Characterization of hippocampal Cajal-Retzius cells during development in a mouse model of Alzheimer＇s disease （Tg2576）

Cajal-Retzius cells are reelin-secreting neurons in the marginal zone of the neocortex and hippocampus.The aim of this study was to investigate Cajal-Retzius cells in Alzheimer’s disease pathology.Results revealed that the number of Cajal-Retzius cells markedly reduced with age in both wild type and in mice over-expressing the Swedish double mutant form of amyloid precursor protein 695(transgenic(Tg) 2576 mice).Numerous reelin-positive neurons were positive for activated caspase 3 in Tg2576 mice,suggesting that Cajal-Retzius neuronal loss occurred via apoptosis in this Alzheimer’s disease model.Compared with wild type,the number of Cajal-Retzius cells was significantly lower in Tg2576 mice.Western blot analysis confirmed that reelin levels were markedly lower in Tg2576 mice than in wild-type mice.The decline in Cajal-Retzius cells in Tg2576 mice was found to occur concomitantly with the onset of Alzheimer’s disease amyloid pathology and related behavioral deficits.Overall,these data indicated that Cajal-Retzius cell loss occurred with the onset and development of Alzheimer’s disease.