Figure 1.
Repeated administration of amphetamine produces behavioral sensitization in 4- to 5-week-old rats. A, On the third day of withdrawal, amphetamine (Amph) rats demonstrated sensitized stereotyped behaviors (during the first hour of the test) and post-stereotypy locomotor hyperactivity (during the second hour of the test) compared with saline (Sal) control rats (*p < 0.05; Duncan's post hoc) in response to an amphetamine challenge injection. Inset, Stereotyped behavior during the first hour of behavioral testing. See Materials and Methods for scoring criteria (Fisher's exact probability test; *p < 0.05). B, Application of TTX rapidly and reversibly blocks peak inward INaT of pyramidal mPFC neurons. A plot of the percentage of baseline of peak INaT evoked by a step in HP from −70 to −20 mV as function of time is shown. Inset, Representative traces of peak Na+ current before, during, and after TTX application.