Estrogen-treated Subjects Research Articles

SAT-440 Modulating Effects of Progesterone on Spontaneous and Ghrelin-Induced GH Secretion in Postmenopausal Women

Introduction. GH secretion is regulated by hypothalamic neuropeptides, sex steroids, and negative feedback signals across the lifespan. GH secretion in premenopausal women is higher than that in age-matched men, and can be amplified by oral estradiol (E2) in postmenopausal (PM) women. In contrast, the effect of progesterone (P) on GH secretion has rarely been studied in the presence or absence of estrogen repletion. Study design: Four parallel groups of PM women (total 40) received (1) im saline and oral placebo, (2) im saline and oral micronized P (3x200mg/day), (3) E2 im (5 mg) and oral placebo, and (4) E2 im and oral P, respectively. Study parameters were overnight (10 h) and ghrelin-stimulated (0.3 µg/kg) GH secretion. Results: Mean E2 levels increased to 88 and 99 pg/mL and mean P to 10.1 and 20.3 ng/dL. Whereas E2 at this dose did not change GH, P vs placebo reduced pulsatile GH secretion to 7.20±2.14 µg/L/10h vs 9.58±1.97 (P=0.045). Mean GH concentrations and burst amplitudes were respectively 0.97±0.31 and 1.52±0.29 (P=0.025), and 2.76±1.04 and 3.95±0.90 (P=0.031). Visceral fat area, determined by CT, was a strongly negative GH predictor of pulsatile GH secretion, R=-0.53 (P=0.001, β=-0.096±0.026). P levels correlated negatively with GH secretion, with or without AVF or E2 in the regression equation (e.g. pulsatile GH secretion: R=-0.69, P=0.005, β=0.693±0.246). P administration also reduced ghrelin-stimulated GH release (9.6±1.9 vs 7.2±2.1 µg/L, P=0.046). Restricting this analysis to estrogen-treated subjects, P decreased ghrelin-stimulated GH secretion from 10.7±2.7 to 2.6±1.3 µg/L/2 h (P=0.002) in a P concentration-dependent manner, viz., R=-0.49 (P=0.04, β=-0.040±0.018). Conclusions. Early follicular phase E2 levels did not impact spontaneous or ghrelin-stimulated GH concentrations, whereas P inhibited 10-h overnight and 2-h ghrelin-stimulated GH secretion a concentration-dependent fashion. Accordingly, the physiological significance of P on GH regulation requires further studies.

Acid phosphatases in the human testis after prolonged estrogen treatment.

The testes of 2 autopsied adult men and 6 subjects, suffering from prostatic carcinoma, were analysed for acid phosphatase activities, Two of the prostatic patients had been receiving estrogen treatment at least for a year and had completely regressed testes. Testes of other subjects contained well-defined tubules with different spermatogenic cells in abundance. The total acid phosphatase activity, assayed in the homogenate, showed a marked reduction in the testes of estrogen-treated subjects. Enzymes were separated by cellulose chromatography or by gel filtration combined with cellulose chromatography. Three activity peaks were resolved by the former and four by the latter technique, when homogenates of the control testes were used. In contrast, two to three strongly reduced activities could be discerned from the testes of estrogen-treated subjects. The specific activity of each enzyme after fractionation was compared between control and regressed testes. No difference was observed in the activities of enzyme I. Enzyme II was markedly reduced in the regressed testes, but was clearly present. Enzymes III and IV were either totally absent or showed a marked reduction in the regressed testes. It is suggested that a correlation exists between the destruction of germ cells, as a consequence of estrogen treatment, and the marked reduction in the activity of enzymes III and IV.

Vitamin C improves endothelial function in healthy estrogen-deficient postmenopausal women

Objective: Estrogen deficiency is associated with increased cardiovascular risk and endothelial dysfunction. Improvements in endothelial function with antioxidants, including vitamin C, have been reported. We aimed to determine the acute effect of vitamin C on endothelial function in healthy women with established menopause. Subjects: Subjects (aged 47-59 years) were at least 1 year postmenopause. Ten (serum estradiol < 50 pmol/l) were not receiving hormone replacement therapy, while eight hysterectomized subjects received subcutaneous estradiol. Design: Forearm blood flow (FBF; strain-gauge plethysmography) responses to intrabrachial artery infusions of incremental doses of acetylcholine (endothelium-dependent vasodilation) and sodium nitroprusside (endothelium-independent vasodilation) were determined at baseline, and following 1.5 g vitamin C given intravenously. Results: At baseline, estrogen-treated subjects had a lower index of insulin resistance (homeostasis model assessment, HOMA) and lower fibrinogen than those of estrogendeficient subjects. There was a trend towards higher baseline FBF and larger baseline FBF response to acetylcholine in estrogen-treated subjects. FBF responses to acetylcholine were significantly enhanced after vitamin C in estrogen-deficient subjects (area under the dose-response curve (AUC): estrogen-deficient 9.9 ± 2.6 vs. 15.1 ± 3.2 (mean ± SEM), p = 0.02; estrogen-treated 17.0 ± 2.9 vs. 21.0 ± 3.2, p = 0.07). Resting FBF and response to sodium nitroprusside were unchanged in either group by vitamin C. Plasminogen activator inhibitor-1 levels fell after vitamin C in the estrogen-deficient group (17.0 ± 1.6 vs. 14.7 ± 0.9 IU/ml, p = 0.03). Conclusions: These results indicate that endothelial function may be improved acutely by antioxidant treatment in postmenopausal women with established estrogen deficiency.

Vitamin C improves endothelial function in healthy estrogen-deficient postmenopausal women

Objective: Estrogen deficiency is associated with increased cardiovascular risk and endothelial dysfunction. Improvements in endothelial function with antioxidants, including vitamin C, have beenreported. We aimed to determine the acute effect of vitamin C on endothelial function in healthy women with established menopause.Subjects: Subjects (aged 47-59 years) were at least 1 year postmenopause.Ten (serum estradiol < 50 pmol/l) were not receiving hormone replacement therapy, while eight hysterectomized subjects received subcutaneous estradiol.Design: Forearm blood flow (FBF; strain-gaugeplethysmography) responses to intrabrachial artery infusions of incremental doses of acetylcholine (endothelium-dependent vasodilation) and sodium nitroprusside (endothelium-independent vasodilation) weredetermined at baseline, and following 1.5 g vitamin C given intravenously.Results: At baseline, estrogen-treated subjects had a lower index of insulin resistance (homeostasis model assessment,HOMA) and lower fibrinogen than those of estrogendeficient subjects. There was a trend towards higher baseline FBF and larger baseline FBF response to acetylcholine in estrogen-treated subjects. FBF responsesto acetylcholine were significantly enhanced after vitamin C in estrogen-deficient subjects (area under the dose-response curve (AUC): estrogen-deficient 9.9 ± 2.6 vs. 15.1 ± 3.2 (mean ±SEM), p = 0.02; estrogen-treated 17.0 ± 2.9 vs. 21.0 ± 3.2, p = 0.07). Resting FBF and response to sodium nitroprusside were unchanged in either group by vitamin C. Plasminogenactivator inhibitor-1 levels fell after vitamin C in the estrogen-deficient group (17.0 ± 1.6 vs. 14.7 ± 0.9 IU/ml, p = 0.03).Conclusions: These results indicate that endothelialfunction may be improved acutely by antioxidant treatment in postmenopausal women with established estrogen deficiency.

Hormonal regulation of serum lipoprotein (a) levels: effects of parenteral administration of estrogen or testosterone in males.

When given orally, estrogens, as well as androgens, lower serum lipoprotein (a)[Lp(a)]levels. To determine whether these effects occur also after parenteral administration of steroids, Lp(a) levels were determined in two groups of elderly males suffering from prostatic carcinoma, who were randomized to treatment with parenteral estrogen (n = 8) or orchidectomy (n = 6). One group of healthy male volunteers (n = 9) was studied after parenteral administration of testosterone. Estrogen was given as im polyestradiol phosphate, 240 mg twice monthly, and testosterone was given as im injections, 250 mg/week. In the orchidectomized subjects, Lp(a) levels increased by 20% by month 3 after treatment (P < 0.05). In spite of drastic changes in serum hormone levels, no change in Lp(a) levels was observed in the estrogen-treated subjects. Concomitantly, low-density lipoprotein cholesterol levels were lowered by 15% and high-density lipoprotein cholesterol levels increased by 20%. Testosterone administration lowered Lp(a) levels by 20% (P < 0.05). No significant changes in serum lipid levels were observed in the testosterone-treated subjects or in the orchidectomy group. Thus, during parenteral administration of estrogens or androgens, diverging effects on Lp(a) and serum lipoproteins were observed. In particular, the mode of administration of estrogen influenced the response in Lp(a) levels. This suggests that the regulatory role of sex hormones on serum Lp(a) levels may depend on their capability to influence hepatic metabolic pathways of Lp(a).

Effect of surgical menopause and estrogen replacement on cytokine release from human blood mononuclear cells.

To determine whether mononuclear cell secretory products contribute to the changes in bone turnover that characterize the development of postmenopausal osteoporosis, we evaluated the effects of oophorectomy and subsequent estrogen replacement on the spontaneous secretion of interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha) and on the phytohemagglutinin A-induced secretion of granulocyte-macrophage colony-stimulating factor (GM-CSF) from peripheral blood mononuclear cells. In 15 healthy premenopausal women who underwent oophorectomy, increases in GM-CSF activity were observed as early as 1 week after surgery, whereas elevations in IL-1 and TNF-alpha and in hydroxyproline/creatinine and calcium/creatinine ratios, two urinary indices of bone resorption, were detectable 2 weeks after the surgical procedure. Six of the oophorectomized women received no estrogen therapy after surgery and in these subjects hydroxyproline/creatinine and calcium/creatinine ratios plateaued 6 weeks postoperatively, and all three cytokines reached the highest levels 8 weeks after oophorectomy, when the study ended. In the remaining 9 women, who were started on estrogen replacement therapy 4 weeks after oophorectomy, decreases in the indices of bone resorption paralleled decreases in the secretion of the cytokines, with lower levels detected after 2 weeks of therapy. In the women who did not receive estrogen therapy, circulating osteocalcin, a marker of bone formation, increased beyond preoperative levels 8 weeks after oophorectomy, whereas in the estrogen-treated subjects osteocalcin remained unchanged in the entire study period. In 9 female controls who underwent simple hysterectomy, cytokine release and biochemical indices of bone turnover did not change after surgery. These data indicate that changes in estrogen status in vivo are associated with the secretion of mononuclear cell immune factors in vitro and suggest that alterations in the local production of bone-acting cytokines may underlie changes in bone turnover caused by surgically induced menopause and estrogen replacement.

Use of direct thyroxine-binding globulin measurement in the evaluation of thyroid function.

Serum thyroxine-binding globulin (TBG) was measured by radioimmunoassay in 295 euthyroid subjects (220 normals and 75 estrogen-treated subjects), in 21 hyperthyroid and 19 hypothyroid patients. In normals, TBG concentration was 1.61 ± 0.29 mg/100 ml (mean ± SD) and a 71% increase was found in estrogen-treated subjects. Hyperthyroid patients had a normal mean TBG and hypothyroid patients showed slightly elevated levels. The usefulness of direct TBG measurement for the evaluation of thyroid function was assessed by comparing the results of T3 resin uptake tests (T3RU) performed in the same subjects. Three lines of evidence demonstrated the advantages of TBG measurement, i) In euthyroid subjects with elevated TBG levels T3RU results underestimated the actual TBG changes, ii) T4 levels correlated more closely with TBG than with T3RU results, iii) T3RU results, depending both on the concentration of hormone and binding protein were found less accurate for the adjustment of total T4 concentrations. Serum TBG and T4 values were used to calculate the free T4 (FT4) concentration. The FT4 was 1.2 ± 0.3 ng/100 ml in normals and the FT4 distribution in estrogen-treated subjects was entirely within the limits of normal subjects. In hypothyroidism FT4 was 0.3 ± 0.2 ng/100 ml and in hyperthyroidism 3.1 ± 1.1 ng/100 ml. Calculated FT4 was compared to direct FT4 measurements in 97 subjects and gave almost identical results. In conclusion, serum TBG can be reliably measured by radioimmunoassay. Adjustment of total T4 concentrations should be performed with TBG-based indices rather than T3RU. Free T4 concentrations can be obtained accurately from total T4 and TBG levels in euthyroidism as well as in pathological states of thyroid function.

Effects of estrogen on human seminiferous tubules: light and electron microscopic analysis.

Morphological features of testes from four subjects after long-term treatment with ethinyl-estradiol (1--2 mg daily) and from five non-treated patients with prostatic carcinoma were studied by means of light and electron microscopy. The non-treated seminiferous tubules contained spermatagonia, spermatocytes, spermatids, spermatozoa, and Sertoli cells and showed no apparent morphologic abnormalities. On the other hand, the estrogen-treated testicular tissue contained only Sertoli cells and very few spermatogonia within the seminiferous tubules. The nuclei of Sertoli cells occasionally contained two nucleoli. The nucleolar complex was composed of a fine granular spherical body surrounded by a large granular, reticular network. The cytoplasm of the Sertoli cell contained osmiophilic lipid-like bodies. These lipid-like bodies appeared more pronounced in patients treated with higher doses of estrogen, suggesting a diminution of secretion of Sertoli cell hormone. Blebbing from the outer nuclear membrane appeared to have formed numerous vesicles in the cytoplasm. These vesicles usually contained several membrane-bound granular bodies. In the estrogen-treated testes, there was a marked increase in thickness and infolding of the basement membrane. Two unusual patterns of the basement membrane were observed: one appeared to be a reticular anastomosis, the other, an electron-dense trilayer. The morphological picture of seminiferous tubules from the estrogen-treated subjects appeared to correlate well with the suppressed plasma and testicular levels of testesterone, the undetectable circulating gonadotrophins, and the elevated plasma and testicular levels of estradiol-17 beta reported by Rodriguez-Rigau et al. ('77).

Preventive Effect of Estrogen on Postmenopausal Bone Loss

• Follow-up studies of bone mineral content in the radius were done in 82 postmenopausal women 4 to 10 years after the first examination. These patients were subdivided into four groups depending on the type of menopause (artificial or natural) and estrogen administration (treated or untreated). Bone mineral mass and combined cortical thickness decreased significantly in both groups of untreated women. Bone mineral loss per year for the untreated women was —9.1 mg/sq cm for castrates and —6.9 mg/sq cm for those with a natural menopause. In neither group was the rate of loss correlated with age. The change in bone mineral mass per year in the estrogen-treated subjects (mean, +3.25 mg/sq cm) differed significantly from that of untreated subjects (mean, —7.99 mg/sq cm). The findings suggest that postmenopausal osteoporosis could be prevented by estrogen treatment. ( Arch Intern Med 135:1436-1440,1975)

Preventive effect of estrogen on postmenopausal bone loss

Follow-up studies of bone mineral content in the radius were done in 82 postmenopausal women 4 to 10 years after the first examination. These patients were subdivided into four groups depending on the type of menopause (artificial or natural) and estrogen administration (treated or untreated). Bone mineral mass and combined cortical thickness decreased significantly in both groups of untreated women. Both mineral loss per year for the untreated women was -9.1 mg/sq cm for castrates and -6.9 mg/sq cm for those with a natural menopause. In neither group was the rate of loss correlated with age. The change in bone mineral mass per year in the estrogen-treated subjects (mean +3.25 mg/sq cm) differed significantly from that of untreated subjects (mean -7.99 mg/sq cm). The findings suggest that postmenopausal osteoporosis could be prevented by estrogen treatment.

Effect of estrogens on canine renal allografts

Immunosuppressive effect of estrogens is unsettled. Our studies, however, have demonstrated that in canine renal allografts they affect the integrity of the capillaries resulting in a decrease in interstitial infiltration and edema, associated with fibrinoid vascular alterations and glomerular changes. Renal plasma flow in estrogen-treated subjects was better than in the untreated control groups. However, a synergic effect with azathioprine (Imuran) was not observed. Except for the decrease in interstitial cellular infiltration associated with administration of estrone and estradiol, other changes were not found in groups treated with various estrogens.

Effect of estrogen administration on extravascular cortisol.

Analyses of arterial-blood radioactive-cortisol disappearance curves in human subjects by means of 2-compartment mathematical models have provided data on extravascular and intravascular cortisol. The intravascular cortisol pool is 460 ± 209 SD μg distributed in a volume equal to plasma volume. Extravascular cortisol is 2 or 3 times as largely distributed in an unknown volume. Estrogen treatment causes a marked increase in intravascular cortisol without significant effect on extravascular cortisol. This is in contrast to ACTH stimulation, which causes proportional increases in both pools. Kinetic processes are changed by estrogen treatment with a resultant tendency for cortisol to remain in the intravascular pool. These data, taken in conjunction with the previously observed lack of hypercorticism in estrogen-treated subjects, are consistent with the hypothesis that it is the extravascular cortisol which is physiologically active. They indicate that a function of transcortin is to maintain a large intrava...

Estrogen Pharmacology

ESTRADIOL depresses the hepatic secretory transport maximum (Tm),1,2for sulfobromophthalein (BSP) in man.3In rats, this hormone similarly delays hepatic removal from plasma of both BSP and the dye phenol-3,6-dibromophthalein disulfonate,4a chemical analog of BSP which does not undergo conjugation during hepatic transit into bile.5The latter finding indicated that, in this experimental context, estrogens act on hepatic processes other than those concerned with dye conjugation, and implied that the BSP retention induced by these hormones in man reflected a decrease in the net rate of hepatic disposal not only of the conjugated form of BSP, but of the free dye as well. The present study was undertaken to examine this possibility by analysis of the BSP components in the plasma of estrogen-treated subjects at appropriate intervals after intravenous injection of the dye. The results confirm that in man the net movement of both free and conjugated BSP out

INCREASED UNBOUND CORTISOL IN THE PLASMA OF ESTROGEN-TREATED SUBJECTS.

INCREASED UNBOUND CORTISOL IN THE PLASMA OF ESTROGEN-TREATED SUBJECTS.

TRANSCORTIN: A CORTICOSTEROID-BINDING PROTEIN OF PLASMA. VII. HALF-LIFE IN NORMAL AND ESTROGEN-TREATED SUBJECTS.

TRANSCORTIN: A CORTICOSTEROID-BINDING PROTEIN OF PLASMA. VII. HALF-LIFE IN NORMAL AND ESTROGEN-TREATED SUBJECTS.

The physiologic significance of 6beta-hydroxycortisol in human corticoid metabolism.

A previously described method for the measurement of 6β-hydroxycortisol (6β-OH-F) in human urine was modified by the use, for recovery purposes, of a radioactive tracer. A significant difference was noted between the mean urinary excretion in the normal male (298 μg per day) and in the normal female (399 μg per day). Administration of large doses of diethylstilbestrol increased the excretion of 6β-OH-F in normal men, without alteration of the adrenal secretory rate for cortisol. 6β-OH-F excretion was determined in various phases of the menstrual cycle, as well as after testosterone administration, and in hypertensive subjects. Abnormal values were observed in several of these urines. Studies of the metabolic fate of tracer doses of radiocortisol indicated that essentially all urinary 6β-OH-F arises from the peripheral metabolism of endogenous cortisol rather than as an independent secretion from the adrenal gland. This conclusion applies to normal and to estrogen-treated subjects as well as to patients with Cushing's syndrome. Hyperestrogenism, Cushing's syndrome, and liver disease are states in which the production of polar metabolites of cortisol is more important quantitatively than under ordinary circumstances. Evidence is cited that the utilization of this alternate pathway of cortisol metabolism may be increased when A-ring reduction is impaired.

Binding of corticosteroids by plasma proteins. VI. The binding of cortisol and aldosterone by corticosteroid-binding globulin and by the estrogen-induced binding system of plasma.

The binding of cortisol-4-C14 and aldosterone-H3 by serum from pregnant or estrogen-treated subjects was directly compared to the binding by serum from control subjects in a system of double equilibrium dialysis. Increased binding of cortisol-4-C14 could be demonstrated by “estrogen” plasma under conditions of minimal cortisol loading only at 37°C. and not at 4°C. This difference of binding behavior is evidence that the binding sites induced by estrogen are qualitatively different from those on normal corticosteroid-binding globulin. The total concentration of cortisol-binding protein induced by estrogens may be two or three times greater than that of corticosteroid-binding globulin. Under physiologic conditions of temperature, aldosterone-H3 is bound primarily by albumin, but at 4° C. aldosterone-H3 is bound about equally by albumin and corticosteroid-binding globulin. At 4° C. the estrogen-induced binding system does not have appreciable affinity for aldosterone-H3.