Effects of implants containing the GnRH agonist deslorelin on testosterone release and semen characteristics in Shetland stallions.

The research aims to study the effects of deslorelin implants on testosterone release and semen characteristics in stallions. It illustrates how different doses of the GnRH agonist deslorelin affect the pituitary functions and reproductive parameters of the stallions.

Research Overview

• The study is founded on the hypothesis that continuous treatment of stallions with GnRH agonist deslorelin suppresses reproductive functions. The research involves a 2-week pre-experimental period followed by an 11-week treatment period using deslorelin implants.
• The investigation involves three groups of stallions. Group D1 received 4.7 mg of deslorelin, Group D2 received 18.8 mg, while Group C remained untreated as control.
• A range of reproductive parameters, including libido, plasma testosterone, sperm motility, sperm count, membrane integrity, DNA fragmentation, and Anti Muellerian hormone (AMH) concentrations, were extensively monitored and evaluated over the treatment period.

Research Findings

• Results reveal that deslorelin reduces pituitary responsiveness to GnRH. However, this happens only with a larger dose of deslorelin (18.8 mg) and the effect lasts for several weeks.
• All groups of stallions responded to hCG with testosterone release at both times of hCG administration.
• All groups had similar concentrations of AMH. The total sperm count significantly increased only in group D2 stallions, but not in groups D1 and C.
• The D2 group also exhibited a transient decrease in the percentage of ESR1-positive spermatozoa. Interestingly, there were no significant differences among the groups in terms of the percentage of motile and membrane-intact spermatozoa, and sperm with DNA fragmentation.

Conclusion

• The research concludes that deslorelin implants do modulate pituitary function in stallions, but the extent of its effects doesn’t significantly impact testicular function. Therefore, it suggests that the use of deslorelin as a GnRH agonist doesn’t significantly inhibit the reproduction functions of stallions.