Crescent-Like Lesions as an Early Signature of Nephropathy in a Rat Model of Prediabetes Induced by a Hypercaloric Diet

Abstract

Diabetic nephropathy (DN) is a major microvascular complication of diabetes. Obesity and hyperlipidemia, fueled by unhealthy food habits, are risk factors to glomerular filtration rate (GFR) decline and DN progression. Several studies recommend that diabetic patients should be screened early (in prediabetes) for kidney disease, in order to prevent advanced stages, for whom the current interventions are clearly inefficient. This ambition greatly depends on the existence of accurate early biomarkers and novel molecular targets, which only may arise with a more thorough knowledge of disease pathophysiology. We used a rat model of prediabetes induced by 23 weeks of high-sugar/high-fat (HSuHF) diet to characterize the phenotype of early renal dysfunction and injury. When compared with the control animals, HSuHF-treated rats displayed a metabolic phenotype compatible with obese prediabetes, displaying impaired glucose tolerance and insulin sensitivity, along with hypertriglyceridemia, and lipid peroxidation. Despite unchanged creatinine levels, the prediabetic animals presented glomerular crescent-like lesions, accompanied by increased kidney Oil-Red-O staining, triglycerides content and mRNA expression of IL-6 and iNOS. This model of HSuHF-induced prediabetes can be a useful tool to study early features of DN, namely crescent-like lesions, an early signature that deserves in-depth elucidation.

Blueberry Consumption Challenges Hepatic Mitochondrial Bioenergetics and Elicits Transcriptomics Reprogramming in Healthy Wistar Rats

“…During the first days of weeks 13 and 14, GTT and ITT were performed to assess the rats’ ability to tolerate a glucose load and to evaluate peripheral insulin sensitivity, respectively, as previously described [ 47 ]. For the GTT, after 6 h of fasting period (between 8:00 a.m. and 2:00 p.m.), conscious rats were intraperitoneally (i.p.)…”

“…To analyze genes of interest in colon tissue, gene expression quantification was performed as previously described [ 47 ]. Real-time PCR were conducted with a SYBR Green real-time PCR kit (Bio-Rad, Hercules, CA, USA), following the manufacturer’s recommendations and gene specific-primers for ZO-1 (Tjp1, Unique Assay ID: qRnoCID0001801), occludin (ocln; Unique Assay ID: qRnoCID0005733, Bio-Rad, Hercules, CA, USA), and mucin-2 (muc2; Unique Assay ID: qRnoCID0003629 Bio-Rad), which were normalized with GeNorm algorithm, where gene stability was attained with glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and hypoxanthine-guanine phosphoribosyltransferase (HPRT).…”

Blueberry Counteracts Prediabetes in a Hypercaloric Diet-Induced Rat Model and Rescues Hepatic Mitochondrial Bioenergetics

“…Following a one-week period of acclimatization, rats were arbitrarily assigned into 3 groups, in a 23-week protocol: control group, received standard chow and tap water (CTRL, n = 8); prediabetic group, received 35% sucrose (Hsu-84100; Sigma-Aldrich, St. Louis, MO, USA) in the drinking water plus standard chow until week 9, further supplemented by high-fat (HF) diet (58Y1, TestDiet, St. Louis, MO, USA) until week 23 (HSuHF, n = 10); and prediabetic group supplemented with BJ (HSuHF + BJ; n = 10), submitted to the same dietary regimen as the prediabetic group but received 25 g/kg BW/day of BJ (in 35% sucrose solution) between weeks 9 and 23. The development of prediabetes in rats, including the protocol of the dietary regimen and the duration, was performed based on our previous study [41].…”

“…injection of insulin solution (0.75 units/kg BW; Actrapid Novo Nordisk, Bagsvaerd, Denmark) in 6-h fasted rats. Blood glucose levels were measured in the tail vein blood collected immediately before (0 min) the injection and 15, 30, 45, 60, and 120 min after, using the same glucometer, as previously described [41]. The area under the curve (AUC) of GTT (AUC GTT ) and the rate constant for glucose clearance (KITT) were calculated as previously reported elsewhere [42,43].…”

“…Serum samples were prepared for the NMR analysis as described previously [41]. Liver metabolites were extracted from liquid N 2 ground samples using a Folch extraction [47].…”