Mean (±SEM) distance traveled scores of rats (n = 8 per group) on the pretreatment day. Rats were injected with saline or NPA immediately before a 30-min placement in the activity chambers on PD 12, PD 16, PD 20, or PD 24.
a Significantly different from the saline control group when collapsed across time blocks 1–6.
b Significantly different from the saline control group on the same time block.