The role of learning and environmental variables on the acquisition of ethanol self -administration in outbred rodents

For several decades, the field of alcohol research has been grappling with a seemingly straightforward question: what factors contribute to or mediate the voluntary intake of a licit yet "addictive" substance such as alcohol? Nevertheless, the search for and description of the mechanisms underlying voluntary alcohol consumption has been plagued with difficulties, in part due to the multiplicity of factors believed to influence alcohol consumption. As alcohol use appears to be a multi-determined behavior, it is suggested that the variability underlying it is apt to be attributed to both pharmacological, as well as, non-pharmacological variables. The present dissertation was designed to assess the role of non-pharmacological variables in the acquisition of voluntary ethanol self-administration in unselected rodents. More specifically, we aimed to determine the role played by the learning ability of individual animals in influencing subsequent ethanol preference. Furthermore, we also wanted to evaluate the role of environmental variables in the acquisition of ethanol intake.;The results of Experiment 1 and Experiment 2 suggested that individual differences in learning ability, as assessed by performance in two different spatial tasks, might be related to the affinity to ingest ethanol. Specifically, it appears that individual differences in spatial ability and its components, such as spatial working memory are likely to be related to ethanol intake. The results of Experiment 3 demonstrated that lesions to the hippocampus, an area largely associated with spatial learning, disrupted the acquisition of ethanol intake in both a limited and continuous access paradigm. Experiment 4 demonstrated that superimposing an operant procedure for access to ethanol and providing animals with a distinct environment during acquisition, elevated ethanol consumption as compared to a standard voluntary intake home-cage procedure. Experiment 5 showed that providing animals with a distinct environment and transport as part of the procedures used during ethanol acquisition increased ethanol intake. Taken together, the studies reported within this dissertation provide support for the role of non-pharmacological factors such as learning ability and environment, in the development of ethanol self-administration within outbred rodents. It is argued that in order to understand the tremendous variability inherent in ethanol self-administration both pharmacological and non-pharmacological factors must be considered.