Effects of zinc supplementation at different levels on nNOS protein expression in hippocampus of rats

  Objective   To find out the effective limits of zinc supplementation for subhealth and to study the possible mechanism.

  Methods   Y-labyrinth test was used to exam the function of learning and memory, and ABC immunohistochemistry were applied to measure the levels of protein expression of nNOS in hippocampus of rats, respectively.

  Results   Zinc supplementation at lower levels1such as 200 mg/(kg·bw)zinc in feeds-could improve learning and memory function by increasing the protein expression of nNOS in hippocampal fo rmation and subregions of CA₁ and CA₃ and dentate gyrus of rats; excessive zinc supplementation beyond the limits1≥600 mg/(kg·bw)zinc in feedscould impair learning and memory by decreasing the protein expression of nNOS in hippocampus of animals.

  Conclusion   Zinc supplementation at lower levels could improve learning and memory function of rats, and increase of the protein ex pression of nNOS in hippocampus might be one of the most important mechanisms of zinc affecting learning and memory.