Hormone Deprivation Research Articles

Adrenal hormone deprivation affects macrophage catecholamine metabolism and β2‐adrenoceptor density, but not propranolol stimulation of tumour necrosis factor‐α production

Catecholamines modulate the production of inflammatory mediators by macrophages in an autocrine/paracrine manner. They also tune β2-adrenoceptor expression. Glucocorticoids influence catecholamine metabolism and adrenoceptor expression in many cell types. We hypothesized that adrenal hormones affect the production of tumour necrosis factor-α (TNF-α) and NO by macrophages by altering the modulatory influence of catecholamines. To prove the hypothesis, peritoneal exudate macrophages from propranolol-treated non-operated and adrenalectomized rats and from corticosterone-supplemented adrenalectomized rats were examined for lipopolysaccharide-stimulated NO and TNF-α production in vitro and for expression of β2-adrenoceptors and major catecholamine-metabolizing enzymes. Glucocorticoid deprivation increased NO production by macrophages, whereas 4 days of propranolol treatment was ineffective in this respect. However, propranolol treatment, via β2-adrenoceptor blockade, increased production of TNF-α by macrophages in both non-operated and adrenalectomized rats (showing dramatically enhanced TNF-α production due to a lack of circulating glucocorticoids) for the same value. The expression of β2-adrenoceptor was increased in peritoneal macrophages that were freshly isolated from non-operated, propranolol-treated and adrenalectomized rats (due to adrenal catecholamine deficiency). Propranolol did not affect macrophage β2-adrenoceptor expression in adrenalectomized rats. Given that propranolol increased the density of macrophage tyrosine hydroxylase expression only in non-operated rats and affected the mRNA expression of monoamine oxidase-A in neither non-operated nor adrenalectomized animals, a significant influence of propranolol on peritoneal exudate cell noradrenaline content was found only in non-operated rats. A lack of circulating adrenal hormones also affected noradrenaline metabolism and content in peritoneal exudate cells including macrophages. Collectively, despite differences in the abundance of macrophage catecholamine-β2-adrenoceptor system components and in the TNF-α response to lipopolysaccharide between adrenalectomized and non-operated rats, propranolol increased TNF-α production by the same amount in macrophages from these two groups of animals.

Ageing is the main determinant of haemodynamics and autonomic cardiac changes observed in post-menopausal female rats

The aim of this study was to evaluate and compare the effects of early and physiological menopause on cardiac autonomic parameters in aged female rats. To this end, female Wistar rats (22 and 82 weeks old, N=96) were divided into 4 groups: Young Sham-operated Rats, Aged Sham-operated Rats, Young Ovariectomised (OVX) Rats, and Aged OVX Rats. Young Sham-operated and OVX rats were used as controls. The cardiac autonomic parameters were investigated using different approaches: 1) pharmacological evaluation of the autonomic tonus with methylatropine and propranolol; 2) isolated cardiac contractility with β-adrenergic agonists; and 3) quantification of the mRNA and protein level expression of cardiac β-adrenergic receptors. Among the groups of aged female rats, both the Sham-operated and OVX rats showed higher basal mean arterial pressure and heart rate (HR) values compared to their respective young counterparts. The aged groups also showed a predominance of the sympathetic autonomic component in the determination of HR, whereas the young rats showed a vagal predominance. An assessment of cardiac contractility showed that aged Sham-operated and OVX rats had lower contractile responses following the administration of dobutamine compared to their respective young counterparts. In addition, the aged groups showed higher mRNA and protein expression levels of the β1-adrenergic receptors. In conclusion, our results show that haemodynamic alterations and impairment of the autonomic parameters were similar between the groups of rats subjected to early and physiological menopause. Moreover, these results seem to be due to the ageing process and not ovarian hormone deprivation.

CHANGES IN THE URINARY BLADDER MORPHOLOGY, MAST CELL POPULATION AND ESTROGEN RECEPTOR ALPHA EXPRESSION FOLLOWING OVARECTOMY AND CHRONIC ESTROGEN REPLACEMENT THERAPY IN ALBINO RATS

11 Acta Endocrinologica (Buc), vol. IX, no. 1, p. 11-22, 2013 *Correspondence to: Dr. Flaviu Alexandru Tabaran, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Department of Pathology, Manastur Street, Nr.3-5, Cluj-Napoca, Cluj, 400372, Romania, E-mail: flaviu_tabaran@yahoo.com Abstract Context. The inflammatory disorders of the urinary bladder represent one of the most frequent disorders associated with hormonal unbalances caused by menopause. The involvement of estrogens and mast cells in this complex mechanism mediated by neuro-hormonal pathway is well known, but the pathogenesis through which the hormonal deprivation is affecting the Estrogen Receptor expression and is predisposing to urinary bladder inflammatory changes is still argued. Objective. To determine the structural changes associated with surgically induced menopause, and the effect of estrogen replacement therapy (ERT) in the urinary bladder morphology, mast cell population and Estrogen Receptor (ERα) expression. Subjects and methods. The effect of ovariectomy and ERT was monitored by quantifying the number of mast cells and the structural changes that the urinary bladder suffers. By immunohistochemistry we assessed the changes of the Estrogen Receptor Alpha (ERα) expression in the urothelium and detrusor muscle. The study was carried out on ovariectomised female rats over a period of 42 days. Results. The main alterations associated with the hormonal deprivation were represented by the growth in number of the bladder mast cells, atrophy of the urothelium and amplification of the expression of ERα from the urothelium, but not from the detrusor muscle. ERT significantly decreased the tissue expression for ERα, reduced the severity of bladder atrophy and the number of mast cells. Conclusions. The estrogenic hormonal substitution can diminish the severity of the atrophic, inflammatory and ERα changes in bladder disorders associated with ovarectomy in rat.

Hypogonadotropic hypogonadism in women: treatment options

Treatment of female hypogonadotropic hypogonadism is geared to mimic normal physiology, allowing for age appropriate development, while preventing complications secondary to sex hormone deprivation. In this paper we review data concerning efficacy and safety of sex hormone replacement therapy at the various stages of female reproduction, taking into account safety profiles of different types of estrogen and progesterone formulations, and their interactions with other components of the pituitary substitutive therapy.

Abstract PD01-04: Deep kinome sequencing identifies a novel D189Y mutation in the Src family kinase LYN as a possible mediator of antiestrogen resistance in ER+ breast cancer

Abstract Estrogen receptor-positive (ER+) breast tumors adapt to hormone deprivation and acquire resistance to aromatase inhibitors (AIs). The proliferative rate of tumor cells measured by Ki67 after short-term treatment with an AI has been proposed as a surrogate endpoint of long term outcome. The purpose of this study was to identify kinase mutations associated with resistance to endocrine therapy as identified by a high Ki67 score after two weeks of pre-surgical therapy with letrozole. We performed deep-kinome sequencing on 4 ER+/HER2– breast tumors that retained high Ki67 scores (14.8 to 24.5%) following short-term letrozole treatment. Genomic DNA from the surgically excised tumors was deep sequenced using a capture approach with 120-bp biotinylated oligonucleotides hybridizing to 612 genes, including 517 kinases with ≥300x coverage. All 4 tumors contained a ‘hot spot’ mutation in PIK3CA, the gene encoding the p110α catalytic subunit of PI3K. One tumor also contained a novel D189Y somatic mutation in LYN, a member of the Src family kinases (SFKs; variant frequency of 8%). D189Y (565G>T) is located in the LYN SH2 domain. Reverse-phase protein array (RPPA) analysis available in 10 tumors in this study revealed a significant correlation (p = 0.006) between Y416 P-Src (which detects all SFKs) and a high post-letrozole Ki67 score. A siRNA screen targeting 779 kinases identified LYN as one of the top hits whose knockdown significantly reduced growth of MCF-7 breast cancer cells with acquired resistance to estrogen deprivation. We next analyzed the Cancer Genome Atlas (TCGA) SNP data to detect copy number changes for 444 tumors where corresponding gene expression data were available. Copy number increases (>0.8 log2 ratio over normal matched DNA) in LYN were present in approximately 10% of breast cancers, with the highest copy number gains observed in luminal B tumors. In contrast, other SFKs showed less frequent copy number increases (YES1 <1%, SRC 2%, FYN 1%). Analysis of the 550 breast cancers in the TCGA identified four additional LYN mutations (E159K, K188N, G418R, A503D), with the first two located in the SH2 domain. Finally, we investigated the role of D189Y LYN in endocrine-resistant breast cancer using ER+ MCF-7 cells transduced with GFP (control), wild-type (WT) LYN, or D189Y LYN vectors. Overexpression of WT or mutant LYN resulted in increased phosphorylation of Src (at Y416), IGF-IR, EGFR, STAT3, AKT, and MAPK. D189Y LYN overexpression also induced phosphorylation of IRS-1. Although stable transduction of either WT or D189Y LYN accelerated MCF-7 cell growth in estrogen-depleted medium, the mutant was more potent than WT LYN at inducing this effect. Further, D189Y LYN overexpression rendered treatment with the ER downregulator fulvestrant or the PI3K inhibitor BKM120 less effective. These results suggest, first, that LYN may play a role in escape from estrogen deprivation in a subset of ER+ breast cancers. Second, ER+ breast cancers harbor multiple molecular alterations capable of mediating hormone-independent growth. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD01-04.

Menopause leads to elevated expression of macrophage-associated genes in the aging frontal cortex: rat and human studies identify strikingly similar changes

BackgroundThe intricate interactions between the immune, endocrine and central nervous systems shape the innate immune response of the brain. We have previously shown that estradiol suppresses expression of immune genes in the frontal cortex of middle-aged ovariectomized rats, but not in young ones reflecting elevated expression of these genes in middle-aged, ovarian hormone deficient animals. Here, we explored the impact of menopause on the microglia phenotype capitalizing on the differential expression of macrophage-associated genes in quiescent and activated microglia.MethodsWe selected twenty-three genes encoding phagocytic and recognition receptors expressed primarily in microglia, and eleven proinflammatory genes and followed their expression in the rat frontal cortex by real-time PCR. We used young, middle-aged and middle-aged ovariectomized rats to reveal age- and ovariectomy-related alterations. We analyzed the expression of the same set of genes in the postcentral and superior frontal gyrus of pre- and postmenopausal women using raw microarray data from our previous study.ResultsOvariectomy caused up-regulation of four classic microglia reactivity marker genes including Cd11b, Cd18, Cd45 and Cd86. The change was reversible since estradiol attenuated transcriptional activation of the four marker genes. Expression of genes encoding phagocytic and toll-like receptors such as Cd11b, Cd18, C3, Cd32, Msr2 and Tlr4 increased, whereas scavenger receptor Cd36 decreased following ovariectomy. Ovarian hormone deprivation altered the expression of major components of estrogen and neuronal inhibitory signaling which are involved in the control of microglia reactivity. Strikingly similar changes took place in the postcentral and superior frontal gyrus of postmenopausal women.ConclusionsBased on the overlapping results of rat and human studies we propose that the microglia phenotype shifts from the resting toward the reactive state which can be characterized by up-regulation of CD11b, CD14, CD18, CD45, CD74, CD86, TLR4, down-regulation of CD36 and unchanged CD40 expression. As a result of this shift, microglial cells have lower threshold for subsequent activation in the forebrain of postmenopausal women.

The Effects of 17β-Oestradiol on Increased α1-Adrenergic Vascular Reactivity Induced by Prolonged Ovarian Hormone Deprivation: The Role of Voltage-Dependent L-type Ca2+ Channels

The present study investigated the hypothesis that the duration of ovarian hormone deprivation before reintroduction of oestrogen affects the role of oestrogen as a mediator of the contractile function of α₁-adrenergic receptors. Rats underwent ovariectomy (OVX) or were sham-operated, and the OVX rats were treated with vehicle (corn oil) or 17β-oestradiol (E₂) for 5 days either 10, 28 or 60 days after OVX. The OVX increased phenylephrine- and Ca²⁺-induced contractions. Interestingly, the phenylephrine-induced contractions were increased at each of the three time points, whereas the Ca²⁺-induced contractions were only increased in the 60-day group. E₂ had biphasic effects on phenylephrine- and Ca²⁺-induced contractility. Indeed, E₂ increased contractions in the 10-day group and diminished contractions in the other groups (the increased contractions were avoided by verapamil). These results indicate that E₂ controls α₁-adrenergic receptor-mediated contractility through effects on L-type Ca²⁺ channels in a way that depends on the timing in which the treatment with E₂ is initiated.

Abstract 645: Aerobic Vs. Resistance Exercise Training In Ovariectomized Hypertensive Rats: Cardiovascular And Oxidative Stress Evaluations

Hypertension becomes more prevalent in menopause women. Aerobic exercise has been indicated as a nonpharmacological treatment for hypertension, however the benefits of resistance exercise are not well know. The purpose of the present study was to investigate the effects of aerobic or resistance exercise training on cardiovascular autonomic control and oxidative stress profile in ovariectomized hypertensive rats. Female spontaneously hypertensive rats (SHR) were divided into 4 groups (n=8 each): sedentary (HS), sedentary ovariectomized(HSO), aerobic trained ovariectomized (HATO) and resistance trained ovoriectomized (HRTO). The moderate intensity aerobic training (AT) was performed on a treadmill (8 weeks) and the moderate intensity resistance exercise training (RT) was performed on a vertical ladder with weights attached to the rat tail (8 weeks). Arterial pressure (AP) and heart rate (HR) were directly recorded and baroreflex sensitivity was evaluated by bradycardic (BR) and tachycardic responses (TR). Oxidative stress was evaluated in cardiac tissue by chemiluminescence, the ratio of glutathione reductase/glutathione oxidized (GSSG-GSH) and superoxide dismutase (SOD) and glutathione peroxidase (GPx) antioxidant enzyme activities. The exercise training induced a reduction in mean AP in trained groups compared to sedentary groups. HR was similar between groups. The AT increased TR in relation to other groups (HATO:-2.74±0.15 vs. HRTO: -1.42±0.2, HSO: -1.4±0.17 e HS -1.91±0.2 bpm/mmHg).However, BR was improved in both HATO (-1.38±0.07 bpm/mmHg) and HRTO (-1.34±0.05 bpm/mmHg) in relation to HS and HSO groups (-1.12±0.1 and -1.01±0.09 bpm/mmHg). Lipid peroxidation was reduced in trained groups in relation to sedentary groups (HRTO: 3538±168 and HATO: 4485±310 vs. HSO: 6514±547 and HS: 6661±566 cps/mg prot). The ratio GSSG-GSH did not differ between groups, however GSSG was higher in HATO group as compared to other groups (HATO: 346±14.5 vs. HRTO: 260±12, HSO:271±12, HS:234±11 μmol/g tissue) and GSH was lower in HRTO group as compared to HATO (HRTO:19±2 vs. HATO: 26±0.7 μmol/g tissue). SOD increased in HRTO in relation to sedentary groups (HRTO: 16.86±0.56 vs. HS:11.47±0.41, HSO: 11.17±0.41 USOD/mg prot) and GPx was higher in HRTO in relation to HSO (HRTO: 60±2.8 vs. HSO: 38.5±1.67 nmol/min/mg prot). In conclusion, aerobic or resistance exercise training induced a reduction in AP, associated with attenuation of baroreflex dysfunction and improvement in oxidative profile in cardiac tissue in ovariectomized hypertensive rats, suggesting a positive role of these nonpharmacological approachs in the management of cardiovascular risk in hypertension after hormones deprivation. Financial Support: FAPESP(2011/16441-0, 2011/15828-9,2010/17188-4)

1075 BENEFITS OF RESISTANCE EXERCISE TRAINING IN OVARIECTOMIZED SPONTANEOUSLY HYPERTENSIVE RATS

Background: Hypertension is a major risk factor in the development of cardiovascular disease and increase in menopause women. Aerobic Exercise has been indicated as a nonpharmacological treatment for hypertension, however the benefits of resistance exercise are not well know. Objectives: Investigate the effects of resistance exercise on cardiovascular autonomic control in ovariectomized hypertensive rats Methodos: Female Wistar (W) and spontaneously hypertensive rats (SHR) were divided into 4 groups (n = 8 each): sedentary W (WS), sedentary SHR (HS), sedentary ovariectomized SHR (HSO) and trained ovariectomized SHR (HTO). The resistance exercise training (RT) was performed in a vertical ladder with weights attached to rat tail (8 weeks; 40-50% maximal load). Arterial pressure (AP) and heart rate (HR) were directly recorded and baroreflex sensitivity (BRS) was evaluated by bradycardic (BR) and tachycardic responses (TR). Results: The mean arterial pressure was higher in HSO (180 ± 4.5 mmHg) and HS (172 ± 3.1 mmHg) compared to HTO (158 ± 2.3 mmHg) and WS (113 ± 1.5 mmHg). The RT induced resting bradycardia (HTO: 322 ± 8.6 bpm) in relation to the other groups. The TR was lower in HS (-1.81 ± 0.06 bpm/mmHg) and HSO (-0.92 ± 0.14 bpm/mmHg) in relation to WS (-2.67 ± 0.2 bpm/mmHg), and was additionally attenuated by ovariectomy (HSO vs. HS). The hypertensive groups had lower BR when compared to WS. The HTO group (-1.42 ± 0.1 bpm/mmHg) showed higher TR in relation to HSO group. Conclusions: Moderate intensity dynamic resistance exercise training induced a reduction in blood pressure and attenuated baroreflex dysfunction in ovariectomized hypertensive rats, suggesting a positive role of this nonpharmacological approach in the management of cardiovascular risk in hypertension after hormones deprivation.

82nd Annual Meeting of the American Thyroid AssociationMEETING ABSTRACTS & PROGRAM

82nd Annual Meeting of the American Thyroid AssociationMEETING ABSTRACTS & PROGRAM

BRCACarriers, Prophylactic Salpingo-Oophorectomy and Menopause: Clinical Management Considerations and Recommendations

Women who inherit a mutation in either the BRCA1 or BRCA2 gene have greatly elevated lifetime risks of ovarian cancer, fallopian tube cancer and breast cancer. Preventive surgical removal of the ovaries and fallopian tubes (salpingo-oophorectomy) is recommended to these women, often prior to natural menopause, to prevent cancer. The ensuing hormone deprivation may impact on health and quality of life. Most of these women experience menopausal symptoms shortly after surgery; however, there may also be longer term consequences that are less well understood. In this review, we highlight recent studies that examine the implications of salpingo-oophorectomy on health and quality of life in BRCA-positive women and we discuss the care of women following prophylactic surgery.

Abstract 614: Mechanism Involved In Fructose Induced Cardiovascular Risk: Evidence In An Experimental Model Of Hypertension And Menopause

The metabolic syndrome is a bunch of ordinary pathologies: abdominal obesity associated to an excess of visceral fat, insulin resistance, dyslipidemia and hypertension. Moreover, the prevalence of hypertension and metabolic dysfunctions sharply increases after the menopause. However, the mechanisms involved in these changes were not well understood. Thus, the aim of this study was to evaluate the effects of ovarian hormone deprivation (9 wks) in hypertensive (or not) female rats submitted (or not) to fructose overload on cardiovascular autonomic control and cardiac oxidative stress. Female Wistar and SHR rats were divided into (n=8/group): control (C), ovariectomized (O), hypertensive ovariectomized (HO) and hypertensive ovariectomized submitted to fructose overload (100g/L in drinking water) (FHO). The arterial pressure (AP) signals were directly recorded. The cardiovascular autonomic modulation was evaluated by pharmacological blockade and by spectral analysis. Oxidative stress profile was evaluated by chemiluminescence (CL) and redox balance of glutathione (GSH/GSSG) determinations. The AP showed increased in the O and HO groups when compared to C group. The FHO group showed increased blood glucose and tryglicerides, insulin resistance; an additional increase in mean AP (174±4 vs. C:108±1; O:121±2; HO:164±5 mmHg), resting tachycardia, reduced vagal tonus (5±3 vs. C:55±5; O:37±6; HO:35±7bpm), increased sympathetic tonus (91±18 vs. 39±10bpm in C), decreased high frequency band of the pulse interval (vagal modulation) and exacerbated increased systolic AP variance and decreased low frequency band of the pulse interval (sympathetic modulation) in relation to other groups. The CL was higher in O and HO groups than C group. FHO group showed additional increase in CL (15043±1333 vs. C: 2661±358; O: 5134±277; HO: 6514±547 cps/mgprot) when compared to other groups. The cardiac GSH/GSSG was lower in FOH group (8.94±0.80 umol/g) in relation to HO group (13.0±1.4 umol/g), indicating impaired redox balance. In conclusion, the fructose overload induced metabolic dysfunctions associated with additional impairment in cardiovascular autonomic control and oxidative stress profile in hypertensive rats submitted to ovarian hormones deprivation.

Endpoints of drug discovery for menopausal vasomotor symptoms

Estrogen supplementation is considered a reliable therapeutic approach to symptoms of vasomotor dysregulation (hot flashes) associated with the menopausal transition and sex hormone deprivation. Implication of changes in central neurotransmission in the pathogenesis of hot flashes has prompted the off-label use of serotonergic and γ-aminobutyric acid-ergic drugs as a therapeutic alternative, claiming similarity of outcomes to those of estrogen treatment. Using telemetric recordings in a rat model of estrogen deficit-induced vasomotor dysregulation, we compared the long- and short-term effects of estrogen supplementation and treatment with neuropharmaceuticals (venlafaxine, desvenlafaxine, fluoxetine, agomelatine, gabapentin) on endpoints of thermoregulation. Among the tested drugs, only fluoxetine was capable to emulate the restorative action of estradiol on the diurnal oscillations in skin temperature and control of heat dissipation. Unlike estradiol, several of the tested compounds produced marked transient decreases in skin temperature within the first 2 hours of application while being unable to restore physiological diurnal patterns of thermoregulation. Our findings suggest that in this animal model of impaired thermoregulation, neuropharmaceuticals may simulate therapeutic effects by eliciting immediate but transient hypothermia, which is not associated with the recovery of physiological control of heat dissipation. Therefore, short-term monitoring of drug actions in this disease model may considerably bias readouts of drug discovery for menopausal vasomotor symptoms.

Minireview: translational animal models of human menopause: challenges and emerging opportunities.

Increasing importance is placed on the translational validity of animal models of human menopause to discern risk vs. benefit for prediction of outcomes after therapeutic interventions and to develop new therapeutic strategies to promote health. Basic discovery research conducted over many decades has built an extensive body of knowledge regarding reproductive senescence across mammalian species upon which to advance animal models of human menopause. Modifications to existing animal models could rapidly address translational gaps relevant to clinical issues in human menopausal health, which include the impact of 1) chronic ovarian hormone deprivation and hormone therapy, 2) clinically relevant hormone therapy regimens (cyclic vs. continuous combined), 3) clinically relevant hormone therapy formulations, and 4) windows of opportunity and optimal duration of interventions. Modifications in existing animal models to more accurately represent human menopause and clinical interventions could rapidly provide preclinical translational data to predict outcomes regarding unresolved clinical issues relevant to women's menopausal health. Development of the next generation of animal models of human menopause could leverage advances in identifying genotypic variations in estrogen and progesterone receptors to develop personalized menopausal care and to predict outcomes of interventions for protection against or vulnerability to disease. Key to the success of these models is the close coupling between the translational target and the range of predictive validity. Preclinical translational animal models of human menopause need to keep pace with changes in clinical practice. With focus on predictive validity and strategic use of advances in genetic and epigenetic science, new animal models of human menopause have the opportunity to set new directions for menopausal clinical care for women worldwide.

Zyflamend, a Combination of Herbal Extracts, Attenuates Tumor Growth in Murine Xenograft Models of Prostate Cancer

Prostate cancer (PrC) is the second deadliest cancer of males in the United States Hormone deprivation therapy (HDT), a common therapy for advanced forms of the disease, results in tumor regression; unfortunately, tumors inevitably become castrate-resistant. Diet is not an appropriate primary therapy for refractory forms of the disease; however, diet may be effective as an adjuvant to HDT, potentially extending the latency period and delaying relapse and/or inhibiting refractory growth. Zyflamend® is a combination of extracts from multiple herbs, each with reported anticancer properties. Zyflamend can inhibit growth of various PrC cell lines, but no studies have investigated its potential use in vivo using a model of castrate-resistant PrC. In this study, oral doses of Zyflamend at human equivalent doses inhibited androgen-dependent and castrate-resistant tumor growth in a mouse model that mimics advanced stages of the disease, and reduced the expression of a number of biomarkers linked to PrC progression including pAKT, prostate specific antigen, histone deacetylases, and androgen receptor. In summary, this is the first article to report that Zyflamend, when provided at human equivalent doses, can potentiate the effects of hormone deprivation on tumor regression and growth inhibition of androgen-dependent and castrate-resistant PrC tumors in vivo.

Estradiol Attenuates Ischemia-Induced Death of Hippocampal Neurons and Enhances Synaptic Transmission in Aged, Long-Term Hormone-Deprived Female Rats

BackgroundTransient global forebrain ischemia causes selective, delayed death of hippocampal CA1 pyramidal neurons, and the ovarian hormone 17β-estradiol (E2) reduces neuronal loss in young and middle-aged females. The neuroprotective efficacy of E2 after a prolonged period of hormone deprivation is controversial, and few studies examine this issue in aged animals given E2 treatment after induction of ischemia.Methodology/Principal FindingsThe present study investigated the neuroprotective effects of E2 administered immediately after global ischemia in aged female rats (15–18 months) after 6 months of hormone deprivation. We also used electrophysiological methods to assess whether CA1 synapses in the aging hippocampus remain responsive to E2 after prolonged hormone withdrawal. Animals were ovariohysterectomized and underwent 10 min global ischemia 6 months later. A single dose of E2 (2.25 µg) infused intraventricularly after reperfusion significantly increased cell survival, with 45% of CA1 neurons surviving vs 15% in controls. Ischemia also induced moderate loss of CA3/CA4 pyramidal cells. Bath application of 1 nM E2 onto brain slices derived from non-ischemic aged females after 6 months of hormone withdrawal significantly enhanced excitatory transmission at CA1 synapses evoked by Schaffer collateral stimulation, and normal long-term potentiation (LTP) was induced. The magnitude of LTP and of E2 enhancement of field excitatory postsynaptic potentials was indistinguishable from that recorded in slices from young rats.Conclusions/SignificanceThe data demonstrate that 1) acute post-ischemic infusion of E2 into the brain ventricles is neuroprotective in aged rats after 6 months of hormone deprivation; and 2) E2 enhances synaptic transmission in CA1 pyramidal neurons of aged long-term hormone deprived females. These findings provide evidence that the aging hippocampus remains responsive to E2 administered either in vivo or in vitro even after prolonged periods of hormone withdrawal.

Tissue Biomarkers for Prostate Cancer Radiation Therapy

Prostate cancer is the most common cancer and second leading cause of cancer deaths among men in the United States. Most men have localized disease diagnosed following an elevated serum prostate specific antigen test for cancer screening purposes. Standard treatment options consist of surgery or definitive radiation therapy directed by clinical factors that are organized into risk stratification groups. Current clinical risk stratification systems are still insufficient to differentiate lethal from indolent disease. Similarly, a subset of men in poor risk groups need to be identified for more aggressive treatment and enrollment into clinical trials. Furthermore, these clinical tools are very limited in revealing information about the biologic pathways driving these different disease phenotypes and do not offer insights for novel treatments which are needed in men with poor-risk disease. We believe molecular biomarkers may serve to bridge these inadequacies of traditional clinical factors opening the door for personalized treatment approaches that would allow tailoring of treatment options to maximize therapeutic outcome. We review the current state of prognostic and predictive tissue-based molecular biomarkers which can be used to direct localized prostate cancer treatment decisions, specifically those implicated with definitive and salvage radiation therapy.

Cardiometabolic benefits of exercise training in an experimental model of metabolic syndrome and menopause

The aim of this study was to investigate the cardiometabolic effects of exercise training in ovariectomized hypertensive rats both submitted and not submitted to fructose overload. Spontaneously hypertensive ovariectomized rats were divided into sedentary and trained (THO) groups submitted to normal chow and sedentary and trained groups submitted to fructose overload (100 g/L in drinking water for 19 wk). Exercise training was performed on a treadmill (8 wk). Arterial pressure (AP) was directly recorded. Cardiovascular autonomic control was evaluated through pharmacological blockade (atropine and propranolol) and in the time and frequency domains by spectral analysis. The THO group presented reduced AP (approximately 16 mm Hg) and enhanced cardiac vagal tonus (approximately 49%) and baroreflex sensitivity (approximately 43%) compared with the sedentary hypertensive ovariectomized group. Exercise training attenuated metabolic impairment, resting tachycardia, cardiac and vascular sympathetic increases, and baroreflex sensitivity decrease induced by fructose overload in hypertensive rats. However, the trained hypertensive ovariectomized group submitted to fructose overload presented higher AP (approximately 32 mm Hg), associated with baroreflex sensitivity (approximately 69%) and parasympathetic dysfunctions compared with the THO group. These data suggest that the metabolic disorders in hypertensive rats after ovarian hormone deprivation could blunt and/or attenuate some exercise training benefits.

Abstract 4825: Inhibition of AKT abrogates resistance to endocrine therapy in estrogen receptor positive breast cancer

Abstract Estrogen receptor α-positive (ER+) breast cancers eventually adapt to hormone deprivation and acquire resistance to aromatase inhibitors. Upon acquisition of hormone independence, ER+ breast cancer cells increase their dependence on the phosphatidylinositol-3 kinase (PI3K)/AKT signaling pathway. Herein we investigated the effects of AKT inhibition on the hormone-independent growth of four ER+ breast cancer cell lines (MCF-7, ZR75-1, MDA-MB-361 and HCC-1428) with acquired resistance to estrogen deprivation (termed long-term estrogen-deprived cells, LTED). Treatment with the ATP-competitive AKT inhibitor AZD5363 inhibited phosphorylation of the AKT/mTOR substrates PRAS40, GSK3β/α, and S6K while inducing hyperphosphorylation of AKT at S473 and T308. AZD5363 suppressed the hormone-independent growth of 3/4 LTED lines. AZD5363 prevented the emergence of hormone-independent MCF-7, ZR75-1, and MDA-361 cells. Further, treatment of ovariectomized athymic mice with AZD5363 suppressed the hormone-independent growth of ER+/PI3K mutant MCF-7 xenografts. Combined treatment with AZD5363 and the ER downregulator fulvestrant more effectively suppressed xenograft growth than either drug alone. AZD5363 also caused dose-dependent inhibition of an ER+ breast cancer explant model unresponsive to fulvestrant or tamoxifen. We next examined whether AKT inhibition results in feedback upregulation of mitogenic signaling pathways. Treatment with AZD5363 resulted in upregulation and phosphorylation of the HER3 receptor tyrosine kinase (RTK), as well as upregulation of insulin receptor (InsR) protein levels and phosphorylation of Src at Y416. A Src family kinase inhibitor suppressed AZD5363-induced upregulation of P-HER3 in MCF-7/LTED cells. Src inhibition or siRNA-mediated knockdown of InsR or IGF-IR significantly enhanced the growth inhibitory effects of AZD5363. Following treatment with AZD5363, phospho-RTK array analysis revealed increased phosphorylation of multiple RTKs in MCF-7/LTED and/or ZR75-1/LTED cells, including InsR, IGF-IR, EGFR, HER2, HER3, HER4, Dtk, and FGFR3. Treatment with AZD5363 also upregulated RTK mRNA levels. Further, treatment of MCF-7/LTED cells with AZD5363 resulted in marked translocation of AKT PH-GFP to the membrane, reflective of increased PIP3 production and, thus, AKT phosphorylation at T308. Pre-treatment with the PI3K inhibitor BKM120 or the IGF-IR/InsR TKI AEW541 prevented AZD5363-induced membrane localization of PH-GFP. These results suggest that 1) AKT signaling is critical for hormone-independent growth of ER+ breast cancer cells in vitro and in vivo; and 2) AKT inhibition in these cells induces feedback upregulation of RTK expression and activity. Thus, inhibitors of AKT merit evaluation as a potential treatment for endocrine-resistant breast cancer. The combination of these agents with inhibitors of upstream RTKs are under evaluation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4825. doi:1538-7445.AM2012-4825

A Lack of Ovarian Function Increases Neuroinflammation in Aged Mice

Although several lines of evidence have indicated that menopause is associated with increased susceptibility to neurological disorders, the mechanisms involved in this phenomenon remain to be elucidated. Because neuroinflammation is a common feature of a number of brain diseases, we hypothesized that the cessation of ovarian functions and the consequent decrease in estrogen receptor (ER)-mediated antiinflammatory activity may represent a trigger for postmenopausal brain dysfunctions. The aim of the present study was to investigate the effects of aging and surgical menopause on the activity of ER in neuroinflammation. The present study shows that ER genes are expressed in the hippocampus, but ER transcriptional activity decreases significantly beginning at 12 months of age in intact and ovariectomized mice. With ovariectomy, we observe an age-dependent accumulation of mRNA encoding inflammatory mediators (e.g. TNFα, IL1β, and macrophage inflammatory protein-2) and changes in the morphology of astroglia and microglia. In addition, we show that aging itself is coupled with an exaggerated response to acute inflammatory stimuli with a major accumulation of TNFα, IL1β, macrophage inflammatory protein-2, and macrophage chemoattractant protein-1 mRNA in response to lipopolysaccharide administration. The response to acute inflammatory stimuli appears to be differentially modulated by the duration of hormone deprivation in 12-month-old mice. Taken together, the present results show that aging is associated with decreased ER activity, despite continuous ER synthesis, and that age-dependent neuroinflammation is strongly influenced by hormone deprivation.