Effects of the Aquatic Extract of Cinnamon Zeylanicum on STZ-Induced Diabetic Rats: A Molecular and Histopathological Study

Background: The prevalence of diabetes mellitus has increased over the past few decades, making it a significant public health challenge of the twenty-first century. Cinnamon, as a traditional medicine, has been used in several regions of the world for its anti-diabetic properties. Objectives: The current study was conducted to determine the effect of Cinnamon Zeylanicum extract on blood glucose levels, oxidative stress markers, and antioxidant enzyme gene expression in diabetic rats. Methods: Forty Sprague-Dawley rats were divided into four groups, each containing 10 rats. A single dose of streptozotocin (50 mg/kg, IP) was used to induce diabetes. In this investigation, 40 mg/kg body weight of cinnamon extract was administered orally. After eight weeks, the levels of glucose, malondialdehyde (MDA), and reduced glutathione (GSH) were determined using biochemical methods. Additionally, the expression levels of catalase and glutathione reductase in the rat liver homogenate were evaluated using real-time PCR. The effect of cinnamon extract on histopathological changes in the rats' liver was also investigated. Results: The findings indicated that the administration of cinnamon extract resulted in a considerable reduction in blood glucose (210 ± 29.9 vs. 449 ± 48.4 mg/dL; P < 0.001) and liver MDA levels (2.01 ± 0.35 vs. 3.05 ± 0.47; P < 0.001) in diabetic rats after eight weeks. However, this extract had no significant effect on GSH levels (4.71 ± 0.25 vs. 4.75 ± 0.42; P = 0.79) in diabetic rats compared to diabetic control rats. The mRNA expression of catalase and glutathione reductase genes in the liver of diabetic control rats (0.73 ± 0.23 and 0.90 ± 0.18, respectively) was significantly lower than that of the healthy control group (1.33 ± 0.37 and 1.46 ± 0.54, respectively) (P = 0.001, P = 0.012). Administration of cinnamon extract increased the expression levels of these antioxidant enzyme genes, but these changes were statistically not significant (P = 0.72 and P = 0.48, respectively). Furthermore, the creation of hyperglycemia led to slight hypertrophic degeneration and lymphocyte infiltration in hepatocytes. Notably, the administration of cinnamon extract was unable to reverse these abnormalities. Conclusions: The findings of our study support cinnamon's anti-diabetic and antioxidant properties in diabetic rats. However, the histological abnormalities in the diabetic rats' livers could not be altered by the administration of cinnamon.