Basic Science and Pathogenesis.

Background: Estrogen is a master regulator of the bioenergetic system in the female brain, exerting broad control over metabolic processes from glucose transport to glycolysis, mitochondrial respiration, and ATP generation. The loss of estrogen during the perimenopausal transition is associated with decline in brain glucose metabolism and mitochondrial function which can contribute to the two-fold greater lifetime risk of Alzheimer's disease in postmenopausal women. While both ERα and ERβ have been reported to mediate E2 regulation of brain bioenergetic function, their cell-type specific contribution to bioenergetic homeostasis has yet to be elucidated.

Allopregnanolone pleiotropic action in neurons and astrocytes: calcium signaling as a unifying mechanism.

Objective: Allopregnanolone (Allo) is a neurosteroid with pleiotropic action in the brain that includes neurogenesis, oligogenesis, human and rodent neural stem cell regeneration, increased glucose metabolism, mitochondrial respiration and biogenesis, improved cognitive function, and reduction of both inflammation and Alzheimer's disease (AD) pathology. Because the breadth of Allo-induced responses requires activation of multiple systems of biology in the absence of an Allo-specific nuclear receptor, analyses were conducted in both neurons and astrocytes to identify unifying systems and signaling pathways.

Methods: Mechanisms of Allo action were investigated in embryonic hippocampal neurons and astrocytes cultured in an Aging Model (AM) media.

Breast cancer therapies reduce risk of Alzheimer's disease and promote estrogenic pathways and action in brain.

Worldwide, an ever-increasing number of women are prescribed estrogen-modulating therapies (EMTs) for the treatment of breast cancer. In parallel, aging of the global population of women will contribute to risk of both breast cancer and Alzheimer's disease. To address the impact of anti-estrogen therapies on risk of Alzheimer's and neural function, we conducted medical informatic and molecular pharmacology analyses to determine the impact of EMTs on risk of Alzheimer's followed by determination of EMT estrogenic mechanisms of action in neurons.

Evidence in support of chromosomal sex influencing plasma based metabolome vs APOE genotype influencing brain metabolome profile in humanized APOE male and female mice.

Late onset Alzheimer's disease (LOAD) is a progressive neurodegenerative disease with four well-established risk factors: age, APOE4 genotype, female chromosomal sex, and maternal history of AD. Each risk factor impacts multiple systems, making LOAD a complex systems biology challenge. To investigate interactions between LOAD risk factors, we performed multiple scale analyses, including metabolomics, transcriptomics, brain magnetic resonance imaging (MRI), and beta-amyloid assessment, in 16 months old male and female mice with humanized human APOE3 (hAPOE3) or APOE4 (hAPOE4) genes.

Allopregnanolone Reverses Bioenergetic Deficits in Female Triple Transgenic Alzheimer's Mouse Model.

Previously, we reported that the neurosteroid allopregnanolone (Allo) promoted neural stem cell regeneration, restored cognitive function, and reduced Alzheimer's Disease (AD) pathology in the triple transgenic Alzheimer's mouse model (3xTgAD). To investigate the underlying systems biology of Allo action in AD models in vivo, we assessed the regulation of Allo on the bioenergetic system of the brain. Outcomes of these analysis indicated that Allo significantly reversed deficits in mitochondrial respiration and biogenesis and key mitochondrial enzyme activity and reduced lipid peroxidation in the 3xTgAD mice in vivo.

Therapeutic progestin segesterone acetate promotes neurogenesis: implications for sustaining regeneration in female brain.

Objective: Neurogenesis is the principal regenerative mechanism to sustain the plasticity potential in adult brains. Decreased neurogenesis parallels the cognition decline with aging, and has been suggested as a common hallmark in the progression of many neurodegeneration diseases. We previously reported that acute exposure to segesterone acetate (ST-1435; Nestorone), alone or in combination with 17β-estradiol (E2), increased human neural stem cells proliferation and survival both in vitro and in vivo.

Sex differences in metabolic aging of the brain: insights into female susceptibility to Alzheimer's disease.

Despite recent advances in the understanding of clinical aspects of sex differences in Alzheimer's disease (AD), the underlying mechanisms, for instance, how sex modifies AD risk and why the female brain is more susceptible to AD, are not clear. The purpose of this study is to elucidate sex disparities in brain aging profiles focusing on 2 major areas-energy and amyloid metabolism-that are most significantly affected in preclinical development of AD. Total RNA isolated from hippocampal tissues of both female and male 129/C57BL/6 mice at ages of 6, 9, 12, or 15 months were comparatively analyzed by custom-designed Taqman low-density arrays for quantitative real-time polymerase chain reaction detection of a total of 182 genes involved in a broad spectrum of biological processes modulating energy production and amyloid homeostasis.

Early intervention with an estrogen receptor β-selective phytoestrogenic formulation prolongs survival, improves spatial recognition memory, and slows progression of amyloid pathology in a female mouse model of Alzheimer's disease.

Our recent developments have yielded a novel phytoestrogenic formulation, referred to as the phyto-β-SERM formulation, which exhibits an 83-fold binding selectivity for the estrogen receptor subtype β (ERβ) over ERα. Earlier studies indicate that the phyto-β-SERM formulation is neuroprotective and promotes estrogenic mechanisms in the brain while devoid of feminizing activity in the periphery. Further investigation in a mouse model of human menopause indicates that chronic exposure to the phyto-β-SERM formulation at a clinically relevant dosage prevents/alleviates menopause-related climacteric symptoms.

Ovariectomy induces a shift in fuel availability and metabolism in the hippocampus of the female transgenic model of familial Alzheimer's.

Previously, we demonstrated that reproductive senescence in female triple transgenic Alzheimer's (3×TgAD) mice was paralleled by a shift towards a ketogenic profile with a concomitant decline in mitochondrial activity in brain, suggesting a potential association between ovarian hormone loss and alteration in the bioenergetic profile of the brain. In the present study, we investigated the impact of ovariectomy and 17β-estradiol replacement on brain energy substrate availability and metabolism in a mouse model of familial Alzheimer's (3×TgAD). Results of these analyses indicated that ovarian hormones deprivation by ovariectomy (OVX) induced a significant decrease in brain glucose uptake indicated by decline in 2-[(18)F]fluoro-2-deoxy-D-glucose uptake measured by microPET-imaging.

Potentiation of brain mitochondrial function by S-equol and R/S-equol estrogen receptor β-selective phytoSERM treatments.

Previously we developed an estrogen receptor β-selective phytoestrogenic (phytoSERM) combination, which contains a mixture of genistein, daidzein, and racemic R/S-equol. The phytoSERM combination was found neuroprotective and non-feminizing both in vitro and in vivo. Further, it prevented or alleviated physical and neurological changes associated with human menopause and Alzheimer's disease.

Continuous versus cyclic progesterone exposure differentially regulates hippocampal gene expression and functional profiles.

This study investigated the impact of chronic exposure to continuous (CoP4) versus cyclic progesterone (CyP4) alone or in combination with 17β-estradiol (E2) on gene expression profiles targeting bioenergetics, metabolism and inflammation in the adult female rat hippocampus. High-throughput qRT-PCR analyses revealed that ovarian hormonal depletion induced by ovariectomy (OVX) led to multiple significant gene expression alterations, which were to a great extent reversed by co-administration of E2 and CyP4. In contrast, co-administration of E2 and CoP4 induced a pattern highly resembling OVX.

2-Deoxy-D-glucose treatment induces ketogenesis, sustains mitochondrial function, and reduces pathology in female mouse model of Alzheimer's disease.

Previously, we demonstrated that mitochondrial bioenergetic deficits preceded Alzheimer's disease (AD) pathology in the female triple-transgenic AD (3xTgAD) mouse model. In parallel, 3xTgAD mice exhibited elevated expression of ketogenic markers, indicating a compensatory mechanism for energy production in brain. This compensatory response to generate an alternative fuel source was temporary and diminished with disease progression.

Estrogen receptor β-selective phytoestrogenic formulation prevents physical and neurological changes in a preclinical model of human menopause.

Objective: As an alternative to estrogen therapy, the efficacy of an estrogen receptor β-selective phytoestrogenic (phyto-β-SERM) formulation to regulate climacteric symptoms and decline in brain responses associated with ovarian hormone loss in menopause was assessed.

Methods: A phyto-β-SERM formulation-containing diet was compared with a commercial soy extract diet and a phytoestrogen-free base/control diet in an ovariectomized (OVX) mouse model of human menopause. Two treatment studies were conducted: (1) a 2-month study assessed the effects of experimental diets on tail skin temperature as a model of menopausal hot flashes, and (2) a 9-month study assessed the long-term impact of the diets on overall health, hair thinning/loss, spatial working memory, and associated protein expression in the hippocampus.

Hippocampal responsiveness to 17β-estradiol and equol after long-term ovariectomy: implication for a therapeutic window of opportunity.

A 'critical window of opportunity' has been proposed for the efficacy of ovarian hormone intervention in peri- and post-menopausal women. We sought to address this hypothesis using a long-term ovariectomized non-human primate (NHP) model, the cynomolgus macaque (Macaca fascicularis). In these studies, we assessed the ability of 17β-estradiol and equol to regulate markers of hippocampal bioenergetic capacity.

The effect of dietary soy isoflavones before and after ovariectomy on hippocampal protein markers of mitochondrial bioenergetics and antioxidant activity in female monkeys.

Estrogen therapy can promote cognitive function if initiated within a 'critical window' during the menopausal transition. However, in the absence of a progestogen, estrogens increase endometrial cancer risk which has spurred research into developing estrogenic alternatives that have the beneficial effects of estrogen but which are clinically safer. Soy protein is rich in isoflavones, which are a class of potential estrogenic alternatives.

17β-Estradiol regulates insulin-degrading enzyme expression via an ERβ/PI3-K pathway in hippocampus: relevance to Alzheimer's prevention.

Insulin-degrading enzyme (IDE), an enzyme that primarily degrades insulin, has recently been demonstrated to play a significant role in the catabolism of amyloid β (Aβ) protein in the brain. Reduced IDE expression and/or activity have been associated with the etiology and development of Alzheimer's disease (AD). Using three model systems, the present investigation provides the first documentation indicating that estrogen robustly regulates the expression of IDE in normal, menopausal and early-stage AD brains.

A select combination of clinically relevant phytoestrogens enhances estrogen receptor beta-binding selectivity and neuroprotective activities in vitro and in vivo.

We have previously shown that a number of naturally occurring phytoestrogens and derivatives were effective to induce some measures of neuroprotective responses but at a much lower magnitude than those induced by the female gonadal estrogen 17beta-estradiol. In the present study, we sought to investigate whether a combination of select phytoestrogens could enhance neural responses without affecting the reproductive system. We performed a range of comparative analyses of the estrogen receptor (ER) alpha/beta binding profile, and in vitro to in vivo estrogenic activities in neural and uterine tissues induced by clinically relevant phytoestrogens: genistein, daidzein, equol, and IBSO03569, when used alone or in combination.

Inferring protein-protein interaction networks from protein complex data.

Present day approaches for the determination of protein-protein interaction networks are usually based on two hybrid experimental measurements. Here we consider a computational method that uses another type of experimental data: instead of direct information about protein-protein interactions, we consider data in the form of protein complexes. We propose a method for using these complexes to provide predictions of protein-protein interactions.

Design, synthesis, and estrogenic activity of a novel estrogen receptor modulator--a hybrid structure of 17beta-estradiol and vitamin E in hippocampal neurons.

We recently discovered that ICI 182,780 (1), an antagonist of estrogen receptor (ER)-dependent proliferation in reproductive tissues, functions as an estrogenic agonist in primary neurons. The present study investigated whether the agonist properties of 1 in neurons could be translated into structural analogs. 7alpha-[(4R,8R)-4,8,12-trimethyltridecyl]estra-1,3,5-trien-3,17beta-diol (2), a hybrid structure of 17beta-estradiol and vitamin E, was synthesized and found to bind to both ERalpha and ERbeta.

Is Melanoma a stem cell tumor? Identification of neurogenic proteins in trans-differentiated cells.

BACKGROUND: Although several genes and proteins have been implicated in the development of melanomas, the molecular mechanisms involved in the development of these tumors are not well understood. To gain a better understanding of the relationship between the cell growth, tumorigenesis and differentiation, we have studied a highly malignant cat melanoma cell line that trans-differentiates into neuronal cells after exposure to a feline endogenous retrovirus RD114. METHODS: To define the repertoire of proteins responsible for the phenotypic differences between melanoma and its counterpart trans-differentiated neuronal cells we have applied proteomics technology and compared protein profiles of the two cell types and identified differentially expressed proteins by 2D-gel electrophoresis, image analyses and mass spectrometry.