Developmental patterns of plasma insulin-like growth factor-1 concentrations in sheep

Roberts, Carol A.; McCutcheon, S. N.; Blair, Hugh T.; Gluckman, Peter D.; Breier, Bernhard H.

doi:10.1016/0739-7240(90)90003-i

Cited by 59 publications

(50 citation statements)

References 23 publications

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“…Thus, the relationship between onset of puberty and the rate of accumulation of muscle and fat is supported by the existence of endocrine factors from both tissues that are thought to directly affect the brain processes that control the initiation of puberty. We found that circulating concentrations of leptin and IGF-I increased progressively as the experiment progressed and puberty approached, consistent with previous reports (Roberts et al, 1990;Foster and Nagatani, 1999), suggesting that the two metabolic hormones inform the central nervous system of the metabolic status of the body, perhaps specifically the accumulation of fat (leptin) and muscle (IGF-I), and thus permit the triggering of puberty. This role for leptin has been largely confirmed in ewe lambs, but the question still remains open for IGF-I or any other endocrine factor associated with muscle.…”

Section: Discussionsupporting

confidence: 91%

“…Overall, it appears that ewe lambs that accumulate fat and muscle rapidly will achieve puberty earlier, be more fertile and have a higher reproductive rate when mated at 8 or 9 months, than their counterparts with lower rates of fat and muscle accumulation. Moreover, growth, fatness and the onset of puberty are all associated with circulating concentrations of IGF-I and leptin (Roberts et al, 1990;Chilliard et al, 2005); thus, we would expect reproductive development to be explained by the secretory patterns of these two metabolic hormones.…”

Section: Introductionmentioning

confidence: 99%

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Selection for superior growth advances the onset of puberty and increases reproductive performance in ewe lambs

Ariza-Nieto

Ferguson

Macleay

et al. 2013

Animal

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The reproductive efficiency of the entire sheep flock could be improved if ewe lambs go through puberty early and produce their first lamb at 1 year of age. The onset of puberty is linked to the attainment of critical body mass, and therefore we tested whether it would be influenced by genetic selection for growth rate or for rate of accumulation of muscle or fat. We studied 136 Merino ewe lambs with phenotypic values for depth of eye muscle (EMD) and fat (FAT) and Australian Sheep Breeding Values at post-weaning age (200 days) for live weight (PWT), eye muscle depth (PEMD) and fat depth (PFAT). First oestrus was detected with testosterone-treated wethers and then entire rams as the ewes progressed from 6 to 10 months of age. Blood concentrations of leptin and IGF-I were measured to test whether they were related to production traits and reproductive performance (puberty, fertility and reproductive rate). In total, 97% of the lambs reached first oestrus at average weight 39.4 6 0.4 kg (mean 6 s.e.m.) and age 219 days (range 163 to 301). Age at first oestrus decreased with increases in values for PWT (P , 0.001), and concentrations of IGF-I (P , 0.05) and leptin (P , 0.01). The proportion of ewe lambs that achieved puberty was positively related with increases in values for EMD (P , 0.01), FAT (P , 0.05) or PWT (P , 0.01), and 75% of the ewe lambs were pregnant at average weight 44.7 6 0.5 kg and age 263 days (range 219 to 307). Ewe lambs that were heavier at the start of mating were more fertile (P , 0.001) and had a higher reproductive rate (P , 0.001). Fertility and reproductive rate were positively correlated with increases in values for EMD (P , 0.01), FAT (P , 0.05), PWT (P , 0.01) and leptin concentration (P , 0.01). Fertility, but not reproductive rate, increased as values for PFAT increased (P , 0.05). Leptin concentration increased with increases in values for EMD (P , 0.001), FAT (P , 0.001), PWT (P , 0.001), PEMD (P , 0.05) and PFAT (P , 0.05). Many of these relationships became non-significant when PWT or live weight was added to the statistical model. We conclude that selection for genetic potential for growth can accelerate the onset of puberty and increase fertility and reproductive rate of Merino ewe lambs. The metabolic hormones, IGF-I and leptin, might act as a physiological link between the growing tissues and the reproductive axis.Keywords: ewe lambs, phenotypic selection, ASBV, reproductive efficiency ImplicationsGenetic selection can improve the rates of growth and muscle development in sheep, and should also permit reproduction at a younger age because the onset of puberty depends on attainment of sufficient body mass. Our data support this hypothesis, suggesting that phenotypic and genetic selection for growth or muscling will improve the reproductive performance of Merino ewes mated to lamb at 1 year of age. These findings will inform bio-economic models and promote genetic selection strategies with a view to improving profitability of sheep production systems by achieving improvements i...

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Selection for superior growth advances the onset of puberty and increases reproductive performance in ewe lambs

Ariza-Nieto

Ferguson

Macleay

et al. 2013

Animal

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“…Plasma concentrations of IGF-I are greater in males than females in postpubertal rats (Gabriel et al 1992, Hu et al 1993, mice (Blair et al 1987), pre-and postpubertal sheep (Roberts et al 1990, Medrano & Bradford 1991, Gatford et al 1996, 1997b, cattle (Bishop et al 1989, Hannon et al 1991, Schwarz et al 1992, Röpke et al 1994, Davis et al 1995, late-gestation fetal and postnatal pigs (Owens et al 1990, Lamberson et al 1995, Bauer & Parvizi 1996 and in turkeys from 1 week of age (Bacon et al 1993). In contrast, most, although not all ( Juul et al 1994) studies in primates have found that plasma IGF-I concentrations are greater in postpubertal females than in males (Copeland et al 1985, Merimee et al 1987, Yamamoto et al 1991, Schwartz & Kemnitz 1992.…”

Section: Insulin-like Growth Factor-imentioning

confidence: 99%

Sexual dimorphism of the somatotrophic axis

Gatford¹,

Egan²,

Clarke³

et al. 1998

Journal of Endocrinology

157

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“…Circulating IGF-I concentrations are elevated at the time of puberty in rodents (Handelsman et al, 1987;Crawford and Handelsman, 1996), primates (Mauras et al, 1996), ruminants (Roberts et al, 1990) and pigs (Prunier and Louveau, 1997). Moreover, IGF-I stimulated gonadotropin-releasing hormone (GnRH) release from hypothalamic explants (Hiney et al, 1991) and LH from rat pituitary cells in culture (Kanematsu et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Insulin-like growth factor-I feedback regulation of growth hormone and luteinizing hormone secretion in the pig: evidence for a pituitary site of action

Barb

Hausman

2009

Animal

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Three experiments (EXP) were conducted to determine the role of insulin-like growth factor-I (IGF-I) in the control of growth hormone (GH) and LH secretion. In EXP I, prepuberal gilts, 65 ± 6 kg body weight and 140 days of age received intracerebroventricular (ICV) injections of saline (n = 4), 25 μg (n = 4) or 75 μg (n = 4) IGF-I and jugular blood samples were collected. In EXP II, anterior pituitary cells in culture collected from 150-day-old prepuberal gilts (n = 6) were challenged with 0.1, 10 or 1000 nM [Ala15]-h growth hormone-releasing hormone-(1-29)NH2 (GHRH), or 0.01, 0.1, 1, 10, 30 nM IGF-I individually or in combinations with 1000 nM GHRH. Secreted GH was measured at 4 and 24 h after treatment. In EXP III, anterior pituitary cells in culture collected from 150-day-old barrows (n = 5) were challenged with 10, 100 or 1000 nM gonadotropin-releasing hormone (GnRH) or 0.01, 0.1, 1, 10, 30 nM IGF-I individually or in combinations with 100 nM GnRH. Secreted LH was measured at 4 h after treatment. In EXP I, serum GH and LH concentrations were unaffected by ICV IGF-I treatment. In EXP II, relative to control all doses of GHRH increased (P < 0.01) GH secretion. Only 1, 10, 30 nM IGF-I enhanced (P < 0.02) basal GH secretion at 4 h, whereas by 24 h all doses except for 30 nM IGF-I suppressed (P < 0.02) basal GH secretion compared to control wells. All doses of IGF-I in combination with 1000 nM GHRH increased (P < 0.04) the GH response to GHRH compared to GHRH alone at 4 h, whereas by 24 h all doses of IGF-I suppressed (P < 0.04) the GH response to GHRH. In EXP III, all doses of IGF-I increased (P < 0.01) basal LH levels while the LH response to GnRH was unaffected by IGF-I (P > 0.1). In conclusion, under these experimental conditions the results suggest that the pituitary is the putative site for IGF-I modulation of GH and LH secretion. Further examination of the role of IGF-I on GH and LH secretion is needed to understand the inhibitory and stimulatory action of IGF-I on GH and LH secretion.

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Developmental patterns of plasma insulin-like growth factor-1 concentrations in sheep

Cited by 59 publications

References 23 publications

Selection for superior growth advances the onset of puberty and increases reproductive performance in ewe lambs

Selection for superior growth advances the onset of puberty and increases reproductive performance in ewe lambs

Sexual dimorphism of the somatotrophic axis

Insulin-like growth factor-I feedback regulation of growth hormone and luteinizing hormone secretion in the pig: evidence for a pituitary site of action

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