Co-localization of cytosolic phospholipase A2 and cyclooxygenase-2 in Rhesus monkey cerebellum

Cytosolic phospholipase A(2) (cPLA(2)), cyclooxygenase (COX)-1 and COX-2 play important and integrated roles in the release and subsequent metabolism of arachidonic acid, an important second messenger, in brain and other tissues. Antibodies to each of these enzymes were used to examine their cellular localization and expression in the cerebellum of the adult macaque, using Western blotting and immunohistochemical methods. COX-2 and cPLA(2) immunoreactivities co-localized on the plasma membrane of Purkinje cells, and within punctate intracellular regions. In contrast, COX-1 immunoreactivity was relatively uniform in Purkinje cell cytoplasm, and was more homogeneous in cells of the granular cell layer and occasionally of the molecular layer. COX-1 immumoreactivity was not found on the cell surface. Labeling of Purkinje cell dendrites was not marked for any of the enzymes. cPLA(2) and COX-2 have been shown to be functionally coupled in a number of cell systems, and in brain following lithium chloride administration to rats. The co-localization of cPLA(2) and COX-2 is consistent with evidence of their functional coupling at brain synapses, and of the presence of an unesterified brain arachidonate pool released by cPLA(2) which is the precursor for prostaglandin formation via COX-2. Published by Elsevier B.V.