Effect of feeding level on serum IGF1 response to GH injection

Abstract

This study was conducted to further understand the mechanism by which nutrition modulates GH-induced changes in serum IGF1 concentration in cattle. Cows were fed hay only or corn-based concentrates in addition to hay for 8 weeks. At week 8, serum concentrations of IGF1, IGF-binding protein 3 (IGFBP3), and acid-labile subunit (ALS) as well as their mRNA levels in liver were determined immediately before and 7 days after an injection of GH formulated for sustained release. GH injection caused greater increases in both serum IGF1 concentration and liver IGF1 mRNA expression in the cows fed concentrates than in those fed hay. In the cows fed concentrates, the magnitude of the GH-induced increase in serum IGF1 concentration was, however, much greater than that in liver IGF1 mRNA expression. This difference was not due to GH-induced IGF1 mRNA being translated more efficiently. GH injection also induced greater increases in serum IGFBP3 and ALS concentrations in the cows fed concentrates than fed hay. The injection, however, did not induce a greater increase in IGFBP3 or ALS mRNA in the cows fed concentrates than fed hay. These data and the fact that the ternary complex of IGF1/IGFBP3/ALS stabilizes each of the components in the blood suggest that in cows, increased nutrition enhances serum IGF1 response to GH not only by increasing IGF1 mRNA response to GH in the liver, but also by elevating IGFBP3 and ALS concentrations in the blood.

Timing and dependence upon mitogen-activated protein kinase signaling for pro-developmental actions of insulin-like growth factor 1 on the preimplantation bovine embryo

“…The concentrations at which IGF1 increased competence for development to the blastocysts stage in the present study is within the range of those found in the blood of lactating and non-lactating cows [26,27]. Surprisingly, IGF1 was more effective at increasing development at 100 ng/mL than at 200 ng/mL.…”

“…Concentrations were chosen so that the second concentration was within the range of values for IGF1 in blood of lactating cows [26,27]. The percentage of oocytes that cleaved (≥2 cell) was observed at Day 3 after insemination (~72 h post-insemination) and the percentage of embryos that became blastocyst was observed at Day 7 (168 h) and Day 8 (192 h) post-insemination.…”

Haplotype effect in the IGF1 promoter accounts for the association between microsatellite and serum IGF1 concentration

“…Epidemiological studies indicate that a high concentration of blood‐circulating IGF1 is a strong risk factor of various cancers including colon cancer, 10 prostate cancer 11 and breast cancer, 12 while a low concentration of blood IGF1 is related to a number of metabolic diseases, such as diabetes mellitus 13 . Although the level of circulating IGF1 is affected by various factors including growth hormone concentration, 14 IGFBP concentration, 15 gender, 16 age, 17 ethnic group 18 and nutritional status, 19 twin studies have demonstrated that 38% of the variance of IGF1 concentration between individuals is contributed by genetic effects 20 . Recently, an association study using tagSNPs covering the IGF1 gene in a cohort of 450 middle‐aged men and women revealed that tagSNPs accounted for 2·1% of population variance of circulating IGF1 concentration 20 .…”

Effects of dietary supplementation and parity of dam on plasma concentrations of Insulin-like growth factor (IGF)-I and IGF-binding protein-3 during post-partum period in dromedary camels

“…It has been documented that the IGF system plays an important role in cell growth, differentiation, and mediation of growth hormone (Daughaday et al, 1989, Wu et al, 2010. Circulating IGF-I is linked to four IGF binding proteins (IGFBP-2, 3, 4 and 5; Silva et al 2009) that regulate its bioavailability.…”