title: Papain and its inhibitor E-64 reduce camelid semen viscosity without impairing sperm function and improve post-thaw motility rates.
abstract: In camelids, the development of assisted reproductive technologies is impaired by the viscous nature of the semen. The protease papain has shown promise in reducing viscosity, although its effect on sperm integrity is unknown. The present study determined the optimal papain concentration and exposure time to reduce seminal plasma viscosity and investigated the effect of papain and its inhibitor E-64 on sperm function and cryopreservation in alpacas. Papain (0.1mg mL-1, 20min, 37°C) eliminated alpaca semen viscosity while maintaining sperm motility, viability, acrosome integrity and DNA integrity. Furthermore E-64 (10 µM at 37°C for 5min after 20min papain) inhibited the papain without impairing sperm function. Cryopreserved, papain-treated alpaca spermatozoa exhibited higher total motility rates after chilling and 0 and 1h after thawing compared with control (untreated) samples. Papain treatment, followed by inhibition of papain with E-64, is effective in reducing alpaca seminal plasma viscosity without impairing sperm integrity and improves post-thaw motility rates of cryopreserved alpaca spermatozoa. The use of the combination of papain and E-64 to eliminate the viscous component of camelid semen may aid the development of assisted reproductive technologies in camelids.
authors.affiliation: Department of Animal Production, Welfare and Veterinary Sciences, Harper Adams University, Newport, Shropshire TF10 8NB, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Kershaw
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camperdown, Sydney, NSW 2006 Australia.
authors.forename: G
authors.initials: G
authors.lastname: Evans
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camperdown, Sydney, NSW 2006 Australia.
authors.forename: R
authors.initials: R
authors.lastname: Rodney
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camperdown, Sydney, NSW 2006 Australia.
authors.forename: W M C
authors.initials: WMC
authors.lastname: Maxwell
mesh_terms: D020101:Acrosome Reaction / Q000187:drug effects; D000818:Animals; D002161:Camelids, New World; D002470:Cell Survival / Q000187:drug effects; D015925:Cryopreservation / Q000662:veterinary; D015853:Cysteine Proteinase Inhibitors / Q000009:adverse effects / Q000494:pharmacology*; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D005632:Fructose / Q000737:chemistry / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D007700:Kinetics; D007785:Lactose / Q000737:chemistry / Q000378:metabolism; D007930:Leucine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D009517:New South Wales; D010206:Papain / Q000009:adverse effects / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012661:Semen / Q000187:drug effects* / Q000502:physiology; D055101:Semen Analysis / Q000662:veterinary; D012662:Semen Preservation / Q000662:veterinary; D013081:Sperm Motility / Q000187:drug effects*; D014783:Viscosity / Q000187:drug effects
chemical_list: D015853:Cysteine Proteinase Inhibitors; D005632:Fructose; D004247:DNA; D010206:Papain; D007930:Leucine; D007785:Lactose; C024974:E 64