LEP and major depressive disorder: Remarkably, our neuron-specific GHSR-deleted mice with DIO showed downregulated inflammatory responses of IL-1β and leptin signaling, exhibiting improved depression in the forced swim test and better spatial memory in the water maze, which are similar to reports by others that elevated IL-1β and leptin levels in the CNS promote cognition and mood dysfunction (22, 51, 66, 67).