Although many studies evaluating antidepressant-like effects of ketamine in animal models use depression models or acute stress paradigms in adults, here we used MD stress to explore the possibility that a single intraperitoneal (i.p.)injection of ketamine is sufficient to exert prolonged antidepressant effects through reversal of LHb neuronal dysfunction and behavioral despair induced by early life stress. The gene discussed is LHB; the disease is depressive disorder.