Contrasting effects of acute and long-term corticosterone treatment on amyloid-β, beta-secretase 1 expression, and nuclear factor kappa B nuclear translocation

Regulation of neuroinflammation is critical to control the detrimental impact of chronic stress in the central nervous system. Neuroinflammation occurs in response to chronic stress, leading to enhanced neuronal damage in the brain. We investigated the regulatory effects of stress hormone corticosterone on neuroinflammation regulator, as well as amyloid-beta and Beta-secretase 1 related signaling. We demonstrate that corticosterone can both positively and negatively regulate amyloid-beta expression, which may be related to the ratio of neuroinflammation regulator and Beta-secretase 1 signaling in rat primary cortical neurons. Thirty minutes of treatment with 1 muM corticosterone significantly decreased the nuclear translocation of neuroinflammation mediator neuroinflammation regulator (Western Blot: P < 0.05, Immunofluorescence: P < 0.001) and production of Beta-secretase 1 enzyme (P < 0.01), which was accompanied by a reduction in amyloid-beta1-42 levels (P < 0.01). In contrast, 1 microM corticosterone treatment over 3 days increased nuclear neuroinflammation regulator localization (P < 0.001), followed by the upregulation of Beta-secretase 1 (P < 0.01) and amyloid-beta1-42 (P < 0.05) expression. This work is the first to demonstrate that the duration of corticosterone exposure can promote or inhibit amyloid-beta production, and to link this effect with Beta-secretase 1 / neuroinflammation regulator signaling, together with providing valuable insight into the mechanisms of neuroinflammation and neuroprotection.