David Olson - US grants

? DESCRIPTION (provided by applicant): The complexity of central nervous system regulation of energy balance and metabolic homeostasis is underscored by the variety of the signals and brain areas that have been implicated in these homeostatic functions. Within the hypothalamus, the paraventricular nucleus is known to be a critical region involved in the regulation of metabolism and autonomic function. Destruction of the PVH has been associated with hyperphagia, excessive weight gain, alterations in glucose and insulin homeostasis, and cardiovascular function. Although the importance of the PVH in endocrine and autonomic function is widely accepted, relatively little is known about the specific mechanisms through which this heterogeneous group of neurons mediates these effects. This proposal aims to test the hypothesis that discrete subsets of PVH neurons play unique roles in metabolic regulation. We focus on analyzing the neural circuitry, physiologic function and transcriptional profile of insulin receptor substrate-4 neurons located within the PVH. To achieve these goals, a novel IRS4-Cre driver line has been generated. Cre-dependent neuronal tracers and neuron modulators will be injected stereotaxically into the PVH of IRS4-Cre mice to map PVHIRS4 neuronal connections and directly test the role of these neurons in energy balance and metabolic control. Elucidation of the anatomic and cellular mechanisms through which the PVH regulates metabolism and endocrine function will yield new insights and potential targets for the treatment of obesity and diabetes.

  PROJECT SUMMARY/ABSTRACT A preponderance of evidence from a combination of human imaging, postmortem studies, and animal models suggests that atrophy of neurons in the prefrontal cortex plays a key role in the pathophysiology of neuropsychiatric diseases such as depression, anxiety disorders, and addiction. These structural changes, such as the retraction of neurites and loss of dendritic spines, can potentially be counteracted by compounds capable of facilitating structural and functional neural plasticity. In fact, the promotion of neural plasticity in the prefrontal cortex has been proposed to play a crucial role in the therapeutic mechanism of fast-acting antidepressants and anxiolytics such as ketamine. Compounds from the iboga and ergoline families of natural products have shown enormous potential for promoting neuritogenesis, spinogenesis, and synaptogenesis in cortical neurons, and have demonstrated plasticity-promoting properties superior to ketamine. However, it is currently unknown which structural features of these molecules contribute to their efficacy. Our overall objective is to produce more effective and safer plasticity-promoting molecules through structure-activity relationship studies of these key scaffolds. To gain access to the large number of structural variants required for these studies, we propose novel synthetic routes to both the iboga and ergoline classes of natural products. The strategies we advance are significantly shorter than previously reported syntheses and allow for facile diversification and analog generation. The compounds that we design and synthesize will be assessed using novel in vitro neural plasticity assays developed in our lab. Ultimately, the work described here will fill the gap in our knowledge about how molecular structure impacts neural plasticity and will prove instrumental to the evolution of next-generation neurotherapeutics.

Project Summary/Abstract - Molecular Genetics Core Given the value of model organisms and molecular genetic tools for the study of diabetes and its co- morbidities, the Molecular Genetics Core (MGC) is designed to aid diabetes researchers in the development of novel rodent models and molecular tools to determine the cellular and molecular mechanisms contributing to diabetes. Established in 2015, the MGC is a fee-for-service core that facilitates the application of molecular genetic methods to diabetes-related research. Specifically, the MGC (1) designs and produces genetically- modified rodent models (using CRISPR/Cas9) for use in diabetes-related research; (2) designs and produces AAV vectors for use in diabetes research; (3) produces and provides specialty viral reagents for use in diabetes research; and (4) provides advice and training in the use of these technologies to members of MDRC laboratories. The MG Core also owns and maintains several pieces of shared equipment for the use of MDRC members located at different sites around the UM medical campus. While CRISPR/Cas9 technology has dramatically increased the speed and decreased the cost at which such models can be generated, the pace at which this new technology continues to evolve prevents many diabetes researchers from taking full advantage of its potential. The MGC fills this gap by using its expertise and personnel to design and construct CRISPR/Cas9 targeting reagents, collaborate with the UM Transgenic Core to test these reagents in embryos and produce founder mice, and identify founders for transfer (along with genotyping protocols) to the MDRC investigator. For the generation of viral reagents, the MGC designs and produces any necessary constructs, which are packaged into viruses by the UM Viral Vector Core. With input from MDRC members and the MGC advisory committee, the MGC also identifies and develops new technologies (viral and genetic) in support of the research programs of MDRC members.

  PROJECT SUMMARY/ABSTRACT A preponderance of evidence from a combination of human imaging, postmortem studies, and animal models suggests that atrophy of neurons in the cortex and/or hippocampus plays a key role in the pathophysiology of both neuropsychiatric and neurodegenerative diseases such as depression, anxiety disorders, Alzheimer's disease, and frontotemporal dementia. These structural changes, such as the retraction of neurites and loss of dendritic spines, can potentially be counteracted by compounds capable of facilitating structural and functional neural plasticity. In fact, the promotion of neural plasticity in the prefrontal cortex has been proposed to play a crucial role in the therapeutic mechanism of fast-acting antidepressants and anxiolytics such as ketamine. Compounds from the iboga and ergoline families of natural products have shown enormous potential for promoting neuritogenesis, spinogenesis, and synaptogenesis in cortical neurons, and have demonstrated plasticity-promoting properties superior to ketamine. However, it is currently unknown which structural features of these molecules contribute to their efficacy. Our overall objective is to produce more effective and safer plasticity-promoting molecules through structure-activity relationship studies of these key scaffolds. To gain access to the large number of structural variants required for these studies, we propose novel synthetic routes to both the iboga and ergoline classes of natural products. The strategies we advance are significantly shorter than previously reported syntheses and allow for facile diversification and analog generation. The compounds that we design and synthesize will be assessed using novel in vitro neural plasticity assays developed in our lab as well as established cellular models of Alzheimer's disease. Ultimately, the work described here will fill the gap in our knowledge about how molecular structure impacts neural plasticity and will prove instrumental to the evolution of next-generation neurotherapeutics.

Hypothalamic circuits mediate their feeding and energy balance effects in part via descending projections to brainstem satiety systems. Cells within the parabrachial nucleus (PBN) respond both to descending hypothalamic control and to ascending inputs from the nucleus of the solitary tract (NTS) that encode peripheral satiety signals emanating from the gastrointestinal tract. Signals of gut status (including distention, nutrient content, etc.) travel via the vagus nerve and the circulation and converge on the area postrema (AP) and nucleus of the solitary tract (AP/NTS). The AP/NTS conveys this gut status information to the PBN and other rostral centers. The PBN relays this information rostrally to the central nucleus of the amygdala (CeA) and elsewhere to promote satiety. CeA-projecting CGRP-expressing PBN (CGRPPBN) neurons promote a negative-valence anorexia and play a requisite role in the generation of conditioned taste aversion to noxious GI stimuli. The observations that local administration of glucagon-like peptide 1 (GLP-1) receptor agonists into the PBN suppress feeding without aversion and that descending Mc4R+ hypothalamic inputs to the PBN suppress feeding with positive valence suggests the distinct nature of rewarding satiety systems and aversive anorexia circuits within the PBN. Importantly circuits mediating aversive symptoms such as nausea are intermingled with satiety systems within the PBN and this interaction limits medical therapies that target the brainstem satiety circuits for therapeutic advantage. Thus, it is crucial to distinguish the brain systems that encode satiety from those that promote nausea and other aversive symptoms. A thorough molecular-functional characterization of PBN cell types is lacking and is critical to understanding the acute and chronic regulation of feeding and anorexia. Our preliminary data reveal that glucagon-like peptide 1 receptor (GLP-1R)-expressing PBN neurons(GLP-1RPBN) are distinct from aversive CGRPPBN neurons and suppress feeding without aversion. We hypothesize that GLP-1RPBN cells are activated by nonaversive satiety signals that convey positive valence, whereas CGRPPBN cells are activated by and mediate the response to aversive GI stimuli. This proposal will test the hypotheses that 1) non-aversive GLP-1RPBN and aversive CGRPPBN neurons lie in distinct circuits and respond to differing stimuli, 2) GLP-1RPBN and CGRPPBN neurons activate different downstream circuits and mediate distinct physiological and behavioral functions and 3) and GLP-1RPBN and CGRPPBN neurons are differentially required for the physiological and pharmacological control of food intake.

Project Summary A preponderance of evidence from a combination of human imaging, postmortem studies, and animal models suggests that atrophy of neurons in the prefrontal cortex plays a key role in the pathophysiology of neuropsychiatric diseases such as depression, anxiety disorders, and addiction. These structural changes, such as the retraction of neurites and loss of dendritic spines, can potentially be counteracted by compounds capable of facilitating structural and functional neural plasticity. In fact, the promotion of neural plasticity in the prefrontal cortex has been proposed to play a crucial role in the therapeutic mechanism of fast-acting antidepressants and anxiolytics such as ketamine. Compounds from the iboga and ergoline families of natural products have shown enormous potential for promoting neuritogenesis, spinogenesis, and synaptogenesis in cortical neurons, and have demonstrated plasticity-promoting properties superior to ketamine. However, it is currently unknown which structural features of these molecules contribute to their efficacy. Our overall objective is to produce more effective and safer plasticity-promoting molecules through structure-activity relationship studies of these key scaffolds. To gain access to the large number of structural variants required for these studies, we propose novel synthetic routes to both the iboga and ergoline classes of natural products. The strategies we advance are significantly shorter than previously reported syntheses and allow for facile diversification and analog generation. The compounds that we design and synthesize will be assessed using novel in vitro neural plasticity assays developed in our lab. Ultimately, the work described here will fill the gap in our knowledge about how molecular structure impacts neural plasticity and will prove instrumental to the evolution of next-generation neurotherapeutics.

Abstract The postdoctoral Pediatric Endocrinology and Diabetes Training Program at the University of Michigan is designed to recruit and provide high quality research training in one of two major tracks, Basic Science or Clinical Investigation & Epidemiology to qualified candidates. Now on its 15th year, the theme of the Program is developmental programming of disorders of glucose metabolism. The program is organized to complement the established training program in clinical pediatric endocrinology for M.D.s, and for basic scientists pursuing a career in endocrine related research, by providing 2 years of intensive postdoctoral training using a closely- mentored research training program individually structured for each trainee. The program is actively supported by 14 faculty from 11 UM Departments/Schools, all with extensive research and mentoring experience within their respective areas of expertise. The Program also includes an extensive didactic component tailored to each trainee?s educational background and research interests. Trainees initiating Basic Science research complete a 3-month course designed to expose them to a variety of state-of-the-art techniques, as well as to skills in performing hypothesis-driven, controlled research studies. Trainees in Clinical Investigation & Epidemiology choose between Outcomes & Epidemiology or Clinical Research. They complete courses leading to either a Master of Public Health in Biostatistics & Epidemiology or a Master of Science in Clinical Research Design & Statistical Analysis. In addition to the formal curriculum, trainees attend weekly clinical and research seminars, receive instruction preparing and delivering oral presentations, and instruction in ethical conduct of research. Mentored research is supported the Medical School resources including the Centers of Comprehensive Diabetes Research, Nutrition Obesity Research, Organogenesis, Human Growth and Development, Comprehensive Metabolomic Center, Molecular & Behavioral Neuroscience Institute and the Michigan Institute for Clinical and Health Research. To optimize each trainee?s potential for development of a successful academic career, trainees are required to submit abstracts to national meetings, submit a first- authored research manuscript, and apply for individual grant funding. Expansion of our Program will help alleviate the critical shortage of successful Pediatric Endocrinologists and Pediatric Physician-Scientists.