CNR1 and Alzheimer disease: In “Retrograde endocannabinoid signaling”, the significantly differential DAG in the AD samples can be converted into 2-arachidonoylglycerol (2-AG) via DAGL α/β, activating presynaptic cannabinoid receptor 1 (CB1) to modulate synaptic plasticity and stress responses [65] (Figure 11E).