title: Effects of cationic antimicrobial peptides on liquid-preserved boar spermatozoa.
abstract: Antibiotics are mandatory additives in semen extenders to control bacterial contamination. The worldwide increase in resistance to conventional antibiotics requires the search for alternatives not only for animal artificial insemination industries, but also for veterinary and human medicine. Cationic antimicrobial peptides are of interest as a novel class of antimicrobial additives for boar semen preservation. The present study investigated effects of two synthetic cyclic hexapeptides (c-WFW, c-WWW) and a synthetic helical magainin II amide derivative (MK5E) on boar sperm during semen storage at 16 °C for 4 days. The standard extender, Beltsville Thawing Solution (BTS) containing 250 µg/mL gentamicin (standard), was compared to combinations of BTS with each of the peptides in a split-sample procedure. Examination revealed peptide- and concentration-dependent effects on sperm integrity and motility. Negative effects were more pronounced for MK5E than in hexapeptide-supplemented samples. The cyclic hexapeptides were partly able to stimulate a linear progressive sperm movement. When using low concentrations of cyclic hexapeptides (4 µM c-WFW, 2 µM c-WWW) sperm quality was comparable to the standard extender over the course of preservation. C-WFW-supplemented boar semen resulted in normal fertility rates after AI. In order to investigate the interaction of peptides with the membrane, electron spin resonance spectroscopic measurements were performed using spin-labeled lipids. C-WWW and c-WFW reversibly immobilized an analog of phosphatidylcholine (PC), whereas MK5E caused an irreversible increase of PC mobility. These results suggest testing the antimicrobial efficiency of non-toxic concentrations of selected cyclic hexapeptides as potential candidates to supplement/replace common antibiotics in semen preservation.
authors.affiliation: Institute for Reproduction of Farm Animals Schönow Inc., Bernau, Brandenburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schulze
authors.affiliation: Leibniz Institute for Molecular Pharmacology, Berlin, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Junkes
authors.affiliation: Department of Biology, Humboldt-University Berlin, Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Mueller
authors.affiliation: Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, Leipzig, Sachsen, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Speck
authors.affiliation: Institute for Reproduction of Farm Animals Schönow Inc., Bernau, Brandenburg, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Ruediger
authors.affiliation: Leibniz Institute for Molecular Pharmacology, Berlin, Germany.
authors.forename: Margitta
authors.initials: M
authors.lastname: Dathe
authors.affiliation: Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Mueller
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D003080:Cold Temperature; D004578:Electron Spin Resonance Spectroscopy; D005079:Excipients / Q000737:chemistry / Q000494:pharmacology; D005260:Female; D007315:Insemination, Artificial; D054806:Magainins / Q000494:pharmacology*; D008297:Male; D010456:Peptides, Cyclic / Q000494:pharmacology*; D012662:Semen Preservation / Q000379:methods; D013081:Sperm Motility / Q000187:drug effects*; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology; D013552:Swine; D029867:Xenopus Proteins / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D005079:Excipients; D054806:Magainins; D010456:Peptides, Cyclic; D029867:Xenopus Proteins; C053301:magainin 2 peptide, Xenopus