Effects of excitotoxic lesions of the ventral hippocampus on the acquisition of conditioned place aversion induced by naloxone-precipitated morphine withdrawal in morphine-treated rats. Ibotenic acid (10 μg/μL) was microinjected into the ventral hippocampus (0.15 μL per site) using the following coordinates: (a) AP, -4.9 mm, ML, ±4.8 mm, DV, -5.5 and -4.6 mm; (b) AP, -5.2 mm, ML, ±4.0 mm, DV, -7.5 and -4.4; (c) AP, +5.5 mm, ML, ±5.0 mm, DV, -6.1 and -5.3 mm. The columns show the time spent in the drug-paired compartment in the preconditioning (Pre) or testing (test) sessions (A) and the CPA score (B). Data are expressed as means±SEM. cP<0.01 compared with the corresponding preconditioning session (Student's t test). VH: ventral hippocampus.