Role of the BLA-Insula circuit in stress-induced aversive drinking and negative affective states

PROJECT SUMMARY In 2023, Alcohol Use Disorder (AUD) affected an estimated 28.9 million people, about 10.5% of the American population ages 12 and older. AUD has consistently been a public health crisis for many decades, costing the US economy $249 billion in 2010. The current treatments available are not effective, further warranting continued work on better understanding the mechanisms and circuits involved in AUD-related behaviors. There are many factors that contribute to excessive alcohol use, however, one major component that could be contributing to the development of AUD is stress. While regular stress can drive problematic alcohol consumption, traumatic stress heightens this correlation and increases the probability of AUD development. Despite this interaction between stress and alcohol, the circuitry recruited during stress and its persistent drive on alcohol consumption and negative affect is still largely unknown. The insula is a highly connected region that is associated with crucial roles in emotional processing and cognitive control. The insula participates in the brain’s salience network by conveying interoceptive cues to guide behavior through cortical and subcortical connections. Human imaging studies suggest a decrease in insular volume in alcohol dependent patients, further implicating the insula’s larger role in AUD-related behaviors. We have shown that the insula is important in regulating negative affective states during abstinence and coping behavior during a stressor. To better understand the insular circuitry recruited during stress, we aimed to identify all upstream inputs onto stress- activated insula neurons using a FosTRAP mouse model and a retrograde viral approach with whole-brain light sheet microscopy. Insular stress ensembles receive the densest projections from the basolateral amygdala (BLA), a region involved in modulation of anxiety-like behaviors, alcohol consumption, fear conditioning, and emotions. This proposal aims to characterize the role of the BLA-insula circuit in traumatic stress-induced negative affective states, binge-like, and aversive drinking by using validated preclinical models of PTSD and alcohol drinking, Single Prolonged Stress (SPS) and drinking in the dark (DID), respectively. We will first establish the BLA-insula pathway’s role in stress valence and AUD-related behavior by using chemogenic manipulation during SPS and probing for affective states and alcohol consumption following stress. Next, we will correlate the physiological stress response with neuronal activity in the BLA-insula pathway during withdrawal from alcohol. To complement, we will use in vivo fiber photometry to measure calcium activity in the BLA terminals present in the insula during drinking following stress. We predict valence of traumatic stress is encoded by the BLA-insula pathway, leading to the initiation and maintenance of alcohol consumption, even in aversive conditions. The studies proposed here will provide a more complete perspective on the interaction between stress and the development of AUD, leading to fruitful contribution to better our treatment options.