Enhanced lysophosphatidylcholine and sphingomyelin contents are characteristic of spermatozoa from obese men—A MALDI mass spectrometric study

The lipids of human spermatozoa are characterized by unique fatty acyl compositions, i.e. considerable amounts of highly unsaturated, in particular docosahexaenoyl (22:6) fatty acyl residues. This makes spermatozoa very sensitive to oxidation. It has already been shown that the most abundant lipid of sperm, phosphatidylcholine (PC), is converted into lysophosphatidylcholine (LPC) under conditions of oxidative stress, and, thus, the PC/LPC ratio may be used as a measure of sperm quality. However, direct correlations between the PC/LPC ratios and certain pathologies are so far missing. We will show here for the first time (by using matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry (MS)) that sperm from obese donors (BMI>35kg/m2) are characterized by (a) a significantly increased LPC as well as (b) an increased sphingomyelin content. This does exclusively hold true for the lipid extracts of the spermatozoa but is not valid for the related seminal fluids.