Figure 1.

Experimental timeline for the neonatal FGF2 treatment and brain collection and behavioral studies in adult animals. On the day after birth (postnatal day (P) 2), bHR and bLR litters were randomly assigned to receive an injection of FGF2 (20ng/g in 50μl in 0.1M PBS w/1% BSA, s.c.) or vehicle (0.1M PBS w/1% BSA, s.c.). Once animals reached adulthood (P60), brains were collected from a subset of animals from each experimental group. The remaining animals were sensitized to cocaine using a paradigm that previously revealed bHR/bLR behavioral differences. On the first day of the paradigm, animals were placed in a novel test cage. Horizontal and rearing movements were monitored in 5-min intervals over three test phases: (1) a 45-min chamber pre-exposure period; (2) 60-min following saline injections; and (3) 60-min following cocaine injection (15 mg/kg, i.p.). Once a day for the next 5 days, rats received cocaine injections (15 mg/kg, i.p.) in a room adjacent to the housing quarters and then returned to home cages. On day 7, rats returned to the activity chambers to again monitor activity during the chamber pre-exposure, post-saline and post-cocaine injection periods.