Figure 4.

Sildenafil regulates tau phosphorylation through GSK3β and CDK5 in Tg2576 transgenic mice. Chronic treatment with sildenafil modulates phosphorylated tau (p-tau; A), pGSK3β-Ser⁹ (B), pGSK3β-Tyr²¹⁶ (C), pAkt (D) and p25/35 (E) expression levels in aged transgenic Tg2576 mice hippocampus but not in the non-transgenic (Non-Tg) group. Representative Western blot bands from hippocampal tissues of Non-Tg mice receiving saline (Non-Tg saline) or sildenafil (Non-Tg sildenafil) and transgenic mice receiving saline (Tg2576 saline) or sildenafil (Tg2576 sildenafil) are shown. The histograms represent the quantification of the immunochemically reactive bands in the Western blot. Data are expressed as mean percentage (±SEM) of the results from the Non-Tg mice receiving saline (Non-Tg saline, 100%). n = 5–6 in each group. *P < 0.05; **P < 0.01, significantly different from Tg2576 saline mice (Kruskal–Wallis followed by Mann–Whitney post hoc test).