Laurdan fluorescence: a simple method to evaluate sperm plasma membrane alterations.
OBJECTIVE
To determine, by a simple fluorescence method, sperm plasma membrane alterations related with changes of lipid bilayer that, together with routine semen analysis, could help to elucidate the causes of the unexplained male infertility problems.


METHODS
Pilot study.


METHODS
Andrology laboratory and biochemistry institute, medical school.


METHODS
Men whose semen was studied for infertility problems.


METHODS
No therapeutic intervention was performed on patients.


METHODS
Presence of spermatozoa plasma membrane alterations evidenced by evaluation of Laurdan fluorescence Generalized Polarization (GP) and reported as a function of increasing cell concentration, spermatozoa total motility, linear speed, and vitality.


RESULTS
Reporting GP values as a function of increasing sperm cell concentration, it is evident that the samples are distributed in two distinct areas: at >32 x 10(6) cells per milliliter, mean GP value was 0.303 +/- 0.015, whereas for lower sperm cell concentrations, the mean GP was 0.365 +/- 0.026 (P<.001). These data indicate that the spermatozoa plasma membranes are characterized by liquid-crystalline phases with different ordering degree and polarity and that about 50% of samples with normal semen characteristics (> or =20 x 10(6) cells per milliliter) show high GP values.


CONCLUSIONS
Laurdan fluorescence can be used as a simple method to evaluate spermatozoa plasma membrane alterations, particularly in a group of infertile men presenting normal semen parameters. In these samples, Laurdan could be used as a simple tool for infertility assessment. In fact, it is known that compositional and physicochemical alterations of bilayer features can be important for the fertilizing ability of spermatozoa because they are necessary for a proper physiological membrane activity.
Ambrosini
A
A
Institute of Biochemistry, Medical School, University of Ancona, Ancona, Italy. zolese@popsci.unian.it
Zolese
G
G
Balercia
G
G
Bertoli
E
E
Arnaldi
G
G
Mantero
F
F
D015081:2-Naphthylamine / Q000031:analogs & derivatives*; D000328:Adult; D002462:Cell Membrane / Q000648:ultrastructure*; D005456:Fluorescent Dyes; D006801:Humans; D007248:Infertility, Male / Q000473:pathology / Q000503:physiopathology*; D007848:Laurates; D008051:Lipid Bilayers; D008297:Male; D010865:Pilot Projects; D013050:Spectrometry, Fluorescence / Q000379:methods; D013076:Sperm Count; D013081:Sperm Motility; D013094:Spermatozoa / Q000648:ultrastructure*
D005456:Fluorescent Dyes; D007848:Laurates; D008051:Lipid Bilayers; D015081:2-Naphthylamine; C065580:laurdan