. Author manuscript; available in PMC: 2021 Sep 14.

Published in final edited form as: J Alzheimers Dis. 2020;78(4):1345–1361. doi: 10.3233/JAD-201146

Table 1.

Three groups of mGluRs and their signaling pathways

mGluR group	Members	Brain region	Type of G protein signaling	Key GPCR pathway	Synaptic location
I	mGluR1	Broad brain regions; high in Hippocampus	Gq/11 orthe excitatory signaling	Phospholipase C/Inositol-1,4,5-triphosphate/Diacylglycerol (PLC/IP3/DAG)	Postsynaptic
I	mGluR5	Broad brain regions	Gq/11 orthe excitatory signaling		Postsynaptic
II	mGluR2	High in grey matter neurons	Gi/o or the inhibitory signaling	Adenylate cyclase (AC) inhibition	Presynaptic; mGluR3 can also be postsynaptic
II	mGluR3	Similar to mGluR2 but also prominent in Glia cells	Gi/o or the inhibitory signaling	Adenylate cyclase (AC) inhibition	Presynaptic; mGluR3 can also be postsynaptic
III	mGluR4	High in Cerebellum; broad brain region	Gi/o or the inhibitory signaling	Adenylate cyclase (AC) inhibition; mGlur6 positively couples to cGMP phosphodiesterase	Presynaptic; mGluR6 is postsynaptic
	mGluR6	High in retinal neurons
	mGluR7	Similar to mGluR4
	mGluR8	Low in most neurons