Molecular aspects of declining sperm motility in older men.
OBJECTIVE
To investigate the molecular mechanism for declining sperm motility in older men.


METHODS
Retrospective and prospective study.


METHODS
University-based andrology unit.


METHODS
Semen was collected from 2,111 patients and sperm donors.


METHODS
None.


METHODS
Age, sperm concentration, ejaculate volume, sperm motility (including velocity average path, velocity straight line, velocity curvilinear, linearity, and lateral head displacement), normal sperm morphology, percentage of abnormally blue-stained flagella, and total and free T, FSH, and LH concentrations were analyzed. In addition, the zinc concentration in the seminal fluid, flagella, and the whole spermatozoa was measured by means of atomic absorption spectrometry.


RESULTS
Patient age correlated negatively with T concentration and sperm motility, including velocity, but positively with the percentage of abnormally stained flagella and the flagellar zinc. Whereas the percentage of abnormally stained flagella correlated negatively with motility and sperm velocity, there was a positive relationship with the flagellar zinc content. Flagellar zinc content was negatively correlated with motility. Testosterone showed a positive relationship with motility and sperm concentration.


CONCLUSIONS
Because the epididymis is functionally T-dependent, our data suggest that the removal of zinc from the outer dense fibers during epididymal sperm maturation is affected in aging men, which in turn will result in decreased sperm motility.
Henkel
Ralf
R
Department of Urology, Friedrich Schiller University, Jena, Germany. rhenkel@uwc.ac.za
Maass
Gesa
G
Schuppe
Hans-Christian
HC
Jung
Andreas
A
Schubert
Jörg
J
Schill
Wolf-Bernhard
WB
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies; D012661:Semen / Q000166:cytology* / Q000502:physiology*; D013081:Sperm Motility / Q000502:physiology*; D018709:Statistics, Nonparametric