Free radicals don’t freeze: why red cell membrane phospholipids stored at low temperatures from schizophrenic patients show increased peroxidation

Abstract

This brief review was stimulated by the finding [1] that in vitro storage of red cell membranes from schizophrenic patients is accompanied by greatly increased loss of unsaturated fatty acids presumably by peroxidation compared to control subjects stored at the same temperature and over the same time period. For highly unsaturated fatty acids such as arachidonic stored at o 70 C the linear loss over time for schizophrenia is twice that of controls. When storage at 20 C and 70 C was compared in control subjects there was no significant difference. However, when phospholipids in membranes from schizophrenic subjects were compared at 20 C and 70 C there was an approximately 50% reduction in polyunsaturated fatty acids at 20 C in the schizophrenic patients compared with 70 C. While it had been well recognised that phospholipids in membranes were subject to storage losses unless kept below 70 C, it had not been realised until now that there was a differential effect between schizophrenic patients and controls over a range of temperatures. What is the cause of these differential storage effects? In prior studies the activity of cPLA2 was found to be increased in schizophrenic patients [2], making it possible that the loss of unsaturated fatty acids in samples stored from schizophrenic patients compared to controls might be linked to the increased activity of cPLA2 prior to freezing. Many other causes of increased peroxidation of fatty acids in schizophrenic patients have been suggested. Would the free radical reaction once started continue at low temperatures? If a free radical chain reaction was to continue then our findings of increased lipid peroxidation in vitro in red blood cell membranes from schizophrenic patients