Effect of GnRH and hCG administration on plasma LH and testosterone concentrations in normal stallions, aged stallions and stallions with lack of libido.
Abstract: Gonadotrophin-releasing hormone (GnRH) (a single intravenous injection with 0.042 mg busereline acetate) was administered to control stallions (n=5), aged stallions (n=5) and stallions with lack of libido (n=5). Jugular blood samples were taken at -10, 0, 10, 20, 40 and 80 minutes after treatment and measured for luteinizing hormone (LH) and testosterone concentrations. A single intravenous injection of hCG (3000 IE) was given 1 day later. Venous blood samples were taken at -60, 0, 15, 30, 60, 120, and 240 minutes after treatment and measured for the testosterone concentration. The experiment was performed in the breeding season. There was a wide variation between stallions in basal concentrations of LH and testosterone. The treatment groups all showed a significant increase in LH and testosterone concentrations after treatment with GnRH. There was a significant difference (P<0.05) between the control, the lack of libido stallions and the aged stallions in the production of LH before and after stimulation with GnRH. The aged stallions had higher basal LH concentrations. GnRH induced a rise in plasma LH in all groups, but the greatest response was observed in aged stallions. No response to GnRH was seen with respect to plasma testosterone. There was an increase in plasma testosterone following hCG; however, this increase was very small in aged stallions. After stimulation with hCG the control and lack of libido stallions had a significant increase (P<0.05) in testosterone production. In conclusion, stimulation with either GnRH or hCG can be a valuable method to test whether the function of the stallion's reproductive endocrine system is optimal.
Publication Date: 2001-05-22 PubMed ID: 11361105DOI: 10.1080/01652176.2001.9695088Google Scholar: Lookup
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- Journal Article
Summary
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This research focuses on the influence of Gonadotrophin-releasing hormone (GnRH) and human chorionic gonadotropin (hCG) on the levels of luteinizing hormone (LH) and testosterone in healthy, aged and libido-lacking stallions. The study found differences in hormonal responses across these groups, suggesting GnRH or hCG may serve as a test for evaluating the functioning of a stallion’s reproductive endocrine system.
Methodology
- A total of 15 stallions were divided into three groups: control stallions (n=5), aged stallions (n=5), and stallions with a lack of libido (n=5).
- Each stallion received a single intravenous injection of GnRH. Blood samples from the jugular vein were then collected at specified intervals post-treatment and analyzed for LH and testosterone levels.
- One day following the GnRH injection, each stallion received an intravenous injection of hCG. Again, blood samples were collected at specific time points post-injection and examined for testosterone concentration.
Findings and Observations
- There were notable differences among the stallions in pre-treatment levels of LH and testosterone.
- All groups showed an increase in LH and testosterone concentrations after the injection of GnRH. However, the aged stallions showed a better response with higher LH levels.
- There was no observed increase in plasma testosterone levels in response to GnRH.
- Following the injection of hCG, there was a slight increase in plasma testosterone levels, particularly in the control and libido-lack group. The testosterone increase was least in aged stallions.
Conclusions
- The results suggest that there are noticeable differences in the endocrine response of control, aged, and libido-lacking stallions to injections of GnRH and hCG.
- The results support the use of GnRH or hCG treatment as a potential method for assessing the extent of functionality of the reproductive endocrine system in stallions.
Cite This Article
APA
Parlevliet JM, Bevers MM, van de Broek J, Colenbrander B.
(2001).
Effect of GnRH and hCG administration on plasma LH and testosterone concentrations in normal stallions, aged stallions and stallions with lack of libido.
Vet Q, 23(2), 84-87.
https://doi.org/10.1080/01652176.2001.9695088 Publication
Researcher Affiliations
- Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
MeSH Terms
- Aging / blood
- Aging / physiology
- Animals
- Chorionic Gonadotropin / administration & dosage
- Chorionic Gonadotropin / pharmacology
- Gonadal Steroid Hormones
- Gonadotropin-Releasing Hormone / administration & dosage
- Gonadotropin-Releasing Hormone / pharmacology
- Horses / blood
- Horses / physiology
- Kinetics
- Libido
- Luteinizing Hormone / blood
- Male
- Sexual Behavior, Animal / drug effects
- Testosterone / blood
Citations
This article has been cited 2 times.- Toishi Y, Tsunoda N, Nagata SI, Kirisawa R, Nagaoka K, Watanabe G, Yanagawa Y, Katagiri S, Taya K. Evaluation of the chemiluminescent enzyme immunoassay system for the measurement of testosterone in the serum and whole blood of stallions.. J Reprod Dev 2018 Feb 27;64(1):41-47.
- Samir H, Sasaki K, Ahmed E, Karen A, Nagaoka K, El Sayed M, Taya K, Watanabe G. Effect of a single injection of gonadotropin-releasing hormone (GnRH) and human chorionic gonadotropin (hCG) on testicular blood flow measured by color doppler ultrasonography in male Shiba goats.. J Vet Med Sci 2015 May;77(5):549-56.
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