Anxiety-like but not despair-like behaviors are further aggravated by chronic mild stress in the early stages of APPswe/PS1dE9 transgenic mice

Abstract

Early Alzheimers disease (AD) and depression share many symptoms, thus it is very difficult to initially distinguish one from the other. Therefore, characterizing the shared and different biological changes between the two disorders will be helpful in making an early diagnosis and planning treatment. In the present study, 8-week-old APPswe/PS1dE9 transgenic mice received chronic mild stress (CMS) for 8 weeks followed by a series of behavioral, biochemical and pathological analyses. APPswe/PS1dE9 mice demonstrated despair- and anxiety-like behaviors, and reduced sociability, accompanied by high levels of soluble beta-amyloid, glial activation, neuroinflammation and brain derived neurotrophic factor signaling disturbance in the hippocampus. Notably, APPswe/PS1dE9 mice exposure to CMS further aggravated anxiety-like behaviors rather than hopelessness and sociability deficits, accompanied with more severe neuroinflammation, and low serum corticosterone increased to the normal level. These results may help to understand the pathogenic mechanism of psychiatric symptoms associated with early AD.