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Induction of Hepatic Insulin-Like Growth Factor Binding Protein-1 (IGFBP-1) in Rats by Dietary n-6 Polyunsaturated Fatty Acids
- Source :
- Proceedings of the Society for Experimental Biology and Medicine. 225:128-135
- Publication Year :
- 2000
- Publisher :
- Wiley, 2000.
-
Abstract
- The insulin-like growth factors (IGFs) are mitogenic polypeptides that have been linked to a variety of normal physiological processes as well as neoplasia. Overexpression of several components of the IGF system is associated with hepatocarcinogenesis in humans and rodents. In rat liver, diets rich in n-6 polyunsaturated fatty acid (PUFA) enhance the development of preneoplastic lesions and tumors. Therefore, the objective of this study was to determine the effect of these dietary fatty acids on the hepatic expression of the various components of the IGF system. The mRNA levels of IGF-1 and the type 1 receptor were not different in livers of rats fed a diet containing 20% corn oil (CO) compared with those fed 5% CO. Analysis of the IGF binding proteins revealed that insulin-like growth factor binding protein-1 (IGFBP-1) levels were altered by the amount and type of dietary fat. A 2.5-fold induction of IGFBP-1 mRNA occurred within 1 week after the animals were fed the 20% corn oil diet compared with those fed 5% CO and was further enhanced to over 6-fold after 1 month. Furthermore, IGFBP-1 protein was only detectable in the livers of animals fed the 20% CO diet. Induction of IGFBP-1 mRNA (4.5-fold) also occurred in rats fed a high-fat diet containing safflower (rich in n-6 PUFAs) compared with those fed a high-fat diet containing menhaden oil (rich in n-3 PUFAs). The induction of IGFBP-1 mRNA was independent of serum insulin levels and the development of insulin resistance. Since IGFBP-1 mRNA is upregulated in regenerating liver, we reasoned that the induction of IGFBP-1 mRNA may be associated with an increase in cell proliferation; however, no difference was observed in the hepatic labeling index of rats fed the 20% CO compared with the 5% CO diet. In summary, these studies show a striking induction by dietary n-6 PUFAs of hepatic IGFBP-1, a protein that has been implicated in liver cancer development.
- Subjects :
- medicine.medical_specialty
medicine.medical_treatment
Biology
General Biochemistry, Genetics and Molecular Biology
Insulin-like growth factor-binding protein
Rats, Sprague-Dawley
Insulin-like growth factor
Liver Neoplasms, Experimental
Insulin resistance
Dietary Fats, Unsaturated
Downregulation and upregulation
Insulin-Like Growth Factor II
Fatty Acids, Omega-6
Internal medicine
medicine
Animals
Humans
Insulin
RNA, Messenger
Insulin-Like Growth Factor I
Receptor
chemistry.chemical_classification
Growth factor
medicine.disease
Rats
Insulin-Like Growth Factor Binding Protein 1
Endocrinology
Insulin-Like Growth Factor Binding Protein 4
Liver
chemistry
Fatty Acids, Unsaturated
Hepatocytes
biology.protein
Female
Insulin Resistance
Cell Division
Corn oil
Polyunsaturated fatty acid
Subjects
Details
- ISSN :
- 15251373 and 00379727
- Volume :
- 225
- Database :
- OpenAIRE
- Journal :
- Proceedings of the Society for Experimental Biology and Medicine
- Accession number :
- edsair.doi.dedup.....45f8fb6862e2f2fc7f00e1b4d773ad78
- Full Text :
- https://doi.org/10.1046/j.1525-1373.2000.22516.x