EFFECT OF GANGLIOSIDES ON DIACYLGLYCEROL CONTENT AND MOLECULAR-SPECIES IN NERVE FROM DIABETIC RATS

The effects of ganglioside treatment on 1,2-diacylglycerol content and on molecular species in 1,2-diacylglycerol, phosphatidic acid and tot al diacylglycerolipids, as well as Na+,K+-ATPase activity, were examin ed in sciatic nerves from streptozotocin-induced diabetic rats. Beginn ing 2 weeks after induction of diabetes, animals were administered mix ed bovine brain gangliosides, AGF1, an inner ester derivative of this mixture, or saline for 5 weeks. The levels of 1,2-diacylglycerol and a rachidonoyl-containing molecular species in age-matched non-diabetic a nimals were not affected by ganglioside treatment. In nerves from sali ne-treated diabetic animals, 1,2-diacylglycerol levels were not reduce d, but both Na+,K+-ATPase activity and all arachidonoyl-containing spe cies except for 18:0/20:4 1,2-diacylglycerol were significantly decrea sed. The content of 1,2-diacylglycerol was lowered by 23 and 16% in bo vine brain ganglioside and AGF1-treated diabetic animals, respectively , and the quantity of 18:0/20:4 1,2-diacylglycerol was also selectivel y reduced. Ganglioside administration did not affect the diminished le vels of arachidonoyl-containing molecular species in 1,2-diacylglycero l, phosphatidic acid or diacylglycerolipids in nerve from diabetic rat s. In the same nerves, bovine brain gangliosides partially and AGF1 co mpletely restored Na+,K+-ATPase activity. The results suggest that gan gliosides depress the content of total 1,2-diacylglycerol and the quan tity of 18:0/20:4 1,2-diacylglycerol, specifically, in diabetic nerve. The possible relationship between the corrective action of gangliosid es on Na+,K+-ATPase activity and the effect of these substances on 1,2 -diacylglycerol molecular species composition and metabolism is discus sed.