Evidence for the presence of a peptide inhibitor of arachidonic acid metabolism in human cerebrospinal fluid

Human cerebrospinal fluid [CSF], incubated with a homogenate of human platelets, inhibited the conversion of arachidonic acid into tri-hydroxy-eicosatrienoic acid, 12-hydroxy-eicosatetraenoic acid and thromboxane B[2], in a concentration-related manner. A preliminary investigation of physicochemical properties and the effect of proteolytic enzymes on CSF indicated that CSF contains a peptide of low molecular weight [about 1400 daltons] that inhibits arachidonic acid metabolism. The presence of such an inhibitor in CSF might represent a natural mechanism for controlling arachidonic acid metabolism in the subarachnoid space and the adjacent tissues