Release of LH, FSH and GnRH into pituitary venous blood in mares treated with a PGF analogue, luprostiol, during the transition period.
Abstract: Nine mares received cannulae to collect blood from the pituitary venous outflow in the intercavernous sinus (ICS) and the jugular vein; in 4 mares, only jugular cannulae were used. Those 4 mares and 3 of the mares with cannulae in both positions received 7.5 mg luprostiol i.m. and 1 mare with both cannulae was treated with 3.75 mg uprostiol i.v. Blood samples were kept before and after treatment at 2-, 5- or 10-min intervals and concentrations of LH, FSH and GnRH were determined by RIA. Treatments resulted in an immediate sharp rise of LH and FSH in ICS and jugular blood samples within 2-10 min, with ICS concentrations rising earlier, and with peak levels of LH 8 to 100 times higher, respectively. In ICS samples, GnRH was elevated consistently only after LH and FSH had reached peak levels. At both locations, LH and FSH concentrations remained elevated 60-120 min after treatment, but had returned to baseline by 240 min. In 5 untreated mares with cannulae at both locations, sampling at 5-min intervals for 12 or 24h revealed no pulses of LH or FSH in 3 mares, and only one pulse a day, preceded by several small rises of GnRH during the hour before the pulses, in 2 mares.
Publication Date: 1987-01-01 PubMed ID: 3119828
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- Journal Article
Summary
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The study investigated the release of hormones LH, FSH, and GnRH in horses after being treated with the drug luprostiol. Through a series of blood samples taken at varying intervals, treatment was found to increase hormone levels, with certain hormones peaking before others.
Methodology
- The study was conducted on 9 horses. Some were fitted with cannulae (tubes insertable into the body) in two positions – the intercavernous sinus (in the pituitary gland area) and the jugular vein, while others only had jugular cannulae.
- Four of the horses with only jugular cannulae and three with cannula in both positions were given 7.5 mg of luprostiol through intramuscular injection. One horse fitted with cannulae in both positions received a 3.75 mg luprostiol intravenous dosage.
- Blood samples were collected before and after treatment at varying intervals (2-, 5- or 10-minutes) to analyze the concentration of the hormones LH, FSH, and GnRH.
Findings
- The treatment caused an immediate and significant increase of LH and FSH hormones in both ICS and jugular blood samples within 2-10 minutes.
- The hormone peaks in the ICS samples occurred earlier and showed up to 100 times higher levels of LH.
- GnRH levels in the ICS samples only consistently increased after LH and FSH had reached their peak levels.
- In both types of samples, elevated levels of LH and FSH were present for 60-120 minutes after treatment, but returned to their baseline levels by 240 minutes.
- In control group of untouched horses, continuous sampling revealed no pulses of LH or FSH in 3 individuals, and only one pulse, which was preceded by small rises of GnRH, per day in 2 horses.
Conclusion
- This study provides evidence of a rapid hormonal response in horses, specifically an increase in LH, FSH, and GnRH levels, following treatment with the drug luprostiol. The varying onset and duration of these peaks suggest differential timing in the hormonal response.
- These findings could have implications on biomedical applications involving the regulation of these hormones in horses, potentially leading to more effective treatment strategies and understanding of horse physiology.
Cite This Article
APA
Jöchle W, Irvine CH, Alexander SL, Newby TJ.
(1987).
Release of LH, FSH and GnRH into pituitary venous blood in mares treated with a PGF analogue, luprostiol, during the transition period.
J Reprod Fertil Suppl, 35, 261-267.
Publication
Researcher Affiliations
- Lincoln College, Canterbury, New Zealand.
MeSH Terms
- Animals
- Estrus
- Female
- Follicle Stimulating Hormone / blood
- Horses / blood
- Jugular Veins / analysis
- Luteinizing Hormone / blood
- Pituitary Gland / blood supply
- Pituitary Gland / drug effects
- Pituitary Gland / metabolism
- Pituitary Hormone-Releasing Hormones / blood
- Prostaglandins F, Synthetic / pharmacology
Citations
This article has been cited 3 times.- Salem SE, Sinnott A, Roach JM, Verheyen KLP, de Mestre AM. Mixed-Effects Modelling of the Risk Factors Associated with Multiple Pregnancies in Thoroughbred Mares.. Animals (Basel) 2022 Jul 20;12(14).
- Bottrel M, Ortiz I, Hidalgo M, Díaz-Jiménez M, Pereira B, Consuegra C, Yousef MS, Dorado J. Hormonal Management for the Induction of Luteolysis and Ovulation in Andalusian Jennies: Effect on Reproductive Performance, Embryo Quality and Recovery Rate.. Animals (Basel) 2022 Jan 8;12(2).
- Midgley AR Jr, McFadden K, Ghazzi M, Karsch FJ, Brown MB, Mauger DT, Padmanabhan V. Nonclassical secretory dynamics of LH revealed by hypothalamo-hypophyseal portal sampling of sheep.. Endocrine 1997 Apr;6(2):133-43.
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