Activation of phosphatidylcholine signaling during oxidative stress in synaptic endings

MATEOS, M.V.; URANGA, R.M.; SALVADOR, G.A.; GIUSTO, N.M.

NEUROCHEMISTRY INTERNATIONAL

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2008 vol. 53 p. 199 - 206

0197-0186

The purpose of the present study was to investigate the involvement of phosphatidylcholine (PC)signalling in synaptic endings incubated under oxidative stress conditions. Synaptosomes purified fromadult rats (4months old) cerebral cortex were exposed to oxidative insult (FeSO4,50 mM) or vehicle, anddiacylglycerol (DAG) generation and free fatty acid (FFA) release were subsequently evaluated usingexogenous [14C]PC as substrate. DAG formation increased after 5, 30, and 60 min of Fe2+-exposure withrespect to the control conditions. The contribution of PC-specific phospholipase C (PC-PLC) andphospholipase D (PLD) pathways to DAG generation was evaluated using ethanol in the enzyme assays.Phosphatidylethanol (PEth) production was measured as a marker of PLD activity. In the presence ofethanol (2%) iron significantly stimulated DAG and PEth production at all times assayed. FFA release fromPC, however, was inhibited after 5 and 60 min of iron exposure. Similar results were observed in agedanimals (28months old)when comparedwith adult animals. DAG generation fromPCwas also evaluatedin the presence of the tyrosine kinase inhibitors genistein and herbimycin A. Inhibition of tyrosine kinaseactivity did notmodify the stimulatory effect exerted by iron on PC-PLC and PLD activities.Moreover, thepresence of LY294002 (a specific PI3K inhibitor) did not alter DAG production. Our results demonstratethat oxidative stress induced by free iron stimulates the generation of the lipidmessenger DAG fromPC insynaptic endings in adult and aged rats. 2008 Elsevier Ltd. All rights reserved.