Endocrine Abstracts

Sphingolipids constitute the structural base for all types of biological membranes, and are numerous in human and animal tissues. Metabolites of sphingolipids act as biological effectors, modulators and mediators in a number of biochemical processes; they are known to be pathogens in various human pathologies.

We aimed at studying activity of sphingomyelinase, concentrations of sphingomyelin and its metabolites, such as ceramide and sphingosine, in organs of rats with experimental diabetes.

Experimental model of obesity and insulin resistance was used to study activity of sphingomyelinase, and concentrations of sphingosine and ceramide. As compared with the controls, in the liver of experimental animals activity of neutral and acid sphingomyelinase was found to increase by 25 and 21% respectively. In skeletal muscles of obese animals, activity of neutral and acid sphingomyelinase increased by 45 and 70% respectively. The findings can be the evidence for stimulation of sphingomyelinase activity in the liver and skeletal muscles in rats with experimental obesity. Significant alterations in the content of sphingomyelin and its metabolites were observed in obese rats; these alterations were found to be oppositely directed. In the liver of obese rats, sphingomyelin was found to decrease by 25%; while in skeletal muscles its concentration decreased more than by 31%. Concentrations of ceramide and sphingosine in the liver of obese rats were found to increase by 15 and 23%, respectively, as compared with the controls. In skeletal muscle of obese rats, concentrations of ceramide and sphingosine increased by 19 and 68% respectively.

We have established increase in the activity of sphingomyelinase and accumulation of ceramide and sphingosine, metabolites of sphingomyelin, in the liver and skeletal muscles of rats with experimental obesity and insulin resistance. Ceramide overproduction plays a key role in the onset and development of insulin resistance.