Developmental exposure to mercury chloride impairs social behavior in male offspring dependent on genetic background and maternal autoimmune environment

To date, the connection between inorganic mercury (Hg) and social behavior remains incompletely understood. The aim of this study was to investigate the influence of maternal autoimmunity by inorganic Hg (Hg2+) exposure on social behavior of offspring. Wild-type (WT) and immunoglobulin deficient (Ig(-/-)) B10.S dams fertilized by male WT B10.S or SJL mice were treated with 50 mu M Hg chloride (HgCl2). Non-pregnant female WT B10.S mice were used to investigate factors regulating HgCl2-induced autoimmunity to brain. HgCl2 selectively impaired social behavior in male offspring, but not female offspring from WT B10.S dams x male SJL, in that only male offspring displayed reduced time distribution with the stranger mouse, decreased sniffing to the stranger mouse and increased self-grooming. HgCl2 did not disrupt social behavior of male or female offspring from WT B10.S dams x male WT B10.S or Ig(-/-) B10.S dams x male SJL. The offspring from WT and Ig(-/-) B10.S dams x male SJL had equivalent autoimmunity to brain antigens during HgCl2 exposure, indicating that maternal, but not offspring-derived anti-brain antibodies (Ab) impaired social behavior of the offspring. Nonpregnant WT B10.S mice treated with HgCl2 had increased anti-brain Ab dependent on increase in CD4 T cell activation and IFN gamma signaling to macrophages. IFN gamma interaction with macrophages drove B cells and plasma cells to produce IgG. Therefore, HgCl2 selectively impaired social behavior in males with certain genetic background via maternally derived anti-brain Ab production, thus providing a novel insight into our current understanding of Hg toxicity.