Diabetes mellitus is a growing health problem worldwide and is associated with severe liver complications. The aim of the present study is to analyse the status of metabolic and free-radical-scavenging enzymes and second messengers in the liver of streptozotocin (STZ)-induced diabetic rats, and to determine the hepatoprotective role of vitamin D 3 . All studies were performed using the liver of adult male Wistar rats. Gene expression studies were carried out using real-time PCR with specific probes. Second messenger levels were determined using 3 H-labelled Biotrak assay kits, and glucose uptake assay with D-[ 14 C]glucose. The present results show that there was a decrease in hepatic glucose uptake, malate dehydrogenase activity, glycogen content, inositol triphosphate (IP 3 ) and cyclic GMP levels, and superoxide dismutase, glutathione peroxidase, phospholipase C, cyclic AMP-responsive element-binding protein, vitamin D receptor (VDR) and insulin receptor (INSR) gene expression in the diabetic rats when compared with the controls (all P,0·05), while cyclic AMP levels and GLUT2 expression were increased (P,0·05). Treatment of the diabetic rats with vitamin D 3 and insulin reversed the altered parameters to near control values. In conclusion, the data suggest a novel role of vitamin D 3 in restoring impaired liver metabolism in STZ-induced diabetic rats by regulating glucose uptake, storage and metabolism. We demonstrated that the restoring effect of vitamin D 3 is mediated through VDR modulation, thereby improving signal transduction and controlling free radicals in the liver of diabetic rats. These data suggest a potential role for vitamin D 3 in the treatment of diabetes-associated hepatic complications.Key words: Vitamin D: Diabetes: Liver: Oxidative stress: Metabolism: Insulin Diabetes-associated complications are major causes of morbidity and mortality. The liver plays a unique role in glucose homeostasis. Because of its anatomical location, it is ideally suited to control the systemic supply of absorbed nutrients, and it is one of only two organs that both consume and produce substantial amounts of glucose. The central role of the liver in the maintenance of blood glucose levels is assured by complex regulation by metabolic substrates, insulin and other hormones (1) . Diabetes-associated hyperglycaemia and hypoinsulinaemia lead to the impairment of hepatic glucose and lipid metabolism. Virtually, the entire spectrum of liver diseases is seen in patients with diabetes, including liver cirrhosis, a significant cause of death in diabetic patients, even more relevant than CVD (2) . Interest in the development of novel antidiabetic agents has been fuelled by the intense complications due to therapeutic treatment of diabetes and associated liver failure (2,3) . An increased prevalence of diabetes has been observed in vitamin D-deficient individuals (4) , and our previous study has shown that vitamin D 3 treatment restores blood glucose homeostasis in streptozotocin (STZ)-induced diabetic rats (5) . Bind...

Diabetes is a global epidemic and more than 50% diabetic patients are also diagnosed with neuropathy, which greatly affects the quality of life of the patients. Available treatments are not always successful due to the limited efficacy and complications, such as addiction and dependency. Studies have implicated that high mobility group box1 (HMGB1) protein plays a crucial role in neuroinflammation and the development of neuropathic conditions. HMGB1 is a proinflammatory cytokine that can be released from necrotic cells in passive form or in response to inflammatory signals as an active form. HMGB1 is the ligand for the receptor for advanced glycation end products (RAGE), and toll-like receptors, (TLR)-2 and TLR4, which also indirectly activates C-X-C chemokine receptor type 4 (CXCR4). We investigated whether blocking of HMGB1 can reduce pain and inflammation in diabetic neuropathic animals to further understand the role of HMGB1 in diabetic neuropathy. Type 2 diabetic rats and mice were treated with natural inhibitor of HMGB1, glycyrrhizin (GLC) for five days/week for four weeks at a dose of 50 mg/kg per day by intraperitoneal injection. The animals were divided into three categories: naïve control, diabetic alone, diabetic with GLC treatment. All of the behavioral analyses were conducted before and after the treatment. The expression of inflammatory markers and changes in histone acetylation in the peripheral nervous system were measured by immunohistochemistry and Western blot analysis after the completion of the treatment. Our study revealed that TLR4, HMGB1, CXCR4, and Nod-like receptor protein 3 (NLRP3) levels were increased in the spinal and dorsal root ganglia (DRG) neurons of Type 2 diabetic mice and rats with painful neuropathy. GLC treatment inhibited the increases in TLR4, NLRP3, and CXCR4 expressions and improved the mechanical and thermal pain threshold in these animals. Immunohistochemical studies revealed that hyperglycemia mediated inflammation influenced HMGB1 acetylation and its release from the neurons. It also altered histone 3 acetylation in the microglial cells. The inhibition of HMGB1 by GLC prevented the release of HMGB1 as well as H3K9 acetylation. These findings indicate that the interruption of HMGB1 mediated inflammation could ameliorate diabetic neuropathy and might exhibit a unique target for the treatment.

No abstract

No abstract

No abstract