The Trace Kynurenine, Cinnabarinic Acid, Displays Potent Antipsychotic-Like Activity in Mice and Its Levels Are Reduced in the Prefrontal Cortex of Individuals Affected by Schizophrenia

Schizophr Bull. 2020 Dec 1;46(6):1471-1481. doi: 10.1093/schbul/sbaa074.

Abstract

Cinnabarinic acid (CA) is a kynurenine metabolite that activates mGlu4 metabotropic glutamate receptors. Using a highly sensitive ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS-MS) method, we found that CA is present in trace amounts in human brain tissue. CA levels were largely reduced in the prefrontal cortex (PFC) of individuals affected by schizophrenia. This reduction did not correlate with age, sex, duration of the disease, and duration and type of antipsychotic medication and might, therefore, represent a trait of schizophrenia. Interestingly, systemic treatment with low doses of CA (<1 mg/kg, i.p.) showed robust efficacy in several behavioral tests useful to study antipsychotic-like activity in mice and rats and attenuated MK-801-evoked glutamate release. CA failed to display antipsychotic-like activity and inhibit excitatory synaptic transmission in mice lacking mGlu4 receptors. These findings suggest that CA is a potent endogenous antipsychotic-like molecule and reduced CA levels in the PFC might contribute to the pathophysiology of schizophrenia.

Keywords: HPLC-mass; MK-801; behavior; electrophysiology; endogenous metabolite; human tissue; kynurenine pathway; mass; metabotropic glutamate receptor; mood disorder.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Antipsychotic Agents / administration & dosage
  • Antipsychotic Agents / pharmacology*
  • Behavior, Animal / drug effects*
  • Cells, Cultured
  • Disease Models, Animal
  • Electrophysiological Phenomena / drug effects*
  • Female
  • Humans
  • Kynurenine / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Middle Aged
  • Oxazines / administration & dosage
  • Oxazines / metabolism*
  • Oxazines / pharmacology*
  • Prefrontal Cortex / metabolism*
  • Rats
  • Rats, Wistar
  • Receptors, Metabotropic Glutamate* / deficiency
  • Schizophrenia / drug therapy*
  • Schizophrenia / metabolism*
  • Tissue Banks

Substances

  • Antipsychotic Agents
  • Oxazines
  • Receptors, Metabotropic Glutamate
  • Kynurenine
  • cinnabarinic acid
  • metabotropic glutamate receptor 4