Early handling effect on female rat spatial and non-spatial learningand memory

Abstract

This study aims at providing an insight into early handling procedures on learning and memory perfor-mance in adult female rats. Early handling procedures were started on post-natal day 2 until 21, andconsisted in 15 min, daily separations of the dams from their litters. Assessment of declarative memorywas carried out in the novel-object recognition task; spatial learning, reference- and working memorywere evaluated in the Morris water maze (MWM). Our results indicate that early handling induced anenhancement in: (1) declarative memory, in the object recognition task, both at 1 h and 24 h intervals; (2)reference memory in the probe test and working memory and behavioral flexibility in the “single-trialand four-trial place learning paradigm” of the MWM. Short-term separation by increasing maternal carecauses a dampening in HPA axis response in the pups. A modulated activation of the stress responsemay help to protect brain structures, involved in cognitive function. In conclusion, this study showsthe long-term effects of a brief maternal separation in enhancing object recognition-, spatial reference-and working memory in female rats, remarking the impact of early environmental experiences and theconsequent maternal care on the behavioral adaptive mechanisms in adulthood.