CNR2 and Huntington disease: CB2-positive microglia have been detected in β-amyloid plaques of Alzheimer's disease patients (Ramirez et al., 2005), in spinal cords of an amyotrophic lateral sclerosis (ALS) mouse model (Shoemaker et al., 2006), in active plaques of patients with multiple sclerosis (MS) (Benito et al., 2007) and in striatal lesions of Huntington's disease (HD) transgenic mouse models and patients (Palazuelos et al., 2009).