The Effects of Bovine Recombinant Growth Hormone Administration on Insulin-like Growth Factor-I and the Haemopoietic System in Thoroughbred Geldings (original) (raw)
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Blood plasma concentrations of insulin-like growth factor-I (IGF-I) in resting standardbred horses
Veterinary journal (London, England : 1997), 2002
A survey of standardbred horses was conducted to build up a normal population profile for insulin like growth factor-I (IGF-I) concentrations in racing standardbreds and to ascertain how age, sex and geographic location affect IGF-I. Blood samples were drawn by jugular venepuncture from 202 racing standardbred horses aged one to eight years located in five different geographic regions of New Zealand. IGF-I concentrations were determined by insulin like growth factor-I binding protein (IGFBP)-blocked radioimmunoassay validated for the horse. As described in other species, age played a significant (P<0.05) role in IGF-I concentrations with the highest concentrations occurring in the younger horses. There was a significant (P<0.05) sex effect, intact males having significantly higher IGF-I concentrations compared of mares and/or geldings. Geographic location had a significant (P<0.05) influence on IGF-I. A significant (P<0.05) trainer effect also was noted both within and b...
Comparison and validation of ELISA assays for plasma insulin-like growth factor-1 in the horse
Open Veterinary Journal
Insulin-like growth factor-1 (IGF-1) plays several important physiological roles, and IGF-related pathways have been implicated in developmental osteochondral disease and endocrinopathic laminitis. This factor is also a downstream marker of growth hormone activity and its peptide mimetics. Unfortunately, previously used assays for measuring equine IGF-1 (radioimmunoassays and ELISAs) are no longer commercially available, and many of the kits on the market give poor results when used on horse samples. The aim of the present study was to compare three different ELISA assays (two human and one horse-specific). Plasma samples from six Standardbreds, six ponies and six Andalusians were used. The human IGF-1 ELISA kit from Immunodiagnostic Systems (IDS) proved to be the most accurate and precise of the three kits; the other two assays gave apparently much lower concentrations, with poor recovery of spiked recombinant human IGF-1 and unacceptably poor intra-assay coefficients of variation (CV). The IDS assay gave an intra-assay CV of 3.59 % and inter-assay CV of 7.31%. Mean percentage recovery of spiked IGF-1 was 88.82%, and linearity and dilutional parallelism were satisfied. The IGF-1 plasma concentrations were 123.21 ±8.24 ng/mL for Standardbreds, 124.95 ±3.69 ng/mL for Andalusians and 174.26 ±1.94 ng/mL for ponies. Therefore of the three assays assessed, the IGF-1 ELISA manufactured by IDS was the most suitable for use with equine plasma samples and may have many useful applications in several different research areas. However, caution should be used when comparing equine studies where different analytical techniques and assays may have been used to measure this growth factor.
Insulin-like growth factor I in growing thoroughbreds
Journal of Animal Physiology and Animal Nutrition, 2007
Growth rate is regulated mainly by the somatotropic axis, a major component in the chemical communication network that links metabolism to nutrient intakes (Le Roith et al., 2001; Yakar et al., 2002). Principle components in the somatotropic axis are insulin, growth hormone (GH) and insulin-like growth factor I (IGF-I). Circulating IGF-I is an especially important, but broadly acting, regulatory factor in skeletal development (Yakar et al., 2002), and healthy skeletal development an important objective for those raising equine athletes. Previous research efforts have examined plasma IGF-I in relation to diet, dam parity, weaning and age (Cymbaluk and Laarveld, 1996; Malinowski et al., 1996; Ropp et al., 2003). Nutrition and environment influence circulating IGF-I, although variable results require careful attention to differences in experimental constraints and applicability of the results (Ketelslegers et al., 1995; Cymbaluk and Laarveld, 1996). The role of the somatotropic axis in facilitating physiological changes in response to the environment has been studied in other species (Sarko et al., 1994; Owens et al., 1999; Lincoln et al., 2001; Gabillard et al., 2003), but similar data for the horse are incomplete and its application unclear. We hypothesize that meals that result in glycaemic and insulinaemic responses significantly greater than
Journal of Endocrinology, 1993
Tissue and plasma levels of insulin-like growth factor-I (IGF-I), and relative levels of liver IGF-I RNA, were measured in 6-month-old ewe lambs which were well fed (n = 10) or starved (n = 10) for 5 days. Half of each nutrition group was given daily (09.00 h) injections of human GH (hGH; 0·15 mg/kg body weight per day). Blood was sampled daily from 09.00 to 12.00 h at 15-min intervals through jugular vein catheters and the lambs were slaughtered 24 h after the fifth injection of hGH. Tissue and plasma IGF-I was extracted using an acid-ethanol-cryo-precipitation technique and estimated by radioimmunoassay. Tissue IGF-I was corrected for retained plasma IGF-I using tissue and blood haemaglobin levels. Liver IGF-I RNA levels were monitored by in-situ hybridization. Plasma IGF-I (nmol/l) was higher in both the fed group and the fed group given GH treatment. Tissue IGF-I from kidneys (nmol/kg) was also higher (P < 0·001) in the fed group. There was no significant difference in IGF-I ...
Reproduction Nutrition Development, 1996
― Plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I) levels were determined in Large White (LW) and Meishan (MS) female pigs at 80 and 185 days of age before and after an infusion of porcine GH. Plasma GH concentration declined with age and was similar in both breeds. Plasma IGF-I concentration did not differ between MS and LW pigs at 80 days of age. It increased with age in LW pigs whereas it remained almost unchanged in MS pigs. GH infusion led to an increase in plasma GH concentration and elicited a rapid and persistent rise in plasma IGF-I levels in both breeds. IGF-I response to GH was lower in LW than in MS pigs at 80 days, whereas the reverse was observed at 185 days of age. It increased with age in LW while it declined in MS pigs. The present results suggest the development of a GH resistance in MS pigs. This is likely associated with sexual maturity. Whether such GH resistance would also be observed in postpubertal LW female pigs remains to be investigated. pig / breed / GH / IGF-I Résumé ― Effet d'une perfusion d'hormone de croissance (GH) sur l'IGF-I (insulin-like growth factor-1) dans le plasma de porcs Large White et Meishan. Les niveaux de GH et d'IGF I ont été déterminés à 80 et à 185 jours d'âge dans le plasma de porcs femelles de race Large White (LW) et Meishan (MS). La concentration plasmatique de GH diminue avec l'âge et elle est similaire chez les porcs LW et MS. La concentration plasmatique d'IGF-I ne diffère pas entre les porcs LW et MS à 80 jours dâge. En revanche, alors que cette concentration augmente avec l'âge chez les porcs LW, elle reste inchangée chez les porcs MS. La perfusion de GH conduit à une augmentation de la concentration plasmatique de GH et à une augmentation rapide et persistante des niveaux plasmatiques d'IGF dans les deux races. Néanmoins, à 80 jours d âge, I augmentation de l'IGF-I est plus faible chez les porcs LW que chez les porcs MS et, à 185 jours dâge, l'inverse est observé. Ces résultats suggèrent le développement avec l'âge d'un état de résistance à la GH chez les porcs MS, qui est probablement en liaison avec la maturation sexuelle. Il reste à déterminer si une telle résistance à la GH serait également observable chez les porcs femelles de race LW après la puberté. porc l race / GH / IGF I
Journal of Equine Science
Plasma concentrations of immunoreactive (ir-) insulin-like growth factor I (IGF-I) were measured in 9 pregnant mares from 30 days before foaling to Day 7 after ovulation of the first post-partum estrus (foal heat) in order to characterize its pattern and investigate its possible role in mares during that time. A marked increase in plasma concentrations of ir-IGF-I was observed during the last month of pregnancy. After foaling, ir-IGF-I sustained its high concentration for the first week after parturition and it gradually decreased thereafter. Throughout the observation period of the current study, a significant positive correlation between ir-IGF-I and FSH (r=0.58, p<0.05) was found. The significant increase in ir-IGF-I and FSH shortly prior to parturition may be responsible for the rapid resumption of ovarian activity in mares and the initiation of foal heat in thoroughbred mares. Statistically significant positive correlation between ir-IGF-I, FSH and ir-inhibin levels observed in the current study confirm the previous suggestion that ir-inhibin secreted during late pregnancy in mares may be biologically inactive.
Relationship between blood plasma IGF-1 and GH concentrations and growth of Holstein steers
… de Producción Animal, 2011
Insulin-like growth factor-1 (IGF-1) and growth hormone (GH) have been studied as indicators of growth potential in beef cattle, but these relationships had not been studied previously in Holstein steers. In this case 12 calves weaned at a mean age of 45 d and body weight (BW) of 54.6 kg were used to obtain, every 28 d during a 336-day experiment, BW data and blood samples. Ten blood samples collected at 30-minute intervals, from 0800 to 1300 h were mixed together and analyzed for concentration of IGF-1 and GH by radio-immuno assay. Linear regression and correlation analyses were performed to determine the relationship between average daily gain (ADG) and BW, and plasma IGF-1 and GH concentrations. The correlations between plasma IGF-1 and ADG or BW were consistently positive (0.47 and 0.48), but those between GH and ADG or BW were negative (-0.31 and-0.37, respectively). Plasma concentration of IGF-1 explained 24% of the variation in ADG, but GH explained only about 10%. Concentration of IGF-1 showed a strong relationship with BW (R 2 = 0.41) throughout a 336-day period of growth. These data indicate that plasma IGF-1 may be useful for predicting performance of Holstein steers.
Acta veterinaria, 2009
Cows in negative energy balance exhibit reduced fertility, mediated by metabolic signals that influence the reproductive system. Measurement of IGF-1 contributes to the diagnosis of negative energy balance. The aim of this study was to investigate possible variations in IGF-1 levels in samples taken at different times of the day. Equine IGF-1 ELISA was used for measuring IGF-1 in bovine samples. Statistical analysis was applied to the results. Using scatter diagrams fitted with Deming regression lines, we established that paired measurements on samples obtained at different times were close to the line of equality. 90% of the absolute differences were less than the reproducibility coefficient, confirming that the level of agreement between the IGF-1 levels at different times of the day was satisfactory. IGF-1 levels in bovine samples were independent of the time of day at which samples were taken.