Insulin glargine affects the expression of Igf-۱r, Insr, and Igf-۱ genes in colon and liver of diabetic rats

Objective(s): The mitogenic effect of the analogous insulin glargine is currently under debate since several clinical studies have raised the possibility that insulin glargine treatment has a carcinogenic potential in different tissues. This study aimed to evaluate the Igf-۱r, Insr, and Igf-۱ gene expression in colon and liver of streptozotocin-induced diabetic rats in response to insulin glargine, neutral protamine Hagedorn (NPH) insulin, and metformin treatments. Materials and Methods: Male Wistar rats were induced during one week with streptozotocin to develop Type ۲ Diabetes (T۲D) and then randomly distributed into four groups. T۲D rats included in the first group received insulin glargine, the second group received NPH insulin, the third group received metformin; finally, untreated T۲D rats were included as the control group. All groups were treated for seven days; after the treatment, tissue samples of liver and colon were obtained. Quantitative PCR (qPCR) was performed to analyze the Igf-۱r, Insr and Igf-۱ gene expression in each tissue sample. Results: The liver tissue showed overexpression of the Insr and Igf-۱r genes (P>۰.۰۰۱) in rats treated with insulin glargine in comparison with the control group. Similar results were observed for the Insr gene (P>۰.۰۱۱) in colonic tissue of rats treated with insulin glargine. Conclusion: These observations demonstrate that insulin glargine promote an excess of insulin and IGF-۱ receptors in STZ-induced diabetic rats, which could overstimulate the mitogenic signaling pathways.

Keywords:

Colon , Diabetes , Insulin glargine , Liver , Metformin , NPH insulin , Rats