Erythrocyte and brain methionine adenosyltransferase activities in patients with schizophrenia

The activity of methionine adenosyltransferase (MAT) was investigated in er ythrocytes and postmortem brain specimens (cortex gyrus frontalis, hippocam pus and thalamus) of patients with schizophrenia treated with neuroleptics. In comparison with the control group, abnormally low values of MAT V-max a nd an increased MAT affinity towards methionine (lower K-m values) were fou nd in erythrocytes. In the brain, a regionally selective decrease of MAT K- m was found in cortex gyrus frontalis but the V-max values were however, un changed. In the regions of cortex gyrus frontalis and hippocampus, but not in thalamus. the values of V-max and K-m were inversely correlated with the duration of schizophrenia. In rats treated for 28 days with the typical ne uroleptic haloperidol and the atypical clozapine, a significant increase of MAT activity was found in the corpus striatum. There is the possibility th at the changes observed in MAT activity in patients with schizophrenia are attributed to the neuroleptic medication.