Features of Alteration in MAPK Pathway Activity in the Postnatal Brain of a Rat Model of Sporadic Alzheimer's Disease.

Early-life factors influence adult-brain vulnerability to sporadic Alzheimer's disease (AD), but the underlying molecular mechanisms are unknown. In this study, we performed an integrated analysis of mitogen-activated protein kinases (MAPK) pathways' (ERK1/2, JNK, and p38 MAPK) activity in the hippocampus and prefrontal cortex of OXYS rats (a model of sporadic AD) on postnatal days 3 and 10 (P3 and P10): critical periods of brain maturation. Wistar rats (healthy controls) showed extensive developmental transcriptional remodeling of all MAPK pathways. OXYS rats exhibited alterations, most pronounced in the prefrontal cortex at P3, with the JNK pathway showing the greatest divergence. At the protein level, OXYS rats failed to show the normal age-related increase in hippocampal ERK1/2 phosphorylation and in JNK1/2 levels in both regions, indicating developmental signaling deficits. p38 MAPK remained stable among Wistar and OXYS rats. Thus, delayed brain maturation, which contributes to accelerated brain aging and neurodegeneration in OXYS rats, occurs simultaneously with alterations in MAPK signaling. These aberrations potentially are able to increase brain susceptibility to age-related pathologies later in life.