These findings suggest that maternal LG in the neonate increases NGFIA expression in the hippocampus and NGFIA binding to the exon 17 promoter. NGFIA might then increase GR expression in hippocampal neurons, and these findings might then provide a mechanism for the effect of maternal care over the first week of life. However, while there are striking differences in NGFIA expression in the offspring of high- and low-LG mothers at day 6 of postnatal life, hippocampal NGFIA expression in adulthood is unaffected by maternal care: there is no difference in hippocampal NGFIA expression in the adult offspring of high- and low-LG dams. We are thus left with the defining question of early experience studies: how are the effects of early life events sustained into adulthood?
