[ toxicity effect of methyl mercury chloride on newborn rat: Enzymatic, histology change and mercury accumulation]

ABSTRACT

Methyl mercury is a well- known environmental pollutant and toxicant to the nervous tissue, particularly during development of prodecure of brain. Low concentration of methyl mercury chloride [MMC] can be transferred to the fetus through the placenta and to newborn offspring through dam. This study aimed at investigating the toxicity significant difference effect of methyl mercury chlyoride on nearborn rat. In this experimental study 21 adult female Wistar rats were divided in 3 groups, 2 experimental and 1 control group, the experimental groups were inoculated with MMC 0.5 and 4.5 mg/kg on the 15[th], 16[th] and 17[th] gestation days. On day 25 after birth, 6 newborn rats from each experimental group were anesthetized. Blood samples were collected, alanine amino transferase [ALT], gamma glutamyle transferase [GGT], aspartate amino transferase [AST], alkaline phosphatase [ALP], tri iodo thyronine [T3], thyroxine [T4] and growth hormone [GH] were determined according to routine laboratory methods and the amount of mercury accumulation in some tissues were measured using atomic absorbtion. Histological examination of the brain, liver and kidney were also performed. The data were analyzed using Kruskal- Wallis and Mann Whitny tests. Serum analysis showed no significant difference in the experimental groups in GGT, AST, ALT, T4 compared to control group [P>0.05]. Also ALP, T3 and GH significantly increased compared to the control group [P<0.05]. The mercury accumulation significantly increased retrospectively in brain, thyroid, kidney and liver with the increase in the injection dose [P<0.005]. In the histopathologic study of the brain, degeneration and apoptosis were observed. This study showes that exposure to the low doses of induced MMC, reduces T3, growth hormone and it decreases ALP level in experimental groups compared to the control group. It may impair memory, learning and growth