From gut to brain: alteration in inflammation markers in the brain of dextran sodium sulfate-induced colitis model mice
Jongho Do 1, Jungmin Woo 1, 2*
1Kyungpook National University Hospital, 2Kyungpook National University School of Medicine
Received: November 21, 2017; Revised: January 11, 2018; Accepted: January 11, 2018; Published online: January 11, 2018.
© The Korean College of Neuropsychopharmacology. All rights reserved.

Objective: Neuropsychiatric manifestations like depression and cognitive dysfunction commonly occur in inflammatory bowel disease(IBD). In the context of the brain-gut axis model, colitis can lead to alteration of brain function in a bottom-up manner. Here, the changes in the response of the hypothalamic-pituitary-adrenal axis and inflammation-related markers in the brain in colitis were studied.
Methods: Dextran sodium sulfate(DSS) was used to generate a mouse model of colitis. Mice were treated with DSS for 3 or 7 days and sacrificed. We analyzed the gene expression of brain-derived neurotrophic factor(BDNF), Cyclooxygenase-2(COX-2), and glial fibrillary acidic protein(GFAP), and the protein expression of GFAP, in the hippocampus, hypothalamus, and amygdala. Additionally, the levels of C-reactive protein(CRP) and serum cortisol/corticosterone were measured.
Results: Alteration of inflammatory-related markers varied depending on the brain region and exposure time. In the hippocampus, COX-2 mRNA, GFAP mRNA, and GFAP protein expression were upregulated during exposure to DSS. However, in the hypothalamus, COX-2 mRNA was upregulated only 3 days after treatment. In the amygdala, BDNF and COX-2 mRNAs were downregulated. CRP and corticosterone expression increased with DSS treatment at day 7.
Conclusion: IBD could lead to neuroinflammation in a bottom-up manner, and this effect varied according to brain region. Stress-related hormones and serum inflammatory markers, such as CRP, were upregulated from the third day of DSS treatment. Therefore, early and active intervention is required to prevent psychological and behavioral changes caused by IBD, and region-specific studies can help understand the precise mechanisms by which IBD affects the brain.
Keywords: Inflammatory bowel disease, stress, Dextran sodium sulfate, corticosterone, neuroinflammation, cortisol, COX-2, GFAP, BDNF