Ryan P. Vetreno, Ph.D. - US grants

DESCRIPTION (provided by applicant): Maturation of reward, affect, and behavioral control coincides with morphological changes in the frontal cortex and limbic brain regions during the transition from adolescence to adulthood. Alcohol consumption during adolescence is highly prevalent, but its impact on maturation is currently unknown. Previous studies from our laboratory have shown that adolescent rats are far more sensitive to ethanol-induced neurodegeneration and inhibition of hippocampal neurogenesis than adults. Adolescent binge ethanol exposure in mice was demonstrated to reduce forebrain volume and cholinergic cell populations in the nucleus basalis that was associated with reversal learning impairment on the Morris Water maze. Although binge drinking is common during adolescence, it is unknown whether alcohol exposure results in persistent changes to brain morphology. Furthermore, it is unknown if binge drinking during adolescence increases the likelihood of developing psychopathology in adulthood. This Postdoctoral Fellowship grant hypothesizes that adolescent intermittent ethanol (AIE) will persistently alter both cellular and morphological maturation of th frontal cortex and limbic system, which will culminate in altered adult cognitive and emotive function. The AIE paradigm will be used in the following 3 Aims: Aim 1. Test the hypothesis that AIE induces persistent changes to adolescent brain morphology that continue into adulthood. Aim 2. Test the hypothesis that adolescent intermittent ethanol (AIE) exposure alters adolescent and adult brain cellular composition and neurogenesis. Aim 3. Test the hypothesis that adolescent intermittent ethanol (AIE) will result in alterations to neurocognitive function that wil be evident in adulthood. Following AIE treatment, neuroimaging will be used to assess brain integrity, cortical thickness, white matter tracts, and regional volumes in adolescent (P56) and adult (P80) rats (Aim 1). Immunohistochemistry will be performed to assess adolescent and adult brain neuronal/glial composition and neurogenesis (Aim 2). Adult rats exposed to AIE will be assessed on a measure of cognition (Barnes maze, spatial and reversal learning) or an emotive behavioral battery (forced swim, open-field, social interaction, elevated plus-maze [Aim3]). The innovative training approach, which involves guidance and instruction from experts in the field of neuroimaging (Styner and Oguz), immunohistochemistry (Crews), and behavioral assessment (Crews) as well as attendance of courses and seminars, will allow for an in depth assessment of the detrimental effects of adolescent alcohol abuse on brain maturation and function in adulthood. Indeed, persistent alterations in behavior, morphology, and brain histology following adolescent alcohol exposure could change attitudes regarding underage drinking and discover new etiological mechanisms of adult brain pathology and mental illness. PUBLIC HEALTH RELEVANCE: Adolescent use of alcohol represents a major public health concern with potential long-lasting impact on health care in the U.S. The adolescent period is characterized by considerable brain development and maturation. Since alcohol affects adolescent brain function differently than adults, it is imperative to determine if exposure during this maturational period confers persistent brain changes that continue into adulthood.

Abstract. This is a revised application for a Mentored Research Scientist Development Award (K01) to support the career development of Dr. Ryan Vetreno as an independent academic research scientist in the field of alcohol research. The applicant?s career and research training will be supervised by an outstanding mentoring team and supported by strong institutional commitment to the candidates? career development. Humans typically begin drinking during adolescence when the brain is maturing and adolescent drinking behavior is characterized by the consumption of large quantities of alcohol in a heavy binge-like intermittent fashion (e.g., weekend drinking). Preclinical models of adolescent binge drinking reveal persistent reductions of basal forebrain cholinergic neurons, diminished hippocampal excitatory neurotransmission, and impaired reversal learning in adulthood. Using the adolescent intermittent ethanol (AIE) model of human adolescent binge drinking, Dr. Vetreno discovered increased expression of the innate immune receptor Toll-like receptor 4 (TLR4), the endogenous TLR4 agonist high-mobility group box 1 (HMGB1), and multiple proinflammatory signaling molecules that persist in the adult brain. The causal relationship between AIE-induced HMGB1-TLR4 innate immune induction and subsequent adult neuropathology is unknown. In his revised application, Dr. Vetreno proposes to test the mechanistic hypothesis that AIE induction of HMGB1-TLR4 signaling causes degeneration of adolescent basal forebrain cholinergic neurons leading to hippocampal dysfunction in adulthood. In order to fully test this hypothesis, Dr. Vetreno and his Mentors have devised a comprehensive mentoring and research plan that will provide him with protected time for intensive training in ex vivo slice culture, electrophysiology, and chemogenetics. The training outlined in this proposal will provide the candidate the means to develop a successful, independent research laboratory at the University of North Carolina at Chapel Hill that will be at the forefront of adolescent alcohol and neuroimmune research. Together, these studies will advance our understanding of the mechanisms underlying persistent changes to adolescent brain development associated with underage binge drinking, provide innovative targets for the development of therapeutic interventions, and will markedly advance Dr. Vetreno?s career development and scientific independence.

ABSTRACT. Adolescent Alcohol in 5xFAD Mouse Model Accelerates Neuroinflammation and Alzheimer?s Disease Pathology Across Aging. Our laboratory and others find adolescent intermittent ethanol (AIE; 2-days EtOH/2-days NO EtOH during adolescence) primes and accelerates adult Alzheimer?s disease (AD)-related degeneration and cognitive deficits that persist in the absence of continued adult EtOH exposure. Our premise for this proposal is built on priming of common mechanisms of pathology, including chronic neuroinflammation and loss of basal forebrain cholinergic neurons (BFCNs). This proposal will test the overarching hypothesis that AIE-induced persistent, life-long loss of BFCNs and chronic neuroinflammation contribute to the onset and progression of AD-associated neuropathology and cognitive decline across aging. This hypothesis is built on our preliminary findings, including (1) AIE increase of receptor for advanced glycation end-products (RAGE) and other neuroinflammatory molecules, induction of AD-associated genes, and reductions of BFCNs, hippocampal neurogenesis, and cognitive function in adulthood; (2) increased RAGE-neuroinflammation and AD-like pathology in post-mortem human AUD brain samples of individuals with an adolescent age of drinking onset. We recently discovered that AIE accelerates adult BFCN neurodegeneration, neuroinflammation, and accumulation of amyloid-? (A?) in a genetic mouse model of AD. We developed an innovative mouse model using the 5xFAD genetic mouse model of AD, which recapitulates the dual A? accumulation and neurodegeneration observed in human AD, crossbred with ChAT- Cre mice to investigate interactions of AIE with A? accumulation across aging on BFCN and hippocampal pathology. Aim 1 tests the hypothesis that AIE accelerates AD-associated neuropathology in the aging brain of ChAT-Cre::5xFAD mice. We expect AIE will accelerate neuroinflammation, neurodegeneration, and AD-associated pathology across ages. Aim 2 tests the hypothesis that AIE-induced basal forebrain RAGE- neuroinflammatory signaling causes BFCN loss, neuroimmune signaling, AD pathology, and cholinergic dysfunction in the aging brain of ChAT-Cre::5xFAD mice. AIE induces RAGE-neuroinflammatory signaling and loss of BFCNs that persists into adulthood. We expect RAGE-neuroinflammatory signaling contributes to AD-associated BFCN pathology. Aim 3 tests the hypothesis that chronic activation of basal forebrain cholinergic activity during AIE prevents loss of hippocampal activity, neurogenesis, and cognitive function, and reduces AD-associated neuropathology in the aging brain of ChAT-Cre::5xFAD mice. AIE increases hippocampal neuroinflammation, reduces neurogenesis, and impairs cognition in adulthood that is prevented by anti-cholinesterase drugs. We expect BFCN activation to both identify cholinergic involvement and recover AD-associated hippocampal pathology. The proposed studies will link early life insults (i.e., adolescent binge drinking) to AD-like neurodegeneration and dementia in the aging brain, and identify potential therapeutics.