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Experimental Diabetes (experimental + diabetes)
Selected AbstractsFunctional Impairment of Renal Organic Cation Transport in Experimental DiabetesBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2002Brett Grover The experiments compared the ability of renal cortex slices from streptozotocin-induced diabetic and non-diabetic rats to accumulate the model cation, 14C-tetraethylammonium under controlled conditions. Initial experiments demonstrated a progressive decline in tetraethylammonium accumulation with increasing duration of diabetes. The maximal decrease was observed at 21 days after streptozotocin injection. Time-dependent incubations revealed that tetraethylammonium uptake from both diabetic and non-diabetic rats followed a curvilinear pattern expected of an active process. However, at steady state the diabetic-derived slices accumulated a significant 38% less tetraethylammonium versus slices from non-diabetics. Concentration-dependent incubations of tetraethylammonium (0.01,10 mM, 60 min.) demonstrated saturable transport in both diabetic and non-diabetic slices with a significantly decreased capacity of diabetic-derived slices to accumulate tetraethylammonium. Cellular respiration rates in the two groups were not different. Insulin treatment of the diabetic rats prevented the transport decline. While the causative factor of the transport impairment in diabetes is unresolved, this study documents an aspect of diabetic nephropathy that has not been previously reported but which may have important implications for renal excretion of cationic drugs and toxicants. The results also provide a mechanism for the well-documented "protection phenomenon" by which the kidneys of diabetic rats are resistant to nephrotoxicity induced by the chemotherapeutic agent cisplatin. [source] The investigation of the ultrastructural neutrophil changes in alloxan-induced diabetes in rats: response to a chemotactic challengeCELL BIOCHEMISTRY AND FUNCTION, Issue 2 2004Nesrin Özsoy Abstract Experimental diabetes is one of the most popular conditions in which to study the relation between neutrophil leukocyte activity and periodontal destruction. The aetiology of neutrophil dysfunction in the gingival tissue associated with diabetes has yet to be clarified. Diabetes in rats decreases neutrophil chemotactic activity in proportion to the severity of this systemic disorder. The present study was carried out to evaluate the relationship between the severity of diabetes and the neutrophil response to two chemotactic agents, and to correlate the observed neutrophil defects with the degree of diabetes. In this study two chemotactic agents, casein (0.2,,l, 2,mg,ml,1) or N-formylmethionylleucylphenylalanine (FMLP; 0.2,,l, 10,4,M), were placed into the gingival crevices of alloxan-induced diabetic rats. Gingival biopsies were taken 15,min later and then at 5-min intervals up to 45,min and investigated by electron microscopy. Adherence and migration were observed in the rats with moderate diabetes 30,min after the application of casein. There was chemotaxis after 35,min of administration of the peptide FMLP. By 40,min neutrophils with pyknotic nuclei were observed. At 45,min neutrophils with a decreased number of granules were present. As the severity of the diabetes increased, the neutrophils degenerated and were structurally distorted. In the rats which had alloxan-induced diabetes there was abnormal periodontal damage. This damage is thought to be related to dysfunctional neutrophils. These findings many contribute to an answer to the following question: why is there an apparent variability in the susceptibilty of periodontal breakdown in diabetics? Copyright © 2003 John Wiley & Sons, Ltd. [source] Insulin mimetic effects of macrocyclic binuclear oxovanadium complexes on streptozotocin-induced experimental diabetes in ratsDIABETES OBESITY & METABOLISM, Issue 6 2003B. Ramachandran Aim:, The vanadium complexes so far tested for their insulin mimetic effects are either mono- or binuclear and contain only acyclic ligands. The leaching or hydrolysis of vanadyl ions from these complexes is much easier, and hence they elicit side effects. In the present study, a new binuclear macrocyclic oxovanadium complex was synthesized, and its efficacy was studied on streptozotocin (STZ)-induced diabetic rats over a period of 30 days. Methods:, The insulin mimetic effect of the complex was tested on the blood sugar level in the STZ-diabetic rats and on the activities of the carbohydrate-metabolizing enzymes present in the liver. Results:, Administration of vanadium complex to STZ-induced diabetic rats decreased blood glucose levels from hyperglycaemic to normoglycaemic when compared to diabetic rats. The activity of carbohydrate-metabolizing enzymes such as hexokinase, glucose-6-phosphate dehydrogenase, glycogen synthase and glycogen content were increased to near normal in vanadium complex-administered diabetic rats. The biochemical studies such as assay of blood urea and glutamate oxaloacetate transaminases revealed that the complex is not toxic to the system. Conclusion:, The nontoxic nature of this complex may be due to the presence of the vanadyl ions in an intact macrocyclic form. Further, the vanadyl ions present in the macrocyclic binuclear oxovanadium complex are very close to each other, and this may enhance the insulin mimetic activity by synergic effect. [source] C-Peptide Deficiency: An Important Pathogenetic Factor In Type 1 Diabetic NeuropathyJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 3 2000Aaf Sima Background: C-peptide has insulin-like effects and ameliorates the acute nerve conduction defect (NCD) in experimental and human type 1 diabetic neuropathy (DN). Methods: In this study, diabetic BB/Wor-rats were treated with rat C-peptide (75 ng/kg) from onset of diabetes for 8 months (prevention-group, PG). In a separate experiment, 5-mo untreated diabetic BB/Wor-rats were started on the same C-peptide treatment continued to 8 mo of diabetes (intervention group, IG). Results: In the PG, the NCD was significantly decreased (p < 0.001) compared to untreated BB/Wor-rats and was similar to that of normo-C-peptidemic and isohyperglycemic type 2 BBZ rats. This effect was associated with significant preventions of nodal changes (p < 0.001) including axo-glial dysjunction (p < 0.001), which was not different from non-diabetic control rats. Axonal atrophy and Wallerian degeneration were significantly prevented (both p < 0.05). In the IG, the NCD decreased significantly (p < 0.01) during the 3 mo treatment period. Associated with the functional improvement, nodal changes improved significantly (p < 0.001) as did axonal degenerative changes (p < 0.01). C-peptide treatment in the IG resulted in a significant increase in the frequency of regenerating fibers (p < 0.001) compared with untreated 5 mo diabetic rats. Conclusion: These studies demonstrate that C-peptide replacement in type 1 diabetes prevents the chronic NCD and structural changes. Furthermore, C-peptide treatment significantly improves the already established functional and structural abnormalities of DN. This is the first demonstration of a therapeutic improvement of established neuropathy in experimental diabetes. We conclude that C-peptide deficiency in type 1 diabetes is an important pathogenetic component of DN and that its replacement may provide a valuable adjunct to intensive insulin treatment. [source] Inhibitors of advanced glycation end-products prevent loss of enteric neuronal nitric oxide synthase in diabetic ratsNEUROGASTROENTEROLOGY & MOTILITY, Issue 3 2008P. V. S. Jeyabal Abstract, Gastrointestinal dysfunction is common in diabetes, and several studies indicate that loss of neuronal nitrergic inhibition may play an important role in its pathogenesis. However, the mechanisms responsible for this effect remain largely unknown. We have previously shown that advanced glycation end-products (AGEs) formed by non-enzymatic glycation dependent processes, can inhibit the expression of intestinal neuronal nitric oxide synthase (nNOS) in vitro acting via their receptor, receptor for AGEs. We now hypothesized that this effect may also be important in experimental diabetes in vivo. We aimed to evaluate the role of AGEs on duodenal nNOS expression and the effects of aminoguanidine (a drug that prevents AGE formation) and ALT-711 (AGE cross-link breaker) in experimental diabetes. Streptozotocin induced diabetic rats were randomized to no treatment, treatment with aminoguanidine (1 g L,1 daily through drinking water) at the induction of diabetes, or treatment with ALT-711 (3 mg kg,1 intraperitoneally), beginning at week 6. A fourth group was used as healthy controls. We performed real time polymerase chain reaction, Western blotting and immunohistochemistry to detect nNOS expression. AGE levels were analysed using sandwich ELISA. Diabetes enhanced accumulation of AGEs in serum, an effect that was prevented by treatment with aminoguanidine and ALT-711. Further, diabetic rats showed a significant reduction in duodenal nNOS expression by mRNA, protein and immunocytochemistry, an effect that was prevented by aminoguanidine. ALT-711 had similar effects on nNOS protein and immunohistochemistry (but not on mRNA levels). The generation of AGEs in diabetes results in loss of intestinal nNOS expression and may be responsible for enteric dysfunction in this condition. This study suggests that treatment directed against AGEs may be useful for the treatment of gastrointestinal complications of diabetes. [source] The effect of streptozotocin-induced diabetes on cardiac ,-adrenoceptor subtypes in the ratAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 1 2001D. J. Sellers 1,The present study investigates the effect of short-term experimental diabetes of 14-days duration on the ,-adrenoceptor subtypes of the rat heart. 2,,-adrenoceptor-mediated functional responses to submaximal doses of isoprenaline were enhanced in Langendorff-perfused hearts from diabetic rats, manifested as greater changes in tension, heart rate and rates of tension development (+dT/dt) and decline (,dT/dt). 3,Radioligand binding data demonstrated that total cardiac ,-adrenoceptor density and affinity for [3H]-dihydroalprenolol was unchanged by diabetes, although a decrease in ,1 -adrenoceptor density and increase in ,2 -adrenoceptor density was observed. 4,In conclusion, hearts from 14-day streptozotocin-induced diabetic rats demonstrate a number of alterations within the ,-adrenoceptor system. However, the enhanced ,-adrenoceptor-mediated responses to isoprenaline were not caused by an overall increase in density of ,-adrenoceptors, but were accompanied by changes in the ratio of the ,-adrenoceptor subtypes. [source] Using gene chips to identify organ-specific, smooth muscle responses to experimental diabetes: potential applications to urological diseasesBJU INTERNATIONAL, Issue 2 2007Jason D. Hipp OBJECTIVE To identify early diabetes-related alterations in gene expression in bladder and erectile tissue that would provide novel diagnostic and therapeutic treatment targets to prevent, delay or ameliorate the ensuing bladder and erectile dysfunction. MATERIALS AND METHODS The RG-U34A rat GeneChip® (Affymetrix Inc., Sunnyvale, CA, USA) oligonucleotide microarray (containing ,8799 genes) was used to evaluate gene expression in corporal and male bladder tissue excised from rats 1 week after confirmation of a diabetic state, but before demonstrable changes in organ function in vivo. A conservative analytical approach was used to detect alterations in gene expression, and gene ontology (GO) classifications were used to identify biological themes/pathways involved in the aetiology of the organ dysfunction. RESULTS In all, 320 and 313 genes were differentially expressed in bladder and corporal tissue, respectively. GO analysis in bladder tissue showed prominent increases in biological pathways involved in cell proliferation, metabolism, actin cytoskeleton and myosin, as well as decreases in cell motility, and regulation of muscle contraction. GO analysis in corpora showed increases in pathways related to ion channel transport and ion channel activity, while there were decreases in collagen I and actin genes. CONCLUSIONS The changes in gene expression in these initial experiments are consistent with the pathophysiological characteristics of the bladder and erectile dysfunction seen later in the diabetic disease process. Thus, the observed changes in gene expression might be harbingers or biomarkers of impending organ dysfunction, and could provide useful diagnostic and therapeutic targets for a variety of progressive urological diseases/conditions (i.e. lower urinary tract symptoms related to benign prostatic hyperplasia, erectile dysfunction, etc.). [source] | ||||||||||