Exenatide and biotin in conjunction with a protein-sparing fast for normalization of beta cell function in type 2 diabetics

Microarray analysis of pancreatic gene expression during biotin repletion in biotin-deficient rats

Biotin is a B vitamin involved in multiple metabolic pathways. In humans, biotin deficiency is relatively rare but can cause dermatitis, alopecia, and perosis. Low biotin levels occur in individuals with type-2 diabetes, and supplementation with biotin plus chromium may improve blood sugar control. The acute effect on pancreatic gene expression of biotin repletion following chronic deficiency is unclear, therefore we induced biotin deficiency in adult male rats by feeding them a 20% raw egg white diet for 6 weeks. Animals were then randomized into 2 groups: one group received a single biotin supplement and returned to normal chow lacking egg white, while the second group remained on the depletion diet. After 1 week, pancreata were removed from biotin-deficient (BD) and biotin-repleted (BR) animals and RNA was isolated for microarray analysis. Biotin depletion altered gene expression in a manner indicative of inflammation, fibrosis, and defective pancreatic function. Conversely, biotin repletion activated numerous repair and anti-inflammatory pathways, reduced fibrotic gene expression, and induced multiple genes involved in pancreatic endocrine and exocrine function. A subset of the results was confirmed by quantitative real-time PCR analysis, as well as by treatment of pancreatic AR42J cells with biotin. The results indicate that biotin repletion, even after lengthy deficiency, results in the rapid induction of repair processes in the pancreas.

Mechanism of the beneficial and protective effects of exenatide in diabetic rats

Glucagon-like peptide 1 (GLP1) agonists are promising therapeutic agents in the treatment of diabetes mellitus. This study examines the mechanism of the protective effects of exenatide in experimental diabetes, employing four groups of ten rats each, in which two groups were streptozotocin-induced diabetic and two were control groups. One control and one diabetic group were treated with exenatide (1 μg/kg body weight (BW)) for 10 weeks. Blood plasma was taken for biochemical analyses while pancreatic tissue was taken for immunofluorescence and immunoelectron microscopy studies and real-time PCR to examine the expression of genes. The results show that exenatide improved BW gain and reduced blood glucose in diabetic rats compared with controls. Similarly, exenatide enhanced insulin release from the pancreatic fragments and improved liver and kidney functions and lipid profile in diabetic rats compared with controls. Exenatide not only induced significant increases in serum insulin level but also elevated the number of insulin-, GLP1- and exenatide-positive cells compared with untreated controls. Exenatide also elevated the number of catalase- and glutathione reductase-positive cells in diabetic rat pancreas compared with controls. Exenatide caused significant elevation in the expressions of pancreatic duodenal homeobox-1, heat shock protein-70, glutathione peroxidase, insulin receptor and GLP1 receptor genes in the pancreas of both control and diabetic rats compared with untreated animals. The results have demonstrated that exenatide can exert its beneficial and protective effects by elevating the levels of endogenous antioxidants and genes responsible for the survival, regeneration and proliferation of pancreatic β-cell.