Coding and Non-coding RNA Expression in Rodent Models of Cocaine Craving

Substance use disorders (SUDs) are difficult to treat, in part because drug craving can be elicited by exposure to drug-associated environments and cues within the environment. Furthermore, this craving becomes more pronounced as abstinence progresses and it can take months to years for cue-elicited craving to finally wane. This important hallmark of addiction is modeled in rodents by exposing them to light/tone cues associated with the self-administration (SA) of cocaine. Cue exposure results in drug-seeking behavior, an animal analogue for drug craving. The overarching goal of this dissertation was to use the rodent SA model to explore the nucleus accumbens (NAc), a key brain region in the neural pathway of craving, and examine ribonucleic acid (RNA) expression that may underlie cocaine-seeking behavior. This includes messenger RNAs (mRNAs), which encode directly for proteins, and non-coding RNAs, which are important regulators of mRNA expression and cellular function. My first experiment aimed to identify non-coding microRNAs, which directly target and suppress mRNA expression, that are differentially expressed in animals with high or low cocaine-seeking behavior. In the second study, I compared RNA-sequencing (RNA-seq) datasets from rodent models of cocaine abstinence and developed a novel workflow to narrow candidate genes. In the final experiment, I utilized RNA-seq and reverse transcription real-time quantitative polymerase chain reaction (RT-qPCR) to identify and explore non-coding, circular RNAs that may influence gene regulatory networks and impact drug-seeking behavior. Overall, these studies promote our understanding of the neurogenetic mechanisms of craving and they suggest recommendations for improving the experimental design of future neurogenomic studies.