[Protection of zinc on hippocampal cholecystokinin of lead-exposed rat].

OBJECTIVE: To investigate the relationship between the effects of zinc on hippocampal cholecystokinin (CCK) positive neurons and learning and memory ability of lead-exposed rats. METHODS: Thirty-six Wistar rats were divided into control group, lead-exposed group (drunk 6.15 mmol/L of lead solution) and lead-zinc group (drunk 6.15 mmol/L of lead + 3.10 mmol/L of ZnSO(4) solution) randomly. Y-maze test was used to study learning and memory ability in rats; Atomic absorption method was used to determine serum and hippocampal lead content; ABC immunohistochemistry and quantitative graphic analysis were used to investigate the changes of CCK positive neurons in different hippocampal subfields in lead-exposed rats. RESULTS: The learning and memory ability in lead-exposed rats were significantly lower (P < 0.05) while the serum and hippocampal lead content in lead-exposed rat were significantly higher (P < 0.05) than those in control and lead-zinc group. The number and optical density of CCK positive neurons in CA(1) and CA(3) areas of lead-exposed rats were significantly lower (P < 0.05) than those in control and lead-zinc group. No differences in these indexes between the control and lead-zinc group were found (P > 0.05). CONCLUSION: Lead may damage the learning and memory ability and affect the number of CCK positive neurons in lead-exposed rats. Zinc might play an important role in preventing lead-induced damages.