INTERACTIONS BETWEEN SULPIRIDE INFUSIONS WITHIN THE PERIFORNICAL REGION OF THE LATERAL HYPOTHALAMUS AND THE NUCLEUS-ACCUMBENS ON MEASURES OF LOCOMOTOR-ACTIVITY AND CONDITIONED PLACE PREFERENCE

There is growing evidence of a functionally significant link between t he perifornical region of the lateral hypothalamus (PFH) and the mesoa ccumbens dopamine projection. The present study assessed the ability o f intra-accumbens dopamine receptor blockade, firstly to impair the lo comotor stimulant properties of intra-PFH sulpiride, and secondly the ability of intra-PFH sulpiride to support a conditioned place preferen ce. Locomotor activity and conditioned place preference training were assessed using an apparatus consisting of three distinctive compartmen ts. Following a pre-exposure session in which groups showed equivalent preference for the three compartments, conditioned place preference t raining was carried out over five drug (0, 0.03 or 0.1 mu g intra-accu mbens sulpiride; 0 or 5 mu g intra-PFH sulpiride) and five vehicle ses sions. For each animal, drug and vehicle treatments were randomly pair ed with one of the two outermost compartments. Locomotor activity was monitored during each session. Intra-PFH sulpiride alone increased loc omotor activity during later sessions, and this gradual increase in lo comotor response, relative to vehicle infusions, was blocked by intra- accumbens sulpiride co-infusion. On the final drug-free test day for c onditioned place preference, animals were again permitted free access to all three compartments, and the time spent in each was compared wit h that on initial exposure. Intra-PFH sulpiride alone supported a cond itioned place preference. Intra-accumbens sulpiride was without intrin sic effect, but nevertheless blocked the ability of intra-PFH sulpirid e to support a conditioned place preference. These data provide furthe r support for a functionally significant link between the PFH and meso accumbens dopamine projection, with regard to the locomotor stimulant properties and ability of intra-PFH infusions of sulpiride to support a conditioned place preference. Behav Pharmacol 1998; 9:345-355 (C) 19 98 Lippincott-Raven Publishers.