Figure 8.

Excitoprotection is partially mediated by stimulating APP shedding from α-secretases. A, The time course of sAPP following lovastatin treatment. Mouse monoclonal antibody 22C11 was used to detect sAPP secretion from the conditioned culture media. B, Both ROCK-specific inhibitor Y27632 and DN ROCK infection stimulate sAPP secretion similarly to lovastatin pretreatment. Soluble sAPP secretion from the conditioned media was assayed as described in A. C, Depletion of sAPP blunts the excitoprotective effect of lovastatin. The conditioned medium after incubation of neurons with lovastatin was removed, followed by replacement of fresh medium or immunoprecipitation with the 22C11 antibody before adding it back to the neurons. Depletion of sAPP was confirmed by Western blot. Trypan blue-positive cells were quantified. Data are presented as the mean ± SD from three independent experiments. *p < 0.001 versus untreated; **p < 0.001 versus NMDA; ***p < 0.001 versus LOV+NMDA. D, Depletion of sAPPα abolishes lovastatin's ability to suppress calpain activity. Neurons were treated the same way as in C and cell extracts prepared were blotted with antibodies, as indicated. E, LY294002 inhibits lovastatin-induced sAPP secretion. The representative Western blots and densitometry analysis are shown. Data are presented as the mean ± SD. *p < 0.01 versus untreated; **p < 0.01 versus LOV.