Administration Of 17beta-estradiol Research Articles

Effects of Hormone Replacement Therapy on Low Bone Mineral Density in Adolescents and Young Women with Hypogonadism: Comparison of Oral and Transdermal 17 Beta-Estradiol Administration

To evaluate the effects of physiological dose 17 beta-estradiol (E2) replacement on low bone mineral density (BMD) and compare the results of oral and transdermal (TD) E2 administration in adolescents and young women with hypogonadism DESIGN, SETTING, AND PARTICIPANTS: We retrospectively reviewed the medical records of patients aged 15 to 24 years who were diagnosed with hypogonadism, who had begun receiving oral or TD E2 replacement, and whose initial dual-energy X-ray absorptiometry scan detected a lumbar spine BMD Z-score of -1 or lower between 2014 and 2018. The patients were divided into 2 groups according to the E2 route of administration as those who received 2 mg orally (Group 1) and 0.1 mg TD (Group 2). None MAIN OUTCOME MEASURE: BMD scans of the patients at baseline and repeated within 2 years after E2 replacement RESULTS: In total, 43 patients who met the inclusion criteria were included in the study. Two groups did not differ for BMD scores at baseline. A significant improvement in BMD was observed with physiological dose E2 replacement in both groups. Mean BMD Z-score increased by +0.7 (95% CI, 0.47-0.93) in response to TD E2 administration, compared with +0.41 (95% CI, 0.25-0.58) during oral E2 replacement (P=.037). We conclude that physiological dose E2 replacement, even within a short period of 2 years, has a significant beneficial effect on bone mass acquisition on the lumbar spine. Our study also demonstrates the possible superiority of TD E2 replacement over the oral route in increasing lumbar spine BMD.

Abstract 218: Pathophysiological Significance of Browning of Perivascular Adipose Tissue in the Development of Atherosclerosis

Background: Perivascular adipose tissue (PVAT) possibly plays a pivotal role in the development of atherosclerosis through its direct local action to the vessels. However, its physiological and molecular mechanisms are less understood. Visceral and subcutaneous white adipose tissues exert a brown adipose tissue-like phenotype under specific conditions such as cold exposure, i.e. browning. We here investigated the pathophysiological role of browning of PVAT against the development of atherosclerosis after endovascular injury. Methods and Results: Endovascular injury was generated by wire insertion into the femoral artery of C57BL/6 female mice. Transcriptome analysis revealed robust upregulation of brown adipose tissue markers such as Ucp1 , Elovl3 , Cox8b and Cidea in injured arteries. Notably, administration of an atheroprotective agent, 17-beta estradiol, significantly inhibited these changes; Ucp1 was the most down-regulated gene by 17-beta estradiol administration in the entire gene set (log2-fold change = -6.58, false discovery rate = 0.003). Consistently, the upregulation of browning markers after endovascular injury and these inhibitions by 17-beta estradiol were confirmed in PVAT by quantitative real-time PCR, western blot and immunohistochemical staining. The present study also demonstrated that vascular injury promotes macrophage infiltration in PVAT accompanied with upregulation of inflammatory cytokine production. Furthermore, we confirmed spatiotemporal synchronicity between browning and inflammation in PVAT by immunohistochemical staining. Conclusions: We observed that endovascular injury elicits browning in PVAT accompanied with exacerbated inflammation, and that atheroprotective 17-beta estradiol strongly inhibits this phenomenon. These findings may provide novel insights into pathogenesis of the atherosclerosis.

Estrogen administration modulates hippocampal GABAergic subpopulations in the hippocampus of trimethyltin-treated rats.

Given the well-documented involvement of estrogens in the modulation of hippocampal functions in both physiological and pathological conditions, the present study investigates the effects of 17-beta estradiol (E2) administration in the rat model of hippocampal neurodegeneration induced by trimethyltin (TMT) administration (8 mg/kg), characterized by loss of pyramidal neurons in CA1, CA3/hilus hippocampal subfields, associated with astroglial and microglial activation, seizures and cognitive impairment. After TMT/saline treatment, ovariectomized animals received two doses of E2 (0.2 mg/kg intra-peritoneal) or vehicle, and were sacrificed 48 h or 7 days after TMT-treatment. Our results indicate that in TMT-treated animals E2 administration induces the early (48 h) upregulation of genes involved in neuroprotection and synaptogenesis, namely Bcl2, trkB, cadherin 2 and cyclin-dependent-kinase-5. Increased expression levels of glutamic acid decarboxylase (gad) 67, neuropeptide Y (Npy), parvalbumin, Pgc-1α and Sirtuin 1 genes, the latter involved in parvalbumin (PV) synthesis, were also evident. Unbiased stereology performed on rats sacrificed 7 days after TMT treatment showed that although E2 does not significantly influence the extent of TMT-induced neuronal death, significantly enhances the TMT-induced modulation of GABAergic interneuron population size in selected hippocampal subfields. In particular, E2 administration causes, in TMT-treated rats, a significant increase in the number of GAD67-expressing interneurons in CA1 stratum oriens, CA3 pyramidal layer, hilus and dentate gyrus, accompanied by a parallel increase in NPY-expressing cells, essentially in the same regions, and of PV-positive cells in CA1 pyramidal layer. The present results add information concerning the role of in vivo E2 administration on mechanisms involved in cellular plasticity in the adult brain.

Role of 17 beta-estradiol administration on altered age related membrane functions in female rats: A therapeutic potential drug for atherosclerosis

Role of 17 beta-estradiol administration on altered age related membrane functions in female rats: A therapeutic potential drug for atherosclerosis

Impact of a six-week olive oil supplementation in healthy adults on urinary proteomic biomarkers of coronary artery disease, chronic kidney disease and diabetes

Impact of a six-week olive oil supplementation in healthy adults on urinary proteomic biomarkers of coronary artery disease, chronic kidney disease and diabetes

IMPACTO CLÍNICO DE ESTROGENOTERAPIA RESIDUAL EN POSMENOPÁUSICAS

Objetivos: a) Determinar la concentración plasmática residual de estrógeno después de siete días de culminada su administración en la mujer posmenopáusica. b) Precisar si hay diferencia de concentración plasmática según administración oral (0, 625mg de estrógenos conjugados) o transdérmica (50 mg 17 beta estradiol). c) Estudiar el impacto clínico de la concentración plasmática residual con el índice Posmenopáusico de Blatt Kupperman (IMBK) MATERIAL Y MÉTODOS: Se efectuó dosaje de concentración plasmática de estrógenos pretratamiento y a los 7 días postratamiento de dos y cuatro meses, usando vía oral y transdérmica; se evaluó sintomatología en esos tres momentos con el IMBK. RESULTADOS: La concentración plasmática de estrógenos, a siete días de concluida la estrogenoterapia, se mantiene por encima de la basal, luego de dos y cuatro meses de tratamiento. El IMBK disminuye en 70%, independiente de la concentración plasmática residual de estrógenos y de la vía de administración. CONCLUSIONES . La concentración plasmática de estrógenos se mantiene por encima de la basal a 7 días de culminada la estrogenoterapia, siendo mayor cuando se usa vía transdérmica, con notable mejoría según IMBK, independientemente de la vía de administración y concentración plasmáitica de estrógenos.

Duodenumda Ovaryum Steroidlerinin Etkisinde Nitrik Oksidin Rolü

Summary The purpose of this study is to determine the distribution and expression of nNOS, eNOS and iNOS and to evaluate the role of ovarian steroids in NOS expressions in the duodenum tissues of rats. Rats in the control group (Ov group) were injected intramuscularly with sesame oil for 10 days, whereas rats in the first, second, and third experimental groups received intramuscular administration of progesterone (P group), 17β-estradiol (E2 group) and 17beta-estradiol and progesterone (E2 + P group), respectively. According to the results of an immunohistochemical evaluation, a severe nNOS expression was observed in both the crypts and nerve fibers of the duodenum in the Ov, P and E2 groups but decreased in the E2 + P group. It was determined that iNOS expression increased in the surface epithelial cells and crypts of P group while it only decreased in crypts of E2 group. There was severe eNOS expression in crypts in all treatment groups, while it only increased in the surface epithelial cells in the E2 group. The results of the current experiment suggest that the effect of ovarian steroids on duodenum absorbtion and microvascular protection can be mediated by crypt and epithelial nNOS, iNOS and eNOS expressions in rats. Besides the estradiol and progesterone administration together inhibit nNOS activitiy in the duodenum.

Temporary Placement of a Covered, Retrievable, Barbed Stent for the Treatment of Hormone-induced Benign Prostatic Hyperplasia: Technical Feasibility and Histologic Changes in Canine Prostates

To evaluate the technical feasibility of a covered, retrievable, barbed prostatic stent and to determine stent-induced histologic changes of the prostate in canine benign prostatic hyperplasia (BPH). BPH was induced in 8 male beagles by administration of dihydrotestosterone and beta-estradiol. Under fluoroscopy guidance, covered, retrievable, barbed stents were placed in the prostatic urethras. Urethrograms were obtained every three to 4 weeks until sacrifice. The stents were removed 8 weeks after placement. The dogs were sacrificed immediately (group A, n = 4) and 8 weeks after stent removal (group B, n = 4). Histologic changes of prostates were microscopically evaluated. Stent placement was technically successful in all dogs. The diameters of the prostatic urethra were 14.1 mm + or - 0.5 and 13.7 mm + or - 0.5 on urethrograms obtained immediately after and 8 weeks after stent removal (P = .268). Stent removal was successful in all dogs except one, in which the stent was obstructed by stone formation. Small sandy stones were identified attached to the removed stents of two dogs. Histologic examination revealed extensive prostatic glandular atrophy involving 95.1% + or - 2.2 (group A) and 94.5% + or - 2.4 (group B) of entire prostate (P = .773). A covered, retrievable, barbed prostatic stent seems to be feasible for use in hormone-induced canine BPH. The stent induced prostatic urethral dilatation, and extensive prostatic glandular atrophy persisted up to 8 weeks after stent removal.

Effect of Endogenous Androgens on 17β-Estradiol-Mediated Protection after Spinal Cord Injury in Male Rats

Several groups have recently shown that 17beta-estradiol is protective in spinal cord injury (SCI). Testosterone can be aromatized to 17beta-estradiol and may increase estrogen-mediated protection. Alternatively, testosterone has been shown to increase excitotoxicity in models of central nervous system (CNS) injury. These experiments test the hypothesis that endogenous testosterone in male rats alters 17beta-estradiol-mediated protection by evaluating a delayed administration over a clinically relevant dose range and manipulating testicular-derived testosterone. Adult male Sprague Dawley rats were either gonadectomized or left gonad-intact prior to SCI. SCI was produced by a midthoracic crush injury. At 30 min post SCI, animals received a subcutaneous pellet of 0.0, 0.05, 0.5, or 5.0 mg of 17beta-estradiol, released over 21 days. Hindlimb locomotion was analyzed weekly in the open field. Spinal cords were collected and analyzed for cell death, expression of Bcl-family proteins, and white-matter sparing. Post-SCI administration of the 0.5- or 5.0-mg pellet improved hindlimb locomotion, reduced urinary bladder size, increased neuronal survival, reduced apoptosis, improved the Bax/Bcl-xL protein ratio, and increased white-matter sparing. In the absence of endogenous testicular-derived androgens, SCI induced greater apoptosis, yet 17beta-estradiol administration reduced apoptosis to the same extent in gonadectomized and gonad-intact male rats. These data suggest that delayed post-SCI administration of a clinically relevant dose of 17beta-estradiol is protective in male rats, and endogenous androgens do not alter estrogen-mediated protection. These data suggest that 17beta-estradiol is an effective therapeutic intervention for reducing secondary damage after SCI in males, which could be readily translated to clinical trials.

Mechanism of salutary effects of estrogen on cardiac function following trauma-hemorrhage: Akt-dependent HO-1 up-regulation*

Because administration of 17beta-estradiol following trauma-hemorrhage improves cardiovascular responses, we investigated whether the salutary effects of 17beta-estradiol on cardiac function are mediated via Akt-dependent heme oxygenase-1 up-regulation under those conditions. Experimental animal study. University laboratory. Male Sprague-Dawley rats. Rats underwent trauma-hemorrhage (mean blood pressure approximately 40 mm Hg for 90 mins) followed by fluid resuscitation. Before resuscitation, rats received either vehicle, 17beta-estradiol (1 mg/kg), or 17beta-estradiol plus the phosphoinositide 3-kinase inhibitor wortmannin (1 mg/kg). At 2 hrs after trauma-hemorrhage or sham operation, the rats were killed. Cardiac function, heart tissue myeloperoxidase activity, cardiac and circulatory cytokine levels, cardiac intercellular adhesion molecule-1, and chemokine levels were measured. Cardiac Akt and heme oxygenase-1 were also determined. We found that 17beta-estradiol prevented the trauma-hemorrhage-induced impairment in cardiac function and increase in cardiac myeloperoxidase activity. Cardiac and systemic interleukin-6 and tumor necrosis factor-alpha levels as well as cardiac intercellular adhesion molecule-1, cytokine-induced neutrophil chemoattractant-1, and macrophage inflammatory protein-2 contents were increased following trauma-hemorrhage, which were normalized by 17beta-estradiol. Administration of 17beta-estradiol following trauma-hemorrhage restored cardiac Akt phosphorylation and further increased heme oxygenase-1 expression. Coadministration of wortmannin following trauma-hemorrhage abolished the previous effects by 17beta-estradiol. These results suggest that the 17beta-estradiol-meditated improvement in cardiac function following trauma-hemorrhage occurs via Akt-dependent heme oxygenase-1 up-regulation.

Signal transducer and activator of transcription 3–stimulated hypoxia inducible factor-1α mediates estrogen receptor-α–induced mesenchymal stem cell vascular endothelial growth factor production

Vascular endothelial growth factor, a critical factor in angiogenesis, mediates stem cell paracrine protective effects on ischemic myocardium. Studies on the role of sex in stem cell function have demonstrated that female mesenchymal stem cells produce greater vascular endothelial growth factor and provide better cardiac protection compared with male mesenchymal stem cells. The purpose of this study was to determine the mechanisms by which estrogen affects mesenchymal stem cell function as a potential therapeutic measure during ex vivo expansion, before therapeutic use. A single-step purification method using adhesion to cell culture plastic was adopted to isolate mesenchymal stem cells from wild-type, estrogen receptor-alpha knockout, estrogen receptor-beta knockout, and signal transducer and activator of transcription 3 knockout mice. Mesenchymal stem cells were treated with or without 17beta-estradiol, estrogen receptor-alpha agonist (propyl pyrazoletriol), and estrogen receptor-beta agonist (diarylpropionitrile). 17beta-estradiol significantly increased mesenchymal stem cell vascular endothelial growth factor production in a dose-dependent manner. Both estrogen receptor-alpha and estrogen receptor-beta were expressed in mesenchymal stem cells. Administration of 17beta-estradiol or estrogen receptor-alpha agonist (not estrogen receptor-beta agonist) elevated mesenchymal stem cell vascular endothelial growth factor, hypoxia inducible factor-1alpha expression, and signal transducer and activator of transcription 3 activation. However, these effects were neutralized in estrogen receptor-alpha knockout mesenchymal stem cells, not estrogen receptor-beta knockout. Signal transducer and activator of transcription 3 knockout abolished estrogen receptor-alpha-induced hypoxia inducible factor-1alpha and subsequent vascular endothelial growth factor production. 17beta-estradiol-induced vascular endothelial growth factor production from mesenchymal stem cells appears to be mediated through estrogen receptor-alpha-activated signal transducer and activator of transcription 3-mediated hypoxia inducible factor-1alpha expression.

Differential actions of estrogen and SERMs in regulation of the actin cytoskeleton of endometrial cells

Estrogen and selective estrogen receptor modulators (SERMs) differentially impact endometrial cell function, however, the biological basis of these differences is not established. Deregulated cell adhesion to the extracellular matrix, cell movement and invasion are related to endometrial disorders, such as endometriosis or endometrial cancer. Remodeling of the actin cytoskeleton is required to achieve cell adhesion and movement. Estrogen receptor (ER) regulates actin and cell membrane remodeling through extra-nuclear signaling cascades. In this article, we show that administration of 17beta-estradiol (E2) and tamoxifen (TAM) to immortalized Ishikawa endometrial cells or to human endometrial stromal cells (ESC) results in remodeling of actin fibers and cell membrane. This is linked to rapid phosphorylation on Thr(558) of the actin-binding protein moesin and enhanced migration and invasion of normal and Ishikawa cells. Raloxifene (RAL) does not result in moesin activation or actin remodeling. When endometrial cells are exposed to E2 in the presence of TAM or RAL, both SERMs interfere with the recruitment of moesin, with the remodeling of the cytoskeleton, and with cell movement and migration induced by E2. The differential actions of E2, TAM and RAL are linked to a distinct modulation of the extra-nuclear signaling of ER to G proteins and to the Rho-associated kinase. These findings increase our understanding of the actions of estrogen and SERMs in endometrial cells and highlight potential molecular targets to interfere with the estrogen-related altered cell adhesion encountered in endometrial disorders.

17 β-estradiol and tamoxifen upregulate estrogen receptor β expression and control podocyte signaling pathways in a model of type 2 diabetes

Diabetic nephropathy remains one of the most important causes of end-stage renal disease. This is particularly true for women from racial/ethnic minorities. Although administration of 17beta-estradiol to diabetic animals has been shown to reduce extracellular matrix deposition in glomeruli and mesangial cells, effects on podocytes are lacking. Given that podocyte injury has been implicated as a factor leading to the progression of proteinuria and diabetic nephropathy, we treated db/db mice, a model of type 2 diabetic glomerulosclerosis, with 17beta-estradiol or tamoxifen to determine whether these treatments reduce podocyte injury and decrease glomerulosclerosis. We found that albumin excretion, glomerular volume, and extracellular matrix accumulation were decreased in these mice compared to placebo treatment. Podocytes isolated from all treatment groups were immortalized and these cell lines were found to express the podocyte markers WT-1, nephrin, and the TRPC6 cation channel. Tamoxifen and 17beta-estradiol treatment decreased podocyte transforming growth factor-beta mRNA expression but increased that of the estrogen receptor subtype beta protein. 17beta-estradiol, but not tamoxifen, treatment decreased extracellular-regulated kinase phosphorylation. These data, combined with improved albumin excretion, reduced glomerular size, and decreased matrix accumulation, suggest that both 17beta-estradiol and tamoxifen may protect podocytes against injury and therefore ameliorate diabetic nephropathy.

Effect of the phytotherapeutic agent Eviprostat® on 17β‐estradiol‐induced nonbacterial inflammation in the rat prostate

Anti-inflammatory medications have been used for the treatment of chronic prostatitis. The phytotherapeutic agent Eviprostat, a popular treatment for benign prostatic hyperplasia in Japan and Germany, has antioxidant and anti-inflammatory activity. We investigated the effects of the phytotherapeutic agent Eviprostat on prostate inflammation induced in castrated rats by the injection of 17beta-estradiol. Ten-month-old male Wistar rats were divided into five groups. Nonbacterial prostatitis was experimentally induced in groups 2-5 by castration followed by daily subcutaneous injection of 17beta-estradiol for 30 days. The rats were orally administered 0.1% Tween-80 (group 2), low-dose Eviprostat (group 3), high-dose Eviprostat (group 4), or cernitin pollen extract (group 5) for the last 2 weeks of 17beta-estradiol administration. Sham-operated rats (group 1) were orally administered 0.1% Tween-80. On the 31st day after surgery, the weight of the prostate and the levels of prostatic proinflammatory cytokines as well as the oxidative-stress marker malondialdehyde were determined and histological alterations noted. Experimentally induced nonbacterial prostatitis led to a significant decrease in prostate weight and increases in malondialdehyde and proinflammatory cytokine levels. Eviprostat significantly suppressed the increases in malondialdehyde and cytokine levels without affecting prostate weight. Histologically, nonbacterial prostatitis was evident in the lateral lobe of the prostate, and Eviprostat treatment significantly suppressed the severity of the lesion. Eviprostat, which has effective antioxidant and anti-inflammatory activities in the prostate, may be useful for the clinical treatment of chronic prostatitis. These activities of Eviprostat may also contribute to the amelioration of prostate inflammation in BPH patients. Prostate 69: 1404-1410, 2009. (c) 2009 Wiley-Liss, Inc.

Rapid change of neuropeptide Y levels and gene-expression in the brain of ovariectomized mice after administration of 17β-estradiol

Estrogen alters excitability and changes synaptic morphology in the rat hippocampal formation. We have compared, by means of radioimmunoassay and in situ hybridization, the effects of short-term treatment with 17beta-estradiol on neuropeptide Y (NPY) in the brain of ovariectomized mice. A highly significant reduction in concentrations of NPY-like immunoreactivity (LI) was observed in the hippocampal formation, some cortical areas and the caudate nucleus 1h after administration of 17beta-estradiol as compared to the control group. In contrast, NPY transcript levels increased in the hippocampal formation (dentate gyrus) and the caudate nucleus, possibly representing a compensatory increase of NPY synthesis following increased estradiol-induced NPY release. These data suggest that 17beta-estradiol, via membrane-related mechanisms, increases NPY release and synthesis in forebrain areas involved in cognition, mood and motor functions.

Rapid Signaling of Estrogen to WAVE1 and Moesin Controls Neuronal Spine Formation via the Actin Cytoskeleton

Estrogens are important regulators of neuronal cell morphology, and this is thought to be critical for gender-specific differences in brain function and dysfunction. Dendritic spine formation is dependent on actin remodeling by the WASP-family verprolin homologous (WAVE1) protein, which controls actin polymerization through the actin-related protein (Arp)-2/3 complex. Emerging evidence indicates that estrogens are effective regulators of the actin cytoskeleton in various cell types via rapid, extranuclear signaling mechanisms. We here show that 17beta-estradiol (E2) administration to rat cortical neurons leads to phosphorylation of WAVE1 on the serine residues 310, 397, and 441 and to WAVE1 redistribution toward the cell membrane at sites of dendritic spine formation. WAVE1 phosphorylation is found to be triggered by a Galpha(i)/Gbeta protein-dependent, rapid extranuclear signaling of estrogen receptor alpha to c-Src and to the small GTPase Rac1. Rac1 recruits the cyclin-dependent kinase (Cdk5) that directly phosphorylates WAVE1 on the three serine residues. After WAVE1 phosphorylation by E2, the Arp-2/3 complex concentrates at sites of spine formation, where it triggers the local reorganization of actin fibers. In parallel, E2 recruits a Galpha(13)-dependent pathway to RhoA and ROCK-2, leading to activation of actin remodeling via the actin-binding protein, moesin. Silencing of WAVE1 or of moesin abrogates the increase in dendritic spines induced by E2 in cortical neurons. In conclusion, our findings indicate that the control of actin polymerization and branching via moesin or WAVE1 is a key function of estrogen receptor alpha in neurons, which may be particularly relevant for the regulation of dendritic spines.

ESTROGEN SUPPRESSES CARDIAC IL-6 AFTER TRAUMA-HEMORRHAGE VIA A HYPOXIA-INDUCIBLE FACTOR 1α-MEDIATED PATHWAY

Cardiac dysfunction is a major concern after trauma-hemorrhage, and increased IL-6 is one of the underlying causes for producing the dysfunction. Studies have shown that administration of 17beta-estradiol (estrogen) after trauma-hemorrhage normalized cardiac IL-6 levels and restored cardiac functions under those conditions. Because hypoxia-inducible factor (HIF) 1 alpha is expressed during hypoxia and cellular stress and up-regulates the expression of IL-6, we hypothesized that HIF-1 alpha induces the increased cardiac IL-6 after trauma-hemorrhage and that estrogen suppresses this induction. To examine this, C3H/HeN mice were subjected to trauma-hemorrhage or sham operation. Vehicle, the HIF-alpha inhibitor YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole, a novel activator of platelet guanylate cyclase], or estrogen was administered to trauma-hemorrhage and sham groups during resuscitation. Mice were killed at 2 h after resuscitation, and cardiac IL-6, HIF-1 alpha, and nuclear factor (NF) kappaB activities were measured. IL-6, NF-kappaB, and HIF-1 alpha levels were markedly elevated after trauma-hemorrhage; all of these parameters were normalized by estrogen as well as YC-1 administration after trauma-hemorrhage. Because elevated IL-6 levels after trauma-hemorrhage were decreased with YC-1 treatment, it indicates that IL-6 expression in cardiomyocytes is induced via HIF-1 alpha. In addition, estrogen decreased the elevated HIF-1 alpha, NF-kappaB, and IL-6 levels after trauma-hemorrhage. These results indicate that the beneficial effects of estrogen on cardiac function after trauma-hemorrhage seem to be mediated by the inhibition of HIF-1 alpha expression and activity.

Estrogen Receptor Alpha Regulates Retinaldehyde Dehydrogenase 1 Expression in Rat Anterior Pituitary Cells

Retinoic acid (RA) plays a critical role in embryonic development, growth, and reproduction. RA is synthesized from retinoids via oxidation processes, and the oxidation of retinal to RA is catalyzed by the retinaldehyde dehydrogenases (RALDHs). We previously reported that RALDH1 mRNA was expressed in the anterior pituitary glands of adult rats and suppressed by administration of 17beta-estradiol in vivo. However, little is known about the mechanism regulating pituitary RALDH1 expression. In order to characterize the mechanism of estrogen-induced RALDH1 reduction, we examined the effect of 17beta-estradiol on the regulation of pituitary RALDH1 gene expression and protein production both in vivo and in vitro. Using quantitative real-time PCR and immunoblot analysis, we found that levels of RALDH1 gene expression and protein production markedly decreased after 1-week treatment with 17beta-estradiol in male rats. In immunohistochemical analysis, RALDH1-immunoreaction was observed in prolactin cells and folliculo-stellate cells. In 17beta-estradiol-treated rats, RALDH1-immunoreactivity was lower in prolactin cells, but not in folliculo-stellate cells. Treatment of isolated anterior pituitary cells with 17beta-estradiol (10(-14) - 10(-8) M) decreased expression of RALDH1 mRNA in a dose-dependent manner. Estradiol-induced suppression of RALDH1 expression was completely blocked by the estrogen receptor (ER) antagonist ICI 182, 780. The ERalpha-selective agonist propylpyrazole triol (10(-8) M) mimicked the effect of 17beta-estradiol on RALDH1 expression, but the ERbeta-selective agonist diarylpropionitrile (10(-8) M) did not. These results strongly suggest that RALDH1 mRNA expression is suppressed by 17beta-estradiol through ERalpha, and that estrogen regulates the expression of RALDH1 and production of RA in the anterior pituitary gland.

Estradiol’s Salutary Effects on Keratinocytes Following Trauma-Hemorrhage Are Mediated by Estrogen Receptor (ER)-α and ER-β

Although administration of 17beta-estradiol (estrogen) following trauma-hemorrhage attenuates the elevation of cytokine production and mitogen-activated protein kinase (MAPK) activation in epidermal keratinocytes, whether the salutary effects of estrogen are mediated by estrogen receptor (ER)-alpha or ER-beta is not known. To determine which estrogen receptor is the mediator, we subjected C3H/HeN male mice to trauma-hemorrhage (2-cm midline laparotomy and bleeding of the animals to a mean blood pressure of 35 mmHg and maintaining that pressure for 90 min) followed by resuscitation with Ringer's lactate (four times the shed blood volume). At the middle of resuscitation we subcutaneously injected ER-alpha agonist propyl pyrazole triol (PPT; 5 microg/kg), ER-beta agonist diarylpropionitrile (DPN; 5 microg/kg), estrogen (50 microg/kg), or ER antagonist ICI 182,780 (150 microg/kg). Two hours after resuscitation, we isolated keratinocytes, stimulated them with lipopolysaccharide for 24 h (5 microg/mL for maximum cytokine production), and measured the production of interleukin (IL)-6, IL-10, IL-12, and TNF-alpha and the activation of MAPK. Keratinocyte cytokine production markedly increased and MAPK activation occurred following trauma-hemorrhage but were normalized by administration of estrogen, PPT, and DPN. PPT and DPN administration were equally effective in normalizing the inflammatory response of keratinocytes, indicating that both ER-alpha and ER-beta mediate the salutary effects of estrogen on keratinocytes after trauma-hemorrhage.

SYSTEMATIC ANALYSIS OF THE SALUTARY EFFECT OF ESTROGEN ON CARDIAC PERFORMANCE AFTER TRAUMA-HEMORRHAGE

Although 17beta-estradiol (estrogen) and estrogen receptor (ER) agonist administration after trauma-hemorrhage improves cardiac function, it remains unknown what the optimal estrogen or ER agonist dosage is to elicit this beneficial effect. To study this, the dose-dependent effects of estrogen, propylpyrazole triol (ER-alpha agonist), and diarylpropionitrile (DPN; ER-beta agonist) on heart performance (+dP/dt) were determined in sham rats and in experimental animals at the time of maximal bleedout (MBO) or at 2 h after trauma-hemorrhage. The results showed that estrogen and DPN induced dose-dependent increases in the maximal rate of left ventricular pressure increase (+dP/dt) in all groups, whereas propylpyrazole triol was ineffective at all doses. The maximal dose and the 50% effective dose of DPN were approximately 100-fold lower than those of estrogen. The half-life of estrogen in plasma was approximately 25 min in sham and MBO groups. A positive correlation between the estrogen-induced increase in +dP/dt and survival in MBO rats were observed. These results collectively suggest that the salutary effects of estrogen on cardiac performance are dose-dependent and mediated via ER-beta.