FIGURE 6.

The ACh-induced Ca²⁺ release in differentiated PC12 cells is mediated by the CD38/cADPR signaling pathway. A, real-time RT-PCR data of NGF-induced CD38 expression in PC12 cells expressed as means ± S.D., n = 3. SDHA was used as an internal control. B, immunoblot analysis of CD38 expression in CD38-shRNA-expressed PC12 cells, or control cells expressed GFP-shRNA, in response to stimulation by NGF (50 ng/ml) for the indicated times. MEK1 expression was used as internal controls. C, NGF-differentiated wild-type PC12 cells showed enhanced Ca²⁺ response to ACh (50 μm) as compared with the non-differentiated cells. D, CD38-knockdown (CD38 shRNA expression) or pretreatments with either a CD38 inhibitor, nicotinamide (20 mm) or a cADPR antagonist, 8-Br-cADPR (100 μm), all inhibited the ACh-induced Ca²⁺ increase in differentiated PC12 cells. Neuronal differentiation was induced by NGF (50 ng/ml) for 7 days. The graphs represent data from three independent experiments expressed as means ± S.E., n = 30–70 cells.