Increased lipid content in the rat axotomized superior cervical ganglion

Transection of postganglionic nerves of the rat superior cervical ganglion results in significant increases in the concentration of lipid as well as the total content of lipid in the ganglion. The purpose of this work was to characterize the effect of axotomy on the major classes of lipid in the ganglion and to examine possible relationships among increases in lipid content and changes in steady-state concentrations of metabolites utilized in lipid biosynthesis. Major classes of lipids in axotomized and contralateral intact ganglia were compared using the Folch extraction and partitioning scheme. Analyses of lipids were carried out 7 days after axotomy because total lipid content was increased maximally at that time. The increase in lipid content in axotomized ganglia was related primarily to an increase in phospholipids. Amounts of gangliosides, cerebrosides, cholesterol, and proteolipid protein did not change significantly after axotomy. The elevation of phospholipid content was accompanied by increases in steady-state concentrations of alpha-glycerophosphate and decreases in Coenzyme A in the ganglion; however, concentrations of acetyl CoA and long-chain acyl CoA compounds did not change significantly in axotomized ganglia. Increases in alpha-glycerophosphate do not appear to arise from enhanced utilization of glucose because alpha-glycerophosphate dehydrogenase activity was decreased in axotomized ganglia and the incorporation of [U-14C] glucose into lipids in explants of the axotomized ganglia in vitro was not elevated. In contrast, incorporation of [U-14C] glycerol into lipids of explants from axotomized ganglia was increased in vitro. The results suggest that utilization of extracellular glycerol for phospholipid biosynthesis may be enhanced in the rat's axotomized superior cervical ganglion.