Xanthurenic acid is a putative endogenous Group II metabotropic glutamate receptor agonist, on sensory transmission in the thalamus. The inhibition of Xanthurenic acid (XA) on sensory can be found when applied iontophoretically and i.v., is similar to that of other Group II mGlu receptor agonists in reducing inhibition evoked in the VB from the thalamic reticular nucleus upon physiological sensory stimulation. Furthermore, it is postulated that Xanthurenic acid may be the first potential endogenous allosteric agonist for the mGlu receptors. As the Group II receptors and kynurenine metabolism pathway have both been heavily implicated in the pathophysiology of schizophrenia, Xanthurenic acid could play a pivotal role in antipsychotic research as this potential endocoid represents both a convergence within these two biological parameters and a novel class of Group II mGlu receptor ligand.