Metabolic clearance rate of insulin-like growth factor-I in fed and starved sheep

Hodgkinson, S. C.; Davis, S. R.; Burleigh, B. D.; Hv, Henderson; Gluckman, Peter D.

doi:10.1677/joe.0.1150233

Cited by 70 publications

(56 citation statements)

References 20 publications

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“…Because the small IGFBP complex is believed to facilitate the trans port of IGF-I from serum to tissues, the preferential asso ciation of IGF-I with these IGFBPs in the proteinrestricted animals might allow a faster transcapillary pas sage and distribution to the tissues. In contrast to the stud ies in rats, a 48-hour fasting in sheep did not affect the clearance of IGF-I [37], This difference might be due to species differences or be related to the differences in the nature and length of the nutritional insult.…”

Section: Insulin-like Growth Factor-binding Proteinscontrasting

confidence: 83%

Nutritional Regulation of the Growth Hormone and Insulin-Like Growth Factor-Binding Proteins

et al. 1996

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Both growth hormone (GH) and insulin-like growth factors (IGFs) associate with specific binding proteins. Besides control by hormones, these binding proteins are nutritionally regulated. The GH-binding protein (GHBP) is the extracellular portion of the GH receptor. Its concentrations in circulation are decreased in severe malnutrition, reflecting a decrease in tissue GH receptor abundance. IGFs are bound to 6 different binding proteins (IGFBPs). IGFBP-3 is relatively stable and is only depressed after prolonged periods of severe malnutrition. In contrast, IGFBP-1 is regulated acutely by nutrient intake, showing major elevations after overnight fasting and rapid postprandial decreases. IGFBP-2 is highly dependent on dietary protein intake. Nutritional factors may regulate the tissue availability and the biological actions of IGFs by their actions on IGFBPs.

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Section: Insulin-like Growth Factor-binding Proteinscontrasting

confidence: 83%

Nutritional Regulation of the Growth Hormone and Insulin-Like Growth Factor-Binding Proteins

et al. 1996

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“…Results from other studies suggest that IGF-I clearance from plasma in older sheep does not alter with fasting (Hodgkinson et al 1987). Further, hepatic IGF-I mRNA is reduced in poorly fed lambs (Pell et al 1993).…”

Section: Discussionmentioning

confidence: 80%

“…These studies indicate that nutritionally driven changes in plasma IGF-I in older animals are probably the result of altered hepatic production of IGF-I. IGF clearance rates in sheep of different ages have not been investigated, but a comparison of two independent reports suggests that the metabolic clearance of IGF-I is greater in 6-than 9-month-old wethers (Hodgkinson et al 1987. Also, the clearance rate is greater for IGF-II than IGF-I .…”

Section: Discussionmentioning

confidence: 95%

Nutritional regulation of IGF-II, but not IGF-I, is age dependent in sheep

Oldham

Martyn²,

Hua³

et al. 1999

Journal of Endocrinology

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In post-natal animals, plasma concentrations of IGF-I are tightly regulated by nutritional status. The current study reports that plasma levels of IGF-II in sheep are also regulated by nutrition, but whether plasma IGF-II is increased, decreased or remains the same, depends on the age of the animal. Ewe lambs, ranging in age from 2 days to 2 years, were fed or fasted for lengths of time between 24 and 72 h. Blood samples were taken at intervals of 24 h throughout the treatment period and immediately before slaughter.Plasma concentrations of IGF-I increased with advancing age in fed animals (P<0·001) and were reduced by fasting in all age groups (P<0·001). Plasma concentrations of IGF-II also increased as animals matured (P<0·001), but did not show an overall effect of the fasting treatment. An interaction between age and nutrition (P<0·001) resulted from a decrease in plasma IGF-II in response to fasting in neonatal animals (P<0·01) and, conversely, increased levels of plasma IGF-II in fasted mature animals (P<0·01 or P<0·001). Fasted sheep of peripubertal age showed no change in plasma levels of IGF-II.The nutritional sensitivity of serum IGF-binding proteins (BPs) also changed with age. The 29 kDa BP, which we presume to be BP1, was elevated by fasting in young animals and reduced slightly in older animals. BP2 was increased to a similar magnitude by fasting at all ages. BP3 was depressed by fasting in young animals and showed little change in adults. In contrast, a 24 kDa BP, which is probably BP4, showed little change in young animals and was reduced substantially in older sheep.In conclusion, the response of plasma IGF-II to fasting suggests that this peptide has functions in mediating nutritional stress which depend on the age of the animal, and also that the role of IGF-II may differ from that of IGF-I in adults.

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“…These authors postulated that the dimin ished t./2 in hypox rats was due to a lack of the GHdependent 150-kD IGFBP [7], There have been only two reports of studies in which IGF-I was administered to domestic animal species: Guler et al [8] reported that the t./2 of l25I-IGF-I administered intravenously to mini pigs was 10-15 min for free IGF-I, 20-30 min for IGF-I bound to the 50-kD IGFBP, and 4-6 h for IGF-I bound to the 150-kD IGFBP. More recently, Hodgkinson et al [9] administered 1311-IGF-I (recombinant human) to sheep and found that the label distributed to three phases with ty, values of 4.0 ± 0.4, 52.4 ± 3.4 and 792 ± 26.5 min. Furthermore, these authors provided evidence that the two phases with the longer tiA values were due to IGFBP-bound label.…”

Section: Discussionmentioning

confidence: 99%

“…An alternate interpretation is that exogenous IGF-I is rapidly cleared from the circulation before it can elicit any significant stimulatory effect on proliferation of target cells because it is not bound to IGF-binding proteins (IGFBPs). Previous studies have reported short circulating half-lives of IGF-I injected into rats [7], hu mans [8], and sheep [9].…”

Section: Introductionmentioning

confidence: 92%

Administration of Recombinant Human Insulin-Like Growth Factor I to Pigs: Determination of Circulating Half-Lives and Chomatographic Profiles

Walton

Gopinath

Burleigh³

et al. 1989

Horm Res

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Recombinant human insulin-like growth factor I (IGF-I) was injected daily (4 or 8 mg/pig) as an intra-arterial bolus into pigs for 3 consecutive days and the serum IGF-I concentration was measured to determine disappearance profiles. IGF-I partitioned to a fast component (half-life, t_½ = 5.7 min) and a slow component (t_½ = 253 min) in pig serum. Chromatography of serum revealed that the fast component comprised unbound IGF-I, whereas the slow component comprised IGF-I bound to 40- and 150-kD serum IGF-binding proteins. In addition, administration of exogenous IGF-I caused significant hypoglycemia.

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Metabolic clearance rate of insulin-like growth factor-I in fed and starved sheep

Cited by 70 publications

References 20 publications

Nutritional Regulation of the Growth Hormone and Insulin-Like Growth Factor-Binding Proteins

Nutritional Regulation of the Growth Hormone and Insulin-Like Growth Factor-Binding Proteins

Nutritional regulation of IGF-II, but not IGF-I, is age dependent in sheep

Administration of Recombinant Human Insulin-Like Growth Factor I to Pigs: Determination of Circulating Half-Lives and Chomatographic Profiles

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