Treatment with FIS significantly increased anxiety-like behaviors [F(1,14) = 320.35, p < 0.001; and F(1,14) = 21.491, p < 0.001 in OT and OE of EPM, respectively]; increased hippocampal NF-κB activation; suppressed hippocampal BDNF and claudin-5 expression; increased blood corticosterone [F(1,14) = 28.813, p < 0.001], IL-6 [F(1,14) = 49.754, p < 0.001], TNF-α [F(1,14) = 34.965, p < 0.001], and LPS levels [F(1,14) = 42.416, p < 0.001]; and induced the activated microglia/monocyte populations into the hippocampus (Figs 3e–i and S2a). Here, CLDN5 is linked to Anxiety.