Fig. 5.
Intracerebroventricular OFQ/N administration blocked acquisition of cocaine-induced behavioral sensitization regardless of context. Rats were treated with either aCSF or OFQ/N (15 nmol, ICV) followed by saline or cocaine (20 mg/kg, IP) in their home cages. The same treatment was given for 3 days, except the dose of OFQ/N was doubled on day 2 and again on day 3. On day 8, rats were habituated to the testing chambers for 1 h, and all rats received a challenge dose of cocaine (7.5 mg/kg, IP) alone. Locomotor activity was measured for an additional 1 h. Data are means±SEM of five to eight rats/group