Lipases of Rat Brain Microsomes

Abstract

There exists a considerable degree of information in regard to the activities of glycerol ester hydrolases from numerous tissue sources. However, little attention has been given to the study of glyceride lipases in brain. Brain, in comparison to other organs, contains smaller quantities of neutral glycerides; amounts of triacylglycerol from whole rat brain have been established at 0.15–0.17 umol/g tissue (1). Numerous observations demonstrate that acylglycerols are metabolically active in brain tissue (2–5). In addition, several findings suggest the possibility for the presence of lipase activity in brain. These include the production of free fatty acids in incubated slices of mouse brain (6), and the rapid appearance and loss of radioactivity inthe triacylglycerols of mouse brain following intracerebral injection of (1-¹⁴C)oleic acid (7). Other observations report a reduction in the concentration of membrane diacylglycerol levels in crude homogenates of rat brain (8) and an increase in the amount of free fatty acids at the onset of brain ischemia (9). Ischemia was in turn accompanied by triacylglycerol breakdown, and the involvement of a separate diacylglycerol lipase was postulated (10).