Curcumin regulates gene expression of insulin like growth factor, B-cell CLL/lymphoma 2 and antioxidant enzymes in streptozotocin induced diabetic rats

Abstract

Background: The effects of curcumin on the activities and gene expression of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione-S-transferase (G-ST), B-cell CLL/lymphoma 2 (Bcl-2) and insulin like growth factor-1 (IGF-1) in diabetic rats were studied.

Methods: Twenty four rats were assigned to three groups (8 rats for each). Rats of first group were non diabetic and rats of the second group were rendered diabetic by streptozotocin (STZ). Both groups received vehicle, corn oil only (5 ml/kg body weight) and served as negative and positive controls, respectively. Rats of the third group were rendered diabetic and received oral curcumin dissolved in corn oil at a dose of 15 mg/5 ml/kg body weight for 6 weeks.

Results: Diabetic rats showed significant increase of blood glucose, thiobarbituric acid reactive substances (TBARS) and activities of all antioxidant enzymes with significant reduction of reduced glutathione (GSH) compare to the control non diabetic group. Gene expression of Bcl2, SOD, CAT, GPX and GST was increased significantly in diabetic untreated rats compare to the control non diabetic group. The administration of curcumin to diabetic rats normalized significantly their blood sugar level and TBARS values and increased the activities of all antioxidant enzymes and GSH concentration. In addition, curcumin treated rats showed significant increase in gene expression of IGF-1, Bcl2, SOD and GST compare to non diabetic and diabetic untreated rats.

Conclusion: Curcumin was antidiabetic therapy, induced hypoglycemia by up-regulation of IGF-1 gene and ameliorate the diabetes induced oxidative stress via increasing the availability of GSH, increasing the activities and gene expression of antioxidant enzymes and Bcl2. Further studies are required to investigate the actual mechanism of action of curcumin regarding the up regulation of gene expression of examined parameters.

Figure 1

RT-PCR analysis of IGF-1 (a), Bcl2 (b), SOD (c), CAT (d) in liver tissues of control non diabetic (C), experimentally diabetic (D) and Curcumin (Cur) treated diabetic rats. RT-PCR was performed with Qiagen one-step. The densitometric analysis of the expresses bands (lower columns) was normalized with that of β-actin and then calculated as relative to the control group. Values are expressed as mean ± SEM for 8 rats. ^*Values are significant different (p < 0.5) compared to control non diabetic group. ^#Values are significant different (p < 0.5) compared to control diabetic group.

Figure 2

RT-PCR analysis of GPX (a) and GST (b) in liver tissues of control non diabetic, experimentally diabetic and curcumin (Cur) treated diabetic rats. RT-PCR was performed with Qiagen one-step. The densitometric analysis of the expresses bands (lower columns) was normalized with that of β-actin and then calculated as relative to the control group. Values are expressed as mean ± SEM for 8 rats. *Values are significant different (p < 0.5) compared to control non diabetic group. #Values are significant different (p < 0.5) compared to control diabetic group.

Figure 3

Real time RT-PCR analysis of IGF-1 (a), Bcl2 (b), SOD (c), CAT (d) in liver tissues of control non diabetic (C), experimentally diabetic (D) and Curcumin (Cur) treated diabetic rats. Values are expressed as mean ± SEM for 8 rats. ^*Values are significant different (p < 0.5) compared to control non diabetic group. ^#Values are significant different (p < 0.5) compared to control diabetic group.

Figure 4

Real time RT-PCR analysis of GPX (a) and GST (b) in liver tissues of control non diabetic, experimentally diabetic and curcumin (Cur) treated diabetic rats. Values are expressed as mean ± SEM for 8 rats. *Values are significant different (p < 0.5) compared to control non diabetic control. #Values are significant different (p < 0.5) compared to control diabetic group.