Correlation between MR-spectroscopic rat hippocampal choline levels and phospholipase A2

Hippocampal choline-containing compounds (Cho) determined with 1H MR spectroscopy (MRS) are decreased in major depression episodes and return to baseline levels after antidepressive electroconvulsive therapy (ECT). A rise in hippocampal Cho has been observed in rats upon electroconvulsive shocks (ECS), an analogue of human ECT. Choline production involves the activity of various phospholipases. In order to investigate whether the increase of Cho correlates with an enhanced expression of phosphoslipase A2 (PLA2) we took rectangular tissue samples from the region of the MRS voxel for immunoblotting. Our data show a significant inverse correlation (p = 0.018) between PLA2 protein levels and MRS Cho/NAA levels suggesting a possible downregulation of PLA2 in compensation for an upregulation of other phospholipases.