Following infusions, animals were returned to their home cages. For stress induction, animals in studies employing HU-210 or AM251 were left in their cages for 10 min before being put into restrainers, while animals for studies employing URB597 were left in their cages for 20 min (to allow time for enzyme inhibition to occur) before being put into restrainers. At the conclusion of the 30 min restraint stress session, a small nick was made at the tip of the tail from which 300 μL of blood was collected for corticosterone analysis. Blood from a tail nick was also collected from the non-stressed rats at 40 or 50 min following bilateral infusions, depending upon the drug infused. All rats were killed in a carbon dioxide chamber 24 h following testing. Brains were removed and fixed in a 4% formalin solution. The brains were frozen and sliced in 50 μm sections and mounted. Placements were verified with reference to the atlas of Paxinos and Watson (1998) and histological analysis demonstrated that approximately 85% of cannula placements were in boundaries of the nuclei of interest (see Fig. 1). Subjects with cannulae outside of the desired structure were excluded from subsequent analysis.
