Basic nutritional investigationEffects of maternal mild zinc deficiency and zinc supplementation in offspring on spatial memory and hippocampal neuronal ultrastructural changes

ObjectiveKnowledge about the hippocampal morphologic mechanisms of learning and memory for maternal mild zinc deficiency during pregnancy/lactation followed by zinc supplementation of pups after weaning is limited. This study examined the effects of zinc deficiency and zinc supplementation on cognition and hippocampal neurons.MethodsOne-day pregnant rats were randomly divided into four groups (n = 12): control (CO), pair-fed (PF), zinc-deprived (ZD), and oral zinc-supplemented (OZS). The CO and PF groups were fed a control diet (zinc 25 μg/g diet), and the others were fed a mildly zinc-deficient diet (zinc 2 μg/g diet) during pregnancy and lactation. After weaning (day 21), offspring in the OZS group were switched to a control diet. After 35 d, the behavioral function of the offspring was tested with the Morris water maze test. The ultrastructure of the hippocampal CA3 area was observed under a transmission electron microscope.ResultsCompared with the CO and PF groups, rats in the ZD group spent more time finding the latent platform and swam longer distances (P < 0.05). The time used finding the platform and the swimming distance in the OZS group were similar to those in the CO and PF groups (P > 0.05). In addition, apoptotic neuronal changes in the hippocampus were observed in the ZD group, whereas the reversal of neuronal morphologic changes was observed in the OZS group.ConclusionThe changes in hippocampal neuron morphology were consistent with the changes in the learning and memory ability of mildly zinc-deficient and zinc-supplemented offspring.