Die Rolle von Glutamat bei der Expression von konditioniertem Belohnungsverhalten unter Berücksichtigung des Einflusses der Amygdala

Experiment 1: It is well known that the social context powerfully influences behaviour. Here we examine whether it also influences drug-seeking. Further, acamprosate and naloxone have been discussed to affect different types of craving: acamprosate was reported to affect withdrawalcraving, while naloxone affects reward-craving. Conditioned drug-seeking was modelled using the conditioned place preference (CPP) paradigm. Socially isolated and group-housed rats were conditioned with morphine and their CPP expression was examined after treatment with acamprosate or naloxone. As a result, no difference in morphine-CPP expression was observed between differentially housed rats. Furthermore, CPP expression was not altered in both groups after treatment with acamprosate or naloxone. In conclusion, two weeks of isolation are not sufficient to alter the rewarding properties of morphine or the effects of treatment with acamprosate and naloxone in rats. Experiment 2: Clinical studies in weaned alcoholics revealed a superior effect of a joint administration of both acamprosate and naloxone in prevention of relapse. Furthermore, an effect of acamprosate on cocaine-conditioned behaviours has recently been reported. Emanating from the results of Exp. 1, only group-housed rats were either conditioned to cocaine or morphine. Thereafter, both groups were tested repeatedly for expression of CPP after acamprosate, naloxone or their joint administration. Additionally, the usefulness and suitability of repeated testing was elaborated. As a result, only acamprosate treatment inhibited expression of cocaine-CPP. Methodologically, repeated testing produced reasonable results and may therefore be considered a useful method to study the effects of anti-craving drugs on CPP expression, thereby reducing the number of experimental animals.