glycogen and Diabetic-Retinopathy

The rod and cone systems of the mammalian retina differ in their structure and functional properties as well as in their metabolic characteristics. This article summarizes basic observations on retinal glucose metabolism reflected in retinal electrophysiology. Metabolic factors might be related to the complex pathogenesis of diabetic retinopathy. Effects of changing glucose concentration and, independently, of insulin on retinal responses obtained in an isolated mammalian eye preparation in vitro and also in vivo are presented. Electron microscopy (EM)-histochemical data reveal a distinctive distribution of glycogen in glia and in various subclasses of neurons in the cat retina. Low glucose, corresponding to hypoglycemia in vivo, affected the light-evoked electrical responses from the rod system, but not from the cone system in vitro. This could be confirmed in the anesthetized cat under glucose clamp conditions. Insulin had no influence on physiological retinal function, except under conditions of low glucose, where it enhanced the reduction in b-wave amplitude. This effect is interpreted as a sign of increased glucose utilization by the retinal Müller (glial) cells.

Topics: Animals; Blood Glucose; Cats; Diabetic Retinopathy; Electroretinography; Energy Metabolism; Glycogen; Hypoglycemic Agents; Insulin; Retina

Topics: Animals; Capillary Permeability; Coloring Agents; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Evans Blue; Glycogen; Neurotransmitter Agents; Rats; Rats, Long-Evans; Retina; Retinal Vessels

Topics: Diabetic Retinopathy; Eye Proteins; Glycogen; Humans; In Vitro Techniques; Lactates; Lactic Acid; Macula Lutea; Microscopy, Electron; Retinal Diseases; Retinal Hemorrhage; Vitreous Body

The pathologies of diabetic micro- and macroangiopathy are different, suggesting that diabetes affects these two types of vascular tissue in a dissimilar manner. We have compared insulin receptors and the effects of insulin on cultured endothelium from calf retinal capillaries and aorta, and the vascular supporting cells, retinal pericytes, and aortic smooth muscle cells. 125I-insulin binds to high affinity insulin receptors on all four cell types. Receptor concentrations were similar except for aortic smooth muscle cells, which have 10-fold fewer receptors than the other cell types. Insulin at a concentration of 10 ng/ml stimulated [14C]glucose incorporation into glycogen in retinal endothelial cells and pericytes and aortic smooth muscle cells, but had no effect on aortic endothelium. Insulin over a concentration range of 10 ng/ml-10 microgram/ml, stimulated [3H]thymidine incorporation into the DNA of retinal pericytes, and endothelial cells and aortic smooth muscle cells but had no effect on aortic endothelial cells. These data suggested that a differential response to insulin may exist between endothelium of micro- and macrovasculature, and suggest that retinal capillary endothelium and retinal pericytes are both very insulin-sensitive tissues.

Topics: Animals; Aorta; Cattle; Diabetes Mellitus, Experimental; Diabetic Angiopathies; Diabetic Retinopathy; DNA; Endothelium; Glucose; Glycogen; Humans; Insulin; Muscle, Smooth, Vascular; Receptor, Insulin; Thymidine

Capillaries from bovine, monkey, and human retinas maintained in tissue culture produced a monolayer of cells. Autoradiographic and electron microscopic evidence indicated that the mural cells (intramural pericytes) were the cells that proliferated. Since intramural pericytes are damaged selectively in diabetes mellitus, their availability in culture will be useful in seeking means to control diabetic retinopathy.

Topics: Animals; Capillaries; Cattle; Cells, Cultured; Diabetic Retinopathy; Glycogen; Haplorhini; Humans; Macaca mulatta; Retinal Vessels; Thymidine

Topics: Animals; Cricetinae; Diabetes Mellitus; Diabetic Ketoacidosis; Diabetic Nephropathies; Diabetic Retinopathy; Disease Models, Animal; Female; Glucose; Glycogen; Glycosuria; Histocytochemistry; Islets of Langerhans; Kidney; Male; Retina

Topics: Animals; Antigens; Basement Membrane; Body Weight; Capillaries; Diabetic Retinopathy; Disease Models, Animal; Endothelium; Eye; Glycogen; Hyperglycemia; Inclusion Bodies; Injections, Intravenous; Insulin; Microscopy, Electron; Mitochondria; Plasma Cells; Polyuria; Rats; Retina; Retinal Vessels; Streptozocin; Time Factors; Trypsin

Topics: Animals; Carbon Isotopes; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Glucosyltransferases; Glycogen; Insulin; Rats; Retina