Membrane fluidity and lipid content of human spermatozoa selected by swim-up method

• Published in: International journal of andrology Vol. 24; no. 6; pp. 327 - 334
• Main Authors: FORCE, A, GRIZARD, G, GIRAUD, M. N, MOTTA, C, SION, B, BOUCHER, D
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell 01.12.2001
• Subjects: Biological and medical sciences; Chromatography, High Pressure Liquid; Creatine Kinase - metabolism; Fundamental and applied biological sciences. Psychology; Humans; Male; Mammalian male genital system; Membrane Fluidity; Membrane Lipids - metabolism; Morphology. Physiology; Spectrometry, Fluorescence; Spermatozoa - enzymology; Spermatozoa - metabolism; Spermatozoa - physiology; Vertebrates: reproduction; Human; Spermatozoa; Fluidity; Plasma membrane; Phospholipid; Lipids; Germinal cell; Cholesterol
• ISSN: 0105-6263; 1365-2605
• DOI: 10.1046/j.1365-2605.2001.00309.x

In this work, we examined whether spermatozoa (spz) from normospermic fertile patients and selected by a swim-up (S-U) procedure had a particular membrane fluidity related to their maturity and their lipid content as compared with the sperm cells from the whole ejaculate (total sperm). Swim-up selected sperm had a reduced cytoplasmic space as revealed by a lower creatine kinase (CK) activity compared with total sperm (2 +/- 1 vs. 12 +/- 5 mUI/10(7) spz, p < 0.05). The cholesterol (Chol) and total phospholipid (PL) contents were significantly lower in S-U selected sperm than in total sperm (0.72 +/- 0.08 vs. 1.20 +/- 0.30 nmol/10(6) spz for Chol and 1.77 +/- 0.17 vs. 2.78 +/- 0.50 nmol/10(6) spz for PL, p < 0.05) and such a decrease was observed for the three major membrane PL: phosphatidylethanolamine (PE), phosphatidylcholine (PC) and sphingomyelin (SM). However, these decreases were not associated with a change in either Chol/PL or PC/(PC + PE) molar ratios. Membrane fluidity estimated by fluorescence polarization remained comparable between the S-U sperm fraction and total sperm (fluorescence polarization anisotropy, r, which is inversely proportional to the fluidity: 0.235 +/- 0.006 vs. 0.230 +/- 0.005). The sperm membrane fluidity obtained in normospermic patients was compared with abnormospermic ones (oligoasthenoteratospermia). In abnormospermic patients, the membrane fluidity was decreased in migrated spermatozoa compared with total sperm (anisotropy: 0.210 +/- 0.010 vs. 0.250 +/- 0.013, p < 0.01). Our data suggest that the S-U method selected a subpopulation of mature spermatozoa characterised by a low content of Chol and PL, likely related to a reduced membrane area. The fact that Chol/PL and PC/(PC + PE) molar ratios were unchanged shows a maintenance of the membrane quality. This was confirmed by the fluorescence anisotropy measurement showing no difference in plasma membrane fluidity between S-U selected sperm and total sperm. In abnormal semen the migrated spermatozoa had a lower fluidity compared with total sperm suggesting a defective sperm function. These results bring new elements characterizing the S-U selected spermatozoa.