. Author manuscript; available in PMC: 2022 Jan 14.

Published in final edited form as: Expert Opin Ther Targets. 2021 Jun 1;25(5):365–380. doi: 10.1080/14728222.2021.1934447

Table 3.

Activations makers of microglia used in diagnostic studies such as PET-imaging.

Activation Marker	Name/Description	Role in Neuroinflammation	Radioligands
TSPO	Translocator Protein - found on outer membrane of mitochondria	Increased expression in Ml microglia. Possibly involved in steroidogenesis, attenuating oxidative stress, apoptosis, cell metabolism.	PK11195, [¹¹C]PBR28
CB2	Cannabinoid receptor-2	Associated with neuronal loss and microglial activation.	[¹¹C]A836339, [¹¹C]NE40
COX-1, COX-2	Cyclooxygenase	COX-1 - Pro-inflammatory microglia COX-2 - Anti-inflammatory microglia; may attenuate BBB permeability	¹¹C-ketoprofen methylester
P2X7	Ionotropic purinergic receptor	Upregulated in neurodegeneration. Most responsive to ATP.	¹¹C-JNJ-54173717
P2Y12	Metabotropic purinergic receptor	Present only on microglia. Initiates signaling cascades.	None currently available.