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Raloxifene prevents cardiac hypertrophy and dysfunction in pressure-overloaded mice.

Ogita H, Node K, Liao Y, Ishikura F, Beppu S, Asanuma H, Sanada S, Takashima S, Minamino T, Hori M, Kitakaze M.

Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Japan.

17beta-estradiol reduces myocardial hypertrophy and left ventricular mass, suggesting that the selective estrogen receptor modulator raloxifene may have similar effects. However, it is not clear whether raloxifene inhibits both cardiac hypertrophy and dysfunction. We used transverse aortic-banded mice to produce pressure-overload cardiac hypertrophy and used neonatal rat ventricular cardiomyocytes to investigate the cellular mechanisms of raloxifene on cardiac hypertrophy. Left ventricular mass and fractional shortening of mice hearts were measured by transthoracic echocardiography. Protein synthesis of cardiomyocytes was evaluated by incorporation of [3H]leucine into cardiomyocytes exposed to angiotensin II. Phosphorylation of mitogen-activated protein (MAP) kinase was also observed in cardiomyocytes. Raloxifene prevented increases in left ventricular mass and decreases of fractional shortening at 4 weeks after aortic banding. Pretreatment with raloxifene before angiotensin II stimulation inhibited the increase in [3H]leucine incorporation into neonatal rat cardiomyocytes in a concentration-dependent manner. This inhibition was partially but not significantly attenuated by N(G)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase, and completely abolished by ICI182780, an estrogen receptor antagonist. Although the phosphorylation of p38 MAP kinase, c-Jun N-terminal kinase (JNK), or extracellular signal-regulated protein kinase (ERK) in cardiomyocytes was significantly increased by angiotensin II stimulation as compared with the control, pretreatment with raloxifene attenuated p38 MAP kinase phosphorylation, but neither JNK nor ERK phosphorylation. We conclude that raloxifene inhibits cardiac hypertrophy and dysfunction and that the inhibition of p38 MAP kinase phosphorylation after the stimulation of estrogen receptors may be involved in the cellular mechanisms of this agent.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14676219&dopt=Abstract raloxifene Evista



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Impact of the selective estrogen receptor modulator, raloxifene, on neuronal survival and outgrowth following toxic insults associated with aging and Alzheimer's disease.

O'Neill K, Chen S, Brinton RD.

Department of Molecular Pharmacology and Toxicology, Pharmaceutical Sciences Center, University of Southern California, Los Angeles, CA 90033, USA.

The current study investigated the estrogen agonist-antagonist properties of the selective estrogen receptor modulator, raloxifene (Ral), on neuroprotection and neuronal markers of memory function. Low concentrations of raloxifene significantly reduced basal markers of membrane damage and had no deleterious effect on neuronal survival. However, high concentrations of raloxifene (1000-5000 ng/ml) induced a significant increase in markers of membrane damage and a significant decrease in neuronal survival. At subtoxic concentrations, raloxifene induced significant neuroprotection against beta amyloid(25-35)-, hydrogen peroxide- and glutamate-induced toxicity. Results of analyses to determine whether raloxifene acted competitively or synergistically with 17 beta-estradiol revealed that a postmenopausal level of 17 beta-estradiol exerted a significantly greater increase in neuronal survival against beta-amyloid- and glutamate-induced toxicity compared to 50 ng/ml raloxifene. The combined presence of raloxifene and 17 beta-estradiol was significantly neuroprotective against beta amyloid(25-35)- and glutamate-induced excitotoxicity but was significantly lower than 17 beta-estradiol alone while not significantly different than raloxifene alone. Morphologic analyses demonstrated that raloxifene significantly increased neuronal outgrowth of hippocampal neurons within a narrow dose range that was blocked by a glutamate NMDA receptor antagonist. Raloxifene did not promote the outgrowth of basal forebrain or cortical neurons. Results of this study indicate that raloxifene exerted partial estrogen agonist action in the absence of 17 beta-estradiol whereas in the presence of 17 beta-estradiol, raloxifene exerted a mixed estrogen agonist-antagonist effect.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14697319&dopt=Abstract raloxifene Evista



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Estradiol and selective estrogen receptor modulators differentially regulate target genes with estrogen receptors alpha and beta.

Kian Tee M, Rogatsky I, Tzagarakis-Foster C, Cvoro A, An J, Christy RJ, Yamamoto KR, Leitman DC.

Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Francisco, San Francisco, California 94143-0556, USA.

Estrogens and selective estrogen receptor modulators (SERMs) interact with estrogen receptor (ER) alpha and beta to activate or repress gene transcription. To understand how estrogens and SERMs exert tissue-specific effects, we performed microarray analysis to determine whether ERalpha or ERbeta regulate different target genes in response to estrogens and SERMs. We prepared human U2OS osteosarcoma cells that are stably transfected with a tetracycline-inducible vector to express ERalpha or ERbeta. Western blotting, immunohistochemistry, and immunoprecipitation studies confirmed that U2OS-ERalpha cells synthesized only ERalpha and that U2OS-ERbeta cells expressed exclusively ERbeta. U2OS-ERalpha and U2OS-ERbeta cells were treated either with 17beta-estradiol (E2), raloxifene, and tamoxifen for 18 h. Labeled cRNAs were hybridized with U95Av2 GeneChips (Affymetrix). A total of 228, 190, and 236 genes were significantly activated or repressed at least 1.74-fold in U2OS-ERalpha and U2OS-ERbeta cells by E2, raloxifene, and tamoxifen, respectively. Most genes regulated in ERalpha cells in response to E2, raloxifene, and tamoxifen were distinct from those regulated in ERbeta cells. Only 38 of the 228 (17%) genes were regulated by E2 in both U2OS-ERalpha and U2OS-ERbeta cells. Raloxifene and tamoxifen regulated only 27% of the same genes in both the ERalpha and ERbeta cells. A subset of genes involved in bone-related activities regulated by E2, raloxifene, and tamoxifen were also distinct. Our results demonstrate that most genes regulated by ERalpha are distinct from those regulated by ERbeta in response to E2 and SERMs. These results indicate that estrogens and SERMs exert tissue-specific effects by regulating unique sets of targets genes through ERalpha and ERbeta

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14699072&dopt=Abstract raloxifene Evista



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Potent inhibition of human liver aldehyde oxidase by raloxifene.

Obach RS.

Pharmacokinetics, Pharmacodynamics, and Drug Metabolism, Pfizer Global Research and Development, Groton Laboratories, Groton, CT 06340, USA. obachrs groton.pfizer.com

The selective estrogen receptor modulator, raloxifene, has been demonstrated as a potent uncompetitive inhibitor of human liver aldehyde oxidase-catalyzed oxidation of phthalazine, vanillin, and nicotine-Delta1'(5')-iminium ion, with K(i) values of 0.87 to 1.4 nM. Inhibition was not time-dependent. Raloxifene has also been shown to be a noncompetitive inhibitor of an aldehyde oxidase-catalyzed reduction reaction of a hydroxamic acid-containing compound, with a K(i) of 51 nM. However, raloxifene had only small effects on xanthine oxidase, an enzyme related to aldehyde oxidase. In addition, several other compounds of the same therapeutic class as raloxifene were examined for their potential to inhibit aldehyde oxidase. However, none were as potent as raloxifene, since IC(50) values were orders of magnitude higher and ranged from 0.29 to 57 micro M. In an examination of analogs of raloxifene, it was shown that the bisphenol structure with a hydrophobic group on the 3-position of the benzthiophene ring system was the most important element that imparts inhibitory potency. The relevance of these data to the mechanistic understanding of aldehyde oxidase catalysis, as well as to the potential for raloxifene to cause drug interactions with agents for which aldehyde oxidase-mediated metabolism is important, such as zaleplon or famciclovir, is discussed.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14709625&dopt=Abstract raloxifene Evista



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Glycosaminoglycan profile in bladder and urethra of castrated rats treated with estrogen, progestogen, and raloxifene.

de Deus JM, Girao MJ, Sartori MG, Baracat EC, Rodrigues de Lima G, Nader HB, Dietrich CP.

Departments of Gynecology and Biochemistry, Federal University of Sao Paulo, Sao Paulo, Brazil.

OBJECTIVE: This study was undertaken to evaluate the action of conjugated equine estrogens alone, medroxyprogesterone, the combination of these estrogens with progestogens, and of raloxifene on the glycosaminoglycan profile in the bladder and urethra of adult oophorectomized rats in comparison with noncastrated rats. STUDY DESIGN: Sixty adult rats, of which 50 were submitted to bilateral oophorectomy, were studied. After 4 days, the latter were assigned to five groups of 10 animals each. For 30 consecutive days the following treatments were given: group 1, conjugated equine estrogens; group 2, conjugated equine estrogens combined with medroxyprogesterone acetate; group 3, medroxyprogesterone; group 4, raloxifene; and group 5, placebo. Thereafter the bladders and urethras of the animals were removed, processed to yield a dry powder of which the sulfated glycosaminoglycan content was determined by densitometry after agarose gel electrophoresis and that of hyaluronic acid by a fluorimetric assay. RESULTS: Glycosaminoglycans found in the bladder and urethra were dermatan sulfate, heparan sulfate, and hyaluronic acid. In the bladder, hypoestrogenism or replacement with estrogens led to a lower sulfated glycosaminoglycan content. Replacement with estrogens and/or medroxyprogesterone reverted this effect. Hypoestrogenism decreased the dermatan sulfate/heparan sulfate ratio and reduced hyaluronic acid content. Estrogen therapy reverted this alteration and medroxyprogesterone addition annulled the estrogenic effect. In the urethra, castration did not alter hyaluronic acid content and sulfated glycosaminoglycan content, but raloxifene decreased the latter. CONCLUSION: Castrated rats had a decrease in sulfated glycosaminoglycans and hyaluronic acid content in the bladder. Hormonal replacement altered the quantity and quality of glycosaminoglycans. In the urethra, raloxifene reduced sulfated glycosaminoglycans.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14710093&dopt=Abstract raloxifene Evista



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Estrogen enhances cystatin C expression in the macaque vagina.

Slayden OD, Hettrich K, Carroll RS, Otto LN, Clark AL, Brenner RM.

Oregon National Primate Research Center, Beaverton, Oregon 97006, USA. slaydeno ohsu.edu

Cystatin C is a secreted inhibitor of cysteine proteinases that participates in extracellular matrix remodeling. Whether hormones affect its expression in the vagina was unknown. Consequently, we examined the effects of estradiol (E(2)), progesterone (P), and raloxifene on vaginal cystatin C in rhesus macaques. In experiment 1, ovariectomized animals were treated sequentially with E(2) (14 d) and E(2) + P (14 d) to induce 28-d menstrual cycles. Vaginal samples were collected on d 6, 8, 14, and 28 of the induced cycle. Some cycled animals were deprived of both E(2) + P for 28 d. In experiment 2, ovariectomized animals were treated for 5 months with E(2) alone, E(2) + P, raloxifene, or left untreated. Total RNA from the vaginal wall was analyzed for the cystatin C transcript with a commercially prepared cDNA array and semiquantitative RT-PCR. Vaginal cryosections were analyzed by in situ hybridization for cystatin C transcript and by immunocytochemistry for the protein. E(2) treatment significantly (5-fold; P < 0.05) increased expression of cystatin C transcript over the levels in the hormone-deprived controls, and cotreatment with P (E(2) + P) blocked this effect. Raloxifene treatment did not affect cystatin C expression. In situ hybridization and immunocytochemistry revealed that cystatin C was localized in fibroblasts and smooth muscle cells throughout the vaginal wall but not in smooth muscle cells of arteries or levator ani myocytes. In summary, E(2) increased vaginal cystatin C expression in the fibroblasts and smooth muscle bundles, P suppressed this effect, and raloxifene had no effects on cystatin C. Elevated cystatin C, by suppressing cysteine proteinase activity, may strengthen the vaginal wall and mitigate the potential for pelvic floor prolapse.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14764809&dopt=Abstract raloxifene Evista