Restraint stress induces β-amyloid precursor protein mRNA expression in the rat basolateral amygdala

Several studies have shown the involvement of β-amyloid precursor proteins (APP) isoforms in physiological process like development of the central nervous system (CNS), functional roles in mature brain, and in pathological process like Alzheimer's disease, neuronal experimental damage, and stress, among others. However, the APP functions are still not clear. In the brain, APP695 isoform is predominantly found in neurons while APP751/770 isoforms are predominantly found in astroglial cells and have been associated to neurodegenerative processes. Acute or chronic stress in rats may trigger specific response mechanisms in several brain areas such as amygdala, hippocampus and cortex with the involvement of multiple neurotransmitters. Chronic stress may also induce neuronal injury in rat hippocampus. In situ hybridization (ISH) was used to investigate the expression of APP695 and APP751/770 mRNA in amygdala and hippocampus of male Wistar rats (n = 4-6 per group) after acute (2 or 6 h) or chronic (2 h daily/7 days or 6 h daily/21 days) restraint stress. Only the APP695 mRNA expression was significantly increased in the basolateral amygdaloid nuclei following acute or chronic restraint. No APP isoform changed in hippocampus after any stress condition. These results suggest that restraint stress induces changes in gene expression of APP695 in basolateral amygdaloid nucleus, an area related to stress response.