Effects of Lead Exposure During Pregnancy on Spatial Learning and Memory in Filial Rats

Objectives To explore the effects of lead exposure during pregnancy on spatial learning and memory in filial rats.

Methods Forty SD pregnant rats were randomly divided into four groups, lead acetate in distilled water were given after conception on the concentration of 125 mg/L(low dose group), 250 mg/L (middle dose group) and 500 mg/L(high dose group)for three exposure groups. The control group was treated with distilled water. All maternal rats received distilled water after delivery. Pups were separated from their mothers on 21 days of age. The lead content of blood, hippocampus and cerebral cortex (whole brain for 0 day-old) of pups was determined by oscilloscope polarograph on 0, 21 and 60 day-old; On the other hand, Morris water maze test was conducted on 21 and 60 day-old.

Results The lead content of blood, hippocampus and cerebral cortex on 0, 21 and 60 day-old in 3 exposure groups were higher than that in the control group (P < 0.05); and the higher concentration of lead exposure, the younger age of rats, and the lead contents in these tissues were higher.In water maze test conducted on 21 days after birth, the escape latency of three lead exposure groups were longer than the control group, and the high dose group was longer than the low dose group (P < 0.05); as for the space exploration experiment, the number of times passing through the platform in the three lead exposure groups was also less than the control group, and the high dose group was less than the low dose group (P < 0.05). The test conducted on 60 days after birth showed that the escape latency was longer and the number of times passing through platform was less in the high dose group than the control group (P < 0.05), no differences was observed among the middle dose group, low dose group and the control group.

Conclusions Prenatal exposure to lead might cause higher lead levels in hippocampus and cerebral cortex of filial rats, and damage their learning and memory function, which might be partially compensated with the increase of age.