Damage and Phenotype Change in PC12 Cells Induced by Lipopolysaccharide Can Be Inhibited by Antioxidants Through Reduced Cytoskeleton Protein Synthesis

The present study investigated changes in cellular phenotype and oxidative stress during the inflammatory response in PC12 cells stimulated by lipopolysaccharide (LPS) and assessed the effects of minocycline, astragalus (AST), and baicalin on inflammation. PC12 cells were exposed to LPS with or without minocycline, AST, or baicalin. Cell viability was measured by a thiazolyl blue tetrazolium bromide (MTT) assay. Contrast and laser confocal microscopy were used to analyze changes in cellular phenotype and cytoskeleton synthesis. Western blotting tested the expression of α7nAChR and vimentin. Inhibitory ratio of superoxide dismutase (SOD) activity and leakage of lactate dehydrogenase (LDH) were detected to evaluate cellular oxidative stress. Results showed that LPS could attenuate PC12 cell viability in a time- and dose-dependent manner, which could be rescued by minocycline. In addition, minocycline could reverse PC12 cell phenotypic change and the synthesis of the mesenchymal cytoskeleton protein vimentin, both induced by LPS. During LPS-initiated inflammation, α7nAChR and vimentin expression were obviously inhibited by minocycline, AST, or baicalin. The inhibitory rate of SOD activity and LDH leakage in PC12 cells were increased by LPS and attenuated significantly when exposed to minocycline, AST, or baicalin. These findings suggest phenotype change, altered cytoskeleton protein synthesis, and oxidative stress are all involved in the inflammatory response in PC12 cells during which α7 nicotinic acetylcholine receptor (α7nAChR) is induced by LPS stimulation. Minocycline, AST, and baicalin have a protective effect against PC12 cell injury, acting as antioxidants and inhibitors of mesenchymal proteins.