Fig 2: Idebenone inhibited the MPTP-induced activation of MAPKs and NF-?B in the SN of PD mice. (A) Expression levels of p-ERK, ERK, p-p38, p38, p-JNK, and JNK in the SN were analyzed by western blotting. (B) Expression levels of p-NF-?B and NF-?B in the SN were analyzed by western blotting. Values are presented as the mean ± standard error. *p < 0.05, ***p < 0.001: idebenone-MPTP vs. corn oil-MPTP; ##p < 0.01, ###p < 0.001: corn oil-MPTP vs. corn oil-saline.

Fig 3: P38MAPK and JNK were responsible for nicotine induced autophagy impairment and caused cardiomyocytes hypertrophy. (A) JNK activation and the expression of autophagy related proteins decreased after pretreatment with the specific inhibitor of JNK SP600125. (B) P38MAPK phosphorylation, LC3-II and p62 protein levels were reduced after treatment with p38MAPK specific inhibitor SB203580. Autophagy flux impairment (C) were also reversed by NAC, SP100625 and SB203580. (Scale bar=20 µm) The specific inhibitor of (D) JNK and (E) p38MAPK pretreatment reversed nicotine induced cardiomyocytes hypertrophy and increased the CTSB activity (F). (****, p < 0.0001; ***, p < 0.001; **, p < 0.01; *, p < 0.05, n = 3).

Fig 4: The schematic diagram of cilostazol's modulation on nicotine-induced autophagy impairment and cardiomyocytes hypertrophy through CTSB/ROS/p38MAPK/JNK pathway. Nicotine activates ROS/p38/JNK signaling and decreases the CTSB activity, which inhibits the fusion of autophagosome and lysosome. Just as the dashed green line showed, a negative feedback exists between ROS and autophagy flux impairment: ROS impairs the fusion of autophagosome and lysosome, and the impaired autophagy flux lead to the ROS accumulation. The nicotine-induced impaired autophagy flux leads to cardiomyocytes hypertrophy in NRVMs. Cilostazol rescues the nicotine-induced ROS accumulation, then dephosphorylates p38/JNK, alleviates autophagy impairment through stimulating CTSB activity and improves cardiomyocytes hypertrophy ultimately.

Fig 5: Cilostazol depressed the activation of p38MAPK and JNK signal. Cilostazol pre-treatment significantly inhibited the phosphorylation of p38MAPK and JNK (A-C). (***, p < 0.001; **, p < 0.01; *, p < 0.05, n = 3).