Derek A. Hamilton - US grants

[unreadable] DESCRIPTION (provided by applicant): Abnormalities in social behavior and cognition are among the many profound consequences of prenatal exposure to alcohol. Such deficits may underlie or exacerbate deficits in other important areas such as school performance, and contribute to the prevalence of clinical behavioral problems such as conduct disorder. At present there are no long-term treatments for abnormal social behavior in children with Fetal Alcohol Spectrum Disorder (FASD). Despite the importance of these problems, surprisingly little is known about the neurobiological, behavioral, and environmental bases of alcohol-related deficits in social behavior and cognition. However, such information is critical for developing and evaluating therapeutic approaches. The objective of the proposed research is to better understand the neurobiological bases of alcohol-related impairments in social behavior. Due to the broad range of factors that could contribute to alcohol-related deficits in social behavior in FASD children, meeting this objective will require systematic research using animal models of prenatal alcohol exposure. Damage to the OPFC has been linked to abnormal social behavior in many species, providing the rationale for the proposed experiments. The specific aims of the proposed research focus on identifying the effects of moderate prenatal ethanol exposure on socially induced structural plasticity in OPFC neurons and immediate early gene expression in OPFC neurons as a marker of neural activity during social interaction. The proposed research will assess whether prenatal alcohol exposure is associated with a decreased capacity for experience-dependent changes in the dendritif fields of individual neurons as a result of social experience and whether such a diminished capacity is related to a decrease in the responsiveness of OPFC neurons to social stimuli and interaction. Once identified, future research can be undertaken to pursue relevant treatments and identify factors that contribute to or alleviate alcohol-induced behavioral impairments. Importantly, identification of impairments in structural plasticity or neural activation in the rat OPFC may lead to therapeutic approaches in humans, and help bridge the gap between basic and clinical research to advance our knowledge regarding the consequences of prenatal alcohol exposure. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): The proposed research seeks to better understand the effects of moderate prenatal ethanol exposure in the rat on the agranular insular cortex and related behavioral deficits. The agranular insular cortex is analogous to primate orbitofrontal cortex and is targeted for investigation based on its involvement in a diverse set of behavioral and cognitive processes, including social behaviors and behavioral flexibility, that are among the persistent consequences of prenatal exposure to moderate levels of ethanol. A broad, long-term goal of the proposed work is to understand how prenatal ethanol exposure causes persistent alterations in these behavioral domains with initial emphasis placed on identifying 1) the frontal cortex circuitry involved in specific ethanol-related deficits and 2) the mechanistic bases of fetal-ethanol-related effects within the critical circuitry. The proposed research will evaluate two hypotheses. The first states that prenatal exposure to moderate levels of ethanol exposure causes deficits in behaviors that critically depend upon the agranular insular cortex. The second states that fetal-ethanol-related reductions in glutamatergic receptor density and synaptic transmission in the agranular insular cortex contribute to these deficits. The research plan for evaluating these hypotheses involves four major components: 1) Demonstration of moderate fetal-ethanol-related deficits in social, learning, and motor behaviors that depend on agranular insular cortex, 2) Confirmation that the specific behavioral deficits observed in component 1 critically depend on agranular insular cortex function by demonstrating qualitatively similar deficits following inactivation of agranular insular cortex in non-exposed rats, 3) Quantification of fetal-ethanol-related alterations in the density and function of glutamatergic receptors in agranular insular cortex, and 4) Evaluating behavioral effects of selective, acute manipulations of glutamatergic receptor function in the agranular insular cortex of ethanol-exposed and non-exposed rats. The latter includes evaluating the capacity for disruptions of glutamatergic receptor function in the agranular insular cortex of non- exposed rats to produce behavioral outcomes similar to those observed following prenatal ethanol exposure, and evaluating the capacity of increases in glutamatergic synaptic transmission to modify behavioral deficits in fetal-ethanol-exposed rats. Future studies will expand this approach to include other neurotransmitter systems and brain regions involved in the behaviors of interest. If successful, the findings obtained from this research will enhance our understanding of the biological bases of fetal-ethanol-related behavioral deficits and may contribute to future development of rational, targeted treatment approaches for these deficits. PUBLIC HEALTH RELEVANCE: The proposed research study will evaluate the effects of prenatal exposure to moderate levels of alcohol in the rat on the frontal cortex, and investigate how these effects influence social behavior and learning in adulthood. The primary goal of this research is to link abnormal social behavior and impaired learning following prenatal alcohol exposure to specific regions of the frontal cortex, and to understand how alcohol affects the functions of these brain regions. The data obtained in the proposed research will improve our understanding of how alcohol exposure causes persistent changes in social behavior and learning, and may ultimately contribute to the development of treatments.

DESCRIPTION (provided by applicant): The proposed research seeks to better understand the effects of moderate prenatal ethanol exposure in the rat on the agranular insular cortex and related behavioral deficits. The agranular insular cortex is analogous to primate orbitofrontal cortex and is targeted for investigation based on its involvement in a diverse set of behavioral and cognitive processes, including social behaviors and behavioral flexibility, that are among the persistent consequences of prenatal exposure to moderate levels of ethanol. A broad, long-term goal of the proposed work is to understand how prenatal ethanol exposure causes persistent alterations in these behavioral domains with initial emphasis placed on identifying 1) the frontal cortex circuitry involved in specific ethanol-related deficits and 2) the mechanistic bases of fetal-ethanol-related effects within the critical circuitry. The proposed research will evaluate two hypotheses. The first states that prenatal exposure to moderate levels of ethanol exposure causes deficits in behaviors that critically depend upon the agranular insular cortex. The second states that fetal-ethanol-related reductions in glutamatergic receptor density and synaptic transmission in the agranular insular cortex contribute to these deficits. The research plan for evaluating these hypotheses involves four major components: 1) Demonstration of moderate fetal-ethanol-related deficits in social, learning, and motor behaviors that depend on agranular insular cortex, 2) Confirmation that the specific behavioral deficits observed in component 1 critically depend on agranular insular cortex function by demonstrating qualitatively similar deficits following inactivation of agranular insular cortex in non-exposed rats, 3) Quantification of fetal-ethanol-related alterations in the density and function of glutamatergic receptors in agranular insular cortex, and 4) Evaluating behavioral effects of selective, acute manipulations of glutamatergic receptor function in the agranular insular cortex of ethanol-exposed and non-exposed rats. The latter includes evaluating the capacity for disruptions of glutamatergic receptor function in the agranular insular cortex of non- exposed rats to produce behavioral outcomes similar to those observed following prenatal ethanol exposure, and evaluating the capacity of increases in glutamatergic synaptic transmission to modify behavioral deficits in fetal-ethanol-exposed rats. Future studies will expand this approach to include other neurotransmitter systems and brain regions involved in the behaviors of interest. If successful, the findings obtained from this research will enhance our understanding of the biological bases of fetal-ethanol-related behavioral deficits and may contribute to future development of rational, targeted treatment approaches for these deficits.

PROJECT SUMMARY Fetal Alcohol Spectrum Disorders (FASD) are a major public health problem with an incidence of 1-5% in the USA and associated annual costs in excess of $4 billion. The majority of FASD cases fall within the less severe range of the spectrum, characterized by behavioral and cognitive deficits in the absence of conspicuous alterations in craniofacial or brain morphology. Memory deficits are among the more profound lifelong, negative effects on exposure to alcohol during prenatal brain development. At present there are no treatments for memory deficits associated with FASD. Lack of knowledge regarding how prenatal alcohol exposure (PAE) alters brain functions critical for memory represents a major barrier to progress on efforts to identify and develop potential treatments. Moderate PAE in rat models of less severe FASD leads to impairments in spatial memory that persist throughout adulthood. The proposed research will test an innovative and novel hypothesis regarding the neural bases of moderate PAE effects on spatial memory. Place cells in the hippocampus increase in activity selectively when an animal occupies a particular spatial location. The population code provided by place cells represents a spatial ?map?. In healthy animals these spatial maps tend to remain stable for months, however, reduced stability in place cells has been linked to spatial memory impairments. Instability in the neural representations of spatial memory may, thus, represent a systems level mechanism for spatial memory impairments observed following PAE. The proposed research will test the hypothesis that PAE reduces place cell stability, and that reductions in place cell stability are predictive of spatial memory impairments following PAE. In the proposed studies adult rats exposed to moderate levels of ethanol during gestational developmental will be implanted with electrodes in the dorsal hippocampus and the stability of hippocampal place cells will be quantified over multiple sessions. If PAE reduces place cell stability, then the pattern of spatially-selective firing of these cells will be more likely to change (?remap?) from session to session. We will examine whether instability in hippocampal place cells of rats exposed to alcohol is predictive of impaired spatial memory in the Morris water task and in a plus-maze task. Significance and Innovation : The proposed research will be the first study to examine the effects of PAE on neural representations of spatial information and the relationship to spatial memory deficits. This project will serve as a foundation for future studies on mechanisms and treatments. Establishing the utility of this model systems approach is important because it could facilitate identification of putative mechanisms underlying PAE-related spatial memory deficits at circuit, network, receptor, and molecular levels of analysis, which could help identify and evaluate treatment strategies. Because spatial memory deficits are observed in children with FASD, studying the neurobiology of spatial memory in rodent models of FASD could also hold considerable translational significance.

PROJECT SUMMARY Fetal alcohol spectrum disorders (FASD) and associated neurologic sequelae occur in 1-5 of 100 births in the U.S. There is no cure. The overarching goal of our research is to understand the molecular mechanisms that lead to neurologic deficits of FASD and, with this knowledge, identify pharmaceutical interventions. Studies in FASD animal models show that alcohol (ethanol) causes loss of hippocampal neurons, impaired synaptic plasticity in hippocampal neurons, and deficits in learning and memory. Our studies in the neonatal mouse model of FASD demonstrate that ethanol induces neuroinflammation in the developing hippocampus including microglial activation and production of pro-inflammatory cytokines and chemokines. Ethanol induction of neuroinflammation in the hippocampus is particularly important to FASD since recent studies demonstrate neuroinflammation during brain development can produce life-long cognitive disorders. The studies proposed here will investigate whether ethanol-induced inflammation is linked to the long-term cognitive deficits in FASD. Further, our studies further demonstrate that treatment with anti-inflammatory peroxisome proliferator activated receptor-? (PPAR-?) agonists protect against ethanol-induced microglial activation and expression of inflammatory molecules in the developing hippocampus. Collectively, this evidence suggests neuroinflammation in the developing hippocampus may contribute to long-term cognitive deficits in FASD. However, critical gaps in knowledge must be addressed before this information can be used toward the treatment of FASD. The proposed studies will test the hypothesis that ethanol induction of neuroinflammation contributes to long-term learning and memory deficits associated with FASD, and anti-inflammatory agents, including PPAR-? agonists, can block these ethanol effects. We will test this hypothesis using our well- established neonatal mouse model of FASD, which represents human third-trimester fetal alcohol exposure. Aim 1 will determine the mechanisms of ethanol-induced neuroinflammation in the developing hippocampus. The role of (A) TLR4 and downstream signaling, (B) NLRP3 inflammasome activation, and (C) CX3CL1? CX3CR1 signaling in ethanol-induced neuroinflammation and neuron loss will be investigated using transgenic mice with genetic knockout of key molecules in these signaling pathways. Aim 2 will determine if ethanol- induced neuroinflammation contributes to long-term impairment of hippocampal synaptic plasticity and long- term learning and memory deficits in FASD, and if suppression of neuroinflammation prevents these deficits. (A) Establish whether TLR4 and downstream signaling, NLRP3 inflammasome activation, and/or CX3CL1? CX3CR1 signaling play a critical role in long-term synaptic plasticity and learning and memory deficits using transgenic mice with genetic knockout of key molecules in these signaling pathways. (B) Evaluate whether anti-inflammatory PPAR-? agonists protect against ethanol impairment of synaptic plasticity and cognitive deficits.