Figure 6.

Inhibition of actin cycling potentiates cocaine-induced reinstatement of drug seeking. a, Rats were extinguished from cocaine self-administration and given cocaine (10 mg/kg, i.p.) to reinstate lever pressing. Thirty minutes before cocaine reinstatement, animals were microinjected with Tat-cof (1 nmol) or Tat-sc (1 nmol) or, 5 min before cocaine, were microinjected with latrunculin (0.5 μg) or DMSO (1%) vehicle. Data are shown as mean ± SEM active lever presses during the extinction trial the day before reinstatement (Extinct) and inactive and active lever presses during reinstatement. The number of determinations is shown in parentheses. For the latrunculin experiment, each animal received only one reinstatement trial, and the data were evaluated with an unpaired Student's t test (latrunculin active lever, t₍₁₃₎ = 2.24; p = 0.043). For the Tat-peptide experiment, each animal received two reinstatement trials, one each with Tat-cof or Tat-sc in random order, and the data were analyzed using a paired Student's t test (Tat-cof active lever, t₍₅₎ = 2.53; p = 0.052). b, Separate rats were pretreated with intra-accumbens drug as in the reinstatement study, and the acute locomotor response was examined in a photocell apparatus. Data are shown as mean ± SEM distance traveled, and cocaine (15 mg/kg, i.p.) was administered at the time indicated by the arrow. *p < 0.05 comparing drug with control.