Table 1.

Molecular pharmacology of selected mGlu₅ receptor orthosteric ligands

Compound	mGlu5 receptor pharmacology	Subtype selectivity	References
Glutamate	Agonist, affinity: 700 nM	1 > 3 ≥ 5 ≥ 2 = 4 = 8 > 6 >>7	(Brabet et al., 1998; Niswender and Conn, 2010)
Quisqualate	Agonist, affinity: 29 nM	5 = 1 > 2 ≥ 3 > group III	(Porter et al., 1992; Mutel et al., 2000)
ACPD	Agonist, affinity: 2.1 μM	2 > 5 = 3> 1 = 6 = 8> 4 >>7	(Tückmantel et al., 1997; Cartmell et al., 1998; Wu et al., 1998)
(S)‐CHPG	Agonist, affinity: 380 μM	5 ≥ 1 > group II and III	(Doherty et al., 1997; Mutel et al., 2000)
(S)‐DHPG	Agonist, affinity: 3.9 μM	5 >1 > group II and III	(Wisniewski et al., 2002; Hathaway et al., 2015)
(S)‐4CPG	Antagonist, affinity: 26 μM	1 > 5 > group II and III	(Hayashi et al., 1994; Thomsen et al., 1994; Doherty et al., 1999; Mutel et al., 2000)
(S)‐MCPG	Antagonist, affinity: 153–316 μM	5 = 1 > group II and III	(Brabet et al., 1995; Kingston et al., 1995; Doherty et al., 1999; Mutel et al., 2000)

CHPG: 2‐Chloro‐5‐hydroxyphenylglycine; 4CPG: 4‐carboxyphenylglycine; MCPG: α‐methyl‐4‐carboxylphenylglycine.