Cyclic nucleotide phosphodiesterase inhibition increases tyrosine phosphorylation and hyper motility in normal and pathological human spermatozoa

Biocell. 2005 Dec;29(3):287-93.


Our objective was to determine the effect of phosphodiesterase (PDE) inhibition on: 1) tyrosine phosphorylation of human spermatozoa at the tail level; and 2) sperm motion parameters and hyperactivated motility. The study was conducted with normozoospermic and asthenozoospermic samples incubated under in vitro capacitating conditions. The main outcome measures were computer-assisted sperm motion analysis and fluorescent immunodetection of phosphotyrosine-containing proteins. Pentoxifylline (PTX) was used as PDE inhibitor because of its wide use in the clinic. PTX-treatment significantly increased sperm velocity, hyperactivated motility and tyrosine-phosphorylation, both in normo and asthenozoospermic samples. Tyrosine-phosphorylation of tail proteins was highly conspicuous in both types of samples, showing no differential pattern after PTX-treatment. Normozoospermic samples treated with pentoxifylline showed an increase in the number of spermatozoa displaying hyperactivated movement and tyrosine-phosphorylation at the tail level. Preliminary data on asthenozoospermic samples exhibiting altered motion characteristics and defective phosphorylation of sperm-tail proteins showed that both defects can be concomitantly overcome by pentoxifylline treatment. Tyrosine-phosphorylation of sperm-tail proteins is underlying the enhancement of hyperactivated motility resulting from PDE inhibition by pentoxifylline.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Fluorescent Antibody Technique, Indirect
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Pentoxifylline / pharmacology*
  • Phosphodiesterase Inhibitors / pharmacology*
  • Phosphorylation / drug effects
  • Sperm Motility / drug effects*
  • Sperm Tail / drug effects
  • Spermatozoa / drug effects
  • Spermatozoa / metabolism*
  • Spermatozoa / pathology
  • Tyrosine / metabolism*


  • Phosphodiesterase Inhibitors
  • Tyrosine
  • Pentoxifylline