Effect of 5 alpha-dihydrotestosterone and dexamethasone on estrogen receptors of the anterior pituitary and uterus.

The administration of 5 alpha-dihydrotestosterone (5 alpha-DHT) and dexamethasone has been shown to attenuate estrogen-induced prolactin release in the estrogen-primed rat. Therefore, the effect of these compounds was studied on anterior pituitary and uterine estrogen receptors. Injection of 0.8 mg/kg body weight of 5 alpha-DHT to ovariectomized adult rats treated with 2 micrograms estradiol/d for 4 days resulted in a significant decrease in occupied nuclear estrogen receptors of the anterior pituitary but not the uterus. Estrogen priming was essential for 5 alpha-DHT effect on occupied nuclear anterior pituitary estrogen receptors because this effect did not occur in ovariectomized vehicle-treated control animals. The administration of 1 mg/kg body weight of dexamethasone brought about a decrease in uterine but not anterior pituitary nuclear estradiol receptors. These results provide further evidence that the regulation of estrogen receptor dynamics is different in the anterior pituitary and the uterus and that different steroids can exert tissue-specific effects.     

Progesterone regulation of estrogen receptor in the rat uterus: A primary inhibitory influence on the nuclear fraction

The purpose of this study was to determine the short-term effects of progesterone action on estrogen receptor (Re) levels in the rat uterus. Ovariectomized, adrenalectomized rats were maintained on subcutaneous Silastic implants containing crystalline estradiol. Progesterone treatment with serum estradiol maintenance caused a rapid decrease (within 4 h) of total Re, attributable to loss of nuclear Re without a significant change in cytosol Re levels. Removal of estradiol implants resulted in an increase in total Re and cytosol Re at all time periods studied without a significant decrease in nuclear Re until 8 h. Combined estradiol withdrawal and progesterone treatment resulted in lower total Re levels and a more rapid decrease in nuclear Re than with estradiol withdrawal alone. These results demonstrate that progesterone rapidly and selectively decreases nuclear Re levels in rat uterus and suggest that this process is not dependent on cytosol Re or serum estradiol levels.     

Chronic estrogen treatment causes an alteration in uterine estrogen receptor dynamics of rats

Estrogen receptor content and dynamics in the uteri obtained from chronically estrogenized rats were analyzed. 12 day treatment with a subcutaneous implantation of a diethylstilbestrol pellet resulted in maximal stimulation of uteri with regard to wet tissue weight, DNA content, as well as progesterone receptor content without significant alteration of the estrogen receptor level. Estrogen receptor dynamics in just ovariectomized or ovariectomized and diethylstilbestrol-stimulated rats elicited by a single injection of estradiol were next examined using the exchange methods. The cytosol receptor content rapidly declined, with a small and temporary accumulation of the nuclear receptor in the uterus from rats continuously exposed to diethylstilbestrol during the preceding 12 days. A relatively rapid cytosol receptor replenishment was also observed in rats pretreated with diethylstilbestrol. This was accompanied by a rapid decrease in the nuclear receptor level to 70% of the preinjection value at 5 h after estradiol administration. These data are in contrast to findings on uteri of ovariectomized and nonestrogen-treated rats, in which a single injection of estradiol resulted in a prolonged nuclear receptor retention and a delayed cytosol receptor replenishment. Adrenalectomy did not result in a significant change of receptor dynamic patterns, suggesting that adrenal steroids do not play a role in the alteration of receptor dynamics elicited by continuous stimulation with diethylstilbestrol. These observations suggest that a continuous exposure of rat uteri to the estrogen causes an altered regulation of estrogen receptor dynamics by the homologous steroid compared to those in chronically estrogen-deprived rats.     

Non-stoichiometric nuclear-cytoplasmic redistribution of estrogen receptor in adult rat uterus, following estradiol injection

In immature and ovariectomized rats acutely injected with estradiol (E2), accumulation of estradiol receptor complexes (E2R) from the uterine cytosol to the nucleus has been shown to be quantitative by numerous investigators. In the present study, translocation of E2R from the cytosol to the nuclear fraction in adult and ovariectomized estrogen prestimulated rats was analyzed. Twenty micrograms of E2, dissolved in saline containing 10% ethanol and 1 g% bovine serum albumin (B.S.A.) were injected intraperitoneally to the animals and 2 h later E2R in the cytosol and crude nuclear fractions were assayed by exchange techniques. Unlike a 91% recovery of the depleted cytosol E2R in the nuclear fraction of ovariectomized rats, only 39.2 and 27.5% were recovered in the adult and ovariectomized estrogen prestimulated rat uterus respectively. Moreover, depending on the temperature and duration of nuclear suspension incubation, from 18 up to 80% of the recovered nuclear E2R were solubilized in the incubation medium and nuclear post-incubation washes and could be measured by hydroxylapatite treatment (HAP). Saturation assays showed a plateau from 12 nM E2 3H onwards up to 80 nM. The Kd values computed for the receptors in the nucleus and HAP in all the three groups were of the order of 2 X 10(-9) M. In conclusion, after E2 administration to adult or ovariectomized estrogen prestimulated rats, a stoichiometric recovery of the depleted cytosol E2R in the nuclear fraction was not observed, even when leakage of nuclear receptor into the medium in course of exchange was taken into account. Chronic estrogenization appeared to modify the dynamics of uterine receptor.     

Effect of hypophysectomy on estrogen conjugation and on plasma and tissue concentrations of tritium after administration of 3H-estradiol-17beta.

Estradiol-17beta-6,7-3H was injected into ovariectomized (control) and ovariectomized, hypophysectomized (hypox) rats in order to study the binding of estradiol in the brain. Hypophysectomy resulted in a significant increase in the concentration of tritium in the hypothalamus, and preoptic area, as well as cortex, muscle, plasma and liver. However, since the liver was lighter in hypox rats, the total tritium content in the liver was unchanged from controls. Part of the weight reduction in the liver was due to a loss of stainable glycogen, which took place within 24 hours of hypox. The increase in circulating tritiated estradiol after hypox led us to investigate hepatic metabolism of estradiol. In vitro studies on liver slices from control and hypox rats demonstrated a significant reduction in the formation of conjugates of estrogen. Specifically, estradiol glucuronide and estrone sulfate formation were reduced in hypox rats and conversely the unmetabolized estradiol concentration was higher. Hypophysectomy for 24 hours results in a significant decrease in hepatic metabolism of estradiol-17beta.     

Integration of the effects of estradiol and progesterone in the modulation of gonadotropin secretion

Estradiol secreted by the maturing follicle is the primary trigger for the surge of gonadotropins leading to ovulation. Progesterone has stimulatory or inhibitory actions on this estrogen-induced gonadotropin surge depending upon the time and dose of administration. The administration of progesterone to immature ovariectomized rats primed with a low dose of estradiol induced a well-defined LH surge and prolonged FSH release, a pattern similar to the proestrus surge of gonadotropins. A physiological role of progesterone is indicated in the normal ovulatory process because a single injection of the progesterone antagonist RU 486 on the day of proestrus in the adult cycling rat and on the day of the gonadotropin surge in the pregnant mare's serum gonadotropin stimulated immature rat resulted in an attenuated gonadotropin surge and reduced the number of ova per ovulating rat. Progesterone administration brought about a rapid LHRH release and an decrease in nuclear accumulation of estrogen receptors in the anterior pituitary but not the hypothalamus. The progesterone effect was demonstrated in vitro in the uterus and anterior pituitary and appears to be confined to occupied estradiol nuclear receptors. In in vivo experiments the progesterone effect on estradiol nuclear receptors appeared to be of approximately 2-h duration, which coincided with the time period of progesterone nuclear receptor accumulation after a single injection of progesterone. During the period of progesterone effects on nuclear estrogen receptors, the ability of estrogens to induce progesterone receptors was impaired. Based on the above results, a model is proposed for the stimulatory and inhibitory effects of progesterone on gonadotropin secretion.     

Role of 17 beta-hydroxysteroid dehydrogenase in the modulation of nuclear estradiol receptor binding by progesterone in the rat anterior pituitary gland and the uterus

Progesterone has been shown to decrease occupied pituitary and uterine nuclear estradiol receptor (E2R) binding in mature and immature estrogen-primed rats. Progesterone has also been shown to stimulate pituitary but not uterine 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) in the rat. The conversion of estradiol to its less active metabolite estrone by 17 beta-HSD and activation of phosphatase are among mechanisms considered to be involved in the reduction of E2R. To determine if 17 beta-HSD stimulation was a mechanism by which progesterone induced nuclear E2R decrease, the synthetic estrogen ethinylestradiol, which is not oxidized by 17 beta-HSD, was used instead of estradiol to prime adult ovariectomized rats. When ethinylestradiol-primed rats received 0.8, 2.0 or 4.0 mg/kg body wt of progesterone 2 h before sacrifice, the total and occupied nuclear E2R accumulation in the anterior pituitary by a subsequent ethinylestradiol injection 1 h later did not show any decrease. This response was different from that observed previously in estradiol-primed animals in which progesterone showed a multiphasic decrease of occupied form of nuclear E2R. However, in the uterus of ethinylestradiol-primed rats, a partial decrease of total and occupied nuclear E2R accumulation was observed in the presence of the three doses of progesterone used. The decrease of uterine nuclear E2R with the three progesterone doses was different from the dose-dependent effect of progesterone observed in the uterus of estradiol-primed rats. Affinity constants of the interaction between [3H]estradiol and the nuclear E2R were similar among groups treated with ethinylestradiol, estradiol and progesterone. These results demonstrate the involvement of 17 beta-HSD in the reduction of anterior pituitary gland E2R by progesterone in the estradiol-treated animals. Furthermore, the mechanism of decrease of E2R by progesterone in the uterus appears to be different from the pituitary gland.     

Estradiol-17β receptors in the immature rat ovary

Estradiol binding components in the cytosol and nuclear fractions of the ovary from immature rats (22–28 days old) were characterized by $\text{in vitro}$ methods. Several of the biochemical characteristics of the estradiol binding components in the ovarian tissue were compared with the estradiol receptor from the uterus. The results suggest that the ovarian estradiol binding components are similar to the specific high affinity estradiol receptors in the uterus. In the cytosol of intact rat ovary a significant fraction of the total binding sites was found to be occupied, presumably by the endogenous estrogen. Following hypophysectomy there was a significant increase in the available cytosol binding sites. Evidence for translocation of cytosol receptor-estrogen (RE) complex to the nucleus was obtained for the ovary. The sedimentation properties of the RE complex of the ovary and the uterus are similar. The ovarian cytosol RE complex sediments at 7-8S in glycerol gradients at low ionic strength and at 4S in sucrose gradients at high ionic strength. Following extraction with 0.4 M KCl the ovarain nuclear RE complex sediments at 5S in sucrose gradients which is identical to that of the uterine nuclear receptor.     

Uptake of estradiol by the rat pineal organ. Effects of cervical sympathectomy, stage of the estrous cycle and estradiol treatment

Rat pineal organs of spayed rats took up and retained estradiol $\text{in vitro}$ up to 32-fold the concentration present in the incubation media. This phenomenon was maximum at 37°C and after 2-h incubations. Most (86–91%) of [³H] radioactivity recovered from the incubated pineals was identified as estradiol by thin-layer chromatography. Treatment with dextran-coated charcoal of nuclei-free pineal homogenates incubated with [³H] estradiol of different SA uncovered a high affinity, low capacity binding of estradiol to cytosol components. Uptake of estradiol by the nuclear fraction also proceeded in a saturable fashion. Similar findings were made in uterine homogenates of spayed rats.Estradiol uptake by the pineal organ and the uterus of cycling rats varied as a function of the stage of the estrous cycle, maxima being observed in diestrus and minima in proestrus. The administration of a priming dose of estradiol benzoate to spayed rats caused high affinity binding components of the pineal cytosol to increase by about 150%. Nuclear binding of estradiol was also increased by the estradiol priming dose. Pineal denervation, i.e., by superior cervical ganglionectomy, caused pineal estradiol uptake to decrease significantly by about 20%. These data suggest that the early steps of estradiol action on the pineal organ may resemble those of the uterus.     

Concentration and turnover of estradiol in the rat uterus in vivo

The concentrations and turnover of estradiol isolated from cytosolic and nuclear fractions of uteri from ovariectomized rats given estradiol, either in single injections or in continuous infusion, were analyzed by gas chromatography-mass spectrometry. The analytical method was validated for different organs and lower limits of analysis were established. After infusion of 20 ng x h-1 for 18-22 h, mean estradiol levels were 2.0-2.4 fmol x mg-1 uterine wet weight in the nuclear fraction, and 1.2-1.5 fmol x mg-1 in the cytosolic fraction. The concentrations were about five times higher after a single injection of one microgram estradiol but the distribution between nuclear and cytosolic fractions was almost the same. The concentrations of estradiol in nuclei from liver and spleen were 50-200 times lower than those in uterus. Taken together with previous knowledge, the results indicate that the distributions of estradiol and its receptor are not the same and that hormone response cannot be predicted from the concentration of receptors alone. The exchange of estradiol molecules in the uterus was followed after a change of the infusion from unlabelled to [11,12,12-2H3]-labelled estradiol, or vice versa. The uterine uptake of estradiol was calculated to be about 0.7 fmol x h-1 x mg-1 uterine wet weight. The half-life time was calculated to be at least 4 h for estradiol molecules isolated from the nuclear fraction and 3 h (significantly shorter) for those isolated from the cytosolic fraction. The results indicate an uptake of 40-90% of all estradiol passing through the uterus in proestrus with only about 10% of available receptors becoming occupied. When the infusion was changed from estradiol to ethynylestradiol, estradiol disappeared from the uterus at the same rate as in the experiments above. Ethynylestradiol was taken up at a rate of about 0.3-0.4 fmol x h-1 x mg-1 tissue. The percentage of total steroid found in the nuclear fraction was higher for ethynylestradiol, about 70%, than for estradiol, about 60%, indicative of a more stable association of receptor to nuclear binding sites when ethynylestradiol is the ligand.     

Uterotropic action of indomethacin on the rat uterus

Administration of indomethacin (10 mg/kg body weight, twice daily for 6 days) resulted in a significant (P less than 0.01) increase in the weight, and cross-sectional area of uteri of ovariectomized rats, whereas no such effects were observed following indomethacin administration to normal cycling rats. Prostaglandin F2 alpha (PGF2 alpha) content (ng/uterus) and concentration (ng/g wet weight) in the uterus of indomethacin-treated animals were reduced 40.4% and 60.8%. Simultaneous administration of either estradiol-17 beta (E2), progesterone testosterone with indomethacin to ovariectomized rats failed to reduce the uterine weight increase. On the contrary, concomitant administration of E2 (25 or 100 ng/day) and indomethacin resulted in uterine weight increases which were greater than those associated with indomethacin alone. Uterine E2 content was significantly higher in animals treated with indomethacin plus E2 as compared to those given estradiol alone. Uterine uptake of 2,4,6,7-[3H]E2 following i.v. administration was greater in animals pretreated with indomethacin (5 mg/kg, twice daily) for 3 days than in ovariectomized controls. These results suggest that prostaglandins may be involved in the regulation of uterine growth.     

Effect of isoflavone administration on age-related hepatocyte changes in old ovariectomized femal Wistar rats

Aging seems to be due to the accumulation of oxidative damage in cells and molecules. On the other hand, menopause and ovariectomy induce deleterious effects on different organs and systems that have been shown to be counteracted by estrogens and in a not so evident form also with phytoestrogens. The present study has investigated whether the administration of a commercial soy extract that contains approximately 10% isoflavones was able to modify some parameters related to oxidative stress and inflammation in hepatocytes isolated from old ovariectomized female Wistar rats. Eighteen 22-month-old animals that had been previously ovariectomized at 12 months of age were divided into four groups: ovariectomized control rats, estradiol-treated ovariectomized females and ovariectomized rats treated with isoflavones. Six intact female rats of 2 months of age were used as reference group. Hepatocytes were isolated and cultured, and carbon monoxide (CO) and nitric oxide (NO) release, as well as adenosyl triphosphate (ATP), cyclic guanosyl monophosphate (cGMP), phosphatidylcholine (PC) and lipid peroxide (LPO) content of cells were evaluated. Uterus was also removed and weighed. Hepatocytes isolated from old ovariectomized rats showed a decrease in ATP content as compared to young animals. Age also induced an increase in LPO cell content. NO, CO and cGMP were augmented with age, and PC synthesis showed a dramatic reduction. Treatment with either estradiol or isoflavones were able to improve all the mentioned parameters altered in hepatocytes isolated from old ovariectomized rats, and the magnitude of the improvement was similar for both treatments. Ovariectomy induced a significant reduction in uterine weight, which was significantly counteracted by estradiol treatment but not by isoflavone administration. In conclusion, the administration of a soy extract containing isoflavones seems to prevent oxidative changes in hepatocytes isolated from old ovariectomized female rats, without modifying uterus weight.     

Discrete early changes in cellular subpopulations of rat uterine and anterior pituitary estrogen receptors in response to acute exposure to exogenous estradiol

Distribution of estrogen receptors among ligand-occupied and unoccupied species in cytosolic and nuclear subcellular compartments has been analyzed as an acute response to administration of 5 micrograms of estradiol in adult female rats. Patterns of anterior pituitary and uterine receptor turnover were monitored at intervals over a 5-h period, using either intact or 2-weeks ovariectomized animals. In terms of total cellular receptor content, initial levels were higher in castrate animals, but rapidly fell to intact levels within an hour following estradiol injection. Cycloheximide given shortly before estradiol had no effect on total pituitary receptor patterns, but appeared to result in an elevation in total uterine receptor content at early intervals. Unoccupied cytosol receptors were rapidly depleted and, with the exception of castrate pituitary samples, showed some replenishment within 5 h, all of which was cycloheximide-sensitive. Initially, occupied cytosol receptors were low in intact rats, but were present at levels approaching those of the unoccupied cytosol receptor forms in the ovariectomized rat tissues. Occupied cytosol receptor levels fluctuated in response to estradiol. Subpopulations of nuclear receptors, especially the unoccupied species, showed significant tissue specificity. In the uterus, unoccupied nuclear forms were initially present in high amounts, and the levels did not change in response to estradiol administration. In the pituitary, the levels of these receptors rose and subsequently fell over the 5-h interval. Cycloheximide conferred a similar biphasic response to estradiol upon the otherwise insensitive unoccupied nuclear forms of the uterus. Occupied nuclear receptors turned over completely during the 5-h study interval, with the kinetics being faster in the castrate than the intact tissues. Cycloheximide affected occupied nuclear forms of the uterus only, dramatically increasing their levels in response to estrogen and causing prolonged retention in the castrate animal model. Collectively, the cycloheximide effects on this system are consistent with early estrogen induction or stimulation of a protein which inhibits accumulation of occupied or unoccupied receptor species within the nucleus. This re-examination of all forms of cellular estrogen receptors as they fluctuate acutely in response to exogenous estrogen has revealed several heretofore undetected responses which must be incorporated into the overall scheme of early estrogen action.     

Effect of ovarian hormones on glycosyltransferase activities in the endometrium of ovariectomized rats.

Some of the properties of galactosyl- and sialyltransferases present in rat endometrial tissue were investigated. The enzyme activities were found to be partly membrane-bound and partly in soluble form. The galactose enzyme was also present in uterine secretions. The specific activities of both galactosyl- and sialyltransferases were greatly enhanced in endometrium of ovariectomized rats following 17 β-estradiol injections, although the enzyme activities in the liver remained unaffected. Mixing experiments with the homogenates of endometrium from control and estradiol-treated rats failed to suggest the presence of any “activator” or “inhibitor” of the enzymes. Diethylstilbesterol, estrone, and estriol also stimulated galactosyl- and sialyltransferase activities, whereas testosterone stimulated sialyltransferase only. Prolactin administration had no effect on either of the enzymes. The effect of estradiol on both enzymes was shown to be dose-dependent and the specific activities of the enzymes started to increase about 6 hr after hormone administration, reaching a peak around 48 h. Progesterone, on its own, had no effect on the galactosyltransferase in ovariectomized rat endometrium but effectively prevented the stimulatory effect of estradiol. When estradiol-primed rats were treated with progesterone, it was found that very small doses of progesterone resulted in decrease of galactosyltransferase activity. In such animals sialyltransferase activity was stimulated by a low concentration of progesterone which was followed by inhibition at higher concentrations. These effects of ovarian hormones on glycosyltransferase activities in endometrium are compatible with earlier reports on the effects of these hormones on glycoprotein and glycosaminoglycan levels in rabbit uterus after ovariectomy (7). Regulation of glycosyltransferase activities in endometrium induced by estradiol and progesterone may bear some relationship to the “receptive” state of the uterus for blastocyst implantation.     

Tamoxifen decreases the estradiol induced progesterone receptors by interfering with nuclear estrogen receptor accumulation

The retention time of the estrogen receptor in the nucleus of target cells after antiestrogen treatment has been shown to be longer than after estradiol. This paper describes the accumulation of nuclear estrogen receptors and the obtention of estrogenic responses (i.e. synthesis of cytosolic progesterone receptors and DNA) in the rat uterus after tamoxifen treatment in the presence or absence of estradiol. One-week ovariectomized adult rats were implanted with a silicone elastomer capsule containing corn oil or 25 micrograms estradiol/capsule (0 h). 48 h after implantation rats were injected with corn oil or 2 mg tamoxifen/kg and decapitated at 72, 96 or 120 h after implantation. In parallel experiments the implants were removed just before the injections of tamoxifen or oil. Tamoxifen injected into rats implanted with oil increased both the occupied nuclear receptors and the progesterone receptors at 96 h. In rats implanted with estradiol, tamoxifen did not increase the occupied nuclear receptors and decreased the levels of progesterone receptor and DNA at 96 h. In rats whose estradiol implants were removed at 48 h tamoxifen did not change the level of occupied nuclear receptors at 72 h but it increased them abruptly at 96 and 120 h. In these rats progesterone receptors decreased at 72 h but they increased at 96 and 120 h, and DNA decreased at 120 h to a lower level than before implantation. The results suggest that when estradiol is acting, tamoxifen is not able to increase the level of occupied estrogen receptor and it acts as an antiestrogen by decreasing the high level of progesterone receptors previously induced by estradiol. When estradiol is not acting tamoxifen behaves as a partial estrogen agonist by inducing progesterone receptors. However, the antiestrogenic action of tamoxifen on the rat uterus DNA does not seem to be affected by estradiol.     

Direct effect of estradiol on the number of dopaminergic receptors in the anterior pituitary, in ovariectomized rats

The effect of estradiol on anterior pituitary dopaminergic receptor content was studied in vivo and in vitro, in relation with the serum PRL secretion. A progressive and significant decrease in the number of these receptors was observed, a few hours before the serum release of PRL induced in ovariectomized females by a sequential treatment with different doses of estradiol benzoate. This decrease in the number of dopaminergic membrane receptors can be obtained as well in vitro, when anterior pituitaries, from ovariectomized rats, are incubated with 17 beta-estradiol. These results suggest that the stimulatory effect of estradiol on PRL secretion may be due, at least in part, to the direct "desensitization" to DA of anterior pituitary cells, which is produced by the decrease of dopaminergic receptor level.     

Effects of Salt Extraction on the Quantitation of Nuclear Estrogen Receptors: Interference by Secondary Estrogen Binding Sites

Abstract

The effects of salt-extraction on type I and type II estrogen binding sites were examined in uterine nuclei. Injection (10 ug) of estradiol or estriol in adult ovariectomized rats induced maximum numbers (80–100%, ~ 1 pmole/uterus) of 0.4 M KCL resistant type I estrogen complexes at 1 hour. Only estradiol, which sustained these levels for long periods of time (4–24 hours) stimulated true uterine growth.

Likewise, a single injection of estradiol, but not estriol, also elevated nuclear type II sites throughout the entire uterine growth period (1–48 hours). However extraction of these nuclei from estradiol injected rats with 0.4 M KCL increased the numbers of type II sites from ~ 1 pmole/uterus (non-extracted nuclei) to ~ 8 pmoles/uterus (salt resistant plus salt-extractable fractions). Sixty percent of these sites were resistant to salt-extraction. Continuous exposure to either estradiol or estriol by beeswax implants stimulated nuclear type II sites which were highly resistant (80%) to KCL-extraction, and additional sites were not exposed by high salt. Thus chronic treatment with both estrogens “locked in” nuclear type II sites such that they were resistant to KCL-extraction. This resistance of type II sites to salt-extraction correlated with the ability of estradiol and estriol implants to stimulate true uterine growth. The procedures presented here for nuclear preparation and assay have reduced non-specific binding considerably in the uterine system, and may eliminate the need to perform exchange assays on salt-extracted nuclei in other systems.     

17β-雌二醇对去卵巢大鼠子宫β-连环素和E-钙粘素蛋白表达的影响

目的旨在研究17β-雌二醇对去卵巢大鼠子宫β-连环素(β-catenin)和E-钙粘素(E-cadherin)蛋白表达的影响。方法将30只健康3月龄雌性SD大鼠,随机分为假手术组、去卵巢组、去卵巢和雌激素给药组。大鼠去卵巢1周后,给药组大鼠颈部皮下注射17β-雌二醇,每周3次,每次50μg/(kg·bw),连续给药10周。采用放免法、免疫组化法和Westernblot方法分别检测大鼠血清E2水平、子宫β-catenin和E-cadherin蛋白的免疫定位和表达。结果大鼠去卵巢后子宫指数和血清E2水平显著下降,但大鼠补充外源性17β-雌二醇后,上述两项指标均显著回升且与假手术组相比无显著差异。免疫组化检测发现,假手术组和去卵巢组大鼠子宫内膜的细胞膜上有β-catenin和E-cadherin蛋白表达,而雌激素给药组大鼠子宫内膜细胞膜和细胞核上都有E-cadherin表达。Westernblotting结果进一步显示,去卵巢组大鼠子宫β-catenin和E-cadherin蛋白表达量极显著低于假手术组和雌激素给药组。结论17β-雌二醇不仅能使E-cadherin蛋白在去卵巢大鼠子宫细胞中的免疫定位发生变化,而且还能刺激β-catenin和E-cadherin蛋白的表达。     

Estradiol and progesterone regulation of immunoglobulin A and G and secretory component in cervicovaginal secretions of the rat

The present study examined the influence of hormones on the levels of immunoglobulins A (IgA) and G (IgG) and secretory component (SC) in cervicovaginal secretions of ovariectomized rats. Administration of estradiol to ovariectomized rats resulted in a significant decline in cervicovaginal content of IgA, IgG and SC. This response was dose dependent and was not prevented by administration of dexamethasone, a potent synthetic glucocorticoid, with estradiol. Treatment of ovariectomized rats with progesterone also lowered the levels of IgA and SC in cervicovaginal secretions. In contrast, dexamethasone had no apparent vaginal effect. The action of estradiol on cervicovaginal IgA, IgG and SC appears to be independent of uterine influence. This conclusion is based upon our observation that estrogen treatment of rats with ligations at their uterocervical junction still have decreased cervicovaginal IgA and SC levels. In parallel with this inhibitory effect, estradiol administration stimulated the accumulation of IgA and SC in uterine secretions. These findings indicate that the sex hormones play a role in regulating IgA, IgG and SC content in cervicovaginal secretions. In addition, it suggests that hormonal balance in females may influence the immune response of the reproductive tract to infectious disease.     

Estrogen interconversions in the induced cycle in female rhesus monkeys

To determine the extractions and interconversions of estrone and estradiol across and within the uterus, [3H]estradiol and [14C]estrone were infused at a constant rate in six ovariectomized female rhesus (Macaca mulatta) monkeys. Studies were done on Days 9, 14, and 23 of artificial menstrual cycles induced by the timed insertion and removal of Silastic capsules of estradiol and progesterone. Measurements of estrogen radioactivity were made from peripheral arterial blood and uterine venous blood as well as from endometrial biopsy samples. A significant increase occurred in the conversion of estradiol to estrone measured within the uterus on Day 23 compared to Days 9 and 14. The conversion of estrone to estradiol, measured within the uterus, fell progressively from Day 9 to Day 23, but this decrease was not significant. The extractions and interconversions across the uterus, and the overall interconversions of estrone and estradiol were not significantly different on Days 9, 14, or 23 of the cycle. Thus, we have been able to confirm in vivo the increase in the activity of the 17 beta-hydroxysteroid dehydrogenase, the enzyme responsible for estradiol to estrone interconversions, shown earlier by studies done in vitro. However, the increase in 17 beta-hydroxysteroid activity in the uterus is not reflected in the overall interconversions of estrone and estradiol as reflected by measurements in peripheral arterial blood.