Pyrroloquinoline quinone (PQQ) has potential to ameliorate streptozotocin-induced diabetes mellitus and oxidative stress in mice: A histopathological and biochemical study

Enhanced oxidative stress and hyperglycemia are associated with diabetes mellitus (DM). As pyrroloquinoline quinone (PQQ) is known to protect cells from oxidative stress, the present study was undertaken to reveal the hitherto unknown effects of PQQ in DM and associated problems in different tissues. Forty two mice were randomly divided into six groups. Group I receiving only citrate buffer served as the normal control, while group II animals were injected with citrate buffer and PQQ at 20 mg/kg for 15 days and served as test drug control. Animals of groups III-VI were rendered diabetic by single dose of streptozotocin (STZ, 150 mg/kg body weight), following which PQQ at a dose of 5, 10 and 20 mg/kg, was injected to the animals of group IV, V and VI respectively for 15 days. At the end, alterations in serum indices such as glucose, different lipids, insulin, amylase, urea, uric acid, serum glutamate pyruvate transaminase and serum glutamate oxaloacetate transaminase; tissue antioxidants and histopathological alterations in liver, kidney and pancreas were evaluated. STZ-treated animals developed oxidative stress as indicated by a significant increase in tissue lipid peroxidation (LPO) and lipid hydroperoxide, serum glucose, total cholesterol, triglyceride and urea, with a parallel decrease in the levels of serum insulin and tissue antioxidants. When diabetic animals received different doses of PQQ, these adverse effects were ameliorated. However, 20 mg/kg of PQQ appeared to be most effective. Findings revealed for the first time that PQQ has the potential to mitigate STZ-induced DM and oxidative damage in different organs of mice, suggesting that it may ameliorate diabetes mellitus and associated problems.