SO022EVALUATION OF GLOMERULAR HEMODYNAMIC CHANGES BY SGLT2 INHIBITION IN TYPE 2 DIABETIC RATS USING IN VIVO IMAGING TECHNIQUES

Abstract Background and Aims In recent clinical trials, the SGLT2 inhibitor (SGLT2i) slowed the progression of kidney disease compared with the placebo in patients with type 2 diabetes. Improvement of glomerular hyperfiltration via tubuloglomerular feedback (TGF) is considered to be one of the possible pathways for renal protection with SGLT2 inhibition (SGLT2i) in diabetic kidney disease (DKD). We have successfully developed the novel method to measure single-nephron GFR (SNGFR) in mice using multiphoton laser microscopy and demonstrated that the adenosine/adenosine A1 receptor (A1aR) pathway plays a pivotal role in the TGF mechanism in the type 1 diabetic model, Akita mice (Kengo Kidokoro, David Z. I. Cherney et al. Circulation. 2019). It has been suggested that the mechanism of improvement effects in glomerular hyperfiltration by SGLT2i is different in type 1 diabetes and type 2 diabetes. However, the detailed regulatory mechanism of GFR by SGLT2i is not fully understood in type 2 diabetes. This study aims to clarify the effects of SGLT2i on glomerular hemodynamics in type 2 diabetic rats. Method Zucker lean (ZL) rats and Zucker diabetic fatty (ZDF) rats were used. In the first experiment, SNGFR and diameters of glomerular afferent/efferent arterioles were measured in both groups. Next, we examined the change of SNGFR and diameters of glomerular afferent/efferent arterioles, as well as urinary excretions of glucose and sodium in ZDF after a single-dose administration of SGLT2i (luseogliflozin; 10mg/kg, gavage) for 120 minutes, which generated the following three groups: SGLT2i group, SGLT2i + adenosine A1 receptor (A1aR) antagonist (8-cyclopentyl-1,3-dipropylxanthine, 1mg/kg) group, and insulin group. Results SNGFR in the ZDF group was significantly higher than in the ZL group. The diameter of the afferent arteriole and efferent arteriole was also wider in ZDF rats than in ZL rats. The SNGFR and diameter of the afferent arteriole were significantly decreased after a single-dose administration of SGLT2i in ZDF. However, there was no significant diameter change in the efferent arteriole. Moreover, a decrease of SNGFR was not observed in the A1aR antagonist group after SGLT2i administration. Urinary excretions of glucose and sodium showed a similar pattern in the SGLT2i and SGLT2i+ A1aR antagonist groups. Conclusion The adenosine/A1aR pathway plays an important role in the regulation of the tonus of the afferent arteriole and is involved in the suppression of glomerular hyperfiltration by SGLT2 inhibition in type 2 diabetes.

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Bardoxolone methyl analogs RTA 405 and dh404 are well tolerated and exhibit efficacy in rodent models of Type 2 diabetes and obesity

AJP Renal Physiology ◽

10.1152/ajprenal.00387.2012 ◽

2013 ◽

Vol 304 (12) ◽

pp. F1438-F1446 ◽

Cited By ~ 37

Author(s):

Melanie Chin ◽

Chun-Yue Ivy Lee ◽

Jen-Chieh Chuang ◽

Ron Bumeister ◽

W. Christian Wigley ◽

...

Keyword(s):

Type 2 Diabetes ◽

Renal Function ◽

Clinical Signs ◽

Diabetic Rats ◽

Rodent Models ◽

Zdf Rats ◽

Structural Injury ◽

Diabetes And Obesity

Bardoxolone methyl and related triterpenoids are well tolerated and efficacious in numerous animal models potentially relevant to patients with Type 2 diabetes and chronic kidney disease. These agents enhance glucose control and regulate lipid accumulation in rodent models of diabetes and obesity, and improve renal function, reduce inflammation, and prevent structural injury in models of renal disease. However, a recent study in Zucker diabetic fatty (ZDF) rats noted poor tolerability with the bardoxolone methyl analog RTA 405 within 1 mo after treatment initiation, although this study was confounded in part by the use of an impure RTA 405 batch. To investigate these discordant observations, the present studies were conducted to further characterize triterpenoids in rodent models of diabetes and obesity. A follow-up study was conducted in ZDF rats with two related triterpenoids (RTA 405 and dh404) for 1.5 mo. Consistent with previous rodent experience, and in contrast to the more recent ZDF report, ZDF rats administered RTA 405 or dh404 exhibited no adverse clinical signs, had laboratory values similar to controls, and exhibited no evidence of adverse liver or kidney histopathology. Additionally, RTA 405 was well tolerated in streptozotocin-induced Type 1 diabetic rats and high-fat-diet-induced obese mice. The present results are consistent with the overall published body of data obtained with triterpenoids and provide further evidence that these molecules are well tolerated without adverse effects on hepatobiliary or renal function in rodent models of diabetes and obesity.

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Boldine Does Not Modify Gender Specific Wound Healing in Zucker Diabetic Rats

Natural Product Communications ◽

10.1177/1934578x1801301116 ◽

2018 ◽

Vol 13 (11) ◽

pp. 1934578X1801301

Author(s):

Renata Köhlerová ◽

Eva Čermáková ◽

Milena Hajzlerová

Keyword(s):

Type 2 Diabetes ◽

Diabetic Rats ◽

Female Rats ◽

Male Rats ◽

Positive Effects ◽

Natural Alkaloid ◽

Anti Inflammatory ◽

Antioxidant Effects

Boldine is a natural alkaloid with anti-inflammatory and antioxidant effects. It reduces glycemia and decreases blood pressure in rats with type 1 diabetes. We have also studied whether boldine has anti-inflammatory and antioxidant effects in rats with type 2 diabetes and whether it can improve healing of their skin wounds, a serious comorbidity of type 2 diabetes. This work also compares lean and obese Zucker diabetic rats, including a comparison of both sexes. After skin excisions, the wounded animals received granules containing boldine ad libitum. The weights of rats, amount of consumed food and wound size were measured regularly. Scar and internal organs were removed and analyzed. Further, the tensile strength of the scar was tested and hydroxyproline content (a marker of collagen) measured. We have not confirmed previously published positive effects of boldine, but we observed important differences between gender and between genotypes. Male rats had higher body weight, liver, kidney and spleen than female rats. Furthermore, their wounds took longer to heal with bigger scar areas.

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Comparison of mechanisms and transferability of outcomes of SGLT2 inhibition between type 1 and type 2 diabetes

Endocrinology Diabetes & Metabolism ◽

10.1002/edm2.129 ◽

2020 ◽

Vol 3 (3) ◽

Author(s):

Oliver Schnell ◽

Paul Valensi ◽

Eberhard Standl ◽

Antonio Ceriello

Keyword(s):

Type 2 Diabetes ◽

Sglt2 Inhibition

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Type 2 diabetes: increased expression and contribution of IKCa channels to vasodilation in small mesenteric arteries of ZDF rats

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00240.2013 ◽

2014 ◽

Vol 307 (8) ◽

pp. H1093-H1102 ◽

Cited By ~ 20

Author(s):

Christian Schach ◽

Markus Resch ◽

Peter M. Schmid ◽

Guenter A. Riegger ◽

Dierk H. Endemann

Keyword(s):

Type 2 Diabetes ◽

Protein Expression ◽

Experimental Models ◽

Diabetic Rats ◽

Mesenteric Arteries ◽

Rt Pcr ◽

Mrna And Protein Expression ◽

Zdf Rats ◽

Endothelium Dependent Relaxation

Impaired endothelial function, which is dysregulated in diabetes, also precedes hypertension. We hypothesized that in Type 2 diabetes, the impaired endothelium-dependent relaxation is due to a loss of endothelium-derived hyperpolarization (EDH) that is regulated by impaired ion channel function. Zucker diabetic fatty (ZDF), Zucker heterozygote, and homozygote lean control rats were used as the experimental models in our study. Third-order mesenteric arteries were dissected and mounted on a pressure myograph; mRNA was quantified by RT-PCR and channel proteins by Western blotting. Under nitric oxide (NO) synthase and cyclooxygenase inhibition, endothelial stimulation with ACh fully relaxes control but not diabetic arteries. In contrast, when small-conductance calcium-activated potassium (KCa) channels and intermediate- and large-conductance KCa (I/BKCa) are inhibited with apamin and charybdotoxin, NO is able to compensate for ACh-induced relaxation in control but not in diabetic vessels. After replacement of charybdotoxin with 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34; IKCa inhibitor), ACh-induced relaxation in diabetic animals is attenuated. Specific inhibition with TRAM-34 or charybdotoxin attenuates ACh relaxation in diabetes. Stimulation with 1-ethyl-2-benzimidazolinone (IKCa activator) shows a reduced relaxation in diabetes. Activation of BKCa with 1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one NS619 leads to similar relaxations of control and diabetic arteries. RT-PCR and Western blot analysis demonstrate elevated mRNA and protein expression levels of IKCa in diabetes. Our results suggest that the compensatory effect of NO and EDH-associated, endothelium-dependent relaxation is reduced in ZDF rats. Specific blockade of IKCa with TRAM-34 reduces NO and EDH-type relaxation in diabetic rats, indicating an elevated contribution of IKCa in diabetic small mesenteric artery relaxation. This finding correlates with increased IKCa mRNA and protein expression in this vessel.

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Delayed bone regeneration and low bone mass in a rat model of insulin-resistant type 2 diabetes mellitus is due to impaired osteoblast function

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00378.2011 ◽

2011 ◽

Vol 301 (6) ◽

pp. E1220-E1228 ◽

Cited By ~ 75

Author(s):

Christine Hamann ◽

Claudia Goettsch ◽

Jan Mettelsiefen ◽

Veit Henkenjohann ◽

Martina Rauner ◽

...

Keyword(s):

Diabetes Mellitus ◽

Type 2 Diabetes ◽

Type 2 Diabetes Mellitus ◽

Bone Regeneration ◽

Rat Model ◽

Diabetic Rats ◽

Low Bone Mass ◽

Insulin Resistant ◽

Zdf Rats

Patients with diabetes mellitus have an impaired bone metabolism; however, the underlying mechanisms are poorly understood. Here, we analyzed the impact of type 2 diabetes mellitus on bone physiology and regeneration using Zucker diabetic fatty (ZDF) rats, an established rat model of insulin-resistant type 2 diabetes mellitus. ZDF rats develop diabetes with vascular complications when fed a Western diet. In 21-wk-old diabetic rats, bone mineral density (BMD) was 22.5% (total) and 54.6% (trabecular) lower at the distal femur and 17.2% (total) and 20.4% (trabecular) lower at the lumbar spine, respectively, compared with nondiabetic animals. BMD distribution measured by backscattered electron imaging postmortem was not different between diabetic and nondiabetic rats, but evaluation of histomorphometric indexes revealed lower mineralized bone volume/tissue volume, trabecular thickness, and trabecular number. Osteoblast differentiation of diabetic rats was impaired based on lower alkaline phosphatase activity (−20%) and mineralized matrix formation (−55%). In addition, the expression of the osteoblast-specific genes bone morphogenetic protein-2, RUNX2, osteocalcin, and osteopontin was reduced by 40–80%. Osteoclast biology was not affected based on tartrate-resistant acidic phosphatase staining, pit formation assay, and gene profiling. To validate the implications of these molecular and cellular findings in a clinically relevant model, a subcritical bone defect of 3 mm was created at the left femur after stabilization with a four-hole plate, and bone regeneration was monitored by X-ray and microcomputed tomography analyses over 12 wk. While nondiabetic rats filled the defects by 57%, diabetic rats showed delayed bone regeneration with only 21% defect filling. In conclusion, we identified suppressed osteoblastogenesis as a cause and mechanism for low bone mass and impaired bone regeneration in a rat model of type 2 diabetes mellitus.

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Abstract 136: Differential Effect of Nitric Oxide on the 26S Proteasome in Type 1 and Type 2 Diabetic Rats

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.32.suppl_1.a136 ◽

2012 ◽

Vol 32 (suppl_1) ◽

Author(s):

Monica P Rodriguez

Keyword(s):

Neointimal Hyperplasia ◽

Diabetic Rats ◽

26S Proteasome ◽

Diabetic Rat ◽

Rodent Models ◽

Protein Ubiquitination ◽

Zdf Rats ◽

Type 2 Diabetic

INTRODUCTION: We have shown that nitric oxide (NO) is more effective at inhibiting neointimal hyperplasia in rodent models of type 2 versus type 1 diabetes. To explain this difference, we looked at the 26S proteasome and deubiquitinating enzyme, USP5, since recent data revealed altered protein ubiquitination in diabetic environments. We hypothesize that NO has a differential effect on the 26S proteasome, the proteasomal activator, PA28-α, and/or USP5 in type 1 vs. 2 diabetic rat models. METHODS: The carotid artery injury model was performed in non-diabetic (LZ), type 1 (streptozotocin-injected LZ [STZ]), and type 2 diabetic (ZDF) rats. Groups included control, injury, and injury+PROLI/NO [n=4-7/group]. At 72hrs, carotid arteries were homogenized. PA28-α and USP5 expression was assessed by Western blot analysis. Vascular smooth muscle cells (VSMC) were harvested from LZ and ZDF rats and exposed to NO. After 24hrs, Western blot analysis for PA28-α and USP5, or the 26S activity assay was performed. RESULTS: ZDF arteries exhibited 2-fold more PA28-α expression versus STZ arteries. While NO caused a 2-fold decrease in PA28-α after injury in LZ arteries, NO caused complete inhibition in STZ and ZDF arteries versus injury alone. Similarly, ZDF arteries showed 2-fold more USP5 expression versus STZ arteries. While NO caused a decrease in USP5 expression in LZ arteries, NO exposure resulted in a doublet formation and no inhibition of USP5 in STZ and ZDF arteries versus injury alone. NO inhibited 26S proteasome activity (p<0.05), but there were no differences between LZ and ZDF VSMC. NO had no effect on USP5 expression in LZ and ZDF VSMC. However, treatment of VSMC with NO caused a concentration-dependent decrease in LZ and increase in ZDF PA28-α expression. CONCLUSION: NO caused significant early changes in PA28-α and USP5 in rodent models of type 1 and 2 diabetes versus non-diabetic rats. NO also increased expression of PA28-α in diabetic VSMC, but did not differentially affect proteasomal activity or protein deubiquitination in vitro. These data indicate a strong relationship between protein ubiquitination and degradation and the development of neointimal hyperplasia in diabetic rat models and may lead to a novel mechanism to prevent restenosis in diabetic patients.

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Effect of heat-killed Streptococcus thermophilus on type 2 diabetes rats

PeerJ ◽

10.7717/peerj.7117 ◽

2019 ◽

Vol 7 ◽

pp. e7117 ◽

Cited By ~ 1

Author(s):

Xiangyang Gao ◽

Fei Wang ◽

Peng Zhao ◽

Rong Zhang ◽

Qiang Zeng

Keyword(s):

Type 2 Diabetes ◽

Gut Microbiota ◽

Fasting Blood Glucose ◽

Streptococcus Thermophilus ◽

Diabetic Rats ◽

Inflammatory Factors ◽

Diabetic Rat ◽

Oral Glucose ◽

Zdf Rats

Background and Aims The link between gut microbiota and type 2 diabetes (T2D) has been addressed by numerous studies. Streptococcus thermophilus from fermented milk products, has been used as a probiotic in previous research. However, whether heat-killed S. thermophilus can improve the glycemic parameters of diabetic rats remains unanswered. In this study, we evaluated the effect of heat-killed S. thermophilus on T2D model rats and the potential mechanisms of the effect. Methods Zucker diabetic fatty (ZDF) rats were used to generate a diabetic rat model induced by feeding a high-fat diet. Heat-killed S. thermophilus were orally administered to normal and diabetic rats for 12 weeks. Intestinal microbiota analysis, histology analysis, oral glucose tolerance test and measurement of inflammatory factors were performed. Results We found that heat-killed S. thermophilus treatment reduced fasting blood glucose levels and alleviated glucose intolerance and total cholesterol in diabetic ZDF rats. Additionally, heat-killed S. thermophilus increased the interleukin 10 while reducing the levels of lipopolysaccharide, interleukin 6, and tumor necrosis factor-α in diabetic ZDF rats. The heat-killed S. thermophilus treatment can normalize the structure of the intestinal and colon mucosal layer of diabetic rats. The characteristics of the gut microbiota in heat-killed S. thermophilus-treated and control rats were similar. At the genus level, the abundances of beneficial bacteria, including Ruminococcaceae, Veillonella, Coprococcus, and Bamesiella, were all significantly elevated by heat-killed S. thermophilus treatment in ZDF diabetic rats. Conclusion Our study supports the hypothesis that treatment with heat-killed S. thermophilus could effectively improve glycemic parameters in T2D model rats. In addition, the potential mechanisms underlying the protection maybe include changing the composition of gut microbiota, reinforcing the intestinal epithelial barrier and the immunity of the intestinal mucosa, decreasing the level of inflammation, and then reducing the insulin resistance.

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