Several cohort studies have reported that dioxin and dioxin-like polychlorinated biphenyls might impair the nervous system and lead to neurological or neurodegenerative diseases in the elder people,but there is limited research on the involved mechanism.By using microarray analysis,we figured out the differentially expressed genes between brain samples from SD rats after low-dose (0.1 μg/(kg·bw)) dioxin exposure for six months and controls.To investigate the function changes in the course of dioxin exposure,Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed on the differentially expressed genes.And the changes of several picked genes have been verified by real-time PCR.A total of 145 up-regulated and 64 down-regulated genes were identified.The metabolic processes,interleukin-1 secretion and production were significantly associated with the differentially expressed genes.And the genes regulated by dioxin also clustered to cholinergic synapse and long-term potentiation.Candidate biomarker genes such as egr1,gad2,gabrb3,abca1,ccr5 and pycard may be toxicological targets for dioxin.Furthermore,synaptic plasticity and neuro-immune system may be two principal affected areas by dioxin.