Figure 6

Cilostazol reduces accumulation of Aβ and huntingtin aggregates in astrocytes. (a,c) Astrocytes were exposed to FITC-Aβ for 1 hour. Fluorescence photomicrographs taken after washout show increased Aβ levels in astrocytes (Scale bar, 20 μm). Addition of cilostazol substantially reduced Aβ loads in astrocytes. Bars indicate relative changes in the fluorescence intensity. Values for individual bars were normalized to control values (mean ± SEM; n = 7; * denote P < 0.05, ** denote P < 0.01 compared with Aβ or Cilo; Two-tailed Student’s t-test for 2 comparisons). (b,d) Western blot analyses of lysates from cells that were sham-washed (CTL), or exposed for 24 hours to Aβ alone or Aβ plus cilostazol (+Cilo). Levels of Aβ monomers, tetramers, and oligomers were decreased by Aβ plus cilostazol compared with Aβ alone. Bars represent the ratio of 6E10 bands to corresponding β-actin bands (mean ± SEM; n = 6; ** denote P < 0.01 compared with CTL, Aβ or Cilo; Two-tailed Student’s t-test for 2 comparisons). (e) Cilostazol reduces mHttQ74 aggregation in astrocytes. Fluorescence photomicrographs of GFP-mHttQ74–transfected astrocytes. Six hours after transfection, astrocytes were treated with cilostazol (+Cilo) for 14 hours. White dots indicate GFP-positive aggregates. Bars denote the percentage of GFP-aggregate-positive cells in all GFP-positive cells (mean ± SEM; n = 5; * denote P < 0.05 compared with mHttQ or Cilo; Two-tailed Student’s t-test for 2 comparisons). Western blot analysis of GFP aggregates obtained from GFP-mHttQ74–overexpressing astrocytes following cilostazol treatment. Transfected cells were sham-washed (mHttQ) or treated with 10 μM cilostazol (+Cilo) for 14 hours. Bars represent the ratio of GFP bands to corresponding β-actin bands (n = 4; * denote P < 0.05 compared with mHttQ or Cilo; Two-tailed Student’s t-test for 2 comparisons).