Polyol pathway and modulation of ischemia-reperfusion injury in Type 2 diabetic BBZ rat hearts

We investigated the role of polyol pathway enzymes aldose reductase (AR) and sorbitol dehydrogenase (SDH) in mediating injury due to ischemia-reperfusion (IR) in Type 2 diabetic BBZ rat hearts. Specifically, we investigated, (a) changes in glucose flux via cardiac AR and SDH as a function of diabetes duration, (b) ischemic injury and function after IR, (c) the effect of inhibition of AR or SDH on ischemic injury and function. Hearts isolated from BBZ rats, after 12 weeks or 48 weeks diabetes duration, and their non-diabetic littermates, were subjected to IR protocol. Myocardial function, substrate flux via AR and SDH, and tissue lactate:pyruvate (L/P) ratio (a measure of cytosolic NADH/NAD+), and lactate dehydrogenase (LDH) release (a marker of IR injury) were measured. Zopolrestat, and CP-470,711 were used to inhibit AR and SDH, respectively. Myocardial sorbitol and fructose content, and associated changes in L/P ratios were significantly higher in BBZ rats compared to non-diabetics, and increased with disease duration. Induction of IR resulted in increased ischemic injury, reduced ATP levels, increases in L/P ratio, and poor cardiac function in BBZ rat hearts, while inhibition of AR or SDH attenuated these changes and protected hearts from IR injury. These data indicate that AR and SDH are key modulators of myocardial IR injury in BBZ rat hearts and that inhibition of polyol pathway could in principle be used as a therapeutic adjunct for protection of ischemic myocardium in Type 2 diabetic patients

Nerve collagens from diabetic and nondiabetic Sprague–Dawley and biobreeding rats: an atomic force microscopy study

Background Alterations in rat's nerve collagens due to diabetes may be related to the permanence of damage due to diabetic neuropathy. We (1) provide a methodology for determining the diameters of collagen fibers accounting for atomic force microscope (AFM) imaging artifacts, (2) present data on structural differences in sciatic nerve endoneurial, epineurial and tail tendon collagens of control and diabetic Sprague–Dawley and BioBreeding rats, and (3) compare results with literature values. Methods We measured collagen diameters and band spacing on endoneurial and epineurial sciatic nerve tissue, and tail tendon, in control and diabetic rats (STZ-induced 12-week diabetic SD and 16-week spontaneously diabetic BB rats). We also developed a model to interpret the raw AFM data. Results All types of fibrillar collagen diameters studied became larger for diabetic versus control animals. Values for diabetic and control collagen fiber diameters in SD rats were 78 nm and 72 nm for SN epineurium, and 49 nm and 43 nm for SN endoneurium. For diabetic and control BB rats, these values were 83 nm and 77 nm (SN epineurium) and 49 nm and 43 nm (SN endoneurium). Values of 161 nm and 125 nm were found for diabetic and control tail tendon of BB rats. No significant changes were observed in any of the five comparisons made in D-band spacings that ranged from 63 to 69 nm. Conclusions The best means we have found to reduce raw AFM data is to measure several diameters with a single scan, using valley-to-valley measurements. Structural, fibrillar collagens of the nerve and tendon become larger in rats exposed to prolonged diabetes. Copyright © 2003 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35243/1/372_ftp.pd

Genetics of the BB rat: association of autoimmune disorders (diabetes, insulitis, and thyroiditis) with lymphopenia and major histocompatibility complex class II

The BB/Wor rat develops spontaneous autoimmune diabetes mellitus and also frequently develops lymphocytic thyroiditis. To clarify the role of T cell lymphopenia and the major histocompatibility complex (MHC) in the development of these autoimmune disorders, we studied back-cross animals between the inbred thyroiditis and diabetes-prone BBNB/Wor subline (MHC RT1.AuBuDuCu) and three nonlymphopenic MHC-congenic rat strains: PVG.RT.1u (RT1.AuBuDuCu), PVG.R8 (RT1.AaBuDuCu), and PVG.R23 (RT1.AuBaDaCav1). We observed that 1) lymphopenia is absolutely required for the development of spontaneous diabetes and insulitis, and is usually associated with the development of thyroiditis; 2) the MHC region to the right of the class I RT1.A locus is strongly correlated with diabetes and insulitis; and 3) this region is also significantly associated with the development of thyroiditis, but the susceptibility of certain MHC class II alleles (u and a) for disease development is distinct for insulitis and thyroiditis. Furthermore, no recombination was observed between lymphopenia (lyp) and the neuropeptide Y (Npy) gene polymorphism, which confirmed that lyp maps very close to Npy. The present data suggest that spontaneous insulitis and thyroiditis in the BB/Wor rat develop through common immune defects involving T cell lymphopenia, but do not always segregate together due to disease-specific interactions with the MHC class II-linked genes