Figure 5.

Effects of catalpol on the upstream proteins of CREB signaling pathway. (A–D) SweAPP N2a cells were treated with catalpol for 1 h. (A,C) Immunoblotting analyses and (B,D) quantifications showing the phosphorylation levels of phospholipase C (PLC) and mitogen-activated extracellular signal-regulated kinase (MEK) markedly increased in cells treated with 200 μM catalpol. (E) Immunoblotting analyses and (F) quantification show that treatments with catalpol at the concentration of 200 μM and 400 μM significantly increased the protein levels of protein kinase A (PKA). (G) Immunoblotting analyses and (H) quantification showed no significant changes of AKT phosphorylation levels could be detected in catalpol-treated cells compared with vehicle control cells. The data are expressed as the mean ± SEM. n = 3. The p values were calculated using one-way ANOVA.