Abnormal serine hydroxymethyl transferase activity in the temporal lobes of schizophrenics

We studied the kinetics of the enzyme serine hydroxymethyl transferase (SHMT) and the concentration of its metabolic substrates serine and glycine, in the postmortem brains of controls and schizophrenics. The Km of SHMT, and the concentration of serine and glycine were all significantly higher in the temporal lobes of brain tissues from schizophrenics than in those from controls. These differences were not observed in the frontal lobe specimens. Neuroleptics, age, sex and autolysis time did not contribute to these differences. The role of SHMT deficiency in schizophrenia is discussed in relation to the production of glycine and 1-carbon units from which purines and thereby adenosine is produced. Both glycine and adenosine are potent neuromodulatory substances for the release of dopamine and glutamate, neurotransmitters which have been implicated in the pathophysiology of schizophrenia.