Methylmercury induces a brain-specific increase in chemokine CCL4 expression in mice

Expression of the chemokine genes Ccl2, Ccl4, Ccl7, Ccl9, and Ccl12 is increased in cerebellum of mice treated with methylmercury. To investigate the effect of methylmercury on other tissues and organs, levels of chemokine mRNA were investigated in mouse cerebrum, kidney, liver, and spleen. In cerebrum, expression levels of the five chemokines were significantly increased after methylmercury treatment. In kidney, expression levels of Ccl2, Ccl7, Ccl9, and Ccl12, but not Ccl4 were increased. No significant effects were seen on mRNA levels of the chemokines in liver and spleen. Thus, although methylmercury increases the expression levels of multiple chemokines in the brain and kidney, expression of Ccl4 increases only in the brain. Hence, this phenomenon may be involved in methylmercury toxicity specific to the central nervous system.