One probable mechanism of the learning-memory damage by lead: The changes of NOS in hippocampus

Objective: To study the effects of lend on the activity and expression of nitric oxide synthase (NOS) and relationship between the effects of lead on learning-memory and changes of NOS in subfields of hippocampus. Methods. Y-maze test was used to study the effects of lead on ability of learning-memory; NADPH-d histochemistry and immunohistochemistry methods were used to investigate the changes of NOS in subfields of hippocampus. Results. Compared with the control group, the ability of learning-memory in lead-exposed rats was significantly decreased (P< 0.05); the number of NOS positive neurons in CA1 region and dentate gyrus of lead-exposed rats was significantly decreased(P<0.05), but no marked changes in CA3 region; the number of nNOS positive neurons in CA1 of lead-exposed rats was also significantly decreased (P<0.05), but no obvious changes in CA3. Conclusion. Lead could damage the ability of learning-memory in rats. Lead could decrease the activity and expression of NOS in hippocampus and had different effects on NOS in different subfields of hippocampus. The changes of NOS in hippocampus induced by lead may be the mechanism of the learning-memory damage by lead.