Characteristics of phospholipid methylation in human erythrocyte ghosts: relationship(s) to the psychoses and affective disorders.
Recent studies have shown that patients with a schizophrenic-like illness have a significant deficit in erythrocyte ghost membrane (EGM) phosphatidylcholine (PC); patients with the most severe deficiency showed a marked decrease in Na+-Li+ counterflow activity (Hitzemann et al. 1984a and b). The present study was undertaken to see if the decrement in PC is associated with a decrease in phospholipid methylation activity. Phospholipid methylation in human EGMs is distinctly different from that in rat EGMs (Hirata and Axelrod 1980) in that the human activity is not Mg++-dependent, and apparent methyltransferase I activity is located in the external membrane surface. The patient population consisted of 20 DSM-III schizophrenics (SCZ), 13 DSM-III schizophreniform (SF) disorder patients, and 11 DSM-III manics (M). Twelve age- and sex-matched controls were used for the comparison group. Methylation activity was significantly decreased in all three patient groups, although the M group had significantly higher activity than the SF group. Twenty-four of the SCZ and SF patients entered a Li+ trial. The Li+ responder group (n = 8) showed significantly lower activity than the nonresponder group (n = 16). Overall, we conclude that the decrement in phospholipid methylation activity partially contributes to the decrement in PC levels.
D000328:Adult; D001714:Bipolar Disorder / Q000188:drug therapy / Q000201:enzymology*; D004910:Erythrocyte Membrane / Q000201:enzymology*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008094:Lithium / Q000627:therapeutic use; D008274:Magnesium / Q000097:blood; D008297:Male; D008745:Methylation; D008780:Methyltransferases / Q000097:blood; D010713:Phosphatidylcholines / Q000097:blood; D010743:Phospholipids / Q000097:blood*; D012559:Schizophrenia / Q000188:drug therapy / Q000201:enzymology*; D013109:Sphingomyelins / Q000097:blood
D010713:Phosphatidylcholines; D010743:Phospholipids; D013109:Sphingomyelins; D008094:Lithium; D008780:Methyltransferases; D008274:Magnesium