It was found that CUMS-exposed KLK8 transgenic rats displayed increased depression-like behavioral responses, as evidenced by decreased sucrose preference (Fig. 2B) and longer immobility time in the FST (Fig. 2C) and increased latency to feed in the NSFT (Fig. 2D), as compared to CUMS-exposed control rats. Here, KLK8 is linked to depressive disorder.