Distinctive mechanisms underlie memory in adult and juvenile animals

Juvenility is a critical developmental stage during which the medial prefrontal cortex (mPFC) undergoes major changes and the brain is vulnerable to environmental factors like stress and/or metabolic challenges. We previously reported that stress affects differently extinction and plasticity in the mPFC in juvenile and adult animals (Schayek and Maroun, 2015). We also showed that chronic exposure to high-fat diet (HFD) starting from juvenility for three months resulted in enhanced fear as compared to similar exposure in adult animals that did not affect behavior (Boitard et al., 2015). Furter we showed the different impact of this diet on the induction of long-term potentiation (LTP). Together, these point to the vulnerability of the juvenile’s brain.

In a series of experiments that I will present we show that acute exposure HFD for 7 days that does not lead to an increase in body weight or in changes in the standard markers of obesity is associated with changes in emotional and cognitive processes; these changes are different in adult and juvenile animals. We further show the different dependency of these HFD-induced changes in memory and plasticity on oxytocin as well as glucocorticoids receptors. Together, we suggest that different mechanisms mediate memory processes in the adult and juvenile animals following HFD or stress and these should be taken into consideration when treating children suffering from anxiety or metabolic disorders.