FIGURE 8.

Sodium phenylbutyrate increased DJ-1 expression and reduced α-synuclein oligomer formation and aggregation in aged transgenic mice. The Y39C transgenic mice were divided into two age groups: 6–8 months old (Young Tg, n = 20) and 10–12 months old (Old Tg, n = 20). Half of the transgenic mice in each age group (n = 10) received PB (1000 mg/liter) in drinking water, while the other mice (n = 10) were given water with equimolar of sodium chloride (vehicle). After 6 weeks and 12 weeks of drug treatment, all mice were tested for motor and cognitive function. After the last behavioral test, half of the mice (n = 5 for each age and treatment group) were sacrificed for biochemical analysis; the remaining half (n = 5 for each age and treatment group) were sacrificed for histology. A, brain tissues (cortex, striatum, and hippocampus) from Young and Old transgenic mice with or without PB treatment were analyzed for α-synuclein aggregation. Western blots showed that PB dramatically reduced α-synuclein oligomer formation in old transgenic mice compared with mice of the same age not receiving PB treatment. A sample blot shows 15 month Tg with (+PB) or without (−PB) treatment), while α-synuclein monomer levels were not changed. B, ratio of α-synuclein oligomer to monomer is shown in Young and Old transgenic mice with or without PB treatment (n = 5, **, p < 0.01). Old transgenic mice had high levels of oligomer (15%). After three months of PB treatment, old mice had much lower levels of oligomer which were similar to the ratio seen in Young transgenic mice. C-D, brain tissues (cortex) from Young and Old transgenic mice with or without PB treatment were analyzed for DJ-1 protein levels using Western blot (C). Results showed that PB treatment significantly increased brain DJ-1 levels in both young and old transgenic mice compared with mice without PB treatment (D; *, p < 0.05, n = 5). E-I, brain sections from Young and Old transgenic mice with or without PB treatment were immunostained with human α-synuclein antibody (LB509). Sections were examined for α-synuclein-positive Lewy body-like inclusions. Sample images from Young and Old transgenic mice with or without PB treatment are shown in E–H. A sample image from 15-month-old non-transgenic mouse is shown in I. J, results showed that the percentage of α-synuclein-positive neurons with LB-like inclusions (arrows) was significantly reduced in Old transgenic mice with PB treatment compared with old mice without PB (*, p < 0.05, n = 5), while there was no significant change in Young transgenic mice after PB treatment. Bar length, 25 μm for E–I.