Toni R. Pak - US grants

[unreadable] DESCRIPTION (provided by applicant): Gonadotropin-releasing hormone (GnRH) is the primary hormone driving all vertebrate reproductive function and is absolutely required for the initiation of pubertal onset. The factors regulating pubertal onset in male mammals are poorly understood, however it is well accepted that gonadal steroid hormones play a prominent role. The recent discovery of estrogen receptors in GnRH neurons suggests the likelihood that estrogen acts directly on the GnRH neuron to modulate its function. The experiments proposed herein will establish: a) the distribution of estrogen receptor beta (ER-beta) and its splice variants in the brain of male mice during sexual maturation; b) if estrogen modulates GnRH promoter activity in vivo and whether this regulation changes across puberty; and c) if estrogen alters GnRH promoter activity through ER-beta or its splice variants in vitro. Overall these studies will provide important information about the mechanisms regulating puberty in male mammals. [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Women who abuse alcohol are twice as likely to develop anxiety disorders compared with men, a phenomenon in which the underlying biological mechanisms are unknown. Our overall objective is to identify the interactive effects of alcohol and estrogen on arginine vasopressin (AVP), a well-established key molecular mediator of anxiety, in order to elucidate the molecular mechanisms predisposing women to increased risk of anxiety disorders. Adolescent binge drinking is a potential risk factor for the development of adult anxiety disorders due to the heightened stress reactivity that occurs as a direct result of increased circulating estrogens during pubertal development. Little is known about the long-term neurobiological consequences of alcohol consumption during puberty, which is a dynamic and important period of brain development that involves changes in cortical gray matter, synaptic connectivity, and increased neurogenesis. Exposure of alcohol during this critical period of extensive brain remodeling may result in permanent neuronal damage or disruptions in the formation of new neuronal connections, which might manifest as adult behavioral psychoses, including anxiety disorder. Our preliminary data show that 1) alcohol exposure during puberty increased AVP gene expression in specific regions of the brain. Therefore, the experiments proposed in Specific Aim 1 will directly test the hypotheses that there is a critical window of time during pubertal development when the AVP system is most vulnerable to the effects of alcohol and (2) that estrogen exacerbates the effects of alcohol on AVP gene expression. Also, our preliminary data demonstrate that alcohol treatment and estrogen receptor ligands increased AVP gene expression in neuronal cells derived from the hypothalamus, and gene expression is closely correlated with the activity of the gene promoter. Alcohol also activates estrogen-signaling pathways in the brain, which suggests that the underlying mechanisms for alcohol-induced changes in AVP may be mediated by estrogen signaling pathways. Therefore, the experiments proposed in Specific Aim 2 will directly test the hypotheses that (1) acute alcohol exposure increases AVP promoter activity in neuronal cells, (2) that there are specific regulatory regions of the AVP promoter that interact with alcohol, and (3) that estrogen and alcohol interact synergistically to increase AVP promoter activity. To date, specific molecular and neuroendocrine markers that are activated by alcohol during puberty have not been identified. This proposal is focused on a specific candidate gene (AVP) and its downstream signaling pathways that are developmentally shaped during puberty. We expect these studies to show that AVP is permanently altered, either as a direct target for alcohol or indirectly through steroid hormone receptor signaling pathways. Thus, the value of this research lies in the potential for therapeutic approaches that would target specific genes and perhaps reverse brain damage caused by alcohol consumption during pubertal development as well as strengthen reasons for abstaining from alcohol during that time. PUBLIC HEALTH RELEVANCE Women who abuse alcohol are twice as likely to develop anxiety disorders compared with men, a phenomenon in which the underlying biological mechanisms are unknown. This proposal is focused on a specific candidate gene (AVP) and its downstream signaling pathways that are developmentally shaped during puberty. We expect these studies to show that AVP is permanently altered, either as a direct target for alcohol or indirectly through steroid hormone receptor signaling pathways. Thus, the value of this research lies in the potential for therapeutic approaches that would target specific genes and perhaps reverse brain damage caused by alcohol consumption during pubertal development as well as strengthen reasons for abstaining from alcohol during that time.

DESCRIPTION (provided by applicant): Menopause is characterized as a state of reproductive senescence coincident with sharply decreased circulating estrogen levels. Recently, the women's health initiative (WHI) conducted a large-scale clinical study designed to evaluate the neurological benefits of estrogen replacement therapy for post-menopausal women. The results of that study, combined with other studies using animal models, have sparked a fervent debate about whether estrogen is beneficial or detrimental to normal brain function. Estrogen signaling in the brain is conveyed by two high specificity receptors, estrogen receptors alpha and beta (ER1, ER2). Data from our laboratory have focused on the biological function of ER2 for two neuronal-specific genes that are estrogen-responsive and dramatically altered as a direct result of the aging process: gonadotropin-releasing hormone (GnRH) and arginine vasopressin (AVP). GnRH is the primary central regulator of reproduction and AVP is a critical regulator of several processes including mood, circadian rhythms, and the stress response. Our data demonstrate that ER2 differentially regulates these genes in the presence and absence of estrogen, leading to our central hypothesis that the basic function of ER2 in the brain changes during the aging process. Understanding the molecular basis and the associated underlying consequences of changes in ER2 signaling is critical for evaluating the efficacy and necessity of exogenous hormone therapies. The activity of estrogen-bound ER2 can be modulated by different mechanisms, including posttranslational modifications of the receptor, recruitment of coregulatory proteins into the transcription complex, or binding to unique cis-acting promoter elements on the target genes. Whether the estrogen-independent activation of AVP and GnRH by ER2 is mediated by one or all of these mechanisms is unknown. The specific aims outlined in this proposal will investigate each of these possibilities using a variety of molecular biology techniques in neuronal cells. The expected results will further our understanding of ER2 signaling in the post-menopausal brain by elucidating the precise molecular mechanisms that drive estrogen-independent regulation of ER2 target genes. PUBLIC HEALTH RELEVANCE: During normal aging, there is a sharp decline in circulating estrogen levels. The positive health benefits of estrogen replacement therapy in the aged brain have gained considerable interest in recent years;however, our understanding of the molecular mechanisms regulating estrogen signaling in neurons is limited. This proposal will investigate the consequences of estrogen-independent gene regulation in neurons, which is imperative to understand in order to critically evaluate the efficacy and necessity of exogenous hormone therapies.

DESCRIPTION (provided by applicant): Adolescent alcohol abuse is a growing national health concern. Recent data from the Department of Health and Human Services: Substance Abuse and Mental Health Services Administration (2005) showed that over 90% of alcohol consumption by youth follows a binge pattern, defined as consuming enough alcohol in a 2- hour time span to raise the blood alcohol concentrations above the legal limit of 0.08%. Moreover, they report that approximately 2, 8, 20, and 50% of teenagers aged 12, 14, 16, and 18 years, respectively, engaged in binge drinking behavior in the month prior to the survey. The adolescent period is marked by formative changes in neuronal structure and function; therefore, alcohol abuse during this vulnerable time period can result in permanent neurological damage and adult behavioral deficits. The overall goals and specific aims of these proposed studies will 1) elucidate the specific mechanistic pathways by which alcohol exposure during adolescence modifies gene expression in the brain, 2) determine how these modifications persist through adulthood, and 3) ascertain how they are transferred by epigenetic inheritance to the next generation. The experiments will utilize both animal models (rat) of adolescent binge drinking and neuronal cell culture studies to determine the effects of alcohol on the developing adolescent brain. Aim 1 employs proteomic techniques, including 2-D fluorescence difference gel electrophoresis combined with electrospray ionization (MSn) mass spectrometry, to identify specific proteins that associate with the glucocorticoid receptor (GR) after alcohol exposure. In addition, functional assays will determine how these protein:protein interactions alter GR target genes responsible for regulating the stress response. Aim 2 employs techniques to quantify and identify epigenetic changes in the DNA methylation patterns of stress-related genes that are induced by adolescent alcohol exposure. Finally, Aim 3 will examine the offspring of animals exposed to alcohol during adolescence to determine the extent that the epigenetic changes associated with adolescent alcohol abuse are transferred to the offspring. The general research strategy for all of the aims will employ both cutting-edge proteomic and epigenetic techniques, along with classical social behavior tasks, to gain a broad mechanistic understanding of how alcohol can produce long-term, possibly permanent changes in the adolescent and adult stress response. These proposed studies fall within the larger scope of the NIH mission to understand how alcohol abuse produces functional changes in the central nervous system to adversely affect human health. Furthermore, these studies conform to the 5-year strategic plan of the National Institutes of Alcoholism and Alcohol Abuse (NIAAA) to take a lifespan perspective on alcohol abuse and determine how alcohol abuse can produce different physiological outcomes dependent upon specific biological life stages.

The Workshop on Steroid Hormones and Brain Function is a conference dedicated to bringing together leading researchers from diverse scientific fields, such as neuroscience, endocrinology, immunology, and molecular biology to enhance collaborations and enrich our collective understanding of these complex systems. Steroid hormones are a class of chemical compounds that are naturally produced in all vertebrate animals that affect every cell type and physiological system from embryonic development through advanced age. The brain is the preeminent coordinator of these chemical signals to regulate everything from molecular processes within the cell to behavioral outcomes. As an example, brain-dependent elevation of the steroid hormone cortisol increases blood glucose levels to support the cellular energy needed to increase heart rate and muscle function when an individual needs to escape from immediate danger. The conference is strongly committed to inclusion and diversity in science and will encourage participation from scientists and trainees from all genders, ethnicities, cultural and socioeconomic backgrounds.

The conference originated in 1993 and has provided an important forum for established scientists and their trainees with the common goal to further understanding of the neuroendocrine processes regulating physiology and behavior. The limited attendance of approximately 100 researches facilitates deeper interactions among the participants compared to other scientific conferences. This year sessions will span topics that include the emerging fields of neuroimmune signaling, neural circuits, environmental influences on brain and behavior, hormone effects on the aging brain, genetics of sex differences, and Hypothalamic-Pituitary-Adrenal axis regulation and stress-related behaviors. The meeting will host a dedicated Young Investigator Symposium where talented early career researchers will showcase their work and receive valuable scientific input from established researchers. The meeting will also host a technical workshop with industry partners to highlight relevant state-of-the art technology, and a grantsmanship workshop for trainees.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.