OBJECTIVETo investigate the effect of lithium on hippocampal cholecystokinin (CCK) and neuronal nitric oxide synthase (nNOS) positive neurons and its relationship to the learning and memory ability of lead exposed rats.

METHODSWistar rats were randomly divided into the control group, the lead group, four lead + LiCl (3, 30, 300, 3,000 mg/kg) groups. Four lead + LiCl groups were fed with food containing 3, 30, 300, 3,000 mg/kg LiCl respectively. The lead + LiCl groups and the lead group were administered with distilled water containing 0.2% PbAc. The body weight was measured and the difference of body development was observed. Y-maze test was used for studying the effects of lead on the learning and the memory ability in rats. ABC immunohistochemistry was used for investigating the changes of CCK positive neurons in hippocampus of lead-exposed rats.

RESULTSCompared with the control group and the lead + LiCl groups, the learning and memory ability of lead exposed rats was significantly higher (P < 0.05). The number of CCK positive neurons in hippocampus lead exposed rats fed with lithium (3, 30, 300 mg/kg) was significantly higher than that in the lead exposed rats (P < 0.05).

CONCLUSIONThe lead may damage the learning-memory ability of the rats. It might be related to the changes of CCK positive neurons in hippocampus in lead exposed rats. The lithium of the low dose might play an important role in preventing lead-induced damages.