Table 1.

Endocannabinoid system (ECS) in neurodegenerative diseases.

Disease	ECS	Observed Change	Model	Reference
HD	Receptors	↓ CB1R	R6/2 mouse	[83]
		↓ CB1R	pre-HD mutation carriers and symptomatic HD patients	[124]
		↓ CB1R	basal ganglia of patients	[126]
		↓ CB1R	grey matter of patients	[127]
		↑ CB2R in astrocytes and reactive microglia	malonate-induced rat model	[54]
AD	EC	↓ anandamide and its precursor	midfrontal and temporal cortices of patients	[133]
		↑ 2-AG	plasma of patients	[137]
		↑ 2-AG	hippocampi of rat model	[138]
	Receptors	↓ CB1R	brains of AD patients	[105]
		alterations of CB1R expression	mouse model of AD	[130]
		unchanged levels of CB1R	hippocampi of patients	[131]
		↓ CB1R	post mortem cortical brain	[134]
		CB1R deficiency	rat model of AD	[135]
	EC enzymes	↑ sn-1-DAGL α and β isoforms, no expression of ABHD6, ↓ MAGL	hippocampi of patients	[131]
		↓ FAAH	frontal cortices of patients	[132]
PD	EC	↑ anandamide	cerebrospinal fluid of patients	[143]
	Receptors	↑ CB1R	basal ganglia of patients	[142]
ALS	EC	↑ anandamide and 2-AG	spinal cords of SOD1 G93A mice	[146]
	Receptors	↑ CB2R	human spinal cord	[147]

↓ decreased level, expression or activity; ↑, increased level, expression or activity; ABHD6, α/β-hydrolase domain-containing 6; AD, Alzheimer’s disease; ALS, amyotrophic lateral sclerosis; 2-AG, 2-arachidonoylglycerol; CB1R, cannabinoid receptor type 1; CBR2, cannabinoid receptor type 2; DAGL, DAG lipase; EC, endocannabinoids; ECS, endocannabinoid system; FAAH, fatty acid amide hydrolase; HD, Huntington’s disease; MAGL, monoacylglycerol lipase; PD, Parkinson’s disease.