Objective   To study the effects of lead exposure during pregnancy on learning, memory and nerve growth factor(NGF)expression in hippocampus of descendants.

  Methods   The contents of lead in hippo campus were measured by atomic absorption spectrophotometer.The levels of NGFmRNA and protein expression in hippocampus were determined by RT-PCR and immuno histochemistry.The changes of learning and memory abilities were observed through spatial water maze test.

  Results   Compared with the control group(0.03±0.01), the contents of lead(μg/g·wet weight)in hippocampus of descendants(1.08±0.37, 1.71±0.33, 2.63±0.41)were significanly increased in the treatment groups respectively(P < 0.01).The expression of NGFmRNA in treatment groups(0.81±0.08, 0173±0.17, 0.41±0.04)were significantly lower than that of control(1.13±0.04)(P < 0.05).The area density of NGF protein in treatment groups(0.118±0.020, 0.080 ±0.014, 0.026±0.012)were significantily lower than that of control(163.27±19.57)(P < 0.01), and the averagegray value of NGFprotein in treatment groups(186.42±10.43, 193.85±15.73, 201.46±19.27)were significantly higher than that of contr ol(163.27±19.57)(P < 0.05).The escape time that infants needed in treatment groups(22.4±10.4), (30.5 ±12.7), (37.6±17.2)s, were longer than that of control(12.7±5.7)s, (P < 0.01).

  Conclusion   Maternal lead exposure duing pregnancy could affect learning and memory functions of infants obviously, which might be highly correlated with the changes of NGFexpression in hippocampus of descendants.