GFAP and Alzheimer disease: In the colon, the expression of the glial fibrillary acidic protein (GFAP; astrogliosis marker) gene was increased in 3xTg-AD mice at 24 weeks compared to its expression at 52 weeks (P = 0.009, Mann-Whitney test) (Fig. 2A), and IL-6 was increased in 3xTg-AD mice at 52 weeks compared to its expression in WT mice at 52 weeks (P = 0.049, Mann-Whitney test) (Fig. 2B).