TABLE 2

Commonly used and new CB receptor radioligands for in vivo use reported since (Casteels et al., 2013; Horti et al., 2014); FFA, S1P, prostanoid, leukotriene, and PAF receptor radioligands for in vivo use

Tool	Data for Corresponding Cold Ligand	Function	Reference
CB₁ Receptor–Selective Ligands
[¹¹C]OMAR	hCB₁ K_i = 11 ± 7 nM	Inverse agonist	Fan et al., 2006
[¹⁸F]MK-9470	hCB₁ IC₅₀ = 0.7 nM	Inverse agonist	Burns et al., 2007
[¹⁸F]MK-9470	hCB₂ IC₅₀ = 44 nM		Burns et al., 2007
CB₂ Receptor–Selective Ligands
[¹¹C]NE40	hCB₁ K_i > 1000 nM		Evens et al., 2009
[¹¹C]NE40	hCB₂ K_i = 9.6 nM	Inverse agonist	Evens et al., 2009
[¹⁸F]-d₂-3	hCB₁ IC₅₀ = 180 nM		Hortala et al., 2014
[¹⁸F]-d₂-3	hCB₂ IC₅₀ = 1.4 nM	Agonist	Hortala et al., 2014
[¹⁸F]5	hCB₂ EC₅₀ = 18.0–62.0 nM	Agonist	Yrjölä et al., 2015
[¹¹C]KD2	hCB₁ K_i > 10,000 nM	Not determined	Mu et al., 2013
[¹¹C]KD2	hCB₂ K_i = 1.7 ± 2.0 nM	Not determined	Mu et al., 2013
[¹¹C]KP23	hCB₁ K_i > 1000 nM	Not determined	Mu et al., 2014
[¹¹C]KP23	hCB₂ K_i = 6.8 ± 5.8 nM	Not determined	Mu et al., 2014
[¹¹C]RSR-056	hCB₂ K_i = 2.5 nM	Not determined	Slavik et al., 2015a
[¹¹C]RS-016	hCB₁ K_i > 10,000 nM	Not determined	Slavik et al., 2015b
[¹¹C]RS-016	hCB₂ K_i = 0.7 ± 0.6 nM	Not determined	Slavik et al., 2015b
[¹⁸F]RS-126	hCB₁ K_i > 10,000 nM	Not determined	Slavik et al., 2016
[¹⁸F]RS-126	hCB₂ K_i = 1.2 ± 0.8 nM	Not determined	Slavik et al., 2016
[¹⁸F]CB91 (trans isomer)	hCB₁ K_i = 300 nM	Not determined	Manera et al., 2009
[¹⁸F]CB91 (trans isomer)	hCB₂ K_i = 9.0 nM	Not determined	Manera et al., 2009
[¹⁸F]CB91 (cis isomer)	hCB₁ K_i = 200 nM	Not determined	Manera et al., 2009
[¹⁸F]CB91 (cis isomer)	hCB₂ K_i = 0.7 nM	Not determined	Manera et al., 2009
Nonselective CB Receptor Ligands
[¹¹C]AZD1940	hCB₁ K_i = 11.75 nM	Agonist	Schou et al., 2013
[¹¹C]AZD1940	hCB₂ K_i = 0.87 nM	Agonist	Schou et al., 2013
FFA Receptor Ligands
[¹⁸F]TAK875	hFFA1 2.4-fold more potent than TAK875	Agonist	Bertrand et al., 2016a
S1P Receptor Rigands
[¹⁸F]17	hS1P_1% Activity^{^a} = 95	Agonist	Shaikh et al., 2015
[¹¹C]TZ3321	hS1P₁ IC₅₀ = 2.13 ± 1.63 nM	Not determined	Jin et al., 2017
	hS1P₂ IC₅₀ > 1000 nM
	hS1P₃ IC₅₀ > 1000 nM
[¹⁸F]28c	hS1P₁ IC₅₀ = 2.63 ± 0.27 nM	Not determined	Rosenberg et al., 2016
	hS1P₂ IC₅₀ > 1000 nM
	hS1P₃ IC₅₀ > 1000 nM
[¹¹C]5a	hS1P₁ IC₅₀ > 1000 nM	Not determined	Yue et al., 2015
	hS1P₂ IC₅₀ = 9.52 ± 0.70 nM
	hS1P₃ IC₅₀ > 1000 nM
DP₁ Receptor Ligands
1-[¹⁴C]	hDP₁ K_i = 1.5 ± 0.57 nM	Antagonist	Sturino et al., 2007
	hTP K_i = 0.84 ± 0.19 nM
	hEP₂ K_i = 410 ± 320 nM
	hEP₃ K_i = 470 ± 46 nM
	hIP K_i = 400 ± 100 nM
2-[¹⁴C]	hDP₁ K_i = 1.1 ± 0.22 nM	Antagonist	Sturino et al., 2007
	hTP K_i = 14 ± 2.7 nM
	hEP₂ K_i = 310 ± 82 nM
LTB4₁ Receptor Ligands
SG380	LTB4₁ IC₅₀ = 18 nM	Antagonist	Harris, 2008
PAF Receptor Ligands
[¹⁴C]WEB2086	hPAF K_i = 30 ± 2.1 nM	Antagonist	Parent et al., 1996
[¹⁴C]E6123	hPAF K_i = 2.7 nM	Antagonist	Tsunoda et al., 1990; Sakuma et al., 1991

↵^a Percentage of activity is percentage reduction in peripheral blood CD4⁺ cells mediated by S1P₁ receptor in mice treated with ligand as compared with control (untreated) mice.