The chicken vitellogenin II gene is flanked by a GATA factor-dependent estrogen response unit

The chicken vitellogenin II (VTGII) gene is flanked by an imperfect estrogen response element (ERE) at -350 and a perfect ERE at -620. In the present study we show that this imperfect ERE lies within an estrogen response unit (ERU) that requires a GATA factor and the estrogen receptor to function as an estrogen-dependent enhancer. We infer that GATA-6 contributes to the estrogen-dependent and liver-specific regulation of the endogenous VTGII gene since this is the predominant GATA factor expressed in adult liver. Our analysis of the VTGII ERU revealed four salient points. First, this ERU is comprised of an ERE and a bank of functionally redundant GATA-binding sites. Second, the GATA-6 transactivation domain is necessary (and sufficient, when tethered near the ERE) to render this ERU functional. Third, ERU enhancer activity is dependent on GATA 6, regardless of whether the resident ERE is imperfect or perfect. Fourth, in contrast to a report that the estrogen receptor antagonizes the activity of another GATA factor (GATA-1), we show that these two factors can function in a synergistic manner within the context of the VTGII ERU.

Effect of estrogen on the expression of galanin mRNA in pituitary tumor-sensitive and tumor-resistant rat strains

The hypothesis that estrogen-induced pituitary tumors are mediated by the neuropeptide galanin was tested using tumor-resistant (Sprague-Dawley; SD) and tumor-sensitive (Fischer 344; F344) rat strains. Diethylstilbestrol (DES) increased expression of galamin mRNA in both strains after 1, 2, and 4 weeks of treatment and doubled pituitary weights in F344 rats while pituitary weights in SD rats were unchanged by DES treatment. In F344 rats, both the expression of galanin mRNA and pituitary weights increased linearly with the length of DES treatment. In SD rats however, despite increasing levels of galanin mRNA, pituitary weights did not increase. These data indicate that galanin gene expression, by itself, is not sufficient to account for increased pituitary growth. However, our data do not rule out the possibility that galanin has an indirect role in promoting pituitary growth.

Lack of activational influence of ovarian hormones on the size of the female rat's corpus callosum

The sex difference in the midsagittal area of the adult rat corpus callosum (CC) has been shown to be mediated, in part, by gonadal steroids in early development, with the sensitive period of hormone action in the female extending at least up to postnatal day 25. Given this prolonged sensitivity, the current study attempted to delineate organizational vs. activational influences of gonadal hormones on the female rat CC. In Experiment 1, callosal size was examined across the estrous cycle at 52 and 90 days of age. In Experiment 2, females were ovariectomized at 78 days and CC parameters assessed at 110 days. Last, in Experiment 3, females were ovariectomized at 78 days and sacrificed at 110 days; in addition, sham females were sacrificed during proestrus or estrus. Neither stage of estrous cycle nor adult ovariectomy affected midsagittal CC size. These results provide evidence for organizational effects of ovarian steroids on the female callosum, with the sensitive period of hormone action ending sometime between days 25 and 78.

Acute immobilization stress and intraventricular injection of CRF suppress naloxone-induced LH release in ovariectomized estrogen-primed rats

The present study was undertaken to evaluate the role and possible interaction of the endogenous opioid peptide (EOP) and corticotropin-releasing factor (CRF) in the acute stress-induced suppression of gonadotropin secretion in ovariectomized estrogen-primed rats. An intravenous (i.v.) injection of naloxone (10 or 20 mg/kg), an EOP antagonist, significantly elevated serum luteinizing hormone (LH) levels within 10 min in non-stressed animals. The naloxone-induced LH release was completely eliminated when tested 30 min after the onset of acute immobilization. In a subsequent study, it was found that suppression of the naloxone-induced LH release occurred as early as 5 min after the stress onset, and was still evident 60 min after the end of a 30-min period of immobilization. The effect of naloxone was restored 3 h after liberation of the animal from the 30-min immobilization. An intraventricular (i.c.v.) injection of CRF (1 or 5 micrograms) also significantly suppressed, in a dose-related manner, the effect of a subsequent i.v. injection of naloxone. However, an i.c.v. injection of alpha-helical CRF(9-41) (25 or 50 micrograms), a CRF antagonist, prior to immobilization, could not interfere with the suppressive effect of stress on naloxone-induced LH release. These results suggest that both acute immobilization stress and CRF can inhibit the LH secretory activity without mediation by EOP neurons. However, the stress-related suppression may involve non-CRF mechanism(s).

Estrogen surge: a regulatory switch for superoxide radical generation at implantation

This study is undertaken to identify the regulatory switch for the activation of superoxide radical generation pathway and repression of superoxide dismutase (SOD) at the time of implantation using estrogen as a control factor and delayed implantation as a model system. The results revealed high SOD activity and negligible oxyradical generation in progesterone-treated animals on day-5 and day-8 (delayed implantation) while an enormous rise in oxyradical generation and an abrupt fall in SOD in animals which received both estrogen and progesterone injections were observed on days 5 and 8 of pregnancy. These results strongly suggest that estrogen regulates superoxide anion radical generation by lowering the SOD activity.

Male reproductive health and environmental xenoestrogens

Male reproductive health has deteriorated in many countries during the last few decades. In the 1990s, declining semen quality has been reported from Belgium, Denmark, France, and Great Britain. The incidence of testicular cancer has increased during the same time incidences of hypospadias and cryptorchidism also appear to be increasing. Similar reproductive problems occur in many wildlife species. There are marked geographic differences in the prevalence of male reproductive disorders. While the reasons for these differences are currently unknown, both clinical and laboratory research suggest that the adverse changes may be inter-related and have a common origin in fetal life or childhood. Exposure of the male fetus to supranormal levels of estrogens, such as diethlylstilbestrol, can result in the above-mentioned reproductive defects. The growing number of reports demonstrating that common environmental contaminants and natural factors possess estrogenic activity presents the working hypothesis that the adverse trends in male reproductive health may be, at least in part, associated with exposure to estrogenic or other hormonally active (e.g., antiandrogenic) environmental chemicals during fetal and childhood development. An extensive research program is needed to understand the extent of the problem, its underlying etiology, and the development of a strategy for prevention and intervention.

Oestrogen as a calcium channel blocker

This paper reviews the evidence for calcium-antagonist properties of oestrogen which may offer long-term protective effects on the cardiovascular system in postmenopausal women. Oestrogen has already been shown to have a beneficial effect on cholesterol metabolism and deposition, thereby inhibiting the formation of atherosclerotic plaque and coronary atheroma. Calcium antagonism, resulting in both acute and chronic modulation of coronary and peripheral vasomotion, is another mechanism by which oestrogens may provide cardiovascular benefits to women, including those with existing cardiovascular disease.

Testosterone enhances whereas estrogen inhibits calcium oxalate stone formation in ethylene glycol treated rats

PURPOSE

The present study was conducted to extend our earlier study on the role of testosterone in the pathogenesis of urolithiasis and to further investigate the influence of sex hormone on the pathogenesis of calcium oxalate stone.

MATERIALS AND METHODS

Adult Sprague-Dawley rats were divided into 9 groups, each containing 10 rats. Two groups of rats were left untreated and served as male and female controls. Another 7 groups of rats were fed a 0.5% ethylene glycol (EG) lithogenic diet for 4 weeks. Among them, 2 groups were male and female rats, 2 groups were castrated, 2 groups were castrated and then were subcutaneously implanted with testosterone, and 1 group of intact female rats was also subcutaneously implanted with testosterone. The stone and crystal deposits were examined by infrared spectrometer and polarizing and scanning electron microscope, respectively. Serum testosterone, creatinine and electrolytes and the renal excretion of, oxalate, citrate and creatinine were determined.

RESULTS

Subcutaneous implantation of exogenous testosterone restored calcium oxalate stone formation in castrated, EG-treated male rats (80%) and enhanced urolithiasis in castrated female rats receiving EG (40%). However, the testosterone effect was less striking in intact female rats fed EG (10%).

CONCLUSIONS

These data suggest that testosterone can promote and estrogen may inhibit calcium oxalate stone formation in EG-treated rats.

Physiological dose of estrogen regulates extrathymic T cells in female mice

Bilateral ovariectomy was performed in female C57BL/6 mice to investigate whether extrathymic T cells in the liver are regulated by physiological doses of estrogen or progesterone. Extrathymic T cells were identified using a two-color immunofluorescence test for CD3 and interleukin-2 receptor beta-chain (IL-2R beta) antigens. The T cells were identified as intermediate CD3+ cells with a high expression of IL-2R beta. It was further demonstrated that the proportion and number of intermediate CD3+ cells decreased in response to ovariectomy, an effect that was countered by estrogen administration. These results suggest that the activation of extrathymic T cells may be regulated by physiological levels of estrogen.

Differential effects of progestins and estrogens on long control regions of human papillomavirus types 16 and 18

We have studied effects of a series of progestins and estrogens on regulation of human papillomavirus (HPV) types 16 and 18 gene expression via long control region (LCR), using a transient expression assay which represented the episomal state of HPVs in precancerous lesions. Results showed that HPV gene expression induced by these steroid analogs were diverse. Gene expression via HPV16-LCR was upregulated 2-3 fold under treatment with 10(-7) M estriol, 17 beta-estradiol, and several progestins including pregnenolone, 17 alpha-hydroxy-progesterone, norethynodrel and cyproterone acetate. However, transcription via HPV18-LCR was not or weakly stimulated by these analogs. Our results can divide these analogs into HPV-enhancing and HPV-nonenhancing groups and accordingly impact the relative risk of individual oral contraceptive ingredient in cervical carcinogenesis.

Progesterone regulates gamma-aminobutyric acid B (GABAB) receptors in the neocortex of female rats

After discovering that binding to GABAB receptors in rat neocortex varied as a function of the estrous cycle of the rat, we asked whether either or both of the major ovarian steroids could affect binding to GABAB receptors in the same way, namely, by regulating the apparent density (Bmax) of GABAB receptors. We report here that in ovariectomized rats, subcutaneous injection of progesterone alone, without the necessity of estrogen priming, increased the Bmax of baclofen binding to GABAB receptors in the neocortex. Radioimmunoassay of plasma progesterone before and after progesterone injections revealed that plasma progesterone levels similar to those reached during the progesterone surge in proestrus were associated with increased baclofen binding. The effect of progesterone upon baclofen binding was evident 4 h but not 1 h following progesterone treatment. There was some specificity with respect to the cortical receptors affected by progesterone in that under our conditions, progesterone did not increase agonist binding to 5-HT1A or GABAA receptors. We interpret our results to indicate that progesterone variation during the estrous cycle could be responsible for a component of the regulation of GABAB receptors that occurs in neocortex during the estrous cycle of the rat.

Different effects of estrogen and progesterone on experimental atherosclerosis in female versus male rabbits. Quantification of cellular proliferation by bromodeoxyuridine

BACKGROUND

The aim of the present study was to compare the effect of estrogen and progesterone on the development of experimental atherosclerosis in female versus male rabbits to assess possible sex-specific differences.

METHODS AND RESULTS

A total of 32 female and 32 male New Zealand White rabbits were ovariectomized or castrated. In addition to a 0.5% cholesterol diet, the rabbits received estradiol alone (1 mg/kg body wt [BW] per week), progesterone alone (25 mg/kg BW per week), or combined estradiol-progesterone in these dosages during 12 weeks. Ovariectomized female and castrated male rabbits served as control groups without hormone treatment. Before excision of the vessels, bromodeoxyuridine labeling was performed to determine the extent of cellular proliferation in the atherosclerotic lesions. The aortic arch was analyzed immunohistologically and morphometrically. An inhibitory effect of estrogen on intimal plaque size was found in female rabbits compared with the ovariectomized control group (0.7 +/- 0.5 versus 3.7 +/- 2.5 mm2, P < .002; proliferating cells, 3.1 +/- 1.8% versus 8.5 +/- 2.6%, P < .002). In combination with progesterone, however, estrogen was not able to reduce intimal plaque size or cellular proliferation. In contrast, estradiol in castrated male rabbits was not associated with an inhibitory effect on cellular proliferation or intimal thickening compared with controls (estrogen treatment, 7.6 +/- 2.1% proliferating cells and 2.8 +/- 1.0 mm2 neointima; control group, 7.2 +/- 2.1% cellular proliferation and 2.9 +/- 1.2 mm2 intimal thickening).

CONCLUSIONS

Our data suggest that the atheroprotective effect of estrogen is probably due to a mechanism that is present in female rabbits only.

Maternity and medicinal plants in Vanuatu. II. Pharmacological screening of five selected species

An ethnobotanical survey of reproductive behaviour in Vanuatu and an extensive literature search have resulted in the selection of five plant species (Asplenium nidus, Hemigraphis reptans, Homalanthus nutans, Dysoxylum gaudichaudianum, Pemphis acidula) used for purposes relating to human reproduction in that country. Preliminary screening was carried out to identify possible oestrogenic activity in these species as well as their effects on isolated rat uteri. Dysoxylum gaudichaudianum presented the most interest due to its spasmolytic activity (musculotropic type). Its mode of action has yet to be determined.

Gastric emptying and gastric-intestinal transit in rats with varying ovarian hormone status

Basal and stimulated gastric emptying and gastrointestinal (GI) transit in rats of varying ovarian hormone status were compared to define direct ovarian hormone effects on GI function. Thyrotropin-releasing hormone (TRH) was used to evoke vagal GI motility stimulation. Adult female Sprague-Dawley rats were anesthetized (equithesin), ovariectomized, and implanted with 28-day estrogen (E), progesterone, (P), E+P, or vehicle (V) pellets; males were also studied. On Day 26, fasted rats were anesthetized (urethane). Nonabsorbable 14C polyethylene glycol-4000 in saline was gavaged at t = 0. At t = 5 minutes, TRH or saline was administered intracisternally. At t = 30 or 60 minutes, the GI tract was removed, ligated, sectioned, and counted. Gastric emptying was expressed as 100% minus the ratio of gastric to total counts; GI transit was expressed as geometric center of radioactivity. In saline-treated rats, gastric emptying and GI transit at 60 minutes varied significantly among ovarian hormone-treated groups, with E lower and males elevated. TRH-significantly increased both variables at both times in all groups. Results are consistent with acceleration of upper GI function in the absence of E, possibly contributing to GI symptoms during menopause and late luteal phase.

[Change of serum amyloid P component concentrations in women]

Serum amyloid P component (SAP) is a glycoprotein which was shown to be deposited in periarterial tissues and the glomerular basement membrane. It plays a part in aging, and the onset of amyloidosis and Alzheimer's disease. In order to investigate the effects of sex steroids on the SAP level in menopausal women, SAP was purified. Anti-SAP was raised through the immunization of rabbits. The SAP level was assayed by micro single radial immunodiffusion. The SAP levels increased with aging from 1.1 +/- 0.8mg/dl (mean +/- S.D.) to 5.08 +/- 1.31mg/dl in women. And the SAP level in males was significantly higher in the 15 to 50 year age group than in females of similar ages (p < 0.001). And in the menstrual cycle, the SAP concentrations were significantly higher in the menstrual period (p < 0.05). During hormonal therapy in climacteric women, the SAP levels decreased significantly (p < 0.001) after Premarin treatment (from 5.66 +/- 1.45mg/dl to 4.15 +/- 0.94 mg/dl) and increased (p < 0.001) after dehydroepiandrosterone therapy (from 4.00 +/- 0.74mg/dl to 6.07 +/- 1.14mg/dl). From these findings, the SAP levels in human were concluded to be age dependently increased, and higher in the menstrual period. And it is suggested that a sex difference in SAP is concerned with the effect of estrogen fluctuation.

Estrogen-induced cell transformation and DNA adduct formation in cultured Syrian hamster embryo cells

To study the possible involvement of DNA damage in cell transformation induced by estrogens, we examined whether DNA adduct formation is elicited in cultured Syrian hamster embryo (SHE) cells treated with estrogens and their derivatives by means of the 32P-postlabeling assay. Morphological transformation of the cells was induced by treatment with diethylstilbestrol (DES) at 1-10 micrograms/mL for 24 h but not by treatment with its derivatives trans, trans-dienestrol (alpha-DIES) or cis, cis-dienestrol (beta-DIES) at 1-10 micrograms/mL for 24 h. Similarly, DNA adduct formation was elicited by exposure of SHE cells to DES at 1-10 micrograms/mL for 24 h but not by either alpha-DIES or beta-DIES. Treatment of SHE cells with DES at 1-10 micrograms/mL for 2 h in the presence of exogenous metabolic activation with rat liver post-mitochondrial supernatant enhanced morphological transformation in a dose-dependent manner. Our previous studies have demonstrated that exposure of SHE cells to DES under the same conditions with exogenous metabolic activation induces somatic mutations at the Na+/K+ ATPase locus. Therefore, we examined whether with exogenous metabolic activation DES induced DNA adduct formation in SHE cells. DNA adducts were not detected when SHE cells were treated with DES at 1-10 micrograms/mL for 2 h in the presence of exogenous metabolic activation. Treatment with 17 beta-estradiol (E2), 2-hydroxyestradiol (2-OH E2), or 4-hydroxyestradiol (4-OH E2) at 1 microgram/mL for 24 h induced DNA adduct formation in the cells, in parallel with the induction of cell transformation. The rank order of DNA adduct formation was 4-OH E2 > 2-OH E2 > E2. The results indicate that estrogens induce DNA adduct formation in cultured SHE cells, but the induction may not be the only mechanism relevant to the initiation of cell transformation.

Immunohistochemical studies on the expression and estrogen dependency of EGF and its receptor and C-fos proto-oncogene in the uterus and vagina of normal and neonatally estrogen-treated mice

BACKGROUND

The final target cell response to estrogen is dependent not only on the estrogen receptor, but also on autocrine/paracrine interactions with growth factors (e.g., EGF) and proto-oncogenes (e.g., c-fos). Because neonatal estrogen treatment results in permanent changes in the female mouse genital tract (permanent vaginal cornification, cervical adenosis and tumors, changed growth control mechanisms in uterus), it was of interest to study possible acute and permanent effects of such treatment on distribution and levels of EGF, its receptor (EGF-r), and c-fos and to relate such changes to morphological development and appearance of epithelial abnormalities.

METHODS

Immunohistochemical techniques using frozen sections from the uterus and vagina of neonatal and adult (ovariectomized, estradiol-treated) females, treated with olive oil or diethylstilbestrol in neonatal life.

RESULTS

A difference in stromal-epithelial distribution of EGF was demonstrated with respect to region studied (uterus, vagina) and age (neonatal, adult). EGF was localized mainly in the uterine stroma but in both vaginal epithelium and stroma (with a different pattern compared to uterus). In neonatal females, EGF occurred in both tissue components in both regions, and the distribution pattern was quite different from that in adult females. The EGF level was increased by estrogen in adult but not in neonatal females. EGF-r and c-fos occurred in both uterine epithelium and stroma and in the vaginal epithelium; levels and distribution pattern were affected by estrogen. Neonatal estrogen treatment increased the levels of uterine EGF and c-fos in adult life.

CONCLUSIONS

There are distinct developmental changes in the distribution and estrogen sensitivity of EGF. Only further studies can prove or disprove the association between the earlier reported disturbed growth control mechanisms in the uterus of adult but neonatally estrogen-treated females and the increased levels of uterine EGF and c-fos. The present results do not seem to explain mechanisms involved in the origin of neonatally estrogen-induced cervicovaginal epithelial abnormalities, nor do they explain the earlier described difference in estrogen-induced proliferative response between the uterine cervix and uterus proper.

Regulation and localization of cellular retinol-binding protein, retinol-binding protein, cellular retinoic acid-binding protein (CRABP), and CRABP II in the uterus of the pseudopregnant rat

Three members of the superfamily of small intracellular carrier proteins for lipophilic compounds are cellular retinol-binding protein (CRBP), cellular retinoic acid-binding protein (CRABP), and cellular retinoic acid-binding protein II (CRABP II). Retinol-binding protein (RBP) is a secreted protein that binds and solubilizes vitamin A for transport. Here we report the coordinate regulation of RBP, CRBP, retinol, and CRABP II in the uterus of the pseudopregnant rat. In the proliferative stage of the uterus, which was induced by PMSG, the messenger RNA (mRNA) and protein levels of RBP and CRBP as well as retinol levels significantly decreased. This pattern of regulation was duplicated by estrogen treatment of prepubertal rats. In addition, CRBP and RBP were found to be colocalized to the stromal cells of the rat uterus by immunohistochemistry and [35S]methionine-labeled affinity chromatography, respectively, and were not detected in other cell populations. CRABP II mRNA and protein expression were up-regulated in the proliferative phase of the uterus brought about by PMSG injection or, alternatively, by estrogen treatment of prepubertal rats. CRABP II was localized to the surface epithelium, but was not seen elsewhere, including glandular epithelium. Immunolocalization of CRABP showed staining of the smooth muscle and stromal cells of the uterus. The appearance of CRABP in the stroma of the uterus also correlated with PMSG injection as well as estrogen treatment. Although estrogen induced the appearance of both binding proteins, CRABP mRNA levels peaked between 4-24 h postestrogen treatment, whereas CRABP II mRNA levels continued to rise 48 h postestrogen treatment. These data demonstrate an important role for vitamin A and retinoid-binding proteins in rat uterine physiology.

Effects of androgens on haemostasis

Androgen deficiency is associated with an increased incidence of cardiovascular disease. There is evidence that thromboembolic disease as well as myocardial ifarction in hypogonadic males are mediated by low baseline fibrinolytic activity. Hypogonadism in males is associated with an enhancement of fibrinolytic inhibition via increased synthesis of the plasminogen activator inhibitor PAI 1. On the other hand, stanozolol and danazol reduce PAI 1 and are associated with increased fibrinolytic activity. However, in male abusers of anabolic steroids the net effect on the haemostatic system may change from anti- to prothrombotic; there appears to be an individual threshold dose above which thrombogenic effects on platelets and vasomotion may overcome the profibrinolytic effects on PAI 1. There are numerous reports on weight-lifters dying of atherothrombotic ischemic heart disease while abusing anabolic steroids. Androgens are known to have profound effects on carbohydrate and lipid metabolism. In fact, much of the individual inconsistency of the effects of androgens on fibrinolytic and haemostatic activity appears to be based on the close interrelationship of these metabolic systems. Androgens may have unfavourable effects on the HDL/LDL cholesterol ratio, on triglyceride levels and on the insulin/insulin-like growth factor 1 (IGF 1) system. Hypertriglyceridemia as well as insulin resistance are both associated with low fibrinolytic activity and increased PAI 1 levels. On the other hand, lipoprotein(a), a recently acknowledged independent risk factor of CVD was shown to respond favourable to androgen treatment, in men as well as in women. In women, agonistic as well as antagonistic effects of estrogens and progestins need to be taken into account. In fact, estradiol may modulate testosterone effects on haemostasis. Androgen medication in premenopausal women, such as danazol, was found to reduce PAI 1 suggesting an improvement of the fibrinolytic activity. Also, in hormone replacement therapy (HRT) androgenic progestins or complex compounds with androgenic effects are associated with a marked reduction of PAI 1 and an improvement of fibrinolytic activity. Further improvement of fibrinolytic activity may be associated with the marked decrease of lipoprotein (a) (Lp(a)) in women on androgenic HRT. However, little is known on the interrelationship of estrogens, 19-nortestosterone or progesterone derivatives and testosterone. an interrelationship that may have substantial impact on the metabolic and particularly haemostatic net effects of a preparation. In summary, information on the effects of androgens on haemostasis is limited and may be particularly incomplete due to the fact that interaction with other sex steroids appears to be an important confounder. In any case, there are numerous effects of synthetic androgens on the synthesis and release of haemostatic factors, namely an increase of the inhibitors of coagulation and a decrease of the inhibitor of the fibrinolytic system. However, the use of androgens in patients with congenital deficiencies of these coagulation factors or previous events of cardiovascular disease has yielded disappointing results. On the other hand, particularly the reduction of fibrinolytic inhibition (PAI 1) and Lp(a) were considered favourable effects of androgens with regard to the risk of cardiovascular disease. Differences between preparations with pronounced androgenic versus antiandrogenic effects and the effect of combined preparations need to be studied in much more detail. The profibrinolytic effects of androgens may be of particular interest with regard to favourable effects of HRT on cardiovascular disease.

Estrogen increases GAP-43 (neuromodulin) mRNA in the preoptic area of aged rats

Estrogen has been shown to affect the growth, differentiation, and survival of brain neurons and to modulate processes involved in synapse formation and connectivity. These trophic effects are diminished with aging as secretion of estrogen declines. The growth associated protein GAP-43 is found concentrated in axonal growth cones and is implicated in neuronal growth and regeneration. Previous studies have established that expression of GAP-43 can be modulated by estrogen in the preoptic area of developing and adult rat brain. This study was undertaken to determine whether this estrogenic regulation of GAP-43 mRNA is retained in aged rat brain. Young (3 months) and aged (24 months) rats were ovariectomized to remove endogenous estrogen and GAP-43 mRNA in the preoptic area was evaluated using in situ hybridization to compare estrogen and vehicle treatments between age groups. The results demonstrate an age-related decline in GAP-43 mRNA hybridization signal that can be restored to levels comparable to that seen in young animals with estrogen treatment.

Influence of oestrogens on muscarinic receptor density and contractile response in the guinea-pig uterus

The objective of this study was to investigate the contractile response in vitro of uterine and myometrial strips from control and oestrogen-treated guinea-pigs to carbachol. In addition, the muscarinic receptor parameters in subcellular preparations from the myometrium of the same animals were evaluated. Strips of guinea-pig uterus contract in response to carbachol in a concentration dependent manner and the effect of carbachol is independent of the presence of an intact endometrium. However, treatment with oestrogen reduces the response to carbachol, when expressed with respect to the effect of KCl. Measurement of the specific binding of [3H]quinuclidinyl benzylate ([3H]QNB) to myometrial membranes from control and oestradiol-treated immature guinea-pigs showed that oestradiol significantly decreased the number of specific binding sites of [3H]QNB, but did not change the apparent affinity of specific [3H]QNB binding. Moreover, the apparent affinity constants for the different antagonists showed a close similarity to those obtained at muscarinic receptors present in the myometrium from control and oestradiol-treated guinea-pigs.

Regulation of steroid glucuronosyltransferase activities and transcripts by androgen in the human prostatic cancer LNCaP cell line

Although much attention has been focused on the synthesis of dihydrotestosterone (DHT), the inactivation and elimination of active androgens can also be key points in regulating androgen levels in tissues such as the prostate. Recent data suggest that 5alpha-reduced C19 steroids can be converted to glucuronide derivatives in the human prostate, leading to complete inactivation of these steroids. These results are supported by the recent finding of at least two steroid uridine diphosphoglucuronosyltransferase (UGT) enzymes in the prostate as well as in the human prostatic cancer LNCaP cell line. To ascertain the role of UGTs in regulating active steroid levels, we investigated the modulation of UGT levels in response to steroid treatments in LNCaP cells. Results demonstrate the down-regulation of UGT activities specific for 3-hydroxysteroids and 17-hydroxy-steroids after treatment with androgens and estrogens. Treating the cells with DHT or R1881 for 7 days inhibited UGT activity by 60%; however, 80% of the total activity was recovered after 5 days in the absence of the androgens. The inhibition of UGT activities by DHT and R1881 increases with the time of incubation and with increasing concentrations of the androgens used. The decrease in UGT enzyme activity occurred in parallel with a diminution in UGT transcript levels, as observed in Northern blot analyses. A correlation between the effect of steroids on the androgen-dependent growth response of LNCaP cells, the secretion of prostate-specific antigen, and the inhibition of UGT activities was clearly demonstrated, which implicates the androgen signaling pathway. Treating cells with Casodex, an androgen antagonist that binds the mutated androgen receptor expressed in LNCaP cells, partially blocked the androgen- and estrogen-induced decrease in UGT activity, suggesting that the regulation of UGT levels involves the androgen receptor. In addition to the formation of DHT, the inactivation of steroids by glucuronidation, which is regulated by steroids themselves, is an important mechanism controlling the level of androgens in the prostate.

Analysis of the role of v-rel in transcriptional regulation of high mobility group 14

The oncogene, v-rel is a member of the rel/NF-kappaB family of transcription factors. It causes a rapidly fatal lymphoma in young chicks and is capable of transforming both fibroblasts and primitive hematopoietic cells in culture. To understand the role of v-rel in transformation we constructed an inducible form of v-rel and used it to identify potential cellular target genes for v-rel regulation. In this paper we show that High Mobility Group Protein 14 (HMG 14) is expressed in a wide variety of v-rel transformed cell types. In addition we show that v-rel participates in the transcriptional regulation of HMG 14 and that extracts from v-relER cells interact with the HMG 14 promoter. These experiments suggest a role for v-rel in the regulation of a unique gene whose protein product may influence gene transcription in a global fashion.

Raloxifene, tamoxifen, nafoxidine, or estrogen effects on reproductive and nonreproductive tissues in ovariectomized rats

For the first time, four well-characterized compounds from four distinct chemical classes were directly compared for efficacy and potency in hone, uteri, lipids, and adipose tissues in an ovariectomized model with 6 month old rats. Five weeks of oral dosing confirmed that ethynyl estradiol, tamoxifen, and raloxifene are potent inhibitors of the loss in volumetric bone mineral density (BMD, mg/cc) induced by ovariectomy, as measured by computed tomography. In the metaphysis of distal femora from ovariectomized rats, analysis showed a significant 12-20% decrease (P< 0.01) in the BMD. Linear regression analysis was used to calculate half-maximal efficacious doses for ethynyl estradiol ED(50) =0.04mg /kg, which was threefold more potent than tamoxifen, which in turn was threefold more potent than raloxifene, which was more efficacious than nafoxidine. In the uterus, raloxifene had minimal effects on the endometrium and smaller effects on uterine eosinophil peroxidase activity than nafoxidine, tamoxifen, or estrogen, respectively. Estrogen was the most potent in reducing cholesterol levels in ovariectomized rats, whereas tamoxifen and nafoxidine were more effective than raloxifene in blocking gain in body weight. Distinct compounds had advantages in the management of bone, uterine, serum cholesterol, and adipose tissues after ovariectomy. The distinct pattern of pharmacological effects may be best understood in terms of their respective chemical structure, specifically estrogens, benzothiophenes (raloxifene), dihydronapthylenes (nafoxidine), and triphenylethylenes (tamoxifen). These data point to advantages of separate compounds in the management of bone, uterine, serum cholesterol, and adipose tissues after estrogen deficiency, and show that the benzothiophene raloxifene has potentially important advantages over estrogen, tamoxifen, or nafoxidine in the uterus.