Most drug addicts begin taking drugs during adolescence, often in social settings in which their peers encourage and reinforce their behavior, yet little preclinical research has investigated how social reward influences initiation and maintenance of drug abuse and dependence. The objective of the proposed research is to develop an animal model for this purpose. Two hypotheses regarding drug: social reward interactions that may contribute to drug-taking and drug-seeking behaviors in adolescents will be examined: 1) pharmacologic effects of drugs may synergistically enhance the rewarding effects of social interaction, and 2) drugs may acquire conditioned reinforcing effects via pairing with social interaction. The proposal focuses on interactions between nicotine and social reward. Nicotine is the pharmacologic agent in tobacco products that is primarily responsible for the reinforcing and dependence-producing effects of smoking and desire to affiliate with other smokers contributes to initiation of smoking in adolescents. Furthermore, rodent self-administration studies have found that not only is nicotine reinforcing, but it is also capable of enhancing the reinforcing effects of other stimuli, such as response-contingent cues that appear in conjunction with nicotine delivery. Research with other drugs suggests that drug states that are not reinforcing on their own can acquire conditioned reinforcing effects via pairing with natural rewards. Therefore, we reasoned that during early use, the nicotine state may acquire conditioned reinforcing effects through association with social reinforcement, such that these effects add to its own mildly reinforcing effects rendering nicotine highly reinforcing. Social reward will be measured using a conditioned place preference method we have recently developed.
The first aim of the proposed research is to establish a conditioned place preference (CPP) method for assessing rewarding effects of intravenous nicotine administration. Next, the ability of nicotine to enhance social reward-CPP will be investigated. Finally, experiments will examine whether previous pairings of nicotine with social interaction will facilitate acquisition, and enhance intake during maintenance, of nicotine self-administration. To our knowledge, these experiments will be the first to examine the influence of social interaction on nicotine self-administration in animals. The animal model will allow investigation of neural mechanisms involved in drug: social reward interactions, and therefore, may offer novel insight into the development of addiction and prevention/intervention strategies involving social interaction. Drug abuse and dependence are major health and societal problems. The proposed research will investigate novel hypotheses regarding the interaction between the rewarding effects of nicotine and social interaction that may contribute to these disorders. The findings could potentially initiate a line of investigation on neural mechanisms involved in these interactions, which may in turn provide insight for understanding and treating drug abuse and dependence. ? ? ? ?
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