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This study comprises 3 experiments exploring the possible benefits and mechanism of action of liposomes for chilling (4°C) canine sperm over a period of 4 days. In the first experiment, 20 ejaculates collected from 5 Beagle dogs were chilled in an extender containing 6% low density lipoproteins (LDL) (Control), or one of 7 extenders containing different concentrations (2, 4, 6, 8, 10, 15, 20%) of liposomes (LIPO). These ejaculates were chilled over 4 days and motility was assessed daily using a Hamilton Thorne analyzer (HTM-IVOS, 14.0). The 2% LIPO obtained the best results (p=0.038) after four days (72.55% motile spermatozoa and 31.4% progressive spermatozoa). In experiment 2, 10 ejaculates were collected from same 5 dogs and chilled in 6% LDL or 2% LIPO-based extenders. Sperm integrity characteristics were assessed prior to refrigeration and every 48h for four days (D0, D2, and D4). Acrosome integrity was assessed using the FITC-PSA test (Fluorescein IsoThiocyanate-Pisum Sativum Agglutinin), plasma membrane (PM) integrity using both the hypo-osmotic swelling test (HOSt) and SYBR14/Propidium Iodide test (SYBR14/PI), and DNA integrity using the Acridine-Orange test (AO). The 2% LIPO extender provided equivalent preservation of sperm integrity parameters to the reference extender (6% LDL). In experiment 3, a Langmuir-Blodgett trough was used to evaluate the mechanistic interactions between LDL, LIPO, prostatic fluid, and the canine spermatozoal membrane during chilling. Results indicate that LDL and LIPO interact differently with the biomimetic membrane. The most likely conclusion of these findings is that LDL and liposomes employ different protective mechanisms during the chilling (4°C) of canine spermatozoa., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The aim of the present study was to evaluate the effect of glutamine on the motility parameters after thawing of epididymal semen of Barb stallions. Semen samples were collected from 22 testicles of slaughtered Barb stallions by retrograde flushing technique. Semen samples were aliquoted and diluted with the following extenders, (1) base medium (BM) (INRA96®+2.5%glycerol+2% egg yolk); (2) BM+25mM Glutamine (C25); (3) BM+50mM Glutamine (C50); (4) BM+75mM Glutamine (C75) and (5) BM+100mM Glutamine (C100). The assessment of Kinematic parameters was established after thawing by using SPA® spain CASA (Computer Automated Sperm Analyzer); and the plasma membrane functional integrity was analyzed by HOST test. At low concentrations, the presence of glutamine (C25 and C50) improved significantly (p<0.05) the kinematics variables (VSL, VAP, LIN and STR). However, higher concentrations of glutamine (C75 and especially C100) significantly decreased the movement of thawed semen. In conclusion, these observations are showing a beneficial effect of glutamine on sperm kinematics at low concentrations and indicated a toxic effect at high concentrations, although, no differences were observed in terms of HOST integrity. [ABSTRACT FROM AUTHOR]