The Glutamate System in Schizophrenia Kynurenic Acid as a Schizophrenogenic Substance

The Glutamate System in Schizophrenia Kynurenic Acid as a Schizophrenogenic Substance 

In contrast to microghal cells, which produce quinolinic acid, astrocytes play a key role in the production of kynurenic acid (KYNA) in the CNS. Astrocytes are the main source of KYNA (Heyes et al., 1997). The cellular localization of the kynurenine metabolism is primarily in macrophages and microglial cells, but also in astrocytes (Speciale and Schwarcz, 1993 Kiss et al., 2003). KYN-OHse, however, a critical enzyme in the 

A second key-player in the metabolizing of 3-HK are monocytic cells infdtrating the CNS. They help astrocytes in the further metabolism to quinolinic acid (Guillemin et al., 2001). However, the low levels of slCAM-1 (lCAM-1 is the molecule that mainly mediates the penetration of monocytes and lymphocytes into the CNS) in the serum and in the CSF of non-medicated schizophrenic patients (Schwarz et al., 2000) and the increase of adhesion molecules during antipsychotic therapy indicate that the penetration of monocytes may be reduced in non-medicated schizophrenic patients (Muller et al., 1999). 

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