Bruce R. Ransom - US grants

The proposed research represents a continuation of studies on some of the basic physiological, morphological, and pharmacological properties of mammalian glia and neurons in in vitro systems. This research will also investigate the characteristics and homeostatic regulation of ionic and volume fluctuations in the extracellular space (ECS) of in vitro preparations. Some of these issues will be carefully studied at different stages during postnatal development and correlated with important morphological or biochemical changes occurring at these times. A new research direction for this plan is the analysis of the single ion channel in cultured or isolated glial cells. Isolated rat optic nerves, tissue slices from rat neocortex, and cultured rodent astrocytes will be used in most experiments and offer several advantages over in vivo preparations including ready access of perfusion solutions to the ECS, direct visualization of microanatomic features of the tissue cells, and relative ease of intracellular recordings from neurons and glia. One component of the project will investigate characteristics of some of these issues in a non-mammalian preparation, the turtle brain. Using intracellular staining and recording techniques the following projects will be undertaken: 1) developmental study of glial cell physiology and morphology in the rat optic nerve; 2) electrophysiological, morphological, and metabolic studies on glia in the rat optic nerve; 3) mechanisms of slow potential generation and ECS ionic homeostasis in turtle cortex; 4) characterization of neural activity-dependent changes of pHo in rat optic nerve and neocortical tissue slice; 5) mechanisms of neural activity dependent ECS shrinkage; 6) patch clamp studies on single ionic channels of glia in vitro.

The proposed research represents a continuation of studies, in vitro, of some of the basic physiological and morphological properties of mammalian glia and neurons, in relation to the ionic and volume regulation of the extracellular space (ECS) of brain. The long term goals of this work are to discover how the basic properties of glia and neurons interact to account for the dynamic, but regulated, ionic and volume flucuations seen in the ECS with brain activity. A new direction for this proposal is to study this issue in a pathological circumstance; specifically, to analyze the pathophysiology of anoxia in white matter of the brain, in mature and developing animals, using the isolated rat optic nerve (RON). Isolated RONs, tissue slices from rat cortex, and cultured astrocytes, will be used in most experiments and offer several advantages over in vivo preparations, including ready access of perfusion solutions to the ECS, direct visualization of microanatomic features of the tissue cells, and great experimental flexibility. Using standard electrophysiological recording techniques, ion-sensitive microelectrodes, and the patch-clamp method, the following projects will be undertaken: 1) developmental study of glial cell physiology and morphology in the RON; 2) patch-clamp studies of single ion channels in cultured glia; 3) analysis of activity dependent and K+ - induced changes in pHo in the RON and cortex; 4) studies on the pathophysiology of anoxia in white matter, using the RON; 5) studies on the mechanism(s) of neural activity dependent and K+ - induced ECS shrinkage; 6) developmental studies on the susceptibility of white matter to anoxic injury. These studies should provide basic new information about the properties of glia and neurons, especially as these relate to ion homeostasis in brain ECS under normal and pathological conditions. These studies are broadly relevant to the clinical problems of stroke, neonatal asphyxia, and brain swelling.

More than a century ago, Golgi suggested that glial cells provide nutrients to neurons. This idea gained credibility when astrocytes, but not neurons, were discovered to contain glycogen, the main energy reserve in the brain. Recent observations on the retinas of the honeybee and rabbit, have provided modem experimental evidence that glial cells can provide fuel to neurons. The role of glycogen, however, remains a mystery. The experiments proposed in this application will critically address the role of glycogen in glial- neuronal interactions during brain energy metabolism. These experiments will be carried out using an advantageous preparation of central nervous system (CNS) white matter, the isolated rat optic nerve. The long term goals of this research are: 1) to learn more about the physiology and function of glial cells, and 2) to understand the mechanisms of CNS white matter injury as occurs with stroke, hypoglycemia, anoxia or trauma, and to devise better ways of minimizing this injury. Broadly stated, the specific aims of this proposal are to learn how glial cells and axons in the CNS interact when deprived of glucose and to understand how glucose deprivation injures central axons. Two hypotheses will be tested: 1) During hypoglycemia in the CNS, astrocytes supply energy substrate to axons in the form of lactate derived from glycogen. Axon function and survival depend on glycogen in the absence of glucose. 2) Axon injury caused by glucose deprivation is Ca2+- dependent and is due to Ca2+ entry mediated by reverse Na+/Ca2+ exchange and Ca channels. The role of astrocytes in supplying energy substrate to axons will be studied using the in vitro rat optic nerve preparation, quantitative electrophysiological techniques to monitor optic nerve function, chemical measurement of glycogen content, and pH, glucose-sensitive, and lactate sensitive microelectrodes. The mechanisms of hypoglycemia-induced axon injury will be studied using quantitative measures of optic nerve function in conjunction with measurement of [Ca2+ ]o using Ca2+-sensitive microelectrodes. These studies will provide useful new information about the manner in which glial cells and neurons interact in the context of brain energy metabolism. They will also assess the importance of astrocytic glycogen for neural function during and for recovery after periods of hypoglycemia, and may suggest novel strategies to stave off neural injury under these conditions.

[unreadable] DESCRIPTION (provided by applicant): The field of Neurology has limited traditional mechanisms for funding the research training the completion of residency. Limited opportunities are sometimes available through participation in sub-specialty clinical training programs. However, these programs do not fill the gap in many areas of neurology where there is a very active research community, but few recognized or stably funded clinical sub-specialty training programs. The University of Washington and an extraordinarily rich environment for research and training in clinically relevant neuroscience as well as the epidemiology of neurological diseases. We have identified a group of 30 faculty members eager to provide neurologists with research training in their field. The proposed research training program will provide structured post-doctoral training opportunities for physicians who have completed clinical training in Neurology. This is a broadly based program in which trainees will have the opportunity to participate in one of four curricula: Basic Science of Neurology, Neurogenetics, Translational Research in Neuromuscular Disease and Clinical Research in Neurology. The first three programs will provide training in laboratory based methods for research in neurological diseases and the fourth will provide access to Masters Degree training from the School of Public Health as well as clinical research training for Neurologists wishing to develop the skills needed for a career in clinical research. Training opportunities will be available at four sites, The University of Washington, Harborview Medical Center, Fred Hutchinson Cancer Research Center and the Seattle VA Medical Center. Trainees will be provided with several levels of mentorship and access to resources for academic career development, and the acquisition of teaching and communication skills. The goal of the program is that every trainee will have obtained the next appropriate level of research funding and an academic position on completion of two or three years in the training program. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): This proposal requests partial support for an international meeting on Glial Biology, as part of the Gordon Research Conference series, to be held in Ventura, California, March 15-20, 2009. The broad and long-term goal of the conference is to increase our understanding of the manner in which glial cells interact with one another and with neurons during normal brain function and in neurological diseases. The biology of astrocytes and microglial cells, more than that of oligodendrocytes, is emphasized in this meeting. The specific aim of this meeting will be to convene 44 speakers to discuss critical areas of glial research with a total of 140 participants, during a five-day conference in a relatively isolated setting. The program will have nine sessions that broadly address glia cell involvement in synaptic structure and function, neurogenesis, brain energy metabolism, cerebral blood flow, and some neurological diseases including tumors and stroke. In addition, two poster sessions will permit all participants to contribute to discussion of these topics. The significance of this application is that the Gordon Research Conference on Glial Biology is a essential component of the recurring conferences that promote worldwide research on glial cells, and help define critical research areas in need of experimental resolution. The health relatedness of this application is that glial cells participate in many, possibly all, neurological diseases. Discussions about current research will advance our understanding of glial cells in both health and disease. In addition, specific presentations at this conference will focus on the involvement of glial cells in brain development, tumor formation and spread, normal and deranged energy metabolism (e.g., stroke and hypoglycemia) and pain perception. PUBLIC HEALTH RELEVANCE: The health relatedness of this application is that glial cells participate in many, possibly all, neurological diseases. Discussions about current research will advance our understanding of glial cells in both health and disease. In addition, specific presentations at this conference will focus on the involvement of glial cells in brain development, tumor formation and spread, normal and deranged energy metabolism (e.g., stroke and hypoglycemia) and pain perception. By helping to define key questions that require experimental resolution we can advance our understanding of how glial cells are involved in neurological diseases, which are the first necessary steps to lessening the burden of these diseases on society.

DESCRIPTION (provided by applicant): This application seeks funding for a one and a half day mentoring symposium entitled How to Combine Clinical and Research Careers in Neuroscience (CCRCN). The program is sponsored by the Association of University Professors of Neurology (AUPN) (www.aupn.org), together with the National Institute of Neurological Disorders and Stroke (NINDS), the American Neurological Association (ANA) and the Child Neurology Society (CNS). The AUPN is the professional organization for Chairs of Neurology Departments, or Divisions, in accredited medical schools in the United States. Its goal is excellence in the care of patients with neurological disease by providing superior education to neurology trainees and by expanding knowledge about neurologic diseases. Two other professional organizations, the American Neurological Association (ANA) and The Child Neurology Society (CNS), share AUPN's and NINDS' concerns regarding the decline in the number of clinician-scientists, and have joined AUPN and NINDS financially supporting the CCRCN. The CCRCN symposium was first offered in 2003 by the AUPN and NINDS to meet the urgent need for more clinician-scientists, specifically in neurology. In 2005, JAMA reported that less than 2% of all physicians are scientists and, despite increases in research activity and funding, this number continues to drop. When this program began in 2003, the trend showed two decades of increasing biomedical research funding but an alarming 22% decrease in the clinician-scientist workforce; studies showed that more than a third of medical school graduates with MD/PhD do not realize their original goal of becoming active clinician-scientists. The specific aims for this symposium are to: 1) encourage medical students with neuroscience research training to pursue clinical training (with special emphasis on neurology); 2) describe and discuss strategies for successfully melding clinical and research careers; 3) discuss the satisfactions and power of a combined research and clinical career; 4) describe and discuss sources of, and strategies for, obtaining long term training and research support; and 5) provide an opportunity for students to meet and network with academicians who have successfully combined clinical and research careers in neuroscience. Medical students who may be candidates for combined research and clinical careers in the neurosciences are invited to apply to attend this meeting. The ideal candidate will have completed preclinical training and at least one additional year of neuroscience research training. Further consideration is given to students who have completed some required clinical clerkships, as this is the time when many students will be thinking about further clinical training. This symposium is highly relevant to the mission of NINDS, which is to reduce the burden of neurological disease. This laudable goal is directly supported by the CCRCN which strives to increase the number of well-trained clinician-scientists working to find treatments, and even cures, for neurological diseases.