Progesterone and estradiol interaction in the regulation of rat uterine weight and estrogen receptor concentration

Changes in sex hormones and their interactions are related to pain perception between different menstrual subphases

Whether sex hormones are related to pain perception across the menstrual cycle is unclear. We examined changes in experimental pain perception in healthy young females between the early to midfollicular subphase (emF) and the midluteal subphase (mL) and explored the role of sex hormones. Sixty-six participants were involved in the study. We tested pressure pain, cold pain, ischemic pain, and needle pain, while at the same time we measured sex hormones levels in two menstrual subphases. Only the right ulna pressure test showed a significant reduction in pain threshold (PPTh3) during the mL. The absolute change of PPTh3 (PPTh3mL - PPTh3emF) was related to the absolute change of prolactin. The relative change of the range of pain tolerance for pressure pain of the right ulna (RPT3rc) was related to the relative change of progesterone (Prc) and estradiol (E2rc) levels, and the interaction effects showed that at Prc ≤ 30, E2rc was positively correlated with RPT3rc. The same, the relative change of pressure pain tolerance of the pulp of the middle finger on the right hand (PPTo4rc) was related to E2rc and Prc, and the results of the interaction between E2rc and Prc suggest that when E2rc is ≤0.8, Prc is positively correlated with PPTo4rc. Two different formulas were applied in this study and showed inconsistent results. Most pain tests showed no difference between the two subphases of the menstrual cycle. Only the relative changes of the PPTo4 and RPT3 are related to the E2rc and Prc, respectively, between menstrual subphases in an interactive way in healthy young women.

Topical estrogen application promotes cutaneous wound healing in db/db female mice with type 2 diabetes

Female sex hormones are beneficial effects for wound healing. However, till date, whether topical estrogen application can promote cutaneous wound healing in diabetes remains unclear. Therefore, the present study aimed to validate the effect of topical estrogen application on cutaneous wound healing in a type 2 diabetes db/db mice model. In total, 22 db/db female mice with type 2 diabetes and eight C57BL/6J female mice were subjected to two full-thickness wound injuries. The mice were divided into the db/db, db/db + estrogen, db/db + vehicle, and wild type (WT) groups. Wound healing was assessed until day 14. The db/db group had a significantly high wound area ratio (wound area/initial wound area) on days 3–14 and a significantly low re-epithelialization ratio on days 7 and 14. Moreover, their angiogenesis ratio was significantly low on day 7 and high on day 14. In contrast, compared with the db/db group, the db/db + estrogen group had a significantly lower wound area ratio on days 1–14 and angiogenesis ratio on day 14, thereby indicating early withdrawal of new blood vessels, as well as a significantly higher re-epithelialization ratio on days 7 and 14 and Ym1⁺ M2 macrophage/macrophage ratio on day 7. Moreover, microarray analysis showed that the top 10 upregulated or downregulated genes in the db/db group were reversed by estrogen treatment, particularly on day 14, in comparison with the WT group. Thus, topical estrogen application reduced the wound area, promoted re-epithelialization and angiogenesis, and increased the number of M2 macrophages in mice with type 2 diabetes. Furthermore, it improved the differential regulation of genes in db/db mice. Therefore, such treatment can enhance cutaneous wound healing in female mice with type 2 diabetes.

Primary endometrial 3D co-cultures: A comparison between human and rat endometrium

Human and rat reproductive systems differ significantly with respect to hormonal cyclicity and endometrial cell behavior. However, species-differences in endometrial cell responses upon hormonal stimulation and exposure to potentially toxic compounds are poorly characterized. In this study, human and rat endometrial hormonal responses were assessed in vitro using a 3D co-culture model of primary human and rat endometrial cells. The models were exposed to the aryl hydrocarbon receptor (AHR) ligands 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), laquinimod, and its AHR active metabolite DELAQ. In both the human and rat endometrial models, estrogen receptor and progesterone receptor gene expression was modulated by the hormonal treatments, comparable to the in vivo situation. AHR gene expression in the human endometrial model did not change when exposed to hormones. In contrast, AHR expression decreased 2-fold in the rat model when exposed to predominantly progesterone, which resulted in a 2.8-fold attenuation of gene expression induction of cytochrome P450 1A1 (CYP1A1) by TCDD. TCDD and DELAQ, but not laquinimod, concentration-dependently induced CYP1A1 gene expression in both human and rat endometrial models. Interestingly, the relative degree of DELAQ to induce CYP1A1 was higher than that of TCDD in the human model, while it was lower in the rat model. These data clearly show species-differences in response to hormones and AHR ligands between human and rat endometrial cells in vitro, which might greatly affect the applicability of the rat as translational model for human endometrial effects. This warrants further development of human relevant, endometrium-specific test methods for risk assessment purposes.

Combined oral contraceptive in female mice causes hyperinsulinemia due to β-cell hypersecretion and reduction in insulin clearance

Oral contraception is the most commonly used interventional method in the world. However, several women employ the continuous use of these hormones to avoid pre- and menstruation discomforts. Some studies indicate that oral contraceptives are associated with disturbances in glycemia and the effects of the use of a continuous regime are poorly elucidated. Herein, we evaluated the effects of the continuous administration of a combined oral contraceptive (COC) composed by ethinyl estradiol (EE) and drospirenone (DRSP) on glucose homeostasis in female mice. Adult Swiss mice received 0.6 μg EE and 60 μg DRSP (COC group) or vehicle [control (CTL)] daily by gavage for 35 days. COC treatment had no effect on body weight or adiposity, but increased uterus weight and induced hepatomegaly. Importantly, COC females displayed normal glycemia and glucose tolerance, but hyperinsulinemia and lower plasma C-peptide/insulin ratio, indicating reduced insulin clearance. Furthermore, COC mice displayed reduced protein content of the β subunit of the insulin receptor (IRβ) in the liver. Additionally, pancreatic islets isolated from COC mice secreted more insulin in response to increasing glucose concentrations. This effect was associated with the activity of steroid hormones, since INS-1E cells incubated with EE plus DRSP also secreted more insulin. Therefore, we provide the first evidence that the continuous administration of EE and DRSP lead to hyperinsulinemia, due to enhancement of insulin secretion and the reduction of insulin degradation, which possibly lead to the down-regulation of hepatic IRβ. These findings suggest that the continuous administration of COC could cause insulin resistance with the prolongation of treatment.

Comparative effect of the aqueous extracts of Aloe buettneri, Dicliptera verticillata, Hibiscus macranthus and Justicia insularis on the sexual maturation of pregnant mare serum gonadotrophin-primed immature female rats

Background

Aloe buettneri, Dicliptera verticillata, Hibiscus macranthus and Justicia insularis are medicinal plants used in the western region of Cameroon to cure infertility among women. This experiment was designed to compare the effect of the aqueous extracts of A. buettneri (AAB), D. verticillata (ADV), H. macranthus (AHM), J. insularis (AJI), their mixture (AME) and the extract obtained from the mixture of their powders (AMP) on some parameters of reproduction.

Materials and methods

High-performance liquid chromatography coupled with the mass spectrometry (HPLC-MS) was used to detect the constituents of different extracts. The extracts (50 mg/kg) were administered to PMSG-primed immature rats (10 rats/group) for 5 days. At the end of the treatment, five animals of each group were sacrificed and various biological markers of reproduction were recorded. The remaining animals were injected with 10 IU of human chorionic gonadotropin (hCG) sacrificed 48 h later and the number of ovarian hemorrhagic points counted.

Results

Fifty-four compounds were found in the various extracts with 37 individually distributed among them and the remaining found in at least two extracts. As compared with the control, the AMP and AJI increased serum estradiol level by 2.36 and 2.23 times, respectively. The AMP was the only extract whose administration resulted in a significant increase (p<0.001) in the serum levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH). Compared with the other extract-treated rats, the AMP-treated rats showed the highest number of hemorrhagic points.

Conclusions

These findings provided evidence on the synergistic effect of compounds present in these plant extracts and supported the usage of the mixture in traditional medicine.

Tributyltin chloride leads to adiposity and impairs metabolic functions in the rat liver and pancreas

Tributyltin chloride (TBT) is an environmental contaminant used in antifouling paints of boats. Endocrine disruptor effects of TBT are well established in animal models. However, the adverse effects on metabolism are less well understood. The toxicity of TBT in the white adipose tissue (WAT), liver and pancreas of female rats were assessed. Animals were divided into control and TBT (0.1 μg/kg/day) groups. TBT induced an increase in the body weight of the rats by the 15th day of oral exposure. The weight gain was associated with high parametrial (PR) and retroperitoneal (RP) WAT weights. TBT-treatment increased the adiposity, inflammation and expression of ERα and PPARγ proteins in both RP and PR WAT. In 3T3-L1 cells, estrogen treatment reduced lipid droplets accumulation, however increased the ERα protein expression. In contrast, TBT-treatment increased the lipid accumulation and reduced the ERα expression. WAT metabolic changes led to hepatic inflammation, lipid accumulation, increase of PPARγ and reduction of ERα protein expression. Accordingly, there were increases in the glucose tolerance and insulin sensitivity tests with increases in the number of pancreatic islets and insulin levels. These findings suggest that TBT leads to adiposity in WAT specifically, impairing the metabolic functions of the liver and pancreas.

Preclinical pharmacological profile of nomegestrol acetate, a synthetic 19-nor-progesterone derivative

BACKGROUND

Nomegestrol acetate (NOMAC), a synthetic progestogen derived from 19-nor-progesterone, recently completed clinical trials for use with 17beta-estradiol in a new monophasic combined oral contraceptive. In this review, published as well as previously unpublished preclinical studies that detail the effects of NOMAC on estrogenic, progestogenic, and androgenic systems, as well as mineralocorticoid, glucocorticoid, bone, and metabolic indices are described.

METHODS

In vitro assays to determine NOMAC structure-activity relationships used tissue derived from rat uteri. Transactivation profiles were performed using Chinese hamster ovary (CHO) cells transfected with cDNAs encoding human steroid receptors. Estrogenic and anti-estrogenic activities were monitored in vivo in rats as well as in vitro in human breast cancer cells. Standard in vivo techniques were used in rats to determine progestational activity; antigonadotropic, androgenic, mineralocorticoid, and glucocorticoid activities; as well as effects on bone and other metabolic indices. Ovulation inhibition was monitored in rats and primates. NOMAC's effects on cardiovascular systems were determined in dogs and primates.

RESULTS

NOMAC was without significant agonistic or antagonistic activity for estrogen receptor alpha or beta in vitro, and inhibited ovulation in rats and monkeys (2.5 mg/kg and 1 mg/kg, respectively). NOMAC lacked androgenic, antimineralocorticoid, glucocorticoid, and metabolic activity and exhibited moderate anti-androgenic activity in rats. NOMAC did not affect bone mineral density (BMD) in rats or hemodynamic and electrophysiologic parameters in dogs and primates.

CONCLUSIONS

NOMAC is a selective progestogen structurally similar to progesterone that has modest anti-androgenic activity and does not affect lipid or carbohydrate metabolism, BMD, or many cardiovascular parameters in selected animal models.

Reproductive consequences of developmental phytoestrogen exposure

Phytoestrogens, estrogenic compounds derived from plants, are ubiquitous in human and animal diets. These chemicals are generally much less potent than estradiol but act via similar mechanisms. The most common source of phytoestrogen exposure to humans is soybean-derived foods that are rich in the isoflavones genistein and daidzein. These isoflavones are also found at relatively high levels in soy-based infant formulas. Phytoestrogens have been promoted as healthy alternatives to synthetic estrogens and are found in many dietary supplements. The aim of this review is to examine the evidence that phytoestrogen exposure, particularly in the developmentally sensitive periods of life, has consequences for future reproductive health.

Effects of progesterone treatment on expression of genes involved in uterine quiescence

An important action of progesterone during pregnancy is to maintain the uterus in a quiescent state and thereby prevent preterm labor. The causes of preterm labor are not well understood, so progesterone action on the myometrium can provide clues about the processes that keep the uterus from contracting prematurely. Accordingly, we have carried out Affymetrix GeneChip analysis of progesterone effects on gene expression in immortalized human myometrial cells cultured from a patient near the end of pregnancy. Progesterone appears to inhibit uterine excitability by a number of mechanisms, including increased expression of calcium and voltage-operated K(+) channels, which dampens the electrical activity of the myometrial cell, downregulation of agents, and receptors involved in myometrial contraction, reduction in cell signal components that lead to increased intracellular Ca(2+) concentrations in response to contractile stimuli, and downregulation of proteins involved in the cross-linking of actin and myosin filaments to produce uterine contractions.

Developmental and Reproductive Effects of SE5-OH: An Equol-Rich Soy-Based Ingredient

Consumption of the isoflavones daidzein, genistein, glycitein, and their structural analogues is generally considered beneficial to human health. Equol is not found in soy, but is converted from daidzein by human gut bacterial flora. Research indicates that between 30-50% of the population is capable of converting daidzein to equol; therefore, there has been recent development of a new equol-rich functional food that relies on bacterial conversion of daidzein to equol under strictly controlled conditions. Therefore, a new equol-rich soy product (SE5-OH) has been developed, based on the bacterial conversion of daidzein; and its reproductive and developmental toxicity has been evaluated in a two-generation study and a developmental toxicity study with Sprague-Dawley rats at dose levels of 200, 1000, and 2000 mg/kg/day by gavage. SE5-OH contains approximately 0.65% equol, 0.024% daidzein, 0.022% genistein, and 0.30% glycitein. From the reproductive study, the no-observed-adverse-effect-level (NOAEL) for SE5-OH determined for both male and female rats is 1000 mg/kg/day (6.5 mg equol/kg/day). In the developmental toxicity phase of the study, no effects by SE5-OH were found in the embryo-fetus at any of the doses tested. The NOAEL for developmental effects of SE5-OH is 2000 mg/kg/day (13 mg equol/kg/day).

Endocrinological properties of two novel nonsteroidal progesterone receptor modulators, CP8816 and CP8863

We have isolated PF1092A, B, and C, novel nonsteroidal progesterone ligands with preferential affinity for the progesterone receptor, from fermentation broth of a fungus [Tabata Y, Miike N, Hatsu M, Kurata Y, Yaguchi T, Someya A, Miyadoh S, Hoshiko S, Tsuruoka T, and Omoto S (1997) J Antibiot 50:304-308; Tabata Y, Hatsu M, Kurata Y, Miyajima K, Tani M, Sasaki T, Kodama Y, Tsuruoka T, and Omoto S (1997) J Antibiot 50:309-313]. The original skeleton of PF1092, tetrahydronaphthofuranone, was modified synthetically to produce a new skeleton, tetrahydrobenzindrone, and in the present study, biological activities of two derivatives, CP8816 [(4aR,5R,6R,7R)-6-(N,N-dimethylaminocarbonyl)oxy-7-methoxy-4a,5,6,7-tetrahydro-1,3,4a,5-tetramethylbenz[f]indol-2(4H)-one] and CP8863 [(4aR,5R,6R,7R)-7-hydroxy-6-(N-methylcarbamoyl)oxy-4a,5,6,7-tetrahydro-1,3,4a,5-tetramethylbenz[f]indol-2(4H)-one], were investigated. Both CP8816 and CP8863 demonstrated selective binding to progesterone receptor and partial agonistic activity in a progesterone-dependent endogenous alkaline phosphatase expression assay. In the Clauberg-McPhail test, progestational activity of CP8816 (0.1 mg/kg s.c. or 10 mg/kg p.o.) was comparable to that of progesterone (0.15 mg/kg s.c.), and oral administration of CP8863 at more than 1.0 mg/kg also exerted similar effects. Anti-estrogenic (antiuterotropic) activity was confirmed on daily oral application of more than 0.1 mg/kg CP8863 for 3 days by inhibition of estrogen-dependent uterine wet weight gain in ovariectomized rats. CP8816 also exerted antiuterotropic activity at doses of 10 mg/kg (s.c.) and 100 mg/kg (p.o.). These results indicate that our nonsteroidal progesterone ligands have affinity for the progesterone receptor with partial progestational activity in vitro and clear progestational effects in vivo. Thus, these progesterone receptor modulator profiles suggest that CP8863 and CP8816 are good candidate compounds for treatment of hormone-dependent gynecological disorders.

MODULATION OF RAT VAGINAL BLOOD FLOW AND ESTROGEN RECEPTOR BY ESTRADIOL

PURPOSE

The effects of subphysiological and physiological levels of estradiol on vaginal blood flow and estrogen receptor were investigated.

MATERIALS AND METHODS

Intact or ovariectomized female Sprague-Dawley rats were used. Two weeks after surgery rats were infused with vehicle (polyethyleneglycol), or estradiol at subphysiological (5 microg daily) or physiological (15 microg daily) concentrations for 14 days using osmotic pumps. Changes in vaginal blood flow elicited by pelvic nerve stimulation were assessed by laser Doppler flowmetry. Total levels of functional estrogen receptor were determined by radioligand binding and Western blot analyses were used to assess estrogen receptor (ER) alpha protein.

RESULTS

Mean plasma estradiol concentration +/- SEM decreased by 63% in the vehicle group (intact 36.5 +/- 10.3 pg/ml). The subphysiological and physiological estradiol groups had plasma levels that were 55% and 83% of the intact group, respectively. Uterine and vaginal wet weight, and vaginal blood flow were significantly decreased in the vehicle group and normalized by physiological levels of estradiol. However, vaginal blood flow was significantly greater in the subphysiological estradiol group compared to intact animals. Specific binding of [H]estradiol in vaginal tissue extracts from intact rats was 0.51 fmol/mg protein and it was increased 30-fold in the vehicle group. ER binding in vaginal tissue in the physiological estradiol group decreased to levels that were comparable to those in intact animals, whereas estrogen receptor binding remained elevated in the subphysiological estradiol group. These changes were paralleled by ERalpha protein levels.

CONCLUSIONS

Estradiol is crucial for maintaining optimal vaginal blood flow in the rat. Lower levels of plasma estradiol trigger compensatory ERalpha up-regulation.

Insulin-like growth factor (IGF)-I obliterates the pregnancy-associated protection against mammary carcinogenesis in rats: evidence that IGF-I enhances cancer progression through estrogen receptor-alpha activation via the mitogen-activated protein kinase pathway

Introduction

Pregnancy protects against breast cancer development in humans and rats. Parous rats have persistently reduced circulating levels of growth hormone, which may affect the activity of the growth hormone/insulin-like growth factor (IGF)-I axis. We investigated the effects of IGF-I on parity-associated protection against mammary cancer.

Methods

Three groups of rats were evaluated in the present study: IGF-I-treated parous rats; parous rats that did not receive IGF-I treatment; and age-matched virgin animals, which also did not receive IGF-I treatment. Approximately 60 days after N-methyl-N-nitrosourea injection, IGF-I treatment was discontinued and all of the animal groups were implanted with a silastic capsule containing 17β-estradiol and progesterone. The 17β-estradiol plus progesterone treatment continued for 135 days, after which the animals were killed.

Results

IGF-I treatment of parous rats increased mammary tumor incidence to 83%, as compared with 16% in parous rats treated with 17β-estradiol plus progesterone only. Tumor incidence and average number of tumors per animal did not differ between IGF-I-treated parous rats and age-matched virgin rats. At the time of N-methyl-N-nitrosourea exposure, DNA content was lowest but the α-lactalbumin concentration highest in the mammary glands of untreated parous rats in comparison with age-matched virgin and IGF-I-treated parous rats. The protein levels of estrogen receptor-α in the mammary gland was significantly higher in the age-matched virgin animals than in untreated parous and IGF-I-treated parous rats. Phosphorylation (activation) of the extracellular signal-regulated kinase-1/2 (ERK1/2) and expression of the progesterone receptor were both increased in IGF-I-treated parous rats, as compared with those in untreated parous and age-matched virgin rats. Expressions of cyclin D₁ and transforming growth factor-β₃ in the mammary gland were lower in the age-matched virgin rats than in the untreated parous and IGF-I-treated parous rats.

Conclusion

We argue that tumor initiation (transformation and fixation of mutations) may be similar in parous and age-matched virgin animals, suggesting that the main differences in tumor formation lie in differences in tumor progression caused by the altered hormonal environment associated with parity. Furthermore, we provide evidence supporting the notion that tumor growth promotion seen in IGF-I-treated parous rats is caused by activation of estrogen receptor-α via the Raf/Ras/mitogen-activated protein kinase cascade.

The role of sex steroid receptors in sheep female reproductive physiology

Cell responsiveness to steroid hormones is related to the number and affinity of its receptors, thus factors affecting steroid expression will influence tissue sensitivity and functionality. The present review discusses the role of oestrogen and progesterone receptors in sheep female reproductive physiology. The mechanism of steroid hormone action in the target cell is introduced first; the tissue distribution, physiological functions and regulation of oestrogen receptor subtypes and progesterone receptor isoforms in ruminants are reported. The role of steroid receptors in target tissues (with emphasis on the uterus and pituitary gland) during different physiological events is addressed in an attempt to clarify oestrogen and progesterone actions in different developmental and reproductive stages: prepubertal period, oestrous cycle, pregnancy, post-partum period and seasonal anoestrus. The present review shows how the distinct reproductive stages are accompanied by dramatic changes in uterine receptor expression. The role of oestrogen and progesterone receptors in the molecular mechanism responsible for premature luteolysis that results in subnormal luteal function is discussed. Finally, the effect of nutrition on sex steroid receptor expression and the involvement on reproductive performance is reported.

Gene expression profiling of the effects of castration and estrogen treatment in the rat uterus

The development and functions of female reproductive tissues are regulated by the actions of two major sex steroid hormones, estrogen and progesterone. To investigate estrogen-dependent gene expression in the rat uterus, we studied the effect of ovariectomy with or without estrogen treatment on the uterine expression of 3000 genes using cDNA microarrays. Many genes were regulated by either treatment, but only few were reciprocally regulated by these contrasting treatments. The present study confirms previous findings and identifies several genes with expressions not previously known to be influenced by estrogen. These genes include follistatin-related protein, Thy-1 glycoprotein, alpha-fodrin, CD24, immediate early response 5, insulin-like growth factor-binding protein 2, growth response protein CL-6 (INSIG-1), ladinin1, class I major histocompatibility complex heavy chain, lactadherin, ezrin, and Fas-activated serine/threonine kinase. Because of their function as regulators of proliferation and apoptosis, CD24, insulin-like growth factor-binding protein 2, and Fas/Fas ligand were examined further by immunohistochemical expression and tissue localization analysis. Our analysis confirms a contrasting regulation of these gene products by ovariectomy and estrogen treatment. The present study identifies novel mediators of estrogen actions in the uterus and provides genome-wide expression data from which novel hypotheses regarding uterine function can be generated.

Priming effects of novel nonsteroidal progesterone receptor modulators CP8816 and CP8863 on the development of adenomyosis in the mouse uterus

The possibility of therapeutic application of novel nonsteroidal progesterone receptor modulators CP8816 and CP8863 for preventing the development of uterine adenomyosis was investigated in mice. First priming effects of CP8816 on 17beta-estradiol (E2)-induced cell division in uterine tissues were examined. As a result, pretreatment with CP8816 or progesterone significantly suppressed the elevation of the mitotic activity in the luminal epithelial cells of mice treated with E2 later. Priming with CP8816 had little effect on the stromal cells, but progesterone priming caused an increase of stromal mitotic activity in mice treated with E2 later. To evaluate the inhibitory effect of these compounds on the development of adenomyosis induced experimentally by pituitary grafting, 7-week-old female mice were isografted with a single anterior pituitary in the uterus and divided into four groups. Two groups of mice were given daily subcutaneous injections of 1 mg of CP8816 or the vehicle alone for 6 weeks from the day after the grafting. Remaining two groups of mice were given oral administration of 1 mg of CP8863 or the vehicle only for 5 weeks starting one week after the grafting. The incidence of adenomyosis was significantly lower in the groups of mice treated with CP8816 and CP8863 than in the respective control groups. The mechanism by which CP compounds inhibited the development of adenomyosis might be related to their priming effects, i.e., their inhibitory effect on epithelial cell division and lack of effect on stromal cell division after subsequent exposure to E2.

A reporter gene assay for the detection of phytoestrogens in traditional Chinese medicine

Bupleurum & Peony Formula (Jia Wei Xiao Yao San) is a herbal formula which possesses a clinical history for the treatment of menopausal syndrome and menstrual irregularity. The present investigation reports the ability to monitor the formula's phytoestrogen content that will allow for the implementation of a standardization protocol that is based on a quantifiable biological response. Utilizing an oestrogen-sensitive chimeric receptor/reporter gene element which has been stably transfected into HeLa cells, the botanical formula was shown to induce the expression of the reporter gene, luciferase, in a dose dependent manner. Pretreatment of the HeLa cells with the botanical formula produced a 5-fold increase in bioluminescence compared with the control. Additionally, our studies showed that the response of the cells, when challenged by the botanical formula, was oestrogen specific. Pretreatment of the cells with tamoxifen effectively blocked the activation of the chimeric oestrogen receptor by the botanical formula. The cell line provides a sensitive assay that can easily detect the presence of phytoestrogens in complex botanical formulas.

Neurochemical characteristics and behavioral responses to psychological stress in ovariectomized rats

The present study was designed to clarify the time-dependent changes in brain monoamine turnover in the frontal cortex, hypothalamus, hippocampus, septum and amygdala after ovariectomy, and the difference in behavioral responses to psychological stress between sham-operated and ovariectomized (OVX) rats. At 2 and 4 weeks after ovariectomy, the turnover rates of dopamine and norepinephrine in all of the brain regions examined did not differ significantly between the sham-operated and OVX rats. However, 5-hydroxytryptamine (5-HT) turnover in all of the brain regions at 2 weeks after OVX was significantly lower than that in sham-operated rats. This difference was greater in the hypothalamus than in other brain regions. At 4 weeks after ovariectomy, 5-HT turnover in all of the brain regions examined was not significantly different between sham-operated and OVX rats. At 2 and 4 weeks after ovariectomy, exploratory behaviour (e.g., locomotor activity, head- dipping, crossing and rearing behaviours) in a non-stressed ovariectomy group did not differ from that in a non-stressed sham-operation group. Locomotor activity and the number of head-dips and crossings significantly (P<0.05) increased after repeated exposure to psychological stress for 5 days in sham-operated rats, but not in those at 2 weeks after OVX. At 4 weeks after ovariectomy, locomotor activity and the number of crossings and rearings in sham-operated and OVX rats were not significantly different in the psychological stress and non-stress groups. However, the number of head-dips significantly (P<0.05) increased with psychological stress in the sham-operated rats, but not in OVX rats. These results suggest that female gonadal hormones may play an important role in the regulation of brain 5-HTergic systems. These interactions between gonadal hormones and 5-HT metabolism may be related to 5-HT-related neuropsychiatric disorders.

Oestrogen-dependent expression of the SM2 smooth muscle-type myosin isoform in rabbit myometrium

Ovarectomized rabbits displayed a decreased SM1 to SM2 ratio of smooth muscle-type myosin heavy chain isoforms compared to unoperated, virgin females which was reversed after 17beta-oestradiol administration to a value similar to that of control animals. When this steroid was given to sexually immature animals or to adult virgin rabbits, SM2 expression was not induced, as also happened with proliferating myometrial smooth muscle cells grown in vitro. In growing rabbit, the 17beta-oestradiol administration induced the formation of the circular and the longitudinal muscle layers, characteristics of sexually competent females. The SM2 isoform was up-regulated during postnatal development and the SM1 to SM2 ratio changed during pregnancy and post-partum period but not with human gonadotropin treatment which increases the level of circulating progesterone. Immunofluorescence staining of adult myometrium with anti-SM2 antibody indicated that this isoform is localized to the longitudinal layer exclusively and, in contrast to the circular layer, its expression was independent of oestrogen level. Difference in oestrogen sensitivity between the two layers was also detected for the expression of the intermediate filament protein vimentin and the thin filament protein calponin. Changes of SM2 expression in the myometrium correlated with variations in the oestrogen receptor density as also confirmed by decreased SM2 content/oestrogen receptor density in the circular layer when ovarectomized females were treated with the oestrogen antagonist ICI 182,780. Our results indicate that: (1) a specific distribution of myosin heavy chain exists within rabbit myometrium, and (2) SM2 myosin expression in this smooth muscle is under oestrogen control.

Sterility in neonatally androgenized female rats and the decidual cell reaction

In female rats, administration of androgen during early postnatal life results in anovulatory sterility characterized by polyfollicular ovaries and persistent vaginal cornification in adulthood. In these androgen-sterilized rats, the acyclic male pattern of gonadotropin secretion results from permanent damage to hypothalamic centers normally responsive to steroid feedback. The capacity of the endometrium to differentiate into deciduoma in response to endometrial stimulation is markedly reduced in the uterus of the androgenized rats receiving an appropriate regimen of progesterone and estrogen injections. The hypothesis is presented that the lowered uterine responsiveness in the androgenized rats is largely ascribable to the effect of androgen given neonatally rather than to the influence of continued exposure to ovarian estrogen. This review deals with the nature of the uterine response to ovarian hormones and the deciduogenic stimulus in androgenized rats in order to verify the mechanism involved in androgen action on the neonatal uterus.