Early repeated maternal separation induces alterations of hippocampus reelin expression in rats.

The long-term effects of repeated maternal separation (MS) during early postnatal life on reelin expression in the hippocampus of developing rats were investigated in the present study. MS was carried out by separating Wistar rat pups singly from their mothers for 3 h a day during postnatal days (PND) 2-14. Reelin mRNA and protein levels in the hippocampus were determined using qRT-PCR and Western blotting, at PND 22, PND 60 and PND 90. MS resulted in the loss of body weight in the developing rats, and reelin mRNA and protein levels in the hippocampus generally were down-regulated over the developing period, but the reelin mRNA and protein levels in the hippocampus of 90-day-old male rats were up-regulated. These findings suggest that the long-term effects of MS on the expression levels of hippocampal reelin mRNA and protein depends on the age at which the stressed rats' brains were collected; reelin had important implications for the maternal-neonate interaction needed for normal brain development. In conclusion, repeated MS occurring during early postnatal life may cause the alterations of hippocampal reelin expression with the increasing age of developing rats.