Spatial memory-related brain activity in normally reared and different maternal separation models in rats

Early life stress comprises a wide range of adverse events that can occur in the subject's early developmental stages: from child abuse to rodent repeated maternal separation models. This study used young adult male Wistar rats that were maternally raised (AFR), maternally separated from post-natal day (PND) 1 to PND10 (MS10), or maternally separated from PND1 to PND21 (MS21), to assess the effects of maternal separation on spatial learning and memory using the Morris Water Maze (MWM). We also performed quantitative cytochrome oxidase (COx) histochemistry on some selected brain areas in order to find out whether maternal separation affects brain energy metabolism. We obtained a similar spatial learning pattern in maternally raised and maternally separated subjects, with MS10 showing faster acquisition; however, different brain networks with different energy consumptions were used by each group. MS10 spent more energy to get the same behavioral outputs, whereas MS21 resembled AFR more in term of energy demands.