cytochrome-c-t and arjunolic-acid

Vascular inflammation and cardiac dysfunction are the leading causes of mortality and morbidity among the diabetic patients. Type 1 diabetic mellitus (T1DM) is associated with increased cardiovascular complications at an early stage of the disease. The purpose of the present study was to explore whether arjunolic acid (AA) plays any protective role against cardiovascular complications in T1DM and if so, what molecular pathways it utilizes for the mechanism of its protective action. Streptozotocin (STZ) was used to induce T1DM in experimental rats. Alteration in plasma lipid profile and release of membrane bound enzymes like LDH (lactate dehydrogenase) and CK (creatine kinase) established the association of hyperlipidemia and cell membrane disintegration with hyperglycemia. Hyperglycemia altered the levels of oxidative stress related biomarkers, decreased the intracellular NAD and ATP concentrations. Hyperglycemia-induced enhanced levels of VEGF, ICAM-1, MCP-1 and IL-6 in the plasma of STZ treated animals indicate vascular inflammation in T1DM. Histological studies and FACS analysis revealed that hyperglycemia caused cell death mostly via the apoptotic pathway. Investigating molecular mechanism, we observed NF-κB and MAPKs (p38 and ERK1/2) activations, mitochondrial membrane depolarization, cytochrome C release, caspase 3 activation and PARP cleavage in apoptotic cell death in the diabetic cardiac tissue. Treatment with AA (20 mg/kg body weight) reduced hyperglycemia, membrane disintegration, oxidative stress, vascular inflammation and prevented the activation of oxidative stress induced signaling cascades leading to cell death. Results suggest that AA possesses the potential to be a beneficial therapeutic agent in diabetes and its associated cardiac complications.

Topics: Animals; Antioxidants; Apoptosis; Chemokine CCL2; Cytochromes c; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Flow Cytometry; Hypoglycemic Agents; Intercellular Adhesion Molecule-1; Interleukin-6; Male; Mitochondria; Mitochondrial Membranes; Oxidative Stress; Rats; Reactive Oxygen Species; Signal Transduction; Triterpenes; Vascular Endothelial Growth Factor A

Increasing evidences in both experimental and clinical studies suggest that oxidative stress is involved in the pathogenesis of diabetic tissue damage. Pancreatic beta-cell death is the cause of decreased insulin production in diabetes. Streptozotocin (STZ) is widely used to induce experimental diabetes due to its ability to selectively target and destroy insulin producing pancreatic beta-cells via the formation of both reactive oxygen species (ROS) and RNS (reactive nitrogen species). This study investigated the prophylactic role of arjunolic acid (AA) against STZ-induced diabetes in the pancreas tissue of the Swiss albino rats (as a working model). We observed that STZ administration (at a dose of 65mg/kg body weight, injected in the tail vain) caused increased production of both ROS and RNS in the pancreas tissue of experimental animals. Formation of these reactive intermediates decreased the intracellular antioxidant defense, increased the levels of lipid peroxidation, protein carbonylation, serum glucose and TNF-alpha. Investigating the signaling pathways, we found that STZ administration caused the activation of phospho-ERK1/2, phospho-p38, NF-kappaB and destruction of mitochondrial transmembrane potential, release of cytochrome c as well as activation of caspase 3 in the pancreas tissue keeping the levels of total ERK1/2 and p38 significantly unchanged. Treatment of animals with AA (at a dose of 20mg/kg body weight, orally) both prior and post to the STZ administration effectively reduced these adverse effects by inhibiting the excessive ROS and RNS formation as well as by down-regulating the activation of phospho-ERK1/2, phospho-p38, NF-kappaB and mitochondrial dependent signal transduction pathways leading to apoptotic cell death. Combining all, these results suggest that AA plays some beneficial roles against STZ-induced diabetes.

Topics: Animals; Antioxidants; Apoptosis; Blood Glucose; Caspase 3; Cytochromes c; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Dose-Response Relationship, Drug; Hypoglycemic Agents; Lipid Peroxidation; Male; Membrane Potential, Mitochondrial; Mitochondria; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; NF-kappa B; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Pancreas; Phosphorylation; Protein Carbonylation; Rats; Reactive Nitrogen Species; Reactive Oxygen Species; Time Factors; Triterpenes; Tumor Necrosis Factor-alpha