Protective Effects of Green Tea Extract against Hepatic Tissue Injury in Streptozotocin-Induced Diabetic Rats

Abstract

Although diabetic hepatopathy is potentially less common, it may be appropriate for addition to the list of target organ conditions related to diabetes. This study was designed to evaluate the hepatoprotective properties of green tea extract (GTE) in STZ-induced diabetes in rats. Wistar rats were made diabetic through single injection of STZ (75 mg/kg i.p.). The rats were randomly divided into four groups of 10 animals each: Group 1, healthy control; Group 2, nondiabetics treated with GTE administered orally (1.5%, w/v); Group 3, diabetics; Group 4, diabetics treated with GTE (1.5%, w/v) for 8 weeks. Serum biomarkers were assessed to determine hepatic injury. Malondialdehyde (MDA) and reduced glutathione (GSH) contents were measured to assess free radical activity in the liver tissue. Hepatic antioxidant activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) were also determined. The biochemical findings were matched with histopathological verifications. Liver MDA content and serum levels of ALT, AST, ALP, and bilirubin in Group 3 significantly increased compared to Group 1 (P < 0.05) and significantly decreased in Group 4 compared to Group 3 (P < 0.05). Serum albumin level and GSH, SOD, CAT, and GSH-Px contents of the liver in Group 3 were significantly decreased compared to Group 1 (P < 0.05) and were significantly increased in Group 4 compared to Group 3 (P < 0.05). Histopathologically, the changes were in the same direction with biochemical findings. This study proved the hepatoprotective activity of GTE in experimentally induced diabetic rats.

Figure 1

Comparison of the effect of GTE (1.5%, w/v) on blood glucose levels among the experimental groups (mean ± SEM). *P < 0.05, ^a,bcompared to Group 1, ^ccompared to Group 3.

Figure 2

Comparison of the effect of GTE (1.5%, w/v) on serum AST level among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 3

Comparison of the effect of GTE (1.5%, w/v) on serum ALT level among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 4

Comparison of the effect of GTE (1.5%, w/v) on serum ALP level among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 5

Comparison of the effect of GTE (1.5%, w/v) on serum bilirubin level among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 6

Comparison of the effect of GTE (1.5%, w/v) on serum albumin level among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 7

Comparison of the effect of GTE (1.5%, w/v) on liver GSH content among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 8

Comparison of the effect of GTE (1.5%, w/v) on liver MDA content among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 9

Comparison of the effect of GTE (1.5%, w/v) on liver SOD activity among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 10

Comparison of the effect of GTE (1.5%, w/v) on liver CAT activity among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 11

Comparison of the effect of GTE (1.5%, w/v) on liver GSH-Px activity among the experimental groups (mean ± SEM). *P < 0.05, ^acompared to Group 1, ^bcompared to Group 3.

Figure 12

Microscopic appearance from the liver tissue of a rat belonged to healthy control group showing normal hepatic structure (H&E, 100x).

Figure 13

Microscopic view from the liver tissue of a rat belonged to non-diabetic rats + GTE (1.5%, w/v) treatment group. There is no treatment-related lesion in the section (H&E, 100x).

Figure 14

Histologic appearance from the liver tissue of a rat belonged to diabetic group showing macrovesicular fatty change in centrilobular portion (H&E, 100x).

Figure 15

Histologic appearance from the liver tissue of a rat belonged to diabetic rats + GTE (1.5%, w/v) treatment group showing no considerable pathologic change (H&E, 100x).