Growth hormone secretion in the horse: unusual pattern at birth and pulsatile secretion through to maturity.
Abstract: A heterologous radioimmunoassay was developed and validated for the measurement of horse GH in plasma. It utilized recombinant-derived bovine GH as the radiolabelled ligand, a guinea-pig anti-porcine GH serum as first antibody and pituitary-derived horse GH as standard. Cross-reactivities were high with all of the pituitary and recombinant-derived GH preparations tested (49-140%) and very low (< 0.3%) with horse FSH, LH and prolactin. A synthetic analogue of GH-releasing factor(1-29) stimulated the expected pattern of GH release in foals. Plasma GH concentrations in foals were low at birth (< 20 ng/ml) but rose sharply to a definite and, in most cases, very large peak (18-195 ng/ml) during the first 30-40 min post partum, followed by a steady decline to basal levels again by 60-100 min post partum. GH secretion was clearly pulsatile in all older foals tested (2 weeks, 1 month and 4 months of age) and in six adults (three mares and three stallions), all bled at 15-min intervals for 7-8 h. Basal levels and pulse amplitudes were higher in foals than in adults and pulse frequency was higher in stallions than in mares (3-5 pulses/8 h vs 1-2 pulses/8 h). Pulsatile secretion was further characterized in one mare by simultaneous sampling of jugular vein and pituitary cavernous sinus blood. Peak GH concentrations in cavernous sinus blood draining the pituitary gland were more than tenfold higher than the corresponding peak concentrations in peripheral circulation.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1993-07-01 PubMed ID: 7852896DOI: 10.1677/joe.0.1380081Google Scholar: Lookup
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- Journal Article
Summary
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The research focuses on recording and analyzing the secretion pattern of the growth hormone (GH) in horses, starting from birth and proceeding through to maturity, using a specially developed radioimmunoassay method.
Methodology and Validation
- The researchers developed a heterologous radioimmunoassay – a method used to measure the amount of a substance (in this case, GH) in plasma.
- They used recombinant bovine GH (growth hormone from cows) as the radiolabeled ligand – a substance that binds to a target molecule (the hormone being studied).
- A guinea pig anti-porcine GH serum, a substance that identifies and neutralizes growth hormone from pigs, was utilized.
- Horse GH derived from the pituitary gland was used as a standard or the baseline for measurement.
- The cross-reactivity, which refers to the degree to which different molecules react to the same antibodies, was high amongst various pituitary and recombinant-derived GH preparations, indicating a substantial degree of compatibility or similarity.
Growth Hormone Secretion Pattern in Foals and Adults
- A synthetic analogue of GH-releasing factor prompted the expected GH release in foals.
- Plasma growth hormone concentrations were low at birth but saw a significant spike within the first 30-40 minutes post-birth. This was followed by a gradual return to basal levels between 60-100 minutes after birth.
- In all the older foals and mature horses tested, GH secretion was pulsatile, meaning it followed a rhythmic, wave-like pattern. Basal levels and pulse amplitude were observed to be higher in foals compared to adults.
- The frequency of GH pulses was observed to be higher in male horses than in females.
Further Characterization
- Pulsatile secretion was further investigated in one mare by simultaneously sampling jugular vein and pituitary cavernous sinus blood.
- Peak GH levels in blood from the pituitary gland were found to be more than ten times higher than peak levels in peripheral circulation, indicating a substantial concentration of the hormone within the pituitary gland.
Cite This Article
APA
Stewart F, Goode JA, Allen WR.
(1993).
Growth hormone secretion in the horse: unusual pattern at birth and pulsatile secretion through to maturity.
J Endocrinol, 138(1), 81-89.
https://doi.org/10.1677/joe.0.1380081 Publication
Researcher Affiliations
- Thoroughbred Breeders' Association Equine Fertility Unit, Newmarket, Suffolk, U.K.
MeSH Terms
- Aging / blood
- Aging / metabolism
- Animals
- Animals, Newborn / blood
- Animals, Newborn / metabolism
- Female
- Follicle Stimulating Hormone / blood
- Growth Hormone / blood
- Growth Hormone / metabolism
- Horses / blood
- Horses / metabolism
- Luteinizing Hormone / blood
- Male
- Prolactin / blood
- Pulsatile Flow
- Radioimmunoassay
- Sexual Maturation / physiology
- Time Factors
Citations
This article has been cited 1 times.- Nacarino-Meneses C, Köhler M. Limb bone histology records birth in mammals. PLoS One 2018;13(6):e0198511.
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