FMR1 and major depressive disorder: For example, treatment of FMR1 knockout mice with monoacylglycerol lipase (MAGL) inhibitors to increase endocannabinoid signaling tone has been shown to normalize cortical responses to sound and diminish anxiety-like behaviors [42] and restore mGluR5-mediated long-term depression in brain slices taken from the ventral striatum of FMR1 knockout mice [27].