Preventive or therapeutic effects of caffeic acid in brain of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treated mice against inflammatory injury were examined. Caffeic acid at 0.5, 1 or 2% was supplied either pre-intake or post-intake for 4 weeks. Brain caffeic acid content was increased by caffeic acid pre-intake at 1 and 2%, and post-intake at 2% (P < 0.05). MPTP treatment enhanced the release of interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)-alpha, IL-4 and IL-10 (P < 0.05). Pre-intake of caffeic acid decreased the production of test cytokines (P < 0.05); however, post-intake only at 2% reduced the level of IL-1beta, IL-6 and TNF-alpha (P < 0.05). MPTP treatment up-regulated mRNA expression of inducible nitric oxide synthase (iNOS), neuronal NOS, cyclooxygenase (COX)-2, glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule 1, and increased production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) (P < 0.05). Caffeic acid pre-intake at test doses and post-intake at 2% declined the expression of iNOS, COX-2 and GFAP; and lowered the production of NO and PGE₂ (P < 0.05). MPTP treatment suppressed mRNA expression of brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor and tyrosine hydroxylase (TH), and lowered dopamine level (P < 0.05). Caffeic acid pre-intake retained the expression of these factors, maintained TH activity and protein production, and dopamine synthesis (P < 0.05). These results suggest that caffeic acid is a potent neuroprotective agent against the development of Parkinson's disease.
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