Effect of Lead (Pb2+) Exposure in Female Pregnant Rats and Their Offspring on Spatial Learning and Memory in Morris Water Maze

Lead (Pb²⁺) is a well known neurotoxin that was frequently found in the environment and chronic exposure to lead has been matter of public health. In the present study the effect of lead on spatial memory in developmentally exposed rats and their dams in Morris water maze task were investigated. Female rats were divided into three groups and two groups exposed to 250 and 750 part per million (ppm) Pb acetate and one group Na acetate , as a control group, through drinking water, ten days prior to mating and continue through pregnancy, pregnant animals were tested in the swim task at gestation day 14±2. Another group of animals exposed to the same concentration of Pb acetate at different developmental stages including a maternally exposed group (including gestation and lactation period) and continuously exposed group (including gestation, lactation and continue to lead exposure until test time). Rats in these groups were tested for spatial learning and memory in Morris water maze task at post natal day (PND) 56.

Exposure to lead did not affect learning ability of dams in Morris water maze performance indicating by no significant differences in escape latency and traveled distance between groups, but, for both maternally-and continuously-exposed groups treated with 750 ppm lead, average escape latency and traveled distance were increased, indicating significant impairment in spatial learning and memory. These results are more direct evidence that indicate developing brain is more susceptible to Pb²⁺ induced neurotoxicity.