Silymarin- and melatonin-mediated changes in the expression of selected genes in pesticides-induced Parkinsonism.

Parkinson's disease (PD) is the second most unconcealed neurodegenerative disorder labelled with motor impairments. Two pesticides, manganese ethylene-1,2-bisdithiocarbamate (maneb) and 1,1'-dimethyl-4,4'-bipyridinium dichloride (paraquat), together, are reported to increase the incidence of PD in humans and Parkinsonism in mice. Conversely, silymarin and melatonin, two naturally occurring antioxidants, rescue from maneb- and paraquat-induced Parkinsonism. The study examined silymarin- and melatonin-mediated changes in the expression of selected genes in maneb- and paraquat-induced Parkinsonism employing mouse discover chips microarrays. The mice were treated intraperitoneally (i.p.), daily, with silymarin (40 mg/kg) or melatonin (30 mg/kg) for 9 weeks along with vehicles. Subsets of animals were also treated with maneb (30 mg/kg; i.p.) and paraquat (10 mg/kg; i.p.), twice a week, for 9 weeks. Whilst the expression of genes in the striatum was determined by microarray, the expression of randomly selected transcripts was validated by quantitative real-time polymerase chain reaction (qRT-PCR). Combined maneb- and paraquat-treatment altered the expression of several genes associated with apoptosis, inflammation, cell cycle, cell-signalling, etc. pathways. Silymarin and melatonin significantly resisted the changes in the expression of a few genes related to apoptosis, inflammation, cell cycle, cell-signalling, etc. The expression patterns of seven randomly selected genes were analyzed by qRT-PCR, which were found to follow the similar trends, as observed with microarray. The results obtained from the study thus demonstrate that despite resemblances, silymarin and melatonin differentially offset maneb- and paraquat-induced changes in transcriptome.