NPTX2 and Anxiety: Since chronic antidepressant treatment or exercise upregulates Nptx2 expression in the hippocampus [1, 13] and Nptx2-deficient mice display more c-Fos-positive cells in the DG and CA3 regions but not the amygdala after acute stress, we hypothesized that hippocampal Nptx2 modulates anxiety behavior.