Here, we investigated the effects of the intracerebroventricular (i.c.v.)injection of a recombinant human CDNF in C57BL/6 mice on physiological parameters (sleep and feed and water consumption), different types of behavior (operant learning, anxiety-related, and depressive-like), serotonin (5-HT) turnover, and the expression of key serotonergic genes. Here, CDNF is linked to Anxiety.