Behavioral alterations induced by HgCl2 depend on the postnatal period of exposure

This paper shows the toxicity of mercury (HgCl2 5 mg/kg/day for 5 days, sc) applied at specific stages of development (1–5, 8–12 or 17–21 days old, 1st, 2nd and 3rd phases, respectively) on the performance of rats in three behavioral tasks and on cerebral mercury levels. The mercury exposure at the 1st and 2nd phases affected the performances of rats in the rim escape. Spontaneous alternation behavior was not altered by mercury exposure. In the open field task, habituation was absent when the rats were treated at the 1st phase, and the crossing response number was lower in rats exposed to mercury at the last period. In general, the brain accumulated large quantities of mercury. In short, the first days of postnatal life (1st phase) appeared to be more sensitive to mercury exposure than the other phases studied, since they presented behavioral deficits even at a time period somewhat after the exposure.