Enzymatic activity of PPT1 and β-glucuronidase over time in brains of treated animals. (A) PPT1 activity was increased in the brain for intracranial (IC-AAV2/9) and combination intracranial/intrathecal (IC/IT-AAV2/9)–treated mice to near–wild-type or supraphysiological levels at all time points measured. There was a small increase in PPT1 activity in the intrathecal (IT-AAV2/9) brain (∼2 to 5% of WT levels) at all time points. (B) β-Glucuronidase activity in the brain is increased in the untreated Ppt1−/− mice until 7 mo, after which these mice are terminal. IT-AAV2/9–treated mouse brains had increased β-glucuronidase levels compared with WT until 9 mo. IC-AAV2/9 and IC/IT-AAV2/9 brains have near-WT levels of β-glucuronidase at all time points, and all are significantly decreased compared with Ppt1−/− mouse levels at 3, 5, and 7 mo. IC-AAV2/9, IC/IT-AAV2/9, and WT mice show decreased β-glucuronidase levels compared with IT-AAV2/9 at 9 mo. Dots represent scatterplots of individual animals. *P < 0.05, **P < 0.01, ***P < 0.001, one-way ANOVA with post hoc Bonferroni correction. Values shown are mean ± SEM (n = 3 mice per group).