A. Effect of Ro5–4864 (10 nM) and PK11195 (10 nM), agonist and antagonist of TSPO, respectively, on the dissipation of inner mitochondrial membrane potential (ΔΨm) (24 h) in cultured astrocytes. The ΔΨm was measured by incubating (15 min) cultures with a tetramethyl-rhodamine ethyl-ester (TMRE, 25 nM), a potentiometric fluorescent dye commonly employed to determine ΔΨm (Rama Rao et al, 2005a; 2005b). Treatment with Ro5–4864 (Ro5) significantly dissipated the ΔΨm as shown by a reduction in TMRE fluorescence, whereas PK 11195 (PK) had no effect. Scale bar = 100 µm. B. Quantitation of TMRE fluorescence. Values are mean ± SEM of the total number of mean pixel values in each experimental group. * vs. control (C), p<0.01.