Quantitative analysis of the effects of single or repeated METH exposure on eNOS mRNA expression in the striata of animals sacrificed 1 hour (A) or 48 hours (B) after the last injection on PND90. 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). Values are background-subtracted mean gray values (mean ± S.E.M.; n = 5–12). No significant differences between treatment groups were observed. (C) Representative images of eNOS mRNA in situ hybridization histochemical staining in rats sacrificed 48 hours after the last injection on PND90. Scale bar = 2 mm, applies to all images.