GPR18 and Anxiety: In the four-plate test, an animal test useful for studying anxiety [24], we demonstrated that the GPR18 agonist PSB-KK-1415 (significantly at a dose of 1 mg/kg and non-significantly by 62% at a dose of 10 mg/kg) increased the number of spontaneous punished crossings, which means that stimulation of GPR18 is associated with an anxiolytic-like effect, and GPR18 may even be involved in the anti-anxiety response of THC [25].