Targeted knockout of a chemokine-like gene increases anxiety and fear responses

Significance Emotion-related responses, such as fear and anxiety, are important behavioral phenomena in most animal species, as well as in humans. However, the underlying mechanisms of fear and anxiety in animals and in humans are still largely unknown, and anxiety disorders continue to represent a large unmet medical need in the human clinic. Animal models may speed up discovery of these mechanisms and may also lead to betterment of human health. Herein, we report the identification of a chemokine-like gene family, samdori ( sam ), and present functional characterization of sam2 . We observed increased anxiety-related responses in both zebrafish and mouse knockout models. Taken together, these results support a crucial and evolutionarily conserved role of sam2 in regulating anxiety-like behavior.