Selective estrogen receptor modulators: an alternative to hormone replacement therapy

Fused thiophene as a privileged scaffold: A review on anti-Alzheimer's disease potentials via targeting cholinesterases, monoamine oxidases, glycogen synthase kinase-3, and Aβ aggregation

As a "silent threat," Alzheimer's disease (AD) is quickly rising to the top of the list of costly and troublesome diseases facing humanity. It is growing to be one of the most troublesome and expensive conditions, with annual health care costs higher than those of cancer and comparable to those of cardiovascular disorders. One of the main pathogenic characteristics of AD is the deficiency of the neurotransmitter acetylcholine (ACh) which plays a vital role in memory, learning, and attention. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) play a crucial role in hydrolyzing ACh. Consequently, a frequent therapy approach for AD is the suppression of AChE and BChE to improve cholinergic neurotransmission and reduce cognitive symptoms. The accumulation of amyloid plaques (Aβ) is a primary factor contributing to neurodegenerative diseases, particularly AD. Glycogen synthase kinase-3β (GSK3-β) is regarded as a pivotal player in the pathophysiology of AD since dysregulation of this kinase affects all major hallmarks of the disease, such as tau phosphorylation, Aβ aggregation, memory, neurogenesis, and synaptic function. One of the most challenging and risky issues in modern medicinal chemistry is the urgent and ongoing need for the study and development of effective therapeutic candidates for the treatment of AD. A significant class of heterocyclic molecules that can target the complex and multifactorial pathogenesis of AD are fused thiophene derivatives. The goal of the current review is to demonstrate the advancements made in fused thiophene derivatives' anti-AD activity. It also covers their mechanisms of action and studies of the structure-activity relationships in addition to the compilation of significant synthetic routes for fused thiophene derivatives with anti-AD potential. This review is intended to stimulate new ideas in the search for more rationale designs of derivatives based on fused thiophene, hoping to be more potent in treating AD.

Therapeutic evolution in HR+/HER2- breast cancer: from targeted therapy to endocrine therapy

Breast cancer, a complex and varied disease, has four distinct subtypes based on estrogen receptor and human epidermal growth factor receptor 2 (HER2) levels, among which a significant subtype known as HR+/HER2-breast cancer that has spurred numerous research. The prevalence of breast cancer and breast cancer-related death are the most serious threats to women's health worldwide. Current progress in treatment strategies for HR+/HER2-breast cancer encompasses targeted therapy, endocrine therapy, genomic immunotherapy, and supplementing traditional methods like surgical resection and radiotherapy. This review article summarizes the current epidemiology of HR+/HER2-breast cancer, introduces the classification of HR+/HER2-breast cancer and the commonly used treatment methods. The mechanisms of action of various drugs, including targeted therapy drugs and endocrine hormone therapy drugs, and their potential synergistic effects are deeply discussed. In addition, clinical trials of these drugs that have been completed or are still in progress are included.

Spectroscopic, theoretical and computational investigations of novel benzo[b]thiophene based ligand and its M(II) complexes: As high portentous antimicrobial and antioxidant agents

The reaction of 3-chlorobenzo[b]thiophene-2-carbohydrazide with 4-(diethylamino) salicylaldehyde gave the new ligand; 3-chloro-N'-(4-(diethylamino)-2-hydroxybenzylidene)-benzo[b]thiophene-2-carbohydrazide. The Cu(II), Co(II), Ni(II), and Zn(II) complexes have been successfully prepared. The ligand and the complexes were characterized by analytical, FT-IR, 1H NMR, mass, UV-visible spectroscopy, molar conductivity, and magnetic susceptibility measurements. The FT-IR spectral data showed that the ligand adopted a tridentate fashion when binding with the metal ions via the nitrogen atoms of the imine (C = N), carboxyl (C = O), and phenolic oxygen (O-H) donor atoms. Density Functional Theory (DFT) estimations for the ligand at the DFT/B3LYP level via 6-31G++ (d, p) replicate the structure and geometry. Finally, HOMO and LUMO analyses were used for the charge transfer interface of the structure. Furthermore, molecular docking and ADME calculations were also performed to correlate and interpret the experimental results. The antimicrobial activity study illustrated enhancement in the activity of the free ligand upon complex formation, and the Cu(II) complex (MIC 25 µg mL-1) may be considered a promising antibacterial agent, and the Ni(II) and Zn(II) complexes (MIC 25 µg mL-1) as promising antifungal agents. Also, synthesized Cu(II) and Zn(II) metal complexes (MIC 3.125 µg mL-1) showed promising anti-TB activity against M. tuberculosis. Further, benzo[b]thiophene-based ligand and its metal complexes were evaluated for in vitro antioxidant activity, and in silico docking studies were carried out against Cytochrome c Peroxidase (PDB ID: 2X08).

To clot, or not to clot: The dilemma of hormone treatment options for menopause

Untreated menopause may have serious health implications, but treatments can have dangerous side effects. We evaluate menopausal symptoms as well as available treatments -the routes of administration and their effect on blood coagulation. Menopausal females may experience hot flushes, vulva- and vaginal atrophy and osteoporosis. Many treatments are available to relieve these symptoms such as Conjugated Equine Estrogen and bioidentical hormones. The routes of administration include oral and transdermal. Hormones that are administered orally undergo a hepatic first pass metabolism. The by-products have a lower efficacy and possibly enhanced side effects. Furthermore, hormone treatments influence the coagulation cascade through coagulation factors or their regulators. Increased coagulation poses a risk for venous thromboembolism. Currently a definite conclusion on whether the side effects from hormone treatments exceed the risk of untreated menopause cannot be made. However, a more individualised approach to hormone treatments may be the most feasible solution to this dilemma.

Protective effects of combining SERMs with estrogen on metabolic parameters in postmenopausal diabetic cardiovascular dysfunction: The role of cytokines and angiotensin II

INTRODUCTION

The beneficial effects of the administration of selective estrogen receptor modulators (SERMs) and estrogen (E2), alone or in combination with each other, have been reported in postmenopausal diabetic cardiovascular dysfunction. In the present study, we determined the mechanism of action of SERMs and E2 on inflammatory balance, angiotensin II (Ang II) serum levels, and glycemic profile in a postmenopausal diabetic rat model.

METHODS

Ovariectomized rats with type 2 diabetes received daily SERMs (tamoxifen and raloxifene) and E2 for one month. After treatment, cardiovascular risk indices, glycemic profile, and serum Ang II, TNF-α and IL-10 levels were measured.

RESULTS

Type 2 diabetes caused an abnormal glycemic profile, which was exacerbated by ovariectomy. All treatments inhibited the effects of diabetes and ovariectomy on the glycemic profile, with combined treatments (SERMs + E2) showing stronger effects. Cardiovascular risk indices that became abnormal by diabetes and worsened by ovariectomy were improved in all treatment modalities. Also, combined treatment reduced serum Ang II, TNF-α, and the ratio of TNF-α to IL-10, indicating an improvement in inflammatory balance.

CONCLUSION

Our study showed the administration of SERMs and E2, alone or in combination, could be an effective alternative in the treatment of menopausal diabetes, and generally, the beneficial effects of combined treatments were more effective than the effects of E2 or SERMs alone. It appears that E2 or SERMs benefit the cardiovascular system by improving inflammatory balance and reducing Ang II levels.

Expedition of sulfur-containing heterocyclic derivatives as cytotoxic agents in medicinal chemistry: A decade update

This review article proposes a comprehensive report of the design strategies engaged in the development of various sulfur-bearing cytotoxic agents. The outcomes of various studies depict that the sulfur heterocyclic framework is a fundamental structure in diverse synthetic analogs representing a myriad scope of therapeutic activities. A number of five-, six- and seven-membered sulfur-containing heterocyclic scaffolds, such as thiazoles, thiadiazoles, thiazolidinediones, thiophenes, thiopyrans, benzothiazoles, benzothiophenes, thienopyrimidines, simple and modified phenothiazines, and thiazepines have been discussed. The subsequent studies of the derivatives unveiled their cytotoxic effects through multiple mechanisms (viz. inhibition of tyrosine kinases, topoisomerase I and II, tubulin, COX, DNA synthesis, and PI3K/Akt and Raf/MEK/ERK signaling pathways), and several others. Thus, our concise illustration explains the design strategy and anticancer potential of these five- and six-membered sulfur-containing heterocyclic molecules along with a brief outline on seven-membered sulfur heterocycles. The thorough assessment of antiproliferative activities with the reference drug allows a proficient assessment of the structure-activity relationships (SARs) of the diversely synthesized molecules of the series.

A one-pot successive cyclization-alkylation strategy for the synthesis of 2,3-disubstituted benzo[b]thiophenes

In this study, a new environmentally benign iodine-mediated one-pot iodocyclization/alkylation strategy for the synthesis of benzo[b]thiophene derivatives starting from 2-alkynylthioanisoles was developed. The synthesis of a diverse population of 2,3-disubstituted benzo[b]thiophenes was achieved in high yields by employing moderate reaction conditions using 1,3-dicarbonyl substrates as the nucleophile and various substituted propargyl alcohols as both the cyclization precursor and the alkylating agent. This method resulted in the formation of a series of complex structures obtained in a single step. Additionally, a strategy was devised for the one pot iodocyclization/oxidation of propargyl alcohols into carbonyl functionalized benzo[b]thiophene structures. These green one-pot reaction processes were designed to reduce wastes and byproducts while generating a complex substitution pattern on the benzo[b]thiophene structure. The reported methodologies may be used to synthesize more functionalized benzo[b]thiophene structures that can be used in both biomedical and organic electronic applications.

Bis benzothiophene Schiff bases: synthesis and in silico-guided biological activity studies

Since benzo [ b ] thiophene scaffold is one of the privileged structures in drug discovery as this core exhibitsactivities for different biological problems, in this study bis (benzo[ b ]thiophene-2-yl) alkyl methanimine derivatives (1-9) were synthesized by reacting benzo[ b ]thiophene-2-carbaldehyde with diamines. All newly compounds were characterized by IR, ¹H NMR and ¹³C NMR spectroscopic methods. Synthesized compounds were investigated using binary QSARbased models on therapeutic activity prediction of synthesized compounds and they showed high predicted activities in following diseases: bacterial, angina, allergy, depression and obesity. Thus, they were then tested for their antimicrobial and antileishmanial activities as a result of this theoretical study. Compound 1(N, N’- (propane-1,3-diyl) bis (1-(benzo [ b ] thiophene-2-yl)) methanimine) was found the most active compound in both diseases. Thus, its molecular docking studies were also carried out.

Computational investigations of the binding mechanism of novel benzophenone imine inhibitors for the treatment of breast cancer

4-Hydroxytamoxifen (4-OHT), the most common hormone used for the treatment of breast cancer, is a selective estrogen receptor modulator (SERM) inhibitor that acts as an antagonist in breast tissue and a partial agonist in the endometrium. However, the detailed molecular mechanism of 4-OHT structure modification has not been well investigated to date. Herein, molecular docking, molecular dynamics simulations and free energy calculations were performed to explore the mechanisms of the molecular interactions between newly designed benzophenone imines (BIs) and the three forms apo, antagonist and agonist of the human estrogen receptor hERα. The proposed inhibitors were designed by replacing the triarylethylene estrogenic scaffold found in 4-OHT with Schiff base triarylimine derivatives. The antiestrogen scaffold i.e. the O-alkyl side chain in 4-OHT was developed by incorporating an alanine amino acid side chain functionality into the triarylimine scaffold. Docking results reveal that the newly designed BIs bind to the hydrophobic open pocket of the apo and antagonist hERα conformations with higher affinity as compared to the natural and synthetic estrogen estradiol (E2) and 4-OHT. The analysis of the molecular dynamics simulation results based on six different systems of the best docked BI (5c) with hERα receptors demonstrates stable interactions, and the complex undergoes fewer conformational fluctuations in the open apo/antagonist hERα receptors as compared to the case of the closed agonist. In addition, the calculated binding free energies indicate that the main factor that contributes to the stabilization of the receptor-inhibitor complexes is hydrophobic interactions. This study suggests that the development of these Schiff base derivatives may be worth exploring for the preparation of new 4-OHT analogues.

Selective activation of estrogen receptors, ERα and GPER-1, rapidly decreases food intake in female rats

Many of estradiol's behavioral effects are mediated, at least partially, via extra-nuclear estradiol signaling. Here, we investigated whether two estrogen receptor (ER) agonists, targeting ERα and G protein-coupled ER-1 (GPER-1), can promote rapid anorexigenic effects. Food intake was measured in ovariectomized (OVX) rats at 1, 2, 4, and 22 h following subcutaneous (s.c.) injection of an ERα agonist (PPT; 0-200 μg/kg), a GPER-1 agonist (G-1; 0-1600 μg/kg), and a GPER-1 antagonist (G-36; 0-80 μg/kg). To investigate possible cross-talk between ERα and GPER-1, we examined whether GPER-1 blockade affects the anorexigenic effect of PPT. Feeding was monitored in OVX rats that received s.c. injections of vehicle or 40 μg/kg G-36 followed 30 min later by s.c. injections of vehicle or 200 μg/kg PPT. Selective activation of ERα and GPER-1 alone decreased food intake within 1 h of drug treatment, and feeding remained suppressed for 22 h following PPT treatment and 4 h following G-1 treatment. Acute administration of G-36 alone did not suppress feeding at any time point. Blockade of GPER-1 attenuated PPT's rapid (within 1 h) anorexigenic effect, but did not modulate PPT's ability to suppress food intake at 2, 4 and 22 h. These findings demonstrate that selective activation of ERα produces a rapid (within 1 h) decrease in food intake that is best explained by a non-genomic signaling pathway and thus implicates the involvement of extra-nuclear ERα. Our findings also provide evidence that activation of GPER-1 is both sufficient to suppress feeding and necessary for PPT's rapid anorexigenic effect.

An overview of benzo[b]thiophene-based medicinal chemistry

Among sulfur containing heterocycles, benzothiophene and its derivatives are at the focus as these candidates have structural similarities with active compounds to develop new potent lead molecules in drug design. Benzo[b]thiophene scaffold is one of the privileged structures in drug discovery as this core exhibits various biological activities allowing them to act as anti-microbial, anti-cancer, anti-inflammatory, anti-oxidant, anti-tubercular, anti-diabetic, anti-convulsant agents and many more. Further, numerous benzothiophene-based compounds as clinical drugs have been extensively used to treat various types of diseases with high therapeutic potency, which has led to their extensive developments. Due to the wide range of biological activities of benzothiophene, their structure activity relationships (SAR) have generated interest among medicinal chemists, and this has culminated in the discovery of several lead molecules against numerous diseases. The present review is endeavoring to highlight the progress in the various pharmacological activities of benzo[b]thiophene derivatives. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic benzothiophene-based medicinal drugs, as well as more effective diagnostic agents and pathologic probes. Also, SAR studies that highlight the chemical groups responsible for evoking the potential activities of benzothiophene derivatives are studied and compared.

Binding of anterior gradient 2 and estrogen receptor-α: Dual critical roles in enhancing fulvestrant resistance and IGF-1-induced tumorigenesis of breast cancer

Anterior gradient 2 (AGR2), an essential cancer biomarker, has been widely reported to be associated with estrogen receptor (ER) positive breast cancer development. Here, we uncovered the role of cytoplasmic and exogenous AGR2, through interaction with ER-α, in enhancing fulvestrant resistance and IGF-1-induced carcinogenesis respectively. Our present study revealed that the endogenous AGR2 level positively correlates with fulvestrant resistance in MCF-7 and T47D cells. AGR2-knockdown in MCF-7 cells strongly enhances the fulvestrant-induced G1 phase arrest and accelerates the fulvestrant-induced ER-α degradation. Furthermore, intracellular AGR2 exhibits a functional interaction with ER-α. On the other hand, extracellular AGR2 remarkably promotes the IGF-1-induced cell proliferation, migration, cell cycle progression and epithelial-mesenchymal transition. Extracellular AGR2 also enhances IGF-1 downstream signaling. We also showed that ER-α specifically interacts with both extracellular AGR2 and IGF-1 receptor as a potential intermediator. Finally, we revealed that the adjuvant therapy of AGR2 monoclonal antibody enhances the inhibitory effects of fulvestrant and linsitinib toward breast cancer development. Our findings, for the first time, point out the different functions of intra- and extra-cellular AGR2, providing new insights into the development of anti-tumor therapies targeting AGR2.

Treatment with bazedoxifene and conjugated estrogens results in regression of endometriosis in a murine model

Bazedoxifene (BZA), a selective estrogen receptor modulator (SERM), inhibits the action of estrogens on endometrial proliferation. Here, we evaluate the effect of a tissue-selective estrogen complex (TSEC) containing BZA and conjugated estrogens (CE) on ectopic endometrial lesions in a mouse model of endometriosis. Experimental endometriosis was created in 60 female CD-1 mice. The mice were randomly divided into 10 groups that received varying doses of either BZA (1, 2, 3, or 5 mg/kg/day), BZA (1, 2, 3, or 5 mg/kg/day) in combination with CE (3 mg/kg/day), CE treatment alone (3 mg/kg/day), or vehicle control for 8 wk. Treatment with BZA alone or the TSEC containing BZA/CE led to a decrease in endometriotic lesion size compared to controls. The mean surface area of the untreated lesions was 19.6 mm(2). Treatment with BZA or BZA/CE resulted in reduced lesion size (to 8.8 and 7.8 mm(2), respectively). No significant difference was found in lesion size between the BZA and BZA/CE treatment groups or between different doses of either treatment. Ovarian cyst formation was not evident in the treated groups. Treatment with the TSEC containing higher BZA dosages (3 and 5 mg/kg/day) led to significantly lower levels of estrogen receptor (Esr1) mRNA expression compared to the control treatment. No differences were observed in expression of progesterone receptor (Pgr). Immunohistochemical analysis also demonstrated a decrease in ESR protein. The combination of CE and BZA may prove to be a novel treatment option for endometriosis.

Lasofoxifene (CP-336,156), a novel selective estrogen receptor modulator, in preclinical studies

Estrogen replacement therapy is reported to reduce the incidence of vertebral fractures in postmenopausal women, however, its compliance is limited because of side effects and safety concerns. Estrogen's side effects on breast and uterine tissues leading to the potential increased risk of uterine and breast cancer limit widespread estrogen usage. Thus, there is a significant medical need for a therapy that protects against postmenopausal bone loss but is free of estrogen's negative effects on reproductive tissues. Selective estrogen receptor modulators (SERMs) have been investigated as an alternative to hormone replacement therapy. One such compound, raloxifene, has been approved for the prevention and treatment of osteoporosis. Lasofoxifene (LAS), a new, nonsteroidal, and potent SERM, is an estrogen antagonist or agonist depending on the target tissue. LAS selectively binds with high affinity to human estrogen receptors. In ovariectomized (OVX) rat studies, LAS prevented the decrease in femoral bone mineral density, tibial and lumbar vertebral trabecular bone mass at an ED100 of about 60 μg/kg/day. LAS inhibited the activation of trabecular and endocortical bone resorption and bone turnover in tibial metaphyses and diaphyses, and lumbar vertebral body in OVX rats. In addition, LAS decreased total serum cholesterol, inhibited body weight gain and increased soleus muscle weight in OVX rats. Similarly, LAS prevented bone loss induced by orchidectomy or aging in male rats by decreasing bone resorption and bone turnover while it had no effect in the prostate. Further, LAS decreased total serum cholesterol in intact aged male rats or in orchidectomized male rats. Synergestic skeletal effects were found with LAS in combination with bone anabolic agents such as prostaglandin E2 (PGE2), parathyroid hormone (PTH) or a growth hormone secretagoue (GHS) in OVX rats. In combination with estrogen, LAS inhibited the uterine stimulating effects of estrogen but did not block the bone protective effects of estrogen. In immature and aged female rats, LAS did not affect the uterine weight and uterine histology. In OVX adult female rats, LAS slightly but significantly increased uterine weight. These results demonstrated that LAS produced effects on the skeleton indistinguishable from estrogen in female and male rats. However, unlike estrogen, LAS had little effect on uterine weight and cellular proliferation of uterus in female rats. In preclinical anti-tumor studies, LAS inhibited human breast cancer growth in mice bearing MCF7 tumors, prevented NMU-induced mammary carcinomas and possessed chemotherapeutic effects in NMU-induced carcinomas in rats. Therefore, we conclude that LAS possesses the antiestrogenic effects in breast tissue and estrogenic effects in bone and serum cholesterol, but lacks estrogen's side effects on uterine tissue. These data support the therapeutic potential of LAS for the prevention and treatment of postmenopausal bone loss and mammary carcinomas in humans.

Assessment of the estrogenic activities of chickpea (Cicer arietinum L) sprout isoflavone extract in ovariectomized rats

AIM

Chickpea (Cicer arietinum L) is a traditional Uighur herb. In this study we investigated the estrogenic activities of the isoflavones extracted from chickpea sprouts (ICS) in ovariectomized rats.

METHODS

Ten-week-old virgin Sprague-Dawley female rats were ovariectomized (OVX). The rats were administered via intragastric gavage 3 different doses of ICS (20, 50, or 100 mg·kg(-1)·d(-1)) for 5 weeks. Their uterine weight and serum levels of 17β-estradiol (E2), follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured. The epithelial height, number of glands in the uterus, and number of osteoclasts in the femur were histologically quantified, and the expression of proliferating cell nuclear antigen (PCNA) was assessed immunohistochemically. Bone structural parameters, including bone mineral density (BMD), bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp) were measured using Micro-CT scanning.

RESULTS

Treatments of OVX rats with ICS (50 or 100 mg·kg(-1)·d(-1)) produced significant estrogenic effects on the uteruses, including the increases in uterine weight, epithelial height and gland number, as well as in the expression of the cell proliferation marker PCNA. The treatments changed the secretory profile of ovarian hormones and pituitary gonadotropins: serum E2 level was significantly increased, while serum LH and FSH levels were decreased compared with the vehicle-treated OVX rats. Furthermore, the treatments significantly attenuated the bone loss, increased BMD, BV/TV and Tb.Th and decreased Tb.Sp and the number of osteoclasts. Treatment of OVX rats with the positive control drug E2 (0.25 mg·kg(-1)·d(-1)) produced similar, but more prominent effects.

CONCLUSION

ICS exhibits moderate estrogenic activities as compared to E2 in ovariectomized rats, suggesting the potential use of ICS for the treatment of menopausal symptoms and osteoporosis caused by estrogen deficiency.

Effects of raloxifene on lipid and bone metabolism in postmenopausal women with type 2 diabetes

Evidence suggests that bone quality is poorer and fracture risk is higher in patients with diabetes, even those with normal bone mineral density. The aim of this study was to determine the effects of raloxifene on lipid, bone, and glucose metabolism in postmenopausal women with type 2 diabetes. The study subjects (144 postmenopausal women aged less than 80 years with type 2 diabetes) were randomly assigned into three groups: no medication, alfacalcidol 1 μg/day, or raloxifene hydrochloride 60 mg/day. The primary endpoint was the change in LDL-C at 6 months. Raloxifene significantly decreased the levels of bone metabolism markers NTX and BAP at 6 months in patients with diabetes. The primary endpoint, LDL-C at 6 months, was significantly lower in the raloxifene group than in the other two groups. However, percent changes in HDL-C were not significantly different among the three groups. Although glucose metabolism was unaffected, homocysteine, a bone quality marker, was significantly decreased at 6 months in the raloxifene group. The percent improvement in LDL-C did not correlate with percent improvement in any bone metabolism or bone quality markers. Raloxifene, unlike estrogen, improved LDL-C and decreased homocysteine, indicating that raloxifene can potentially improve LDL-C as well as bone quality in postmenopausal women with type 2 diabetes.

Sex hormones, aging, and Alzheimer's disease

A promising strategy to delay and perhaps prevent Alzheimer's disease (AD) is to identify the age-related changes that put the brain at risk for the disease. A significant normal age change known to result in tissue-specific dysfunction is the depletion of sex hormones. In women, menopause results in a relatively rapid loss of estradiol and progesterone. In men, aging is associated with a comparatively gradual yet significant decrease in testosterone. We review a broad literature that indicates age-related losses of estrogens in women and testosterone in men are risk factors for AD. Both estrogens and androgens exert a wide range of protective actions that improve multiple aspects of neural health, suggesting that hormone therapies have the potential to combat AD pathogenesis. However, translation of experimental findings into effective therapies has proven challenging. One emerging treatment option is the development of novel hormone mimetics termed selective estrogen and androgen receptor modulators. Continued research of sex hormones and their roles in the aging brain is expected to yield valuable approaches to reducing the risk of AD.

The role for estrogen receptor-alpha and prolactin receptor in sex-dependent DEN-induced liver tumorigenesis

Mice treated neonatally with diethylnitrosamine (DEN) develop liver tumors in a male-dominant manner, reflecting the male bias in human hepatocellular carcinoma. Evidence suggests that estrogen, androgen, prolactin (PRL) and growth hormone (GH) modify liver tumorigenesis. We determined the roles of estrogen receptor-α (ERα) and prolactin receptor (PRLR) using receptor null mice, ERαKO (C57Bl/6J) and PRLR-KO (129Ola-X-C57BL/6), in the neonatal-DEN model of liver tumorigenesis. In both mouse strains, females had reduced tumorigenesis compared with males (P < 0.01), regardless of ERα or PRLR status. Tumorigenesis was not affected by ovariectomy in C57Bl/6J mice but it was increased by ovariectomy in the mixed strain, 129Ola-X-C57BL/6, regardless of PRLR status. ERαKO males had 47% fewer tumors than ERα wild-type males (P < 0.01). On the other hand, estradiol treatment protected against tumorigenesis in males only in the presence of ERα. As evidenced by liver gene expression, lack of ERα did not alter the pattern of GH secretion in males but resulted in the male GH pattern in females. These observations indicate that ERα is not required for lower tumorigenesis in females, but it is required for the protective effects of exogenously delivered estradiol. Unexpectedly, the results indicate that ERα plays a role in promotion of liver tumors in males. In addition, it can be concluded that sex differences in liver tumorigenesis cannot be explained by the sexually dimorphic pattern of GH secretion. The results also rule out PRL as the mediator of the protective effect of the ovaries.

Regulation of synaptic plasticity by hippocampus synthesized estradiol

Estradiol is synthesized from cholesterol in hippocampal neurons of adult rats by cytochrome P450 and hydroxysteroid dehydrogenase enzymes. These enzymes are expressed in the glutamatergic neurons of the hippocampus. Surprisingly, the concentration of estradiol and androgen in the hippocampus is significantly higher than that in circulation. Locally synthesized estradiol rapidly and potently modulates synaptic plasticity within the hippocampus. E2 rapidly potentiates long-term depression and induces spinogenesis through synaptic estrogen receptors and kinases. The rapid effects of estradiol are followed by slow genomic effects mediated by both estrogen receptors located at the synapse and nucleus, modulating long-term potentiation and promoting the formation of new functional synaptic contacts. Age-related changes in hippocampally derived estradiol synthesis and distribution of estrogen receptors may alter synaptic plasticity, and could potentially contribute to age-related cognitive decline. Understanding factors which regulate hippocampal estradiol synthesis could lead to the identification of alternatives to conventional hormone therapy to protect against age-related cognitive decline.

Activation of ERα is necessary for estradiol's anorexigenic effect in female rats

While there is considerable evidence that the ovarian hormone estradiol reduces food intake in female rats, it is unclear which estrogen receptor (ER) subtype, ERα or ERβ, mediates this effect. While several studies have demonstrated that activation of ERα, but not ERβ, is sufficient to reduce food intake in ovariectomized (OVX) rats, there are limited data regarding which receptor subtype is necessary. Here we used the selective ERα and ERß antagonists, MPrP and PHTPP, respectively, to investigate this question. We found that antagonism of ERα, but not ERβ, prevented the decrease in food intake following acute administration of estradiol in OVX rats. In addition, antagonism of ERα prevented the estrous-related, phasic reduction in food intake that occurs in response to the rise in circulating levels of estradiol in cycling rats. We conclude that activation of ERα is necessary for the anorexigenic effects of exogenous and endogenous estradiol in female rats.

The effects of raloxifene on mammographic breast density: a review of clinical trials

OBJECTIVE

Breast density is an independent risk factor for the development of invasive breast cancer (BC). It has been hypothesized that because raloxifene (RLX) has been shown to reduce BC risk, its use will result in reduced breast density.

METHODS

This article provides a review of seven clinical studies that examined the effects of RLX on breast density.

RESULTS

Overall, RLX did not increase or decrease mammographic breast density. This article provides a review of the various methods used to determine breast density in these RLX studies and offers a potential explanation as to why the studies failed to show an effect on mammographic density.

CONCLUSIONS

Presently, no clinical recommendations can be made with regard to RLX and its effects on breast density. To determine the effect of RLX on breast density, larger studies need to be conducted in postmenopausal women with high breast density at baseline who are at high risk for BC, with a standardized method of breast density measurement.

Expressions of vascular endothelial growth factor and nitric oxide synthase III in the thyroid gland of ovariectomized rats are upregulated by estrogen and selective estrogen receptor modulators

BACKGROUND

Estrogen promotes the growth of thyroid cells. Therefore, we analyzed the influence of estrogen and selective estrogen receptor modulators (SERMs) on the expression of vascular endothelial growth factor (VEGF) and nitric oxide synthase III (NOS III) in the thyroid gland of ovariectomized (Ovx) rats.

METHODS

Wistar rats were divided into five groups, and bilateral ovariectomies were performed, except on the Sham-operated controls (Sham). Rats were grouped as follows: Sham; Ovx; and Ovx rats treated with daily subcutaneous injections of estradiol benzoate 3.5 microg/kg, tamoxifen 2.5 mg/kg, or raloxifene 2.5 mg/kg for 50 consecutive days. Control animals received vehicle (propyleneglycol), and at the end of the treatment, rats were sacrificed. The thyroid glands were excised, weighed, and processed for analysis of the expression of VEGF or NOS III by immunohistochemistry. The mean vascular areas were evaluated by immunodetection of alpha-smooth muscle actin.

RESULTS

Thyroid weight and mean vascular area were lower in Ovx as compared with Sham, Ovx + estradiol benzoate, Ovx + Tam, or Ovx + Ral (p < 0.01). VEGF (p < 0.01) and NOS III expressions (p < 0.05) were significantly lower in the Ovx group, as compared with Sham, Ovx + estradiol benzoate, Ovx + Tam, and Ovx + Ral. Immunoreactivity for both VEGF and NOS III was mainly detected in the cytoplasm of the follicular epithelial cells.

CONCLUSIONS

Our data suggest that estrogen and SERMs regulate the thyroid gland vascularization and that tamoxifen and raloxifene behave like estrogen does. Estrogen and SERMs upregulate VEGF and NOS III in such a way as to reverse the effects detected on the thyroid microvasculature of the Ovx rats.

Tamoxifen–2-hydroxylpropyl-β-cyclodextrin-aggregated nanoassembly for nonbreast estrogen-receptor-positive cancer therapy

Background: Tamoxifen (Tam) is used for the treatment and prevention of estrogen-receptor-positive human breast and other cancers. Its use in ovarian cancer has not been well studied. Method: We formulated and characterized a water-soluble Tam–2-hydroxylpropyl-β-cyclodextrin (HPβCD; 1:2 M) complex. Results: The differential scanning calorimetery of Tam–HPβCD indicated the transition of Tam from crystalline to amorphous form on addition of HPβCD. 1H-nuclear magnetic resonance nuclear overhauser effect cross-peaks between phenyl moieties of Tam and HPβCD, and downfield shifts in H-3 (0.26) and H-5 (0.29) protons of HPβCD suggested the inclusion of Tam in HPβCD cavity. Transmission-electron microscopy studies of HPβCD and the Tam–HPβCD complex revealed the formation of aggregated nanoassembly at 60–180 nm. Dimethyl thiazol diphenyltetrazolium bromide assay demonstrated 7.37 ± 2.32% cell survival of OAW-42 cells with 3 µg/ml Tam concentration. Conclusion: The Tam–HPβCD nanoassembly entered the cell owing to enhanced permeability and retention property of tumor cell and antiestrogenic Tam and, therefore, resulted in excellent anticancer efficacy in the ovarian cancer cell line.

Beneficial effects of raloxifene and atorvastatin on serum lipids and HDL phospholipids levels of postmenopausal women

Selective oestrogen receptor modulators (raloxifene) and statins (atorvastatin) have been shown to reduce the risk of cardiovascular disease associated with the postmenopausal status. Their beneficial effects may be mediated partly by favourable changes in serum lipids and particular on HDL phospholipid composition. In the present study, individual administration of either raloxifene (Group A) or atorvastatin (Group B) or both (Group C) was compared for a period of 3 months and their effects on total lipids and HDL phospholipids were evaluated. The combined treatment of raloxifene and atorvastatin resulted in profound changes in the majority of serum lipids, including a significant reduction in total cholesterol and triglycerides (P<0.001), a rise in total phospholipids (P<0.01) and a reduction in LDL-C and Apo B levels (P<0.001). Furthermore, Apo A-I was elevated (P<0.001) whereas total HDL phospholipids were significantly increased (P<0.05). Specifically, HDL phosphatidylcholine levels were markedly increased (P<0.001) and HDL lysophosphatidylcholine, sphingomyelin and phosphatidylinositol levels were reduced (P<0.05). A further attempt to evaluate each treatment group was performed and the significance of these results is discussed.

Evidence of improved serum fatty acid profile of postmenopausal women receiving atorvastatin and raloxifene

Raloxifene and atorvastatin have been shown to reduce the risk of cardiovascular disease associated with postmenopausal status and it has been postulated that their effects may be partly mediated by favourable changes in serum lipids and fatty acid composition. In the present study, individual administration of either raloxifene (Group A) or atorvastatin (Group B) or both (Group C) was compared for a period of 3 months and their effects on total lipids and fatty acids composition was evaluated. Postmenopausal women receiving both raloxifene and atorvastatin showed significant changes in the majority of serum lipids with important reductions in total cholesterol (p < 0.001), triglycerides (p < 0.001), LDL-C (p < 0.001) and Apo B levels (p < 0.001). Phospholipids concentrations (p < 0.01) as well as Apo A-I were also significantly raised (p < 0.001). Furthermore, oleic acid (18:1) and linoleic acid (18:2) levels were significantly increased (p < 0.01 and p < 0.001 respectively) followed by a marked reduction in palmitic acid (16:0) and arachidonic acid (20:4) concentrations (p < 0.01 and p < 0.001 respectively). The results of the study indicate that the serum lipid and fatty acid composition in postmenopausal women is influenced by the combined treatment of raloxifene and atorvastatin and a further attempt to evaluate the significance of these results is discussed.

Comparative analysis of oestrogen and raloxifene effects on the phospholipid composition of high density lipoproteins in healthy postmenopausal women

The beneficial effect of selective oestrogen receptor modulators such as raloxifene in cardiovascular disease may be mediated partly by favourable changes in the phospholipid composition of high density lipoprotein (HDL) subclasses. In Group A (oestrogen alone) HDL2 phosphatidylcholine increased (P<0.001), while there was a decrease in HDL2 phosphatidylinositol (P<0.05) and HDL2 phosphatidylethanolamine (P<0.05) compared to controls (baseline). In the same group, HDL3 phosphatidylcholine increased (P<0.001) and HDL3 phosphatidylethanolamine decreased (P<0.01). In Group B (raloxifene) HDL2 phosphatidylcholine increased (P<0.001) as well as HDL2 diphosphatidylglycerol (P<0.01) while there were decreases in HDL2 sphingomyelin (P<0.01) and HDL2 phosphatidylethanolamine (P<0.05). In the same group, an increase in HDL3 phosphatidylcholine (P<0.001) and a reduction in HDL3 phosphatidylinositol (P<0.05) were observed as well as a decrease in HDL3 phosphatidylethanolamine (P<0.01) and HDL3 diphosphatidylglycerol (P<0.05). The significance of these results is discussed.

Protective actions of sex steroid hormones in Alzheimer's disease

Risk for Alzheimer's disease (AD) is associated with age-related loss of sex steroid hormones in both women and men. In post-menopausal women, the precipitous depletion of estrogens and progestogens is hypothesized to increase susceptibility to AD pathogenesis, a concept largely supported by epidemiological evidence but refuted by some clinical findings. Experimental evidence suggests that estrogens have numerous neuroprotective actions relevant to prevention of AD, in particular promotion of neuron viability and reduction of beta-amyloid accumulation, a critical factor in the initiation and progression of AD. Recent findings suggest neural responsiveness to estrogen can diminish with age, reducing neuroprotective actions of estrogen and, consequently, potentially limiting the utility of hormone therapies in aged women. In addition, estrogen neuroprotective actions are also modulated by progestogens. Specifically, continuous progestogen exposure is associated with inhibition of estrogen actions whereas cyclic delivery of progestogens may enhance neural benefits of estrogen. In recent years, emerging literature has begun to elucidate a parallel relationship of sex steroid hormones and AD risk in men. Normal age-related testosterone loss in men is associated with increased risk to several diseases including AD. Like estrogen, testosterone has been established as an endogenous neuroprotective factor that not only increases neuronal resilience against AD-related insults, but also reduces beta-amyloid accumulation. Androgen neuroprotective effects are mediated both directly by activation of androgen pathways and indirectly by aromatization to estradiol and initiation of protective estrogen signaling mechanisms. The successful use of hormone therapies in aging men and women to delay, prevent, and or treat AD will require additional research to optimize key parameters of hormone therapy and may benefit from the continuing development of selective estrogen and androgen receptor modulators.

Effect of a putative ERalpha antagonist, MPP, on food intake in cycling and ovariectomized rats

Estrogens exert many of their behavioral effects by binding to nuclear estrogen receptor (ER) proteins, ERalpha and ERbeta. Recent studies involving ER knockout mice and selective ER agonists suggest that estradiol's anorexigenic effect is mediated via activation of ERalpha. To investigate this hypothesis, we examined whether the presumptive ERalpha antagonist, MPP, could block estradiol's anorexigenic effect. In the first series of experiments, the effects of MPP on food intake and uterine weight were monitored in ovariectomized (OVX) rats treated with either a physiological dose of estradiol benzoate (EB) or a selective ERalpha agonist (PPT). In the final experiment, food intake was monitored following acute administration of MPP in ovarian-intact (cycling) female rats. Contrary to our hypothesis, MPP failed to attenuate either EB's or PPT's ability to decrease food intake and increase uterine weight in OVX rats. However, in ovarian-intact rats, a similar regimen of MPP treatment attenuated the phasic decrease in food intake that is associated with estrus. We conclude that MPP may be a useful tool to investigate the behavioral actions of endogenous estradiol, but may have limited utility in studying the behavioral effects of exogenous estradiol in OVX rats.

Raloxifene plus 17beta-estradiol inhibits proliferation of primary cultured vascular smooth muscle cells and human mammary endothelial cells via the janus kinase/signal transducer and activator of transcription3 cascade

Long-term use of estrogen replacement therapy increases the risk of breast cancer. Presently, we investigated the effects and mechanisms of Raloxifene, a second generation selective estrogen receptor modulator, plus 17beta-estradiol on the proliferation of primary cultured vascular smooth muscle cells (VSMC) and human mammary endothelial cells (HMEC). Raloxifene plus 17beta-estradiol inhibited angiotensin II-induced VSMC proliferation and rapid phosphorylation of STAT(3); these effects were blocked by AG490, the janus kinase/signal transducer and activator of transcription3 (JAK/STAT(3)) inhibitor. STAT(3) production was not affected. In primary cultured HMEC, immunofluorescence identified the ERbeta subtype, but not the ERalpha subtype, in the nucleus. Raloxifene plus 17beta-estradiol inhibited 17beta-estradiol-induced proliferation of HMEC. Western blot analysis established that Raloxifene attenuated the 17beta-estradiol-induced phosphorylation of STAT(3), and that this effect was blocked by AG490. We conclude that Raloxifene plus 17beta-estradiol inhibits the proliferation of VSMC and HMEC through the JAK/STAT(3) cascade, which in primary cultured HMEC may be implemented through ERbeta.

Effectiveness of raloxifene on bone mineral density and serum lipid levels in post-menopausal women with low BMD after discontinuation of hormone replacement therapy

OBJECTIVE

To evaluate the effect of raloxifene on bone mineral density (BMD) and serum lipid levels in post-menopausal women who had discontinued hormone replacement therapy (HRT).

METHODS

Thirty-four post-menopausal women with low BMD who had taken 60 mg of raloxifene daily for 12 months after discontinuing HRT were evaluated retrospectively. Information about their demographics, fracture history, BMD, lipid profiles and adverse events were collected from medical records and intranet database. The outcome measures were changes in the spine (L2-L4) and femur BMD, serum lipid concentrations, fracture rate and tolerability.

RESULTS

The post-menopausal women had a significant increase in their spine (L2-L4) and femur BMD from their baseline BMD [spine, 2.9 +/- 4.6% (P < 0.001); femur, 3.0 +/- 6.6% (P = 0.01)]. Serum low-density lipoprotein (LDL) cholesterol was significantly reduced by 22.6% below baseline after 12 months (P = 0.007). No fractures were observed during therapy. Raloxifene was well tolerated. The most common adverse event was hot flash, which was generally mild.

CONCLUSIONS

Raloxifene increases BMD at important skeletal sites, and lowers LDL cholesterol with tolerable adverse events.

The Cardiovascular Effects of Selective Estrogen Receptor Modulators

Coronary artery disease (CAD) is the main contributor of mortality among postmenopausal women. Menopause-associated estrogen deficiency has both metabolic and vascular consequences that increase the risk for CAD. Hormone therapy (HT) has been reported to have a beneficial effect on metabolic and vascular factors influencing the incidence of CAD. Although observational studies have reported that HT reduces significantly the risk for CAD, randomized clinical trials (WHI, HERS, ERA) have questioned the efficacy of HT in primary and secondary CAD prevention despite confirming the lipid-lowering effect of HT. In the aftermath of the WHI, increased interest has been given to the action of selective estrogen receptor modulators (SERMs) and their effect on the cardiovascular system. The chemical structure of SERMs, either triphenylethilyn (tamoxifen) or benzothiophene (raloxifene) derivatives, differs from that of estrogens. SERMs are nonsteroidal molecules that bind, with high affinity, to the ER. SERMs induce conformational changes to the ligand-binding domain of the ER that modulate the ability of the ER to interact with coregulator proteins. The relative balance of coregulators within a cell determines the transcriptional activity of the receptor-ligand complex. SERMs therefore may express an estrogen-agonist or estrogen-antagonist effect depending on the tissue targeted. SERMs express variable effects on the metabolic and vascular factors influencing the incidence of CAD. SERMs have been reported to modulate favorably the lipid-lipoprotein profile. Toremifene expresses the most beneficial effect followed by tamoxifene and raloxifene, while ospexifene and HMR-3339 have the least effect and may even increase triglycerides. Raloxifene and tamoxifene decrease serum homocysteine levels and C-reactive proteins (CRP), which are both markers of CAD risk. Raloxifene has been reported to increase the nitric oxide (NO)-endothelin (ET)-1 ratio and, thus, contribute to proper endothelial function and vasodilation. Toremifene has no effect on the NO-ET-1 ratio. Finally, raloxifene decreases the vascular cell adhesion molecules and the inflammatory cytokines TNF-alpha and IL-6. Of the SERMs, raloxifene has had the most extensive evaluation regarding the effect on the vascular wall of endothelium. Although not confirmed by large clinical trials, raloxifene has been reported to have an effect on the cohesion of the intercellular junction (VE-cadherin) and the synthesis-degradation of extracellular matrix (MMP-2). The Multiple Outcomes Raloxifene Evaluation (MORE) study has reported that raloxifene may have a cardioprotective effect when administered to postmenopausal women at high risk for CAD disease.

Solid-phase synthesis of 2,3-disubstituted benzo[b]thiophenes and benzo[b]selenophenes

A concise and efficient solid-phase synthesis of benzo[b]thiophenes and benzo[b]selenophenes based on a combination of palladium-mediated coupling and iodocyclization protocols has been developed.

Protective effect of plant extract from Onobrychis ebenoides on ovariectomy-induced bone loss in rats

OBJECTIVE

Certain plant extracts have been the object of recent studies due to their mild estrogenic action and their possible potential role in osteoporosis prevention and/or treatment. The present study was undertaken to investigate the possible protective effect of the aqueous solution of the plant Onobrychis ebenoides, with proven in vitro mild estrogenic action, on bone mass loss of the ovariectomized (Ovx) rat experimental model of osteoporosis.

METHODS

Forty intact female mature (10-month-old) Wistar rats were separated into three groups: Ovx, Ovx plus plant extract (Ph) and sham-operated (control). Ph administration in the drinking water at a dose of 300 mg/kg body weight/day commenced immediately after Ovx. Bone mineral density (BMD) values, percentage change from the baseline measurement and histomorphometry of the tibia, as well as body and uterine weight, were examined and compared between groups.

RESULTS

Comparison of BMD absolute values of the whole tibia of Ovx + Ph and Ovx animals at both 3 and 6 months post-Ovx were highly significant (p < 0.0005), showing a protective effect on treated animals. The extract did not appear to have such a beneficial effect on BMD of the proximal tibia of the treated animals compared to the Ovx animals after 3 months; however, a significant protective effect was observed at 6 months post-Ovx in treated animals compared to the Ovx (p = 0.015). When the % changes from baseline measurement of the whole tibia of Ovx + Ph and controls were compared, there was no significant difference at 3 or 6 months, demonstrating a highly protective effect; the respective comparisons of proximal tibia % changes did not display such protection. Body and uterine weight comparisons showed no significant difference between Ovx and treated rats, whereas, the level of significance for each group compared to controls was p < 0.0005.

CONCLUSIONS

The Ph studied showed a highly significant protective effect on BMD of the whole tibia of Ovx rats after 3 and 6 months of treatment, compared to the non-treated animals. Its effect on the proximal tibia was less pronounced, but also statistically significant compared to non-treated rats after 6 months. The lack of significant effect on body and uterine weight is in favor of its selective estrogen receptor modulator-like activity, and merits further studies.

Tamoxifen fails to affect central serotonergic tone but increases indices of anxiety in female rhesus macaques

The selective estrogen receptor modulator (SERM), tamoxifen, effectively slows the progression of estrogen-positive breast cancer and aids in the prevention of cancer in at-risk women. Tamoxifen is well characterized with regards to its effects on breast cancer, but its effects on other estrogen-related systems, particularly neural circuits regulating brain function and mood, are poorly understood. Using ovariectomized rhesus monkeys, we examined the effects of tamoxifen, with and without estrogen replacement therapy (ERT), on social behavior and central serotonin (5HT) systems thought to influence these behaviors. Relative to placebo treatments, estrogen treatment increased serotonergic tone, based on response in prolactin and cortisol to fenfluramine, a 5HT releasing agent. Tamoxifen neither blocked nor enhanced this effect, indicating it to be neither an antagonist nor an agonist on serotonergic activity. In contrast, CSF measures of the 5HT metabolite, 5HIAA, were not significantly affected by treatment. Tamoxifen-treated animals showed increases in measures of anxiety, compared with ERT-treated animals, suggesting that this SERM may be anxiogenic. Co-treatment with estrogen attenuated the anxiogenic properties of tamoxifen. These data show that tamoxifen administration increased anxiety levels, but the affect was not associated with differences in central levels of the serotonin tone.

Herbal extract prevents bone loss in ovariectomized rats

This research aims to test a new drug candidate based on a traditional medicinal herb, F1, an herbal extract obtained from Astragalus membranaceus and its main ingredient, 1-monolinolein that may have fewer side effects and less uterine hypertrophy. In vitro experiments, human osteoblast-like cell lines, MG-63 and Saos-2, were analyzed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and an alkaline phosphatase (ALP) assays. Mouse osteoclasts were induced through a calcium-deficient diet and inhibition effects were measured. In vivo experiments were done using ovariectomized (OVX) rats for 9 weeks. At necropsy, uterus weights were measured, trabecular bone area (TBA) of tibia and lumbar vertebra were measured bone histomorphology. In results, cell proliferation and ALP activity in Saos-2 by ether F1 or 1-monolinolein did not increased significantly compared to the control. The F1 inhibited osteoclast development (IC25 = 3.37 x 10(-5) mg/mL) less than 17beta-estradiol. The OVX rats administered F1 (2 mg/kg/day and 10 mg/kg/day) showed an increase in TBA of the tibia significantly (136.3 +/- 4.2% and 138.5 +/- 10.3% of control). In conclusions, the herbal extract, F1 inhibited tibia and lumbar bone loss and did not cause uterine hypertrophy. However, 1-monolinolein, the main ingredient of the herbal extract, did not inhibit bone loss.

Comparative study of the short-term effects of a novel selective estrogen receptor modulator, ospemifene, and raloxifene and tamoxifen on rat uterus

To investigate the differential short-term effects of selective estrogen receptor (ER) modulators (SERMs) on uterus, we treated adult ovariectomized rats with a novel SERM, ospemifene (Osp), two previously established SERMs (tamoxifen and raloxifene (Ral)) and estradiol. The expression of two estrogen-regulated early response genes c-fos and vascular endothelial growth factor (VEGF), and DNA synthesis were analysed at 1-24 h after treatment of ovariectomized rats. Induction of c-fos mRNA by each of the SERMs showed a biphasic pattern with peaks at 3 and 20 h, respectively. The maximum level of VEGF mRNA was observed at 1 h after raloxifene and 6 h after tamoxifen or ospemifene treatment. Maximum levels of the c-fos and VEGF mRNA after raloxifene treatment were higher than those seen after treatments with E2 or a corresponding dose of tamoxifen or ospemifene. DNA synthesis was significantly increased by ospemifene, tamoxifen and raloxifene both in luminal and glandular epithelium. The stimulation was transient, peaking at 16 h. In comparison, the maximum level observed at 16 h after E2 treatment sustained at least until 24 h. DNA synthesis in stromal cells was increased by the SERMs but not by E2 at 24 h. When treated together with E2, the SERMs were able to antagonise E2-stimulated DNA synthesis at 16 h. Our results demonstrate that the initial response of uterus to ospemifene, raloxifene and tamoxifen includes activation of early response genes and even transient stimulation of DNA synthesis in spite of their different long-term effects. However, the early stimulatory events may be mediated by different mechanisms leading to diverging pathways in various tissue compartments and development of differential SERM-specific long-term responses of uterus.