Project description:Diabetes is a disease now affecting more than 20 million people in the United States alone. When left untreated it has numerous debilitating effects including diabetic retinopathy, which is characterized by the death of retinal neurons as well as a breakdown of the retinal vascularization. This leads to nearly 24,000 cases of blindness each year among diabetic patients. Studies have shown the importance of both nitric oxide and the gene VEGF in retinopathy, however little is known about the condition's progression. This study would determine which genes are affected early in diabetes and more generally, give insite into how neural degeneration occurs in the retina. We aim to show the gene-level changes in the diabetic mouse retina five weeks after induction of diabetes. Our laboratory's primary focus is on NO production through nNOS, iNOS and endothelial (eNOS). We hope to be able to correlate some of the transcript level changes with genes known to be involved in the NO signalling pathways. Previous data by our lab and others have shown that neuronal nitric oxide synthase (nNOS) and inducible NOS (iNOS) are upregulated under diabetic conditions in the retina. Additional work in our lab has shown that the lack of nitric oxide (NO) produced by nNOS may affect neurotransmitter production, particularly with GABA. We have also shown that mice with induced diabetes show neurochemical changes in the retina after only one to three weeks. Thus, we expect to see gene level changes associated with the retina before psysological changes in newly diabetic mice. Adult CD1 mice of random sexes are injected with the drug streptozotocin on three successive days while fasting 8 hours before the injection. This drug selectivley destroys the beta-islet cells of the pancrease. Their blood sugar levels are then tested after a resting period. Mice with glucose levels above 250mg/dL are considered diabetic from the date of the last injection. Mice are then sacrificed after the waiting period by breif isoflourine inhalation followed by decapitation. Retinas are immediately removed in cold HBSS and RNA is extracted using Trizol extraction. To get adequate amounts of RNA, we will pool four retinas (2 animals) together.

Project description:Purpose. Patients with diabetic retinopathy may experience severe vision loss due to macular edema and neovascularization secondary to vascular abnormalities. However, before these abnormalities become apparent, there are functional deficits in contrast sensitivity, color perception, and dark adaptation. The goals of this study are to evaluate early changes (up to 3 months) in retinal gene expression, selected visual cycle proteins, and optokinetic tracking (OKT) in streptozotocin (STZ)-induced diabetic rats.Methods. Retinal gene expression in diabetic Long Evans rats was measured by whole genome microarray 7 days, 4 weeks, and three months after onset of hyperglycemia. Select gene and protein changes were probed by PCR and immunohistochemistry respectively, and OKT thresholds were measured using a virtual optokinetics system. Results. Microarray analysis showed that the most consistently affected molecular and cellular functions were cell-to-cell signaling and interaction, cell death, cellular growth and proliferation, molecular transport, and cellular movement. Further analysis revealed reduced expression of several genes encoding visual cycle proteins including lecithin:retinol acyltransferase (LRAT), retinal pigment epithelium (RPE)-specific protein 65kDa (RPE65) and RPE retinal G protein coupled receptor (RGR). Immunohistochemistry revealed a decrease in RPE65 in the RPE layer of diabetic rats. These molecular changes occurred simultaneously with a decrease in OKT thresholds by 4 weeks of diabetes. Conclusions. The data presented here are further evidence that inner retinal cells are affected by hyperglycemia prior to vasculopathy suggesting that glial and neuronal dysfunction may underlie some of the early visual deficits in diabetics. At each of the three timepoints (day 7, day 28, and day 84) one retina each from three diabetic rats were pooled for analysis on a single microarray chip. Three independent experiments were conducted for each group (n=9 animals/group). Each timepoint contained a hyperglycemic (STZ) and a control (buffer injection only) group. Additionally, on day 7 gene changes in the retina of rats which received a single injection of STZ, but did not develop hyperglycemia (STZ-non-c) were analyzed.

Project description:Diabetes is a disease now affecting more than 20 million people in the United States alone. When left untreated it has numerous debilitating effects including diabetic retinopathy, which is characterized by the death of retinal neurons as well as a breakdown of the retinal vascularization. This leads to nearly 24,000 cases of blindness each year among diabetic patients. Studies have shown the importance of both nitric oxide and the gene VEGF in retinopathy, however little is known about the condition's progression. This study would determine which genes are affected early in diabetes and more generally, give insite into how neural degeneration occurs in the retina. We aim to show the gene-level changes in the diabetic mouse retina five weeks after induction of diabetes. Our laboratory's primary focus is on NO production through nNOS, iNOS and endothelial (eNOS). We hope to be able to correlate some of the transcript level changes with genes known to be involved in the NO signalling pathways. Previous data by our lab and others have shown that neuronal nitric oxide synthase (nNOS) and inducible NOS (iNOS) are upregulated under diabetic conditions in the retina. Additional work in our lab has shown that the lack of nitric oxide (NO) produced by nNOS may affect neurotransmitter production, particularly with GABA. We have also shown that mice with induced diabetes show neurochemical changes in the retina after only one to three weeks. Thus, we expect to see gene level changes associated with the retina before psysological changes in newly diabetic mice. Adult CD1 mice of random sexes are injected with the drug streptozotocin on three successive days while fasting 8 hours before the injection. This drug selectivley destroys the beta-islet cells of the pancrease. Their blood sugar levels are then tested after a resting period. Mice with glucose levels above 250mg/dL are considered diabetic from the date of the last injection. Mice are then sacrificed after the waiting period by breif isoflourine inhalation followed by decapitation. Retinas are immediately removed in cold HBSS and RNA is extracted using Trizol extraction. To get adequate amounts of RNA, we will pool four retinas (2 animals) together. Keywords: dose response

Project description:There has been an incresing body of epidemiologic and biochemical evidence implying the role of cerebral insulin resistance in Alzheimer-type dementia. For a better understanding of the insulin effect on the central nervous system we performed microarray-based gene expression profiling in the hippocampus, striatum and prefrontal cortex of streptozotocin-induced and spontaneously diabetic Goto-Kakizaki rats as model animals for type 1 and type 2 diabetes, respectively. Following pathway analysis and validation of gene lists by RT-PCR, 30 genes from hippocampus, such as the inhibitory neuropeptide galanin, synuclein gamma and uncoupling protein 2, and 22 genes from the prefrontal cortex, e.g. galanin receptor 2, protein kinase gamma and epsilon, ABCA1, CD47 and the RET protooncogene, were found to exhibit altered expression levels in type 2 diabetic model animals in comparison to non-diabetic control animals. These gene lists proved to be partly overlapping and encompassed genes related to neurotransmission, lipidmetabolism, neuronal development, insulin secretion, oxidative damage and DNA repair. On the other hand, no significant alterations were found in the transcriptomes of the corpus sriatum in the same animals. Changes in the cerebral gene expression profiles seemed to be specific for the type 2 diabetic model, as no such alterations were found in streptozotocin-treated animals. According to our knowledge this is the first characterization of the whole-genome expression changes of specific brain regions in a diabetic model. Our findings shed light on the complex role of insulin signaling in fine-tuning brain functions, and provide further experimental evidence in support of the recently elaborated theory of type 3diabetes. Experiments were performed with 9 animals from each group. Wistar rats (control), streptoztocin-treated Wistar rats (type 1 diabetes) and Goto-Kakizaki rats (type 2 diabetes). The brain was removed and the striatum, hippocampus and prefrontal cortex were dissected. Samples from 3-3 identically treated animals were pooled. That means, 3 biological parallels were prepared from each brain region of type 1 or type 2 diabetic and control animals, amounting to a total of 27 different pooled samples.

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Whole genome microarray of the retina reveals a progressive response with increasing duration of diabetes.

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