Tau phosphorylation, but not cleavage, is increased in STZ-injected animals. Mice were injected with STZ at 12 wk of age and killed at 24 wk (12 wk diabetes). The low-STZ group received 50 mg/kg STZ for 5 consecutive days, and the high-STZ group received one injection of 150 mg/kg. A, Cortex lysates are immunoblotted for the phosphorylated (pTau) and total tau. B, The densitometric analysis indicates significant increase in tau phosphorylation at pT231 and pS199/202 for the high-STZ group compared with control or low-STZ group. *, P < 0.01. C, Brain slices are stained with antibody against phosphorylated tau at Ser199/202 (pS199/202). Arrows indicate the increased tau staining in high-dose STZ brains. Bar, 50 μm. D, Cortex lysates are immunoblotted with TauC3 antibody to detect cleaved tau (arrows). GAPDH, Glyceraldehyde 3-phosphate dehydrogenase.