Contributions of early life adversity, sex, and traits towards compulsive opioid self-administration
Abstract
Many people try addictive drugs, but only a small percentage transition from situational/recreational use to the escalating, compulsive, and relapsing disorder of addiction. It is therefore important to characterize the individual differences that render individuals vulnerable to addiction. Substantial evidence suggests that individual differences in early life experience, biological sex, personality traits, and neurobiology of the reward system are all associated with the development of addiction. A dimensional model of how all these factors relate to addiction is necessary, but simultaneously and experimentally probing all these processes in humans is impossible. I therefore conducted a large-scale study to explore these phenomena in rats.
Throughout ‘adolescence’ (PND 21-35), I exposed a group of rats to a variety of stressors [i.e., forced-swim, restraint, predator odour, food-restriction, and social isolation; termed ‘early life adversity’ (ELA)]. As adults (PND 60-140), I assessed them on numerous addiction-relevant behavioural traits (i.e., impulsivity, anxiety, novelty-preference, and attraction to reward cues). After trait assessment, I observed the rats’ propensity to self-administer the opiate remifentanil. I then killed a subset of rats and quantified DA receptor mRNA in the mPFC.
ELA decreased impulsivity and decreased the rate of acquisition of opiate self-administration in male rats only. Compared to males, female rats exhibited greater anxiety-like behaviour and potentiated opioid self-administration. Anxiety-like behaviour and attraction to reward cues predicted several addiction-relevant behaviours.
Description
Keywords
Psychology--Behavioral
Citation
Hynes, T. (2017). Contributions of early life adversity, sex, and traits towards compulsive opioid self-administration (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25447