The long-term effects of adolescent ethanol drinking on cortical astrocytes

About This Grant

PROJECT SUMMARY/ABSTRACT Adolescent brain development makes individuals particularly vulnerable to the negative and long-lasting consequences of adolescent alcohol drinking. Adolescent alcohol use is associated with delayed maturation of the prefrontal cortex, leading to cognitive dysfunction and a loss of inhibitory control. The rodent medial prefrontal cortex (mPFC) is functionally homologous to the human dorsolateral PFC, each having similar layered structures and circuitry. Importantly, rodent models of adolescent drinking show similar mPFC-related deficits as humans, including reduced behavioral flexibility, increased impulsivity, impaired working memory, and abnormal social interaction. These long-lasting mPFC neuronal and behavioral effects are believed to be driven by changes in mPFC glutamate transmission. Despite this, the mechanisms underlying the long-term consequences of adolescent alcohol drinking on PFC glutamate function remain not well understood. Astrocytes are a compelling mechanism through which adolescent alcohol drinking can produce long- lasting changes in PFC function into adulthood. Astrocytes continue to mature into young adulthood in rodents, making them developmentally vulnerable to the effects of alcohol. Additionally, they mediate synapse formation and elimination during development to assemble the neural circuits that last into adulthood, as well as regulate glutamate uptake and release at synapses to optimize neuronal function and prevent glutamate excitotoxicity. Thus, changes in astrocytes following adolescent alcohol drinking are likely driving the long-term changes in mPFC glutamate function. In this proposal, we will examine how adolescent ethanol drinking (AIE) produces long-term changes in astrocyte distance from synaptic contacts, and their regulation of glutamate synapses in mPFC prelimbic (PL) layer 2/3 and 5 in male and female mice. We will also examine the astrocyte-specific mechanisms that are affected by AIE in adulthood and pharmacologically target these mechanisms to examine if they contribute to acute ethanol regulation of PL glutamate synapses. We have intentionally designed this project to maximize its interdisciplinary nature. We will label PL astrocytes using viral infusions, as well as employ immunofluorescence staining methods to label synaptic contacts and characterize layer 2/3 and 5 astrocytes. This will greatly complement our electrophysiology experiments, which will examine astrocyte regulation of PL layer 2/3 and 5 glutamate synapses in water and AIE mice of both sexes. We will then extend analysis to the transcription level to identify astrocyte-specific mechanisms that are altered by AIE. I will learn single-nucleus RNA sequencing to identify if subgroups of astrocytes that populate layers 2/3 and 5 are differentially affected by AIE. My mentors and consultants will help me establish these sequencing techniques in Dr. Florence Varodayan’s laboratory. Collectively, this work will provide insight into the long-term changes in PFC function following adolescent alcohol drinking.