The Reduction of Tau Hyperphosphorylation by Cornel Iridoid Glycosides Is Mediated by Their Influence on Calpain Activity

Figure 4

Effects of treatment with CIG, morroniside, and loganin on dibucaine-treated cells. (a) CIG reduced calpain activity in calpain-activated N2a cells. The expression of spectrin (b) α II, (c) calpain 1, (d) phosphorylation of GSK-3β at Ser 9, (e) PP2A-c, and GAPDH in dibucaine (200 μM) led to the detection of calpain-activated N2a cells by western blots and semiquantitative analysis. (f) The activity of PP2A in dibucaine led to calpain-activated N2a cells. Mean ± SEM, n = 3; , compared with the N2a group; #, ##, ###, compared with the dibucaine group. Morroniside (240 μM), loganin (120 μM), IG: cornel iridoid glycosides; GSK-3β: glycogen synthase kinase 3β; PP2A: protein phosphatase 2A; and GAPDH: glyceraldehyde 3-phosphate dehydrogenase.

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