Effect of GnRH (Lecirelinum) on some quality parameters of rabbit ejaculate

Abstract

The aim of this study was to evaluate the effect of two concentrations of GnRH in insemination doses on selected quality parameters of rabbits ejaculate in vitro.

Insemination doses (ID) were diluted to a concentration of 50 x 10⁶ spermatozoa in ID (0.5 ml). Subsequently ID was divided into 3 samples (control - C, experiment 1, experiment 2). Implementor GnRH (Lecirelinum – commercial product Supergestran, Ferring Pharmaceuticals, the Czech Republic) was added to experimental insemination dose samples at concentrations as follows: experiment 1 to 0.2 ml (5 mg) GnRH / ID and experiment 2 to 0.3 ml (7.5 mg) GnRH / ID. Experimental samples were compared with the control sample. For the assessment of spermatozoa motility the CASA (Computer-Assistend Sperm Analysis) system SpermVision (MiniTüb, Tiefenbach, FRG) with a microscope Olympus BX 51 (Olympus, Japan) was used. Monitored spermatozoa parameters were motility (%), progressive motility (%), velocity (μm/s), curvilinear velocity of motility (μm/s) and beat cross frequency.

In experimental samples (experiment 1, 2) increase of the spermatozoa motility values was detected in time periods of 1 and 3 hours (1 hour – C: 47.30 ± 7.99%, experiment 1: 86.39 ± 5.60%, experiment 2: 72.48 ± 3.80%, 3 hours – C: 57.09 ± 23.36%, experiment 1: 89.42 ± 2.41%, experiment 2: 63.92 ± 12.65%) and decrease over a period of 6 hours (C: 64.65 ± 8.60%, experiment 1: 35.26 ± 5.22%, experiment 2: 50.08 ± 8.27%). Progressive spermatozoa motility within time periods of 1 and 3 hours showed a similar trend as spermatozoa motility (1 hour – C: 30.50 ± 7.35%, experiment 1: 79.18 ± 6.58%, experiment 2: 59.85 ± 6.03%; 3 hours – C: 42.06 ± 22.69%, experiment 1: 82.31 ± 3.64%, experiment 2: 44.45 ± 12.01%) and decreased over a period of 6 hours (C: 56.34 ± 8.88%, experiment 1: 23.36 ± 5.95%, experiment 2: 39.07 ± 11.17%). Spermatozoa curvilinear velocity in experiment 1 reached after 1 hour 82.26 ± 4.47 μm/s, after 3 hours 68.40 ± 3.20 μm/s, after 6 hours 58.21 ± 3.89 μm/s; in experiment 2 was after 1 hour 62.00 ± 4.33 μm/s, after 3 hours 44.37 ± 9.19 μm/s and after 6 hours 52.73 ± 9.10 μm/s, in control group after 1 hour 71.86 ± 8.19 μm/s, after 3 hours 62.35 ± 7.89 μm/s and after 6 hours 73.93 ± 8.18 μm/s.

Lower concentration of the implementor (1 to 0.2 ml GnRH / ID) ​​increased level of motility, progressive motility, velocity and curvilinear velocity of motility in the time period 1 and 3 hours after GnRH implementor application compared with the control sample. In 6 hours after application only lower changes of monitored parameters has occurred. The effect of GnRH under in vivo conditions may vary significantly comparing with results obtained in vivo.