The objective of the research described in this thesis was to demonstrate the role of gene-environment interactions in the emergence of individual differences in cocaine use. For this purpose we... Show moreThe objective of the research described in this thesis was to demonstrate the role of gene-environment interactions in the emergence of individual differences in cocaine use. For this purpose we used two inbred mouse strains, the C57Bl/6 (C57) and DBA/2 (DBA), which are known to differ in drug-intake and to be differentially sensitive to several stressors. We studied the impact of early life experiences (long-term influence) as well as a later life psychosocial stressor (short-term influence) on adult drug intake behavior in these two mouse strains. To study the impact of the early life environment, we manipulated the maternal environment of the mice by fostering them with non-related mother strains showing either high or low pup-oriented behaviour. The late life experience consisted of a short-lasting period of group housing in adulthood. Cocaine self-administration in mice with a C57 background was not affected by either changes in postnatal maternal environment or a short group housing experience in adulthood, while these same experiences did affect mice with a DBA background. As a first step towards the biological mechanisms underlying this gene-environment interaction we found that vasopressin was differentially regulated in the extended amygdala of the DBA mice. Show less