) using the same methods. To confirm the differential effect of letrozole and anastrozole on each plasma estrogen fraction, we re-analyzed plasma samples obtained from a previous intrapatient cross-over study comparing letrozole and anastrozole using an improved RIA (detection limits of 0.67, 1.14, and 0.55 pmol/L for E(2), E(1), and E(1)S, respectively). Letrozole consistently suppressed each plasma estrogen fraction below the levels recorded for anastrozole: E(2) (average suppression by 95.2% versus 92.8%; P = 0.018), E(1) (98.8% suppression versus 96.3%; P = 0.003), and E(1)S (98.9% suppression versus 95.3%; P = 0.003). Our data reveals that letrozole (2.5 mg o.d.) is more effective compared with anastrozole (1.0 mg o.d.) with respect to tissue as well as plasma estrogen suppression in patients with postmenopausal breast cancer.

Association of genetic polymorphisms in CYP19A1 and blood levels of sex hormones among postmenopausal Chinese women

Circulating estrogen levels have been related to the risk of several female cancers. Blood levels of estrogen are controlled by estrogen synthesis enzymes. Genetic variation of estrogen genes thus may influence circulating estrogen levels. We investigated the associations of genetic polymorphisms in CYP19A1, a critical gene involved in estrogen synthesis, with plasma levels of sex hormones among postmenopausal Chinese women. Included in this study were 345 postmenopausal community controls from a population-based case-control study conducted in Shanghai. Fasting blood samples from those women were measured for blood estradiol, estrone, estrone sulfate, and testosterone. A total of 19 genetic polymorphisms in CYP19A1 were genotyped using ABI7900 or PCR-restriction fragment length polymorphism methods. Differences in plasma levels of hormones by genotype were examined using variance analysis. The geometric means of plasma levels of estradiol, estrone, estrone sulfate, and testosterone were 10.1, 16.8, 969.0, and 202.9 pg/ml, respectively, for this study population. We found that plasma levels of estrone were associated with rs28566535 (P=0.0180), rs730154 (P=0.0141), and rs936306 (P=0.0274) in block 2. In the same block, the haplotype CGCTA was related to level of estrone (P=0.0064). Single nucleotide polymorphism rs1902584 in block 1 was associated with estradiol only in overweight postmenopausal women. No clear association with sex hormones was noted for the other genetic polymorphisms evaluated in the study. Single nucleotide polymorphisms in blocks 1 and 2 of the CYP19A1 gene are related to plasma levels of estrogen among postmenopausal Chinese women and may therefore play an important role in the etiology of hormone-related cancers.

The effect of long-term resveratrol treatment on relaxation to estrogen in aortae from male and female rats: Role of nitric oxide and superoxide

Resveratrol, which is found in several foods, has vasorelaxing and estrogen-like activities. The aim of the present study was to determine whether the relaxation to estrogen is differently modified between male and female genders after long-term resveratrol treatment. To test this, we compared endothelium-dependent and -independent relaxations to estrogen in the aortae of control and resveratrol-treated male and female rats. Nitric oxide and superoxide levels were also evaluated to explain the mechanism of action of resveratrol. Concentration–response curves to estrogen (10 − 10–10 − 4 M) were obtained in aortic rings with and without endothelium from control or long-term resveratrol-treated (50 mg/l in drinking water for 21 days) male and female rats. Estrogen produced mainly endothelium-dependent relaxation in aortic rings of rats, with a higher potency in females than males. Resveratrol treatment increased both endothelium-dependent and -independent relaxations to estrogen especially in aortae from males. The relaxations to estrogen in the aortae of resveratrol-treated rats were inhibited, almost to the same extent as those of control, by pretreatment with ICI 182,780 (10 − 6 M), an estrogen receptor antagonist. In both genders, resveratrol treatment increased basal nitric oxide and nitrite/nitrate productions and decreased both basal and NAD(P)H-induced superoxide productions in the aortae. In addition, plasma estrogen levels were found decreased in long-term resveratrol-treated animals of both genders. The improvement in the relaxations to estrogen observed in resveratrol-treated animals could be related to elevated nitric oxide and/or decreased superoxide productions and possibly mediated by classical estrogen receptors. The modulating effect of resveratrol on estrogen responsiveness may differ between male and female.

Effects of estrogen on the mechanical behavior of the human Achilles tendon in vivo

The purpose of this study was to elucidate the effect of normal fluctuating [non-monophasic oral contraceptive pill (MOCP) users] and low, consistent (MOCP users) endogenous plasma estrogen levels on the strain behavior of the Achilles tendon in vivo. Twenty women (age 28.0 +/- 4.2 yr, height 1.67 +/- 0.07 m, mass 61.6 +/- 6.8 kg) who had been using the MOCP for at least 12 mo together with 20 matched women who were non-MOCP users (age 31.9 +/- 7.3 yr, height 1.63 +/- 0.05 m, mass 62.5 +/- 5.9 kg) participated in this study. Non-MOCP users were tested at the time of lowest (menstruation) and highest (approximately same as ovulation) estrogen, whereas MOCP users, who exhibited constant and attenuated endogenous estrogen levels, were tested at day 1 and day 14 of their cycle. At each test session, maximal isometric plantarflexion efforts were performed on a calf-raise apparatus while synchronous real-time ultrasonography of the triceps surae aponeurosis was recorded. Achilles tendon strain (%) was calculated by dividing tendon displacement during plantarflexion by resting tendon length. Repeated-measures ANOVA revealed a significant (P < 0.05) main effect of subject group with significantly lower Achilles strain (25.5%) in the MOCP users compared with the non-MOCP users. In conclusion, acute fluctuations in plasma estrogen across the menstrual cycle in non-MOCP users did not alter the strain behavior of the Achilles tendon. Conversely, long-term exposure to attenuated estrogen in MOCP users resulted in a decrease in Achilles tendon strain, which is thought to be attributed to the effects of endogenous estrogen on collagen synthesis. These findings have a number of important functional and clinical implications.

Role of Hormonal and Other Factors in Human Prostate Cancer

American men have a lifetime risk of about 18% for prostate cancer diagnosis. Large international variations in prostate cancer risks and increased risks among migrants from low- to high-risk countries indicate important roles for environmental factors. Major known risk factors include age, family history, and country/ethnicity. Type 2 diabetes appears to reduce risk, while high birth weight and adult height are linked to increased risk of aggressive prostate cancer. Limited evidence supports an association with a history of sexually transmitted infections. A previous meta-analysis of eight cohort studies indicated no associations with plasma androgen, estrogen, or sex hormone binding globulin (SHBG) levels. However, there were dose-response relationships with baseline plasma testosterone levels in two studies that adjusted for other serum hormones and obesity. Finasteride (a drug that blocks testosterone activation) reduced prostate cancer risk by 25%. Low-frequency genes linked to familial prostate cancer only explain a small fraction of all cases. Sporadic cases were linked to relatively common polymorphisms of genes involved in (1) androgen synthesis, activation, inactivation and excretion, (2) hormone and vitamin D receptors, (3) carcinogen metabolism, and (4) DNA repair. Epidemiologic evidence supports protective roles for dietary selenium, vitamin E, pulses, tomatoes/lycopene, and soy foods, and high plasma 1,25-dihydroxyvitamin D levels. There is inadequate evidence that vegetables, fruit, carotenoids, and vitamins A and C reduce risk and that animal fat, α-linoleic acid, meat, coffee, and tea increase risk. Two major cohort studies found dose-response relationships with dietary calcium intake. Total dietary energy intake may enhance risk. Limited evidence supports a protective role for physical activity and elevated risk for farmers and other men with occupational pesticide exposure, particularly to organochlorine compounds and phenoxy herbicides. There is inadequate evidence for a relationship with alcohol or smoking. Most known or suspected external risk factors may act through hormonal mechanisms, but our review found little supporting evidence, and substantial further research is needed.

Estrogen suppression in premenopausal women following 8 weeks of treatment with exemestane and triptorelin versus triptorelin alone

Luteinizing hormone-releasing hormone (LHRH) agonists (e.g., triptorelin) reduce ovarian estrogen production in premenopausal women with hormone-sensitive breast cancer. Aromatase inhibitors (e.g., exemestane) inhibit extraovarian production of estrogen and may further reduce circulating estrogens when combined with an LHRH agonist. Healthy premenopausal women were randomized to receive 3.75 mg triptorelin (T) on days 1 and 29 with 25 mg exemestane (EX) or matched placebo once daily for 8 weeks, from day 1 to day 56. The primary objective was to evaluate the effect of T +/- EX on estradiol (E(2)) suppression by comparing the AUC(day 36-57 )for the 2 treatments. Secondary objectives included evaluation of estrone (E(1)), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) suppression; effects of EX on the T-induced gonadotrophin and estrogen flare; pharmacokinetics (PK); and safety. Twenty-eight (14 in each arm) were evaluable for efficacy and PK. Mean plasma estrogen levels (AUC(day 36-57)) were significantly lower for subjects who received T + EX than for subjects who received T alone (20.6 vs. 54.0 pg d/ml [-62%; P < 0.05], and 38.9 vs. 198.0 pg d/ml [-80%; P < 0.01] for E(2) and E(1), respectively). Coadministration of EX did not affect the initial flare or subsequent suppression of LH and FSH following the first dose of T, or the PK of T. Both treatments were well tolerated. Coadministration of T and EX resulted in greater estrogen suppression than when T was given alone. These findings could translate into improved clinical outcomes for premenopausal breast cancer patients receiving LHRH agonists.

Angiotensin converting enzyme inhibitor up regulates the expression of estrogen receptors in the kidney in old female rats.

Several lines of evidence suggest that there is an interaction between the renin angiotensin system and estrogen with age. The present study was performed to test the hypothesis that chronic administration of an angiotensin converting enzyme inhibitor, enalapril, will result in changes in estrogen and or it receptors in the kidney in aging female SD rats. Enalapril, 250 mg/l in the drinking water was given to female SD rats, 12 moss of age for one month. At the end of the study blood was collected for measurement of plasma levels of estradiol and FSH by radioimmunoassay. Kidneys were removed and separated in cortex and medulla for determination of estrogen receptors. Western blot was performed using specific antibodies against estrogen receptor α and β in kidney cortex and medulla. Chronic administration of enalapril did not modify plasma estrogen levels. However, estrogen receptors α and β protein expression were significantly upregulated (2 fold increases, p&lt;0.05) in kidney cortex and medulla in the enalapril treated rats. Our study suggests that angiotensin II modulates the expression of estrogen receptors in kidney cortex and medulla in old female SD rats.

Dose‐response effect of estrogen on the kidney and heart

Recent clinical trials indicate that estrogen replacement therapy (ERT) may increase the risk of cardiovascular diseases. Here we studied whether the adverse effects of ERT are related to the doses used. Ovariectomized (OVX) mice received 17β‐estrodial (E2) at 0.001 (VL, very low), 0.42 (L, low), 4.2 (M, moderate) or 28.3 μg/d (H, high) for 60 days. E2 at moderate and high doses increased plasma estrogen levels by about 4.5‐fold. This was associated with ascites, nephrydrosis, proteinuria and fluid retention in uterus horns. Low dose of E2 restored plasma estrogen and uterus weight to levels similar to normal controls and no fluid retention or renal damage were found in this group of mice. Moderate and high doses of E2 also increased cardiac ANP mRNA expression and PKC and PI3K phospholyration. Aside from diastolic function, blood pressure and cardiac function were not altered by ERT at any given dose. These results suggest that ERT dosage could be an important determinant for a beneficial or detrimental outcome.

Effect of dioxin exposure on aromatase expression in ovariectomized rats

Because of their persistence in the environment dioxins are one of the most concerned classes of carcinogens. Displaying both pro- and anti-agonistic properties to some hormone receptors, the pollutants are also known to be endocrine disruptors. Humans can be exposed to this pollutant through contaminated food, air, drinking water, etc. The female hormone estrogen may initiate various physiological functions, and excessive exposure to this hormone is a documented risk factor for carcinogenesis. Cyp19 (aromatase) catalyses the last step of estrogen biosynthesis, while cyp1a1 can hydroxylate and deactivate the hormone. In the present study, we investigated the effect of 2,3,7,8-tetrachlorodibenzo- para-dioxin (TCDD) on aromatase expression in the brain and adipose tissue in ovariectomized Sprague Dawley rats. Female rats were given 2.5 μg/kg TCDD p.o. before and after ovariectomy. Real-time PCR and western blot analysis indicated that pre-ovariectomy administration of TCDD could significantly reduce aromatase expression in the brain but increase the expression in the adipose tissue. In addition, increased plasma estrogen level and uterine weight were observed in these rats. These parameters did not change in rats with post-ovariectomy TCDD treatment. Our results suggested that the timing of exposure to the toxicant could determine the estrogenicity of TCDD. No correlation between cyp1a1 and cyp19 expression was observed.

Cyclic changes in endometrial echotexture of cows using a computer-assisted program for the analysis of first- and second-order grey level statistics of B-Mode ultrasound images

The aim of this study was to test the suitability of a computer-assisted echotexture analysis program for analysing first- and second-order grey level statistics of grey levels of B-Mode ultrasound images to examine morphologic changes in the endometrium during oestrous cycle in cows. Four Simmental cows were examined for two consecutive oestrous cycles. Echotexture of the endometrium was assessed by mean grey level (MGL) and homogeneity (HOM) of digitised B-Mode images of the uterine body and both uterine horns. As there were no differences ( P > 0.05) in MGL and HOM, respectively, between the images of the uterine body and the uterine horns, the mean values of all endometrial images were used for subsequent analyses of MGL and HOM. The factor ‘day of oestrous cycle’ showed a highly significant ( P < 0.0001) effect and the factor ‘cow’ showed a significant ( P < 0.05) effect on MGL and HOM. No differences ( P > 0.05) in both echotexture parameters were measured between oestrous cycles within cows. MGL was negatively related to HOM ( r = −0.66; P < 0.0001). Low MGL and high HOM occurred on Day 0 (= ovulation) and between Days −3 and −1. While MGL was consistently ( P > 0.05) low between Days −3 and −1, significant changes of HOM with maximum levels on Day −2 ( P < 0.05) were observed during this time. MGL was consistently ( P > 0.05) high between Days 4 and 13 while HOM was consistently ( P > 0.05) low between Days 2 and 13. From Day −3 to Day −1 ( r = 0.48; P < 0.05) plasma oestrogen levels were correlated with HOM, but not with MGL ( P < 0.05). The results of this study show that changes in endometrial morphology of cows can be measured using a computer-assisted texture analysis program.

An optimised, highly sensitive radioimmunoassay for the simultaneous measurement of estrone, estradiol and estrone sulfate in the ultra-low range in human plasma samples

Following the introduction of potent aromatase inhibitors for the treatment of breast cancer patients, highly sensitive methods have become mandatory to evaluate the influence of these drugs on plasma estrogen levels. Commercially available kits for estrogen measurements are not suitable for these kinds of evaluations due to their detection limits that are close to baseline estrogen levels in postmenopausal women. We describe here an optimised radioimmunoassay suitable for the simultaneous measurement of plasma estrone (E 1), estradiol (E 2) and estrone sulfate (E 1S) levels in the ultra-low range. Following incubation with [ 3H]-labelled estrogens as internal standards, crude estrogen fractions were separated by ether extraction. The E 1S fraction was hydrolysed with sulfatase followed by eluation on a Sephadex column. Free estrogens (E 1, E 2) were separated by chromatography (LH-20). Estrone and E 1S (following hydrolysis) were converted into E 2, and each estrogen fraction was measured by the same highly sensitive and specific radioimmunoassay using estradiol-6-(O-carboxymethyl)-oximino-2-(2-[ 125I]-iodo-histamine) as ligand. Although several purification steps were involved, the internal recovery values for tritiated estrogens were found to be 88%, 90%, and 49% for E 1, E 2 and E 1S, respectively. The intra-assay coefficient of variation was <5% for all recovery measurements. The detection limits were calculated following repeated blank measurements and found to be 1.14 pmol/L for E 1, 0.67 pmol/L for E 2, and 0.55 pmol/L for E 1S, respectively. The intra-assay coefficient of variation (CV) was found to be 3.4% for E 1, 5.1% for E 2 and 6.1% for E 1S, while the inter-assay CV was 13.6%, 7.6% and 7.5% for E 1, E 2, and E 1S, respectively. Considering normal plasma levels for E 2 (15 pmol/L), E 1 (80 pmol/L) and E 1S (400 pmol/L) in postmenopausal women, the method allows theoretically to detect suppression of plasma E 2, E 1 and E 1S levels by 95.5%, 98.6% and 99.9% when starting from average, normal postmenopausal levels. Thus, the method presented here is to our knowledge the currently most sensitive assay available for plasma estrogen measurements in the ultra-low range and, as such, a reliable tool for a proper evaluation of potent aromatase inhibitors and other potential drugs influencing on plasma estrogen levels.

A prospective study of grapefruit and grapefruit juice intake and breast cancer risk

Sir, In a recent interesting study by Monroe et al (2007), grapefruit intake was associated with an increase in breast cancer risk, and they hypothesised that this might be mediated by an effect on endogenous oestrogen levels. However, the researchers were unable to examine grapefruit juice intake. Therefore, we examined grapefruit and grapefruit juice intake and breast cancer risk in the Nurses' Health Study. Briefly, the Nurses' Health Study is a prospective cohort consisting of women aged 30–55 years in 1976 (Kim et al 2006). Medical and lifestyle information was obtained with general follow-up questionnaires every 2 years and with semi quantitative food frequency questionnaires that included intakes of grapefruit and grapefruit juice in 1984, 1986, 1990, 1994, and 1998. In both age-adjusted (not shown) and multivariate analyses adjusted for standard breast cancer risk factors, we found no overall association with either grapefruit or grapefruit juice intake and breast cancer risk among all women in the cohort, and among postmenopausal women only (Table 1). Furthermore, our results did not change once additional covariates – alcohol, saturated fat, dietary fibre, and soluble fibre – included by Monroe et al were added to our models. Table 1 Multivariate relative risks of breast cancer incidence between 1984 and 2002 by cumulatively averaged grapefruit and grapefruit juice intake Stratification by BMI did not alter the breast cancer risk with either grapefruit or grapefruit juice intake. However, stratification by hormone therapy showed a significant decrease in risk of breast cancer with greater intake of grapefruit in women who never used hormone therapy (multivariate RR comparing ¼ grapefruit or more per day to none=0.78, 95% CI, 0.59–1.04, P trend=0.03). This is contrary to the findings of Monroe et al, who observed a significant increase in risk of breast cancer with greater consumption of grapefruit in this subgroup. Furthermore, the association between grapefruit (not grapefruit juice) intake and breast cancer risk differed significantly by oestrogen and progesterone receptor status of the tumours. No association was observed in women with oestrogen and progesterone receptor positive cancers. However, in women with oestrogen and progesterone receptor negative cancers, there was a significant decrease in breast cancer risk with increased consumption of grapefruit (multivariate RR comparing ¼ grapefruit or more per day to none=0.60, 95% CI, 0.37–0.98, P trend=0.03). We also examined cross-sectionally the relationship between consumption of grapefruit and grapefruit juice and plasma levels of oestrogens among 701 postmenopausal women not using hormone replacement. No significant correlation was observed (grapefruit, grapefruit juice) for plasma oestradiol (r=0.02, −0.04), oestrone (r=0.00, −0.02), or oestrone sulphate (0.09, 0.01). Our findings do not support an adverse effect of consumption of grapefruit or grapefruit juice on risk of breast cancer or on endogenous hormone levels.

Memory impairments with adjuvant anastrozole versus tamoxifen in women with early-stage breast cancer

Hormones have been implicated as modulators of cognitive functioning. For instance, results of our previous work in women with breast cancer showed that cognitive impairment was more severe and involved more memory domains in those who received adjuvant tamoxifen therapy compared with women who received chemotherapy alone or no adjuvant therapy. Recently aromatase inhibitors such as anastrozole have been used in lieu of tamoxifen for the adjuvant treatment of postmenopausal women with hormone receptor-positive, early-stage breast cancer. Plasma estrogen levels are significantly lower in women who receive anastrozole compared with those who receive tamoxifen. We hypothesized, therefore, that anastrozole would have a more profound effect on cognitive function than tamoxifen, a mixed estrogen agonist/antagonist. To test this hypothesis we compared cognitive function in women with early-stage breast cancer who received tamoxifen with those who received anastrozole therapy in a cross-sectional study. We evaluated cognitive function, depression, anxiety, and fatigue in 31 postmenopausal women with early-stage breast cancer who were between the ages of 21 and 65 years and treated with tamoxifen or anastrozole for a minimum of 3 months. The results showed that women who received anastrozole had poorer verbal and visual learning and memory than women who received tamoxifen. Additional, prospective studies are needed to validate and confirm the changes in cognitive function associated with hormone therapy for breast cancer.