title: Testosterone replacement therapy improves erythrocyte membrane lipid composition in hypogonadal men.
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of testosterone replacement therapy (TRT) on erythrocyte membrane (EM) lipid composition and physico-chemical properties in hypogonadal men.
  
  
  METHODS
  EM isolated from three patients before and after TRT with injectable testosterone undecanoate or testosterone gel were used for analysis of the phospholipid and fatty acid composition, cholesterol/phospholipid ratio, membrane fluidity, ceramide level and enzyme activities responsible for sphingomyelin metabolism.
  
  
  RESULTS
  TRT induced increase of phosphatidylethanolamine (PE) in the EMs and sphingomyelin. Reduction of the relative content of the saturated palmitic and stearic fatty acids and a slight increase of different unsaturated fatty acids was observed in phosphatidylcholine (PC). TRT also induced decrease of the cholesterol/total phospholipids ratio and fluidization of the EM.
  
  
  CONCLUSIONS
  The TRT induced increase of PE content and the reduction of saturation in the PC acyl chains induced alterations in the structure of EM could result in higher flexibility of the erythrocytes. The increase of the SM-metabolizing enzyme neutral sphingomyelinase, which regulates the content of ceramide in membranes has a possible impact on the SM signaling pathway.
  
  
  CONCLUSIONS
  We presume that the observed effect of TRT on the composition and fluidity of the EM contributes for improvement of blood rheology and may diminish the thrombosis risk. Larger studies are needed to confirm the findings of this pilot study.
authors: Clinic of Endocrinology, Alexandrovska University Hospital, Medical University - Sofia, Sofia, Bulgaria.
authors: Petya
authors: P
authors: Angelova
authors: Albena
authors: A
authors: Momchilova
authors: Diana
authors: D
authors: Petkova
authors: Galya
authors: G
authors: Staneva
authors: Roumen
authors: R
authors: Pankov
authors: Zdravko
authors: Z
authors: Kamenov
mesh_terms: D000328:Adult; D002518:Ceramides / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000737:chemistry* / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007006:Hypogonadism / Q000188:drug therapy* / Q000503:physiopathology; D050356:Lipid Metabolism / Q000187:drug effects*; D008297:Male; D008560:Membrane Fluidity / Q000187:drug effects; D008875:Middle Aged; D010714:Phosphatidylethanolamines / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism; D013739:Testosterone / Q000031:analogs & derivatives / Q000627:therapeutic use*; D013927:Thrombosis / Q000517:prevention & control
chemical_list: D002518:Ceramides; D010714:Phosphatidylethanolamines; D013109:Sphingomyelins; C483858:phosphatidylethanolamine; D013739:Testosterone; C010792:testosterone undecanoate