Figure 4. Intracerebroventricular TOMA effects on tau pathology in P301L. Representative epifluorescence images of the CA1 region of 8-month-old P301L mice intracerebroventricularly immunized with TOMA or nonspecific IgG antibody (anti-rhodamine), immunostained with Thr231-green (A, D), T22-red (B, E), and merged + DAPI (C, F). A, Strong immunoreactivity with Thr231 in the perikaryon (solid white arrows) and neuronal processes (solid yellow arrows) of control IgG-treated mice compared with TOMA-treated mice (open white and yellow arrows; D). B, Tau oligomers as detected by T22 in somata (solid white arrows) and neuronal processes (solid yellow arrows) of IgG-treated mice. E, TOMA reduced tau oligomers in the perikaryon (open white arrows), neuronal processes (open yellow arrows), and the perinuclear area (asterisks). Scale bar, 15 μm. G–L, Quantification of changes observed in brain sections of frontal cortex from 8-month-old P301L mice immunized with TOMA and P301L mice injected with control IgG and immunostained with Thr231, T22, and HT7. G–I, Percentage of total immunoreactivity in cell bodies in the dentate gyrus. Shown is the reduction of Thr231 (G), T22 (H), and HT7 (I) immunoreactivity in cell bodies of mice immunized with TOMA compared with control mice. ★p < 0.02; ★p < 0.05; ★p < 0.02, respectively; Student's t test. J–L, Percentage of the immunoreactivity in neuronal processes in CA1 from P301L mice treated with TOMA and control mice. Reduction of Thr231 (J) and T22 (K) immunoreactivity in the TOMA group compared with the control group. ★p < 0.01; ★★p < 0.003. L, Significant increase in HT7 (specific for human tau) immunoreactivity in the TOMA-treated mice compared with control mice. ★p < 0.04. Bars represent the means and error bars the SEM, unpaired Student's t test. The levels of tau oligomers and monomers in mouse brain homogenates were assessed by Western blot using Tau-5, AT100, and AT180. M, Western blot of PBS soluble fraction from brain homogenate of mice immunized with the nonspecific IgG antibody (lanes 1–4) and mice immunized with TOMA (lanes 5–8) detected with Tau-5 antibody and reprobed with AT100 and AT180. Internal control is shown at the bottom. N, Graphs represent the relative band intensity for AT100 and AT180 (arbitrary units, AU). The differences were statistically significant. ★★p < 0.005; ★p < 0.02, Student's t test, respectively. Bars represent means and error bars SEM.