Induced Inflammatory and Oxidative Markers in Cerebral Microvasculature by Mentally Depressive Stress.

Background: Cerebrovascular disease (CVD) is recognized as the leading cause of permanent disability worldwide. Depressive disorders are associated with increased incidence of CVD. The goal of this study was to establish a chronic restraint stress (CRS) model for mice and examine the effect of stress on cerebrovascular inflammation and oxidative stress responses.

Methods: A total of forty 6-week-old male C57BL/6J mice were randomly divided into the CRS and control groups. In the CRS group ( = 20), mice were placed in a well-ventilated Plexiglas tube for 6 hours per day for 28 consecutive days. On day 29, open field tests (OFT) and sucrose preference tests (SPT) were performed to assess depressive-like behaviors for the two groups ( = 10/group). Macrophage infiltration into the brain tissue upon stress was analyzed by measuring expression of macrophage marker (CD68) with immunofluorescence in both the CRS and control groups ( = 10/group). Cerebral microvasculature was isolated from the CRS and controls ( = 10/group). mRNA and protein expressions of tumor necrosis factor- (TNF-), interleukin-1 (IL-1), interleukin-6 (IL-6), vascular cell adhesion molecule-1 (VCAM-1), and macrophage chemoattractant protein-1 (MCP-1) in the brain vessels were measured by real-time PCR and Western blot ( = 10/group). Reactive oxygen species (ROS), hydrogen peroxide (HO), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activities were quantified by ELISA to study the oxidative profile of the brain vessels ( = 10/group). Additionally, mRNA and protein expressions of NOX subunits (gp91, p47, p67, and p22) in the cerebrovascular endothelium were analyzed by real-time PCR and Western blot ( = 10/group).

Results: CRS decreased the total distances ( < 0.05) and the time spent in the center zone in OFT ( < 0.001) and sucrose preference test ratio in SPT ( < 0.01). Positive ratio of CD68 was increased with CRS in the entire region of the brain ( < 0.001), reflecting increased macrophage infiltration. CRS increased the expression of inflammatory factors and oxidative stress in the cerebral microvasculature, including TNF- ( < 0.001), IL-1 ( < 0.05), IL-6 ( < 0.05), VCAM-1 ( < 0.01), MCP-1 ( < 0.01), ROS ( < 0.001), and HO ( < 0.001). NADPH oxidase (NOX) was activated by CRS ( < 0.01), and mRNA and protein expressions of NOX subunits (gp91, p47, p67, and p22) in brain microvasculature were found to be increased.

Conclusions: To our knowledge, this is the first study to demonstrate that CRS induces depressive stress and causes inflammatory and oxidative stress responses in the brain microvasculature.