Cumulative low doses of the organic pesticide rotenone in the adult rat substantia nigra pars compacta

Adult male Sprague Dawley rats (5 month-old at the beginning of the study) were subcutaneously exposed to 0.5 mg.kg/d rotenone or the corresponding solvent (PEG/DMSO, 1/1) for 28 days. At the end of the experiment, animals were sacrificed by decapitation and brains were rapidly taken out within 30-40 s. Total RNA was prepared from laser-capture microdissected rat substantia nigra pars compacta (Snpc). Changes in transcript abundance within SNpc were analyzed on samples from solvent and rotenone-exposed groups (n = 3 per group) using CodeLink™ Rat Whole Genome bioarrays containing 34,000 transcripts and EST probes (GE Healthcare, Amersham, Saclay, France). Two groups of rats were exposed either to rotenone (CR rats) or to solvents (CS rats) in order to analyse pesticides impact on gene expression.