Quantitative analysis of the effects of single or repeated METH exposure on protein nitration in the striata of animals sacrificed 1 hour after the last injection on PND90. Protein nitration data are expressed as average (avg.) gray values (mean ± S.E.M.; n = 6–12) obtained from densitometric analysis of immunohistochemically stained sections. Treatment group designations indicate PND60 treatment:PND90 treatment, resulting in the four treatment groups: Saline:Saline (SS), METH:Saline (MS), Saline:METH (SM), and METH:METH (MM). **Significant main effect of PND90 treatment, P < 0.01.