[Effect of manganese exposure on brain development in postnatal mice]

Effects of manganese (Mn) exposure on brain development in postnatal mice were studied. The results were as follows: (1) The gain of body weight, brain weight and the ratio of brain weight to body weight in the high dose Mn-exposed group was significantly decreased. (2) In the Morris Water Maze Test, the average latency discovering the hidden platform was obviously increased every day during the first 5 days in the high Mn-exposed group, but the latency probing the quadrant in which the hidden platform was located previously was reduced at the 6th day. (3) The protein content of brain tissue was significantly decreased in the high Mn-exposed mice, but the activity of AChE in brain was decreased. (4) The immunoreactivity of glial fibrillary acid protein (GFAP) and the average relative density of GFAP-positive products in hippocampus (area CA3) of both low and high Mn-exposed group, especially the high dose ones, was significantly higher than that of the control group.