FIGURE 3.

DOR and MOR differently regulated Aβ42 production and release. Aβ42 concentrations were measured in the cell lysate and medium shed (N = 3 in each group). (A) Effects of DOR activation and inhibition on Aβ42 production and release in PC12 cell line. *p < 0.05, **p<0.01 vs. (C). Note that DOR antagonist naltrindole significantly increased the Aβ42 levels in both cell lysate and medium shed though UFP-512 did not induce any significant change. (B) DADLE- and DAMGO-induced changes in Aβ42 production and release in PC12 cell line. The PC12 cells were treated with DADLE or DAMGO at 1 and 5 μM. *p < 0.05, **p < 0.01 vs. (C). Note that 30-min cell exposure to DADLE or DAMGO did not cause a significant change in the level of Aβ42 as well as its release. After prolonging the exposure time to 48 h, the Aβ42 production was slightly reduced by 1 μM DADLE treatment in the cell lysate portion, whereas the application of DAMGO remarkably increased the levels of Aβ42 in both cell lysate and medium shed. (C) The activation of DOR and MOR adversely regulated Aβ42 production in APPswe SH-SY5Y cell model. *p < 0.05, **p < 0.01 vs. (A). Note that the 48-h exposure of UFP-512 to APPswe SH-SY5Y cells largely decreased Aβ42 production in cell lysate portion, but not in medium shed, while the addition of DOR antagonist naltrindole reversed such changes. Low concentration of DADLE also significantly attenuated Aβ42 production in APPswe SH-SY5Y cell model. In the contrast, DAMGO remarkably enhanced Aβ42 production and release with the concentration increased.