Figure 7

Mitochondrial impairment induced by thapsigargin was prevented by cyclosporine A in neurons that expressed mutant huntingtin. A, representative fluorescence images of cortical neurons loaded with calcein blue AM (Calcein B) and transfected with GFP alone, Q25-GFP (normal huntingtin), or Q104-GFP (mutant huntingtin). Normal and mutant huntingtin expression is indicated by GFP fluorescence intensity (white arrows) and calcein blue staining reveals neuronal morphology. Bar = 10 μm. B, transfected neurons were loaded with MitoRed for determination of mitochondrial potential. Representative trends show that the expression of Q104-GFP significantly reduced mitochondrial potential during treatment with 1 μM thapsigargin (Th). C, quantitation of mitochondrial potential levels showed significant mitochondrial damage in neurons that expressed Q104-GFP. Data correspond to the mean ± S.E.M. of 4 independent experiments. *, p < 0.05 compared with Q25-GFP neurons treated with thapsigargin. D, neurons transfected with GFP, Q25-GFP, or Q104-GFP were treated with 0.5 μM CsA for 2 h before mitochondria potential measurements. Representative trends show that the inhibition of mPTP by CsA prevented mitochondria injury induced by thapsigargin in Q104-GFP positive neurons. E, quantitation of mitochondria potential levels shows that CsA treatment significantly prevented mitochondrial impairment in neurons expressing Q104-GFP compared with the other conditions. Data correspond to the mean ± S.E.M. of 4 independent experiments. * p < 0.05 compared with Q25-GFP neurons treated with thapsigargin. ** p < 0.05 compared with Q104-GFP neurons treated with thapsigargin.