Quantitative determination of erythrocyte o-alkyl / o-alk-1-enyl glycerolipid ratios in human sleep disorders by thin-layer chromatography

Aim: Previous studies indicate that sleep restriction causes alterations in circadian rhythm which is associated with metabolic diseases such as obesity and diabetes. Some plasma lipids exhibiting circadian oscillation were reported to display alterations caused by sleep restriction. However it is currently not clear how sleep disorder related alterations in circadian rhythm influences peroxisomal lipid metabolism. To this end comparison of erythrocyte alkyl-/alkenyl glycerolipid ratios between subjects with and without sleep disorders were made. Material and Method: Blood samples were obtained from 30 healthy and 30 subjects diagnosed as having sleep apnea associated sleep disorders. The separation of erythrocyte alkyl-/alkenyl-glycerolipids was conducted by t.l.c. Alkyl-/alkenyl-glycerolipid ratios were determined photodensitometrically. Results: Comparison of alkyl-/alkenyl glycerolipid ratios in erythrocytes of healthy controls and subjects with sleep disorders yielded no statistically significant differences. However, though insignificant, the glycerolipid ratios in erythrocytes was found to be lower in sleep disorder affected subjects compared to controls. It was considered that this could be attributed to an increase in the percentage of alkenyl glycerolipids due to sleep disorders. Conclusion: The current results warrants reinvestigation of erythrocyte alkyl-/ alkenyl-glycerolipid ratios in subjects with sleep apnea affected subjects since we believe that individual variations in lipid parameters under circadian control could obscures the possible link between the peroxisomal lipids of erythrocytes and sleep apnea realted sleep disorders. In order to overcome this we suggest that samples of the same indiviual before and after the treatment of apnea should be compared. Key Words: Circadian rhythm, Sleep disorders, Plasmalogen, Peroxisome, Thin Layer Chromatography