High Insulin Concentrations Repress Insulin Receptor Gene Expression in Calf Hepatocytes Cultured &lt;i&gt;in Vitro&lt;/i&gt;

Zhang, Zhigang; Li, Xiaobing; Liu, Guowen; Gao, Li; Guo, Changming; Kong, Tao; Wang, Hongbin; Gao, Ruifeng; Wang, Zhe; Zhu, Xiaoning

doi:10.1159/000330072

Cited by 19 publications

(15 citation statements)

References 29 publications

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“…Zhang et al . [24] reported low INSR gene expression levels in calf cultured hepatocytes in response to high insulin concentrations. However, it should be noted that in the present study even the highest insulin levels were within physiological levels.…”

Section: Discussionmentioning

confidence: 99%

Is hepatic lipid metabolism of beef cattle influenced by breed and dietary silage level?

et al. 2014

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BackgroundIn ruminants, unsaturated dietary fatty acids are biohydrogenated in the rumen and are further metabolised in various tissues, including liver, which has an important role in lipid and lipoprotein metabolism. Therefore, manipulation of muscle fatty acid composition should take into account liver metabolism. In the present study, the influence of breed and diet on liver lipid composition and gene expression was investigated in order to clarify the role of this organ in the lipid metabolism of ruminants. Forty purebred young bulls from two phylogenetically distant autochthonous cattle breeds, Alentejana and Barrosã, were assigned to two different diets (low vs. high silage) and slaughtered at 18 months of age. Liver fatty acid composition, mRNA levels of enzymes and transcription factors involved in lipid metabolism, as well as the plasma lipid profile, were assessed.ResultsIn spite of similar plasma non-esterified fatty acids levels, liver triacylglycerols content was higher in Barrosã than in Alentejana bulls. Moreover, the fatty acid composition of liver was clearly distinct from the remaining tissues involved in fatty acid metabolism of ruminants, as shown by Principal Components Analysis. The hepatic tissue is particularly rich in α-linolenic acid and their products of desaturation and elongation. Results indicate that DGAT1, ELOVL2, FADS1 and FADS2 genes influence the fatty acid composition of the liver the most. Moreover, genes such as DGAT1 and ELOVL2 appear to be more sensitive to genetic background than to dietary manipulation, whereas genes encoding for desaturases, such as FADS1, appear to be modulated by dietary silage level.ConclusionsOur results indicate that liver plays an important role in the biosynthesis of n-3 LC-PUFA. It is also suggested that dietary silage level influences the hepatic fatty acid metabolism in a breed-dependent manner, through changes in the expression of genes encoding for enzymes associated with the desaturation and elongation pathway. The importance of devising custom-made feeding strategies taking into account the genetic background is, therefore, stressed by the results from this experiment.

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Section: Discussionmentioning

confidence: 99%

Is hepatic lipid metabolism of beef cattle influenced by breed and dietary silage level?

et al. 2014

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“…These adaptations are increased lipid mobilization, ketogenesis and lipid oxidation [6][7][8], reduced levels of thyroid hormones [9], changed STH to IGF-I ratio [10], increased levels of cortisol [11], changes in hepatic insulin receptors abundance, increased activity of hepatic enzymes [6,12,13] and reduced concentration of Ca and P [14,15]. However, there is a lack of literature data related to the direct relationship between the value of the indexes of insulin resistance and metabolic or endocrine parameters.…”

Section: Introductionmentioning

confidence: 99%

Relationship between the indexes of insulin resistance and metabolic status in dairy cows during early lactation

et al. 2017

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Insulin resistance is a phenomenon which accompanies the ongoing metabolic adaptation in cows during early lactation. The aim of our study was to determine the linear correlations of HOMA (Homeostatic Model Assessment), QUICKI (Quantitative Insulin Sensitivity Check Index) and RQUICKI (Revised Quantitative Insulin Sensitivity Check Index) indexes of insulin resistance with the metabolic status of cows (concentration of hormones, metabolites and body condition score). The experiment included 40 Holstein-Frisian cows in the fi rst week after calving. Indexes of insulin resistance valued: 18.68±5.43 (HOMA), 0.39±0.06 (QUICKI) and 0.45±0.06 (RQUICKI). Linear correlations were examined by testing the coeffi cient of correlation (r), determination (r 2 ,%) and regression parameter beta (b) in linear equation. A negative correlation was found between HOMA and IGF-I (insulin growth factor I) (r=-0.51, r²=25.0, b=-1.1257, p<0.01). HOMA showed a positive correlation with BHB (betahidroxybutyrate) (r=0.48, r²=23.2, b=0.0234, p<0.01). A positive correlation was found between QUICKI and IGF-I (r=0.30, r²=10.0 b=46.7900, p<0.05) and cholesterol (r=0.44, r²=18.3, b=1.9021, p<0.01). In contrast, QUICKI and BHB (r=0.51, r²=27.1, b=-1.7241, p<0.01), just like QUICKI and BCS (r=0.46, r²=20.9, b=-2.424, p<0.01), showed a negative correlation. RQUICKI showed positive correlations with IGF-I (r=0.48, r²=22.8, b=28.1230, p<0.01), T4 (r=0.47, r²=22.1, b=87.142, p<0.01) and triglycerides (r=0.36, r²=13, b=0.0407, p<0.05) but negative correlations with cortisol (r=-0.36, r²=13.0, b=-9.0332, p<0.05), STH (somatotropic hormone) (r=-0.42, r²=17.3, b=-5.4976, p<0.01), BHB (r=-0.62, r²=38.3, b=-1.1872, p<0.01), total bilirubin (r=-0.58, r²=33.7, b=-7.131, p<0.01) and BCS (body condition score) (r=-0.6, r²=36.4, b=-1.8347, p<0.01). In conclusion, indexes of insulin resistance may be used to evaluate the metabolic status of cows in early lactation. RQUICKI might be the most appropriate predictor of metabolic status due to its linear relationship with most of the parameters included in homeorhetic process.

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“…Quantification of INSR mRNA levels using lymphoblastoid cells and RT-PCR analysis could facilitate genetic analyses of insulin resistance mechanisms like the pedigree of Case 2.The mRNA expression level of INSR was significantly higher in the mother of Case 2, who carried a heterozygous Ser98Arg mutation, than in the normal control. Insulin itself has been suggested to regulate INSR expression, forming a negative feedback loop between INSR expression and insulin signals 24. Therefore, INSR mRNA levels may be higher in the mother of Case 2 because of compensation for low insulin signaling.…”

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confidence: 99%

Molecular mechanisms of insulin resistance in 2 cases of primary insulin receptor defect-associated diseases

et al. 2017

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High Insulin Concentrations Repress Insulin Receptor Gene Expression in Calf Hepatocytes Cultured <i>in Vitro</i>

Cited by 19 publications

References 29 publications

Is hepatic lipid metabolism of beef cattle influenced by breed and dietary silage level?

Is hepatic lipid metabolism of beef cattle influenced by breed and dietary silage level?

Relationship between the indexes of insulin resistance and metabolic status in dairy cows during early lactation

Molecular mechanisms of insulin resistance in 2 cases of primary insulin receptor defect-associated diseases

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