The Short-term Mentored Career Enhancement Award in Basic Behavioral and Social Sciences: Cross-Training at the Intersection of Animal Models and Human Investigation (K18) is a unique opportunity to fund significant and innovative research while simultaneously building the skill set, and thereby future scientific discovery potential, of a scientist. The current application proposes to secure training in human investigation for Gretchen Neigh, Ph.D., a behavioral neuroendocrinologist currently adept at the use of animal models to address questions of the neurobiological basis of behavior. Dr. Neigh's research portfolio focuses on potential metabolic underpinnings of behavioral disorders such as Major Depressive Disorder (MDD) and Post-Traumatic Stress Disorder (PTSD). The work proposed serves the dual purpose of extending Dr. Neigh's innovative hypotheses regarding glucose transport and origin of neuropsychiatric disorders from her current work in rodent models to assessments using human investigation. This training experience will provide a foundation for translational reciprocity in Dr. Neigh's research program and address a question of fundamental importance: assessment of the potential role of metabolism in manifestation of MDD and/or PTSD. Over 23 million people in the United States suffer from MDD or PTSD and these disorders compromise quality of life and generate significant economic burden. Both human and animal studies have provided evidence of changes in cerebral metabolism in these conditions and related animal models. The alterations in metabolic activity are generally attributed to reduced glutamate release from neurons which thereby decreases regional glucose transport. Counter to this traditional dogma, it is possible that a primary change in facilitated glucose transport subsequently suppresses neuronal activity. Facilitated glucose transport is mediated by a family of transporters (GLUT) that are responsible for glucose transport across the endothelial cells of the blood brain barrier, and for uptake of glucose into astrocytes and neurons. Deficits in the expression and translocation of members of the GLUT family have been linked to neuropathological conditions including Alzheimer pathology, post-ischemic brain function, and post- traumatic brain injury deficits. Alterations in the expression o translocation of members of the GLUT family in either the endothelial cells of the blood brain barrier, astrocytes, or neurons, could alter neuronal energy supply and thereby neuronal function, subsequently altering behavior. A polymorphism in GLUT1 has been demonstrated in humans and linked to altered progression and prognosis in cancer and diabetic nephropathy. Alterations in the availability of GLUT1, due to genetic differences in expression, may alter the relative risk 0f development of aberrant behaviors following trauma, leading to the manifestation of MDD and/or PTSD. Given the crucial role of GLUT proteins in the transport of energy substrates into cerebral tissue, evidence of altered cerebral metabolism in neuropsychiatric disorders, and evidence that glucose transporters are altered after stress exposure in animal models, the proposed work tests the hypothesis that a polymorphism in GLUT 1 will decrease the incidence of MDD and/or PTSD following trauma exposure. This work challenges the standard paradigm because cerebral GLUT is a novel point of origin for consideration in the pathophysiology of MDD and PTSD as it is generally accepted that the changes in glucose transport that are documented in imaging of patients are the result of altered neuronal activity as opposed to the cause of altered neuronal activity.
Specific Aim 1 will determine the extent to which a polymorphism in GLUT 1 decreases the manifestation of MDD following trauma exposure. DNA samples will be assessed for the rs710218 polymorphism in GLUT 1. Multivariate analyses will be conducted to determine if individuals that have been exposed to trauma and have the polymorphism are resistant to the manifestation of MDD.
Specific Aim 2 will ascertain the degree to which a polymorphism in GLUT 1 decreases the incidence of PTSD following trauma exposure. Similar to work described in Aim 1, Aim 2 will again assess the influence of the GLUT 1 polymorphism on outcome from trauma, but in this case the focus will be on PTSD. Completion of the proposed work will provide novel and innovative insight into a potential metabolic susceptibility of genetic origin to trauma-induced mental health impairments. Appreciation for the role of metabolic factors in the manifestation of behavioral disorders will provide a new direction of consideration for novel therapeutic options. In addition, the proposed work will facilitate the cross- training of an established behavioral neuroscientist, Dr. Gretchen Neigh, currently specialized in investigation of the neural substrates of behavior using animal models, in human investigation. Enhancement of Dr. Neigh's training will lead to increased translational reciprocity in her research program and through her interactions with trainees and collaborators will improve interactions between clinical and basic researchers in the behavioral sciences.
Major depressive disorder (MDD) and post-traumatic stress disorder (PTSD) are two of the leading causes of disability in the United States. A growing number of studies indicate that genetic susceptibility in combination with environmental exposure lead to the manifestation of MDD and/or PTSD. The ultimate goals of this proposal are to: 1) build the research base of the United States by cross-training a basic behavioral neuroscientist in the area of human investigation, and 2) determine if a polymorphism in glucose transporter 1 protects against the manifestation of PTSD or MDD following trauma in a high-risk environment.