5-Lipoxygenase in the Prefrontal Cortex of Suicide Victims.

5-lipoxygenase (5-LOX), an enzyme involved in leukotriene synthesis, is expressed in the brain and has been associated with Alzheimer's disease and depression. Recently, it has been suspected that leukotriene receptor antagonists might be associated with suicide. In this work, we investigated the 5-LOX protein in the brain samples from depressed suicide victims and matching controls. We used Western immunoblotting with an antibody against Ser(523)-phosphorylated 5-LOX (p5-LOX) to evaluate protein kinase A-mediated 5-LOX phosphorylation, and in addition, an antibody against the total 5-LOX protein. In the total homogenate of the prefrontal cortex samples, 5-LOX content did not differ in the control and suicide groups but p5-LOX was significantly elevated in the suicide samples. The 5-LOX protein content was reduced in the membrane fraction and increased in the cytosol fraction of suicide victims. We propose that further studies of brain 5-LOX are needed to elucidate the functional implications of the protein alterations observed in our present study, and to further explore a putative role of 5-LOX in depression and suicide.