Chronic Variable Stress Alters Inflammatory and Cholinergic Parameters in Hippocampus of Rats

In the present study we investigated the effect of chronic variable stress (CVS) on some parameters of the immune system, including levels of cytokines [interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF- alpha)] and chemokine CCL2 (MCP-1) in the hippocampus of rats. Acetylcholinesterase activity was also evaluated. Sixty-day old Wistar rats were submitted to different mild stressors for 40 days. After the last stress section, the cytokines and MCP-1 were determined by immunoassay and acetylcholinesterase activity by colorimetric method. Results showed that chronic stress significantly increased the levels of IL-1 beta, IL-6 and TNF-alpha, but did not alter the levels of MCP-1. In addition, acetylcholinesterase activity was increased in the hippocampus of rats subjected to CVS. These findings suggest that inflammation and cholinergic dysfunction may be, at least in part, important contributors to the neurological dysfunction observed in some depressed patients.