CLDN5 and major depressive disorder: For example, expression of claudin-5 is decreased in the brains of depressed patients, and it positively correlates with resilience to social stress in mice [166] and in a mouse model of depression, transient reduction of claudin-5 levels with siRNA exacerbates depression-like behaviors, while chronic antidepressant treatment rescued claudin-5 loss and promoted resilience [166].