The rats were food-restricted throughout the duration of the experiments to keep them at 85% of their free-feeding body weight (adjusted for growth). The care and use of all subjects in this Gefitinib nmr study were conducted in agreement with the ethical principles of the Brazilian College in Animal Experimentation (COBEA, http://www.cobea.org.br), which in turn conform to international guidelines for research involving animals. The apparatus consisted of eight
symmetrical arms (70 cm long and 10 cm wide, with side walls 4 cm high), radiating from an octagonal central platform (33 cm wide). The platform was enclosed by a wall 30 cm high that served as a frame for guillotine doors at the beginning of each arm. These doors were operated by overhead strings and regulated access to each arm. As a reward, a piece of a peanut was placed in a small black cup at the end of each arm. The radial maze was made of transparent Plexiglas mounted over wood of the same shape, and it was supported by a metal structure 100 cm above the
floor. The maze was kept in a constant position in the middle of a square room and illuminated by fluorescent lights. The door and a large window in the room were Selleckchem Cyclopamine occluded by gray paint, and all of the other objects in the room (e.g., cabinet, rack, desk, bench, and chairs) were maintained in the same position
during the experiment. All procedures in the radial maze were performed as previously described (Silva de Melo et al., 2005). Briefly, each session was performed once a day. The animals were introduced to the Teicoplanin apparatus and habituated to the environment and the manual handling by the experimenter. During training, the animals remained in the maze until they had entered each arm of the maze once in a given session, and training continued until the rats reached a criterion of no more than one error (re-entry into an arm previously visited during the same session) per session over three consecutive sessions (acquisition of the task). After their performance stabilized in the radial maze, the animals underwent surgery for implantation of a bilateral cannula in the mPFC. For the delay procedure, the rats were initially allowed to enter each of four randomly pre-selected arms to get a reward, whereas access to the other four arms was blocked (pre-delay period). After obtaining the reward from each of the pre-selected arms, the animals were returned to their home cages for an interval of retention. After the delay period, all of the maze arms were opened, and the animals were returned to the center of the maze and allowed to complete choices to obtain rewards in the four previously obstructed arms (post-delay period).