The Effect of pH on Glycolysis and Phosphofructokinase Activity in Cultured Cells and Synaptosomes

Abstract: Several G_i-linked neurotransmitter receptors, including dopamine D₂ receptors, act synergistically with Ca²⁺-mobilizing stimuli to potentiate release of arachidonic acid (AA) from membrane phospholipids. In brain, AA and its metabolites are thought to act as intracellular second messengers, suggesting that receptor-dependent potentiation of AA release may participate in neuronal transmembrane signaling. To study the molecular mechanisms underlying this modulatory response, we have now used Chinese hamster ovary cells transfected with rat D₂-receptor cDNA, CHO(D₂). Two antisense oligodeoxynucleotides corresponding to distinct cDNA sequences of cytosolic, AA-specific phospholipase A₂ (cPLA₂) were synthesized and added to cultures of CHO(D₂) cells. Incubation with antisense oligodeoxynucleotides inhibited D₂ receptor-dependent release of AA but had no effect on D₂-receptor binding or D₂ inhibition of cyclic AMP accumulation. In addition, pharmacological experiments showed that D₂ receptor-dependent AA release was prevented by nonselective phospholipase inhibitors (such as mepacrine) but not by inhibitors of membrane-bound, non-AA-specific PLA₂ (such as p -bromophenacyl bromide). cPLA₂ is expressed in brain tissue. The results, showing that cPLA₂ participates in receptor-dependent potentiation of AA release in CHO(D₂) cells, suggest that this phospholipase may serve a similar signaling function in brain.