Effects of Long-term Administration of Oral Sodium Nitrate on Liver Enzyme Concentrations in Type 2 Diabetic Male Rats

Introduction: Liver disorders in patients with type 2 diabetes (T2D) are mostly associated with higher serum levels of liver enzymes. This study aimed to investigate the effect of nitrate administration on the serum levels of alanine amino transferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) in rats with T2D. Materials and Methods: In this study, 24 male Wistar rats were divided into four groups: control, control+nitrate, diabetes, and diabetes+nitrate. T2D was induced using a combination of high-fat diet and injection of low-dose streptozotocin (30 mg/kg). The rats in the nitrate-treated groups received sodium nitrate (100 mg/L in drinking water) for six months. The serum levels of ALT, AST, and ALP were measured at the beginning of the study and at three and six months after nitrate administration. Results: Diabetic rats showed increased levels of ALT, AST, and ALP in the serum at six months. Nitrate decreased the serum level of ALT by 17.6% (65.7±4.8 vs. 55.8±2.3 UI/L; P=0.0659), AST by 52.2% (161.3±13.3 vs. 106.0±6.1 UI/L; P<0.0001), and ALP by 15.1% (606.2±35.5 vs. 514.4±12.6 UI/L; P=0.0339) within six months. Conclusion: Long-term and low-dose nitrate administration improved the liver function of rats with T2D, as reflected by the reduced serum levels of ALT, AST, and ALP.