Figure 4.

Metformin attenuated SHSY5Y cells injury induced by MPP⁺. To activate AMP-activated protein kinase (AMPK), SHSY5Y cells were preincubated with MET (2mM) for 1 hour, and MPP⁺ (200 μM) was added for 48 hours. To block AMPK or autophagy, SHSY5Y cells were preincubated with Compound C (CC) (10 μM) for 30 minutes or with 3-Methyladenine (3MA) (5mM) for 3 hours before MET addition. Cytotoxicity was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) conversion and lactate dehydrogenase (LDH) release (a). Levels of pAMPK, AMPK, and light chain 3 (LC3) were determined by western blotting (b-c). Data are presented as the mean±SEM of 3 independent experiments. ^* P<.05, ^** P<.01, and ^*** P<.001 vs untreated cells. ^# P<.05, ^## P<.01, and ^### P<.001 vs MPP⁺-treated cells. ^&& P<.01 and ^&&& P<.001 vs MET/MPP⁺ co-treated cells. MET, metformin.