Diabetic Fatty Rats Research Articles

Chronic melatonin treatment improves obesity by inducing uncoupling of skeletal muscle SERCA-SLN mediated by CaMKII/AMPK/PGC1α pathway and mitochondrial biogenesis in female and male Zücker diabetic fatty rats

Melatonin acute treatment limits obesity of young Zücker diabetic fatty (ZDF) rats by non-shivering thermogenesis (NST). We recently showed melatonin chronically increases the oxidative status of vastus lateralis (VL) in both obese and lean adult male animals. The identification of VL skeletal muscle-based NST by uncoupling of sarcoendoplasmic reticulum Ca2+-ATPase (SERCA)- sarcolipin (SLN) prompted us to investigate whether melatonin is a SERCA-SLN calcium futile cycle uncoupling and mitochondrial biogenesis enhancer. Obese ZDF rats and lean littermates (ZL) of both sexes were subdivided into two subgroups: control (C) and 12 weeks orally melatonin treated (M) (10 mg/kg/day). Compared to the control groups, melatonin decreased the body weight gain and visceral fat in ZDF rats of both sexes. Melatonin treatment in both sex obese rats restored the VL muscle skin temperature and sensitized the thermogenic effect of acute cold exposure. Moreover, melatonin not only raised SLN protein levels in the VL of obese and lean rats of both sexes; also, the SERCA activity. Melatonin treatment increased the SERCA2 expression in obese and lean rats (both sexes), with no effects on SERCA1 expression. Melatonin increased the expression of thermogenic genes and proteins (PGC1-α, PPARγ, and NRF1). Furthermore, melatonin treatment enhanced the expression ratio of P-CaMKII/CaMKII and P-AMPK/AMPK. In addition, it rose mitochondrial biogenesis. These results provided the initial evidence that chronic oral melatonin treatment triggers the CaMKII/AMPK/PGC1α axis by upregulating SERCA2-SLN-mediated NST in ZDF diabetic rats of both sexes. This may further contribute to the body weight control and metabolic benefits of melatonin.

Cardioprotective effects of aerobic training in diabetic rats: Reducing cardiac apoptotic indices and oxidative stress for a healthier heart.

The present study evaluated the effects of aerobic training with variable intensities on apoptotic indices of cardiac tissue in fatty diabetic rats. Twenty-four male Wistar rats were randomly divided into non-diabetic (ND, n=8), trained diabetic (TD, n=8), and control diabetic (CD, n=8) groups. Following a high-fat dietary regimen, type 2 diabetes was induced by streptozotocin, with blood glucose levels above 300 mg/dL considered indicative of diabetes. The TD group underwent aerobic exercise five times a week for six weeks. Subsequently, measurements were taken for left ventricular end-diastolic (LVEDV) and end-systolic volumes (LVESV), ejection fraction (EF%), catalase, caspase-9, P53, glucose, insulin, and HOMA-IR. Aerobic training led to a significant decrease in blood glucose levels (P < 0.01), caspase-9 (P < 0.05), HOMA-IR (P < 0.05), and P53 expression (P < 0.001) compared with the CD group. LVEDV and LVESV decreased significantly (P < 0.05 for both), while LVEF increased significantly (P < 0.05). Catalase activation showed an insignificant increase in the TD group pre- to post-training compared to CD. Incremental aerobic exercise training (6 weeks) may exert a cardioprotective effect in diabetic rats by reducing apoptosis and oxidative stress indices, while simultaneously increasing aerobic fitness and reducing body weight.

Melatonin Improves Skeletal Muscle Structure and Oxidative Phenotype by Regulating Mitochondrial Dynamics and Autophagy in Zücker Diabetic Fatty Rat.

Obesity-induced skeletal muscle (SKM) inflexibility is closely linked to mitochondrial dysfunction. The present study aimed to evaluate the effects of melatonin on the red vastus lateralis (RVL) muscle in obese rat models at the molecular and morphological levels. Five-week-old male Zücker diabetic fatty (ZDF) rats and their age-matched lean littermates (ZL) were orally treated either with melatonin (10 mg/kg body weight (BW)/24 h) (M-ZDF and M-ZL) or non-treated (control) (C-ZDF and C-ZL) for 12 weeks. Western blot analysis showed that mitochondrial fission, fusion, and autophagy were altered in the C-ZDF group, accompanied by reduced SIRT1 levels. Furthermore, C-ZDF rats exhibited depleted ATP production and nitro-oxidative stress, as indicated by increased nitrites levels and reduced SOD activity. Western blotting of MyH isoforms demonstrated a significant decrease in both slow and fast oxidative fiber-specific markers expression in the C-ZDF group, concomitant with an increase in the fast glycolytic fiber markers. At the tissue level, marked fiber atrophy, less oxidative fibers, and excessive lipid deposition were noted in the C-ZDF group. Interestingly, melatonin treatment partially restored mitochondrial fission/fusion imbalance in the RVL muscle by enhancing the expression of fission (Fis1 and DRP1) markers and decreasing that of fusion (OPA1 and Mfn2) markers. It was also found to restore autophagy, as indicated by increased p62 protein level and LC3BII/I ratio. In addition, melatonin treatment increased SIRT1 protein level, mitochondrial ATP production, and SOD activity and decreased nitrites production. These effects were associated with enhanced oxidative phenotype, as evidenced by amplified oxidative fiber-specific markers expression, histochemical reaction for NADH enzyme, and muscular lipid content. In this study, we showed that melatonin might have potential therapeutic implications for obesity-induced SKM metabolic inflexibility among patients with obesity and T2DM.

Neuroprotective Effects of a Serotonin Receptor Peptide Following Sham vs. Mild Traumatic Brain Injury in the Zucker Rat.

Accelerated cognitive decline frequently complicates traumatic brain injury. Obesity and type 2 diabetes mellitus drive peripheral inflammation which may accelerate traumatic brain injury-associated neurodegeneration. The Zucker rat harbors G-protein coupled receptor agonist IgG autoantibodies and in vitro neurotoxicity caused by these autoantibodies was prevented by a novel synthetic fragment of the serotonin 2A receptor. The aim of the present study was to test whether genetic obesity manifested in Zucker diabetic fatty rat is associated with greater spatial memory impairment before and after mild traumatic brain injury compared to Zucker lean rats. Furthermore, we investigated whether these neurodegenerative complications can be lessened by administration of a novel putative neuroprotective peptide comprised of a fragment of the second extracellular loop of the serotonin 2A receptor. Age-matched lean and fatty diabetic Zucker rats were tested in the Morris water maze (spatial memory) prior to receiving a sham-injury or lateral fluid percussion (LFP) mild traumatic brain injury. Behavioral testing was repeated at 1-week, 1-month, and 3-month intervals following injury. A synthetic peptide consisting of a portion of the 5-hydroxytryptamine (serotonin) 2A receptor (2 mg/kg) (vehicle, or an inactive scrambled version of the peptide (2 mg/kg)) was administered via intraperitoneal route every other day for 7 days after sham or LFP injury to lean rats or 7 days before and after sham or LFP injury to fatty rats. Mild traumatic brain injury impaired recall of spatial memory in fatty and lean rats. Zucker fatty rats subjected to sham-injury or mild TBI experienced a significantly greater longitudinal decline in recall of spatial memory compared to lean Zucker rats. A synthetic peptide fragment of the 5-hydroxytryptamine 2A receptor significantly enhanced acquisition of spatial learning and it appeared to strengthen recall of spatial learning (one-week) after sham injury in Zucker rats. These data suggest that the Zucker diabetic fatty rat is a suitable animal model to investigate the role of metabolic factor(s) in accelerated cognitive decline. A novel synthetic peptide comprised of a fragment of the second extracellular loop of the human serotonin 2A receptor appeared to have neuroprotective effects on both acquisition and recall of spatial memory in subsets of Zucker rats, with relatively greater benefit in sham-injured, lean Zucker rats.

Empagliflozin treatment differentially modifies visceral and subcutaneous adipose tissue lipidomes and pro-inflammatory cytokines in zucker fatty diabetic rats

Abstract EMPA-REG OUTCOME (Empagliflozin, Cardiovascular Outcome Event Trial) trial highlighted the relevance of pharmacological inhibition of sodium-glucose cotransporter 2 (SGLT2) for the treatment of patients with type 2 diabetes mellitus (T2DM) and/or cardiovascular disease. Although the pathways through which SGLT2 inhibitors exert a beneficial effect on the cardiovascular system are still unknown, it has been suggested that energy metabolism regulation and a reduction of systemic inflammation could be some of the mechanisms implicated. Available data also suggests that empagliflozin treatment could be able to exert regulatory effects on adipose tissue (AT) depots. The aim of our study was to evaluate the impact of empagliflozin treatment on the lipidome of visceral (VAT) and subcutaneous adipose tissue (SAT) depots in a rat model of obesity and T2DM. Diabetic obese Zucker Fatty (ZDF) rats were treated with 30 mg/kg/day of empagliflozin p.o for 6 weeks. The lipidomes of VAT and SAT depots were analyzed using ultra-high performance liquid chromatography coupled to mass spectrometry. Empagliflozin's effect on pro-inflammatory markers in AT was analyzed by RT-PCR. In VAT, 18 metabolites were significantly altered in empagliflozin-treated rats vs. controls. Nearly all diglycerides tested (13 of 14) were significantly increased in treated rats, as the most notable altered chemical class. Furthermore, 3 oxidized fatty acids (FA) and FA like gadoleic acid and linoleic acid were also significantly increased. In SAT, a total of 14 metabolites were significantly altered. Most of them (13 of 14) were glycerophospholipids. Significantly lower levels of 4 lysophosphatidylethanolamines, 4 lysophosphatidylcholines, and 3 lysophosphatidylinositols and higher levels of 2 phosphatidylcholines were shown. In contrast to VAT, a significant decrease in most of these metabolites was observed in empagliflozin-treated samples. Several ratios of metabolites were also calculated to infer the potential enzyme activities related to lipid metabolism in both VAT and SAT. However, the ratios studied were only statistically significant in VAT of empagliflozin-treated rats vs. control, where the main potential enzyme activities altered were desaturases and elongases. Empagliflozin treatment also reduces the expression of the pro-inflammatory cytokines interleukin-1 beta (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNFα) and monocyte-chemotactic protein-1 (MCP-1) in VAT, with no changes in SAT, except for interleukin-13 (IL-13), which also decreases compared to untreated diabetic ZDF rats. In conclusion, empagliflozin increased oxidized FA and diglycerides in VAT and decreased glycerophospholipid levels in SAT. The anti-inflammatory effect of empagliflozin in VAT is not observed in SAT. The effect of empagliflozin on the regulation of the adipose tissue lipidome and inflammatory profile is different depending on the localization of the depots. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Boehringer Ingelheim Pharma GmbH and Co

Effect of electroacupuncture on protein expressions of SOCS3 and IRS-1 in hypothalamus and pancreas islet morphology in diabetic fatty rats

To observe the effect of electroacupuncture (EA) on protein expressions of suppressor of cytokine signaling 3 (SOCS3) and insulin receptor substrate-1 (IRS-1) in hypothalamus and morphology of pancreas islet in Zucker diabetic fatty (ZDF) rats, and to explore its possible mechanism on improving plasma glucose and insulin resistance of type 2 diabetes mellitus (T2DM). Twelve SPF male ZDF rats were selected and fed with high-fat diet for 4 weeks to establish the T2DM model, after modeling, the rats were randomly divided into a model group and an EA group, 6 rats in each one. Besides, 6 SPF male Zucker lean rats were selected as a blank group. In the EA group, EA was applied at "Pishu" (BL 20), "Weiwanxiashu" (EX-B 3), "Zusanli" (ST 36) and "Sanyinjiao" (SP 6), with continuous wave, 15 Hz in frequency, 2 mA in intensity, once a day, 20 min each time, 6 times a week for 4 weeks. The fasting plasma glucose (FPG) was measured before and after intervention. The serum level of fasting insulin (FINS) was measured by radioimmunoassay, and the homeostasis model assessment of insulin resistance index (HOMA-IR) was calculated; the morphological change of pancreas islets was observed by HE staining; the protein expressions of SOCS3 and IRS-1 in hypothalamus were detected by Western blot. Before intervention, compared with the blank group, FPG in the model group and the EA group was increased (P<0.01). After intervention, compared with the blank group, FPG, serum level of FINS and HOMA-IR were increased (P<0.01), the protein expression of SOCS3 was increased while IRS-1 was decreased in the hypothalamus in the model group (P<0.01). Compared with the model group, FPG, serum level of FINS and HOMA-IR were decreased (P<0.01), the protein expression of SOCS3 was decreased while IRS-1 was increased in the hypothalamus in the EA group (P<0.01). In the model group, the shape of pancreas islets was irregular, the area of pancreas islets and the number of islet β cell nuclei were decreased, the nuclei of islet β cell was compensatory enlargement. In the EA group, the shape and the area of pancreas islets and the number of islet β cell nuclei were improved, the compensatory increase of islet β cell nuclei was alleviated compared with the model group. Electroacupuncture can reduce the fasting plasma glucose, improve the morphology of pancreas islets, and alleviate the insulin resistance in ZDF rats. The mechanism may relate to the down-regulation of SOCS3 and up-regulation of IRS-1 in the hypothalamus, and improving the function of hypothalamus in regulating peripheral glucose metabolism.

851-P: Oral Long-Acting Menin Inhibitor Normalizes Type 2 Diabetes Mellitus (T2DM) in Two Rat Models

Menin is a scaffold protein that has been recognized for its role in T2DM as a key regulator of β-cell proliferation. Menin inhibition has previously been shown to improve glycemic control in diabetic mice. Herein, we report the first evidence that BMF-219, an orally bioavailable, selective, irreversible menin inhibitor, restores glycemic control in Zucker Diabetic Fatty (ZDF) Rat and Streptozotocin-induced Rat (STZ) models of T2DM. Rats were treated daily with BMF-219, vehicle, or pioglitazone for 16 days. BMF-2was well tolerated throughout the conduct of the study. BMF-2treatment resulted in a significant 50% reduction in fasting and non-fasting blood glucose levels, reduced serum insulin and c-peptide levels (p&amp;lt;0.05) , and reduced HOMA-IR (p&amp;lt;0.001) after two weeks of treatment in ZDF rats. BMF-2decreased glucose levels at all timepoints during an oral glucose tolerance test at Day 15 (AUC reduction of 54%, p&amp;lt;0.001) and at Day 29 (AUC reduction of 40%, p&amp;lt;0.05, ∼2 weeks after the last dose) in the ZDF model, indicating prolonged glycemic control. Strikingly, BMF-219, but not pioglitazone, reduced blood glucose levels during an OGTT in STZ animals (AUC reduction of 41%, p&amp;lt;0.05, see figure) . Significant reductions in blood lipemic levels (p&amp;lt;0.01) and body weight were observed in both models. Collectively, our data indicate the novel and marked potential of BMF-2as an oral, long-acting treatment for T2DM. Disclosure T. Butler: Employee; Biomea Fusion Inc. W. Li: None. B. Law: Stock/Shareholder; Biomea Fusion Inc., Mirum Pharmaceuticals. T. Archer: Employee; Biomea Fusion. T. Kinoshita: None. P. Somanath: Employee; Biomea Fusion, Inc. Stock/Shareholder; Biomea Fusion, Inc.

213-OR: Antidiabetic Potential of Novel, Long-Acting Amylin Analogue ZP8396 in ZDF Rats

Amylin improves glucose homeostasis through at least three distinct mechanisms of action, including prevention of the postprandial rise in plasma glucagon, slowing of gastric emptying, and increased satiety, leading to decreased caloric intake and potential weight loss. Clinical efficacy has been demonstrated with short-acting amylin analogue pramlintide. ZP8396, currently in phase 1 clinical testing, is a long-acting, amylin analogue designed to improve solubility, stability and allow for co-formulation with other relevant peptides. We previously reported that ZP8396 provides body weight reduction in DIO rats alone and in combination with semaglutide, a once-weekly GLP-1 agonist (Skarbaliene et al, Obesity Week 2021) . Here we investigated the antidiabetes potential of ZP8396 in Zucker Diabetic Fatty (ZDF) rats. The antidiabetes potential after a single subcutaneous (s.c.) injection of ZP8396 (nmol/kg) or vehicle was measured in ZDF rats (aged 12-13 weeks, n=10) , an animal model of type 2 diabetes, and continuously monitored for 168 h after dosing.ZP8396 induced a significant body weight loss in ZDF rats vs. vehicle group. A significant decrease in body weight was observed in rats treated with ZP8396 from initiation of the dosing and up to 96 h post-dose. In addition, single s.c. injection of ZP8396 showed a significant reduction in blood glucose levels at 24 h post-dose, reaching a 20 % difference in blood glucose levels vs. vehicle group (14,97±0,39 and 18,60±1,18 mmol/L, respectively; p &amp;lt;0.05) . Also, ZP8396 significantly reduced plasma glucagon levels, reaching a 55% difference in ZP8396-treated diabetic rats vs. vehicle group at 24 h post-dose (p &amp;lt;0.05) . In conclusion, in diabetic rat ZP8396 improved glycaemic status, supporting that long-acting amylin analogues may provide future valuable therapeutic options to manage diabetes. Further preclinical characterization of the antidiabetes effects of long-term treatment with ZP8396 is ongoing. Disclosure J.Skarbaliene: Employee; Zealand Pharma A/S, Stock/Shareholder; Zealand Pharma A/S. T.Baader-pagler: Employee; Boehringer Ingelheim International GmbH. P.Eriksson: Employee; Zealand Pharma A/S.

Fructose prevents the development of hyperglycaemia in WBN/Kob diabetic fatty rats via maintaining high insulin levels.

Fructose is considered to negatively affect type 2 diabetes mellitus (T2DM); however, there are contradictory reports. The present study aimed to elucidate the effects of fructose-rich diet (FRD) on glucose metabolism of Wistar Bonn Kobori (WBN/Kob) fatty diabetic (WBKDF) rats, a spontaneous T2DM model, and Wistar rats. Wistar Bonn Kobori fatty diabetic and Wistar rats were fed either FRD or standard diet (STD) for 4weeks. The food intake, body weight, plasma glucose and insulin were measured weekly. After the 4-week challenge, rats were subjected to an intravenous glucose tolerance test (IVGTT). The liver and pancreas were used for histological analysis. The 4-week challenge of FRD in Wistar rats did not cause hyperglycaemia, but increased insulin resistance (Homeostatic Model Assessment for Insulin Resistance [HOMA-IR]). Feeding WBKDF rats with a FRD accelerated obesity, but prevented the onset of severe hyperglycaemia via maintaining high plasma insulin levels. Homeostatic Model Assessment for Insulin Resistance in WBKDF rats was not changed by FRD feeding. Intravenous glucose tolerance test revealed that FRD feeding in Wistar rats did not affect glucose tolerance, but slightly increased the plasma insulin level. In contrast, FRD feeding in WBKDF rats significantly reduced the glucose tolerance, but insulin response was not improved. Fructose-rich diet feeding did not alter the β cell area in Wistar rats, but significantly increased it in WBKDF rats. In conclusion, FRD caused insulin resistance in Wistar rats, suggesting that fructose overconsumption is a risk factor for T2DM, whereas FRD inhibited severe hyperglycaemia by maintaining high insulin levels in WBKDF rats. Fructose may be a beneficial sugar for T2DM patients with severe obesity-induced insulin resistance.

Exercise Ameliorates Diabetic Kidney Disease in Type 2 Diabetic Fatty Rats.

Lifestyle improvement, including through exercise, has been recognized as an important mode of therapy for the suppression of diabetic kidney disease (DKD). However, the detailed molecular mechanisms by which exercise exerts beneficial effects in the suppression of DKD have not yet been fully elucidated. In this study, we investigate the effects of treadmill exercise training (TET) for 8 weeks (13 m/min, 30 min/day, 5 days/week) on kidney injuries of type 2 diabetic male rats with obesity (Wistar fatty (fa/fa) rats: WFRs) at 36 weeks of age. TET significantly suppressed the levels of albuminuria and urinary liver-type fatty-acid-binding protein (L-FABP), tubulointerstitial fibrosis, inflammation, and oxidative stress in the kidneys of WFRs. In addition, TET mitigated excessive apoptosis and restored autophagy in the renal cortex, as well as suppressed the development of morphological abnormalities in the mitochondria of proximal tubular cells, which were also accompanied by the restoration of AMP-activated kinase (AMPK) activity and suppression of the mechanistic target of rapamycin complex 1 (mTORC1). In conclusion, TET ameliorates diabetes-induced kidney injury in type 2 diabetic fatty rats.

Ocular changes –cataract and retinal lesion- in Spontaneously Diabetic Torii (SDT) fatty rats, an obese type 2 diabetic model

Cataract and retinopathy remain the preventable cause of blindness worldwide, and many pharmacological strategies have been proposed for the treatment of these eye diseases. Animal models play an important role in understanding the pathophysiological features of eye disease and developing for a new therapy. In this study, we investigated the development of cataract and retinal lesion with diabetes using an obese type 2 diabetic models SDT fatty rat. Macroscopic analysis in eyes was performed from 16 to 24 weeks of age and histological analysis was performed at 24 weeks of age. As a result, the lens cloudiness was observed from 19 weeks of age and the degree of the cloudiness was more progressed until 24 weeks of age. Histopathological findings, such as degeneration of lens fiber and shortening and irregular arrangement of cone and rod in retinal tissue, were observed at 24 weeks of age. In conclusion, SDT fatty rats may be useful to understand the pathological features in diabetic cataract and retinopathy develop a new therapy for the disease.

Melatonin Improves Endoplasmic Reticulum Stress-Mediated IRE1α Pathway in Zücker Diabetic Fatty Rat.

Obesity and diabetes are linked to an increased prevalence of kidney disease. Endoplasmic reticulum stress has recently gained growing importance in the pathogenesis of obesity and diabetes-related kidney disease. Melatonin, is an important anti-obesogenic natural bioactive compound. Previously, our research group showed that the renoprotective effect of melatonin administration was associated with restoring mitochondrial fission/fusion balance and function in a rat model of diabesity-induced kidney injury. This study was carried out to further investigate whether melatonin could suppress renal endoplasmic reticulum (ER) stress response and the downstream unfolded protein response activation under obese and diabetic conditions. Zücker diabetic fatty (ZDF) rats and lean littermates (ZL) were orally supplemented either with melatonin (10 mg/kg body weight (BW)/day) (M–ZDF and M–ZL) or vehicle (C–ZDF and C–ZL) for 17 weeks. Western blot analysis of ER stress-related markers and renal morphology were assessed. Compared to C–ZL rats, higher ER stress response associated with impaired renal morphology was observed in C–ZDF rats. Melatonin supplementation alleviated renal ER stress response in ZDF rats, by decreasing glucose-regulated protein 78 (GRP78), phosphoinositol-requiring enzyme1α (IRE1α), and ATF6 levels but had no effect on phospho–protein kinase RNA–like endoplasmic reticulum kinase (PERK) level. In addition, melatonin supplementation also restrained the ER stress-mediated apoptotic pathway, as indicated by decreased pro-apoptotic proteins phospho–c–jun amino terminal kinase (JNK), Bax, and cleaved caspase-3, as well as by upregulation of B cell lymphoma (Bcl)-2 protein. These improvements were associated with renal structural recovery. Taken together, our findings revealed that melatonin play a renoprotective role, at least in part, by suppressing ER stress and related pro-apoptotic IRE1α/JNK signaling pathway.

Beneficial effects of proximal intestinal bypass reconstruction on glucose metabolism in a type 2 diabetes animal model: a possible reconstruction strategy for diabetic gastric cancer patients.

PurposeProximal intestinal bypass (PIB), such as Billroth II or Roux-en-Y gastrojejunostomy after curative distal gastrectomy for gastric cancer induces beneficial effects on glycemic control in patients with type 2 diabetes. We aimed to characterize the long-term evolution of pancreatic beta cells and insulin signaling in target tissue after a PIB procedure.MethodsZucker diabetic fatty rats were randomly assigned to the PIB, sham-operated PIB pair-fed, and ad libitum fed groups. Oral glucose tolerance (GT) and plasma insulin levels were measured periodically at 16 weeks postoperatively. Histomorphometric analyses were performed to evaluate changes in islet architectures and intranuclear pancreatic duodenal homeobox 1 (PDX1) expression in beta cells. Insulin signaling changes in visceral adipocytes were measured by the phosphorylated Akt/Akt ratio.ResultsContrary to the progressively deteriorating GT and plasma insulin levels in sham-operated animals, these were preserved in PIB animals (P < 0.01) at 16 weeks postoperatively. The proportion of the islets having asteroid-like expanding projection was higher in PIB animals than in sham-operated animals (P < 0.01). PIB animals had 3-fold wider fractional area of beta cells (P < 0.01) and 3-fold higher proportion of beta-cell nuclear PDX1 expression (P < 0.01) than sham-operated animals. PIB animals had significantly higher levels of Akt phosphorylation in the visceral adipocytes (P < 0.05). The PIB did not substantially affect weight and food intake postoperatively.ConclusionThe PIB preserved the plasma insulin levels and the wider beta-cell area over time and facilitated insulin signaling in the visceral fats. It could be considered as a possible reconstruction strategy for diabetic gastric cancer patients.

Region-specific brain area reductions and increased cholecystokinin\xa0positive neurons in diabetic OLETF rats: implication for anxiety-like behavior

Metabolic disorders can induce psychiatric comorbidities. Both brain and neuronal composition imbalances reportedly induce an anxiety-like phenotype. We hypothesized that alterations of localized brain areas and cholecystokinin (CCK) and parvalbumin (PV) expression could induce anxiety-like behavior in type 2 diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats. Twenty-week-old OLETF and non-diabetic Long-Evans Tokushima Otsuka (LETO) rats were used. The areas of corticolimbic regions were smaller in OLETF rats. The densities of CCK positive neurons in the lateral and basolateral amygdala, hippocampal cornu ammonis area 2, and prelimbic cortex were higher in OLETF rats. The densities of PV positive neurons were comparable between OLETF and LETO rats. Locomotion in the center zone in the open field test was lower in OLETF rats. These results suggest that imbalances of specific brain region areas and neuronal compositions in emotion-related areas increase the prevalence of anxiety-like behaviors in OLETF rats.

Calorie restriction delays cardiac senescence and improves cardiac function in obese diabetic rats.

The aims of this study were to investigate the impact of caloric restriction (CR) on cardiac senescence in an animal model of diabetes and examine the signal transduction mechanisms for changes in cell survival as well as cardiac function. Male 8-week-old Otsuka Long-Evans Tokushima fatty (OLETF) diabetic rats were divided into 2 groups: a group fed ad libitum (AL), and a group fed with CR (30% energy reduction). Long-Evans Tokushima Otsuka (LETO) non-diabetic rats were used as controls. LETO rats were divided into 3 groups: a high fat diet (HFD) group with a 22% increase in caloric intake, a CR group, and a group fed AL. At 40weeks of age, the telomere length was significantly shorter in the heart tissue of HFD rats but was not altered by CR in experimental rats with or without CR, however, telomerase activity in both strains of CR rats was significantly elevated. Protein expression of IGF-1, Sirt 1 and phospho-FoxO1 was increased in both CR groups. Echocardiography showed that CR preserved LV diastolic function with a significantly shorter E-wave deceleration time and a greater E/A ratio compared with the AL groups. These findings suggest that CR protocol increased telomerase activity without changing of telomere length, enhanced autophagy and improved LV diastolic function in animal model of diabetes rats. It is finally suggested that those impacts may be important for the maintenance of normal cardiac function and for delayed cardiac aging.

Melatonin Improves Mitochondrial Dynamics and Function in the Kidney of Zücker Diabetic Fatty Rats.

Obesity and associated diabetes (diabesity) impair kidney mitochondrial dynamics by augmenting fission and diminishing fusion, which results in mitochondrial and renal dysfunction. Based on available evidence, the antioxidant activities of melatonin may improve impaired renal mitochondrial function in obese diabetic animals by restoring the imbalanced dynamics through inhibiting fission and promoting fusion. Male Zücker diabetic fatty (ZDF) rats and lean littermates (ZL) were orally treated either with melatonin (10 mg/kg BW/day) (M-ZDF and M-ZL) or vehicle (C-ZDF and C-ZL) for 17 weeks. Kidney function was evaluated by measurement of total urine volume, proteinuria, creatinine clearance, and assessment of kidney mitochondrial dynamics and function. C-ZDF exhibited impaired dynamics and function of kidney mitochondria in comparison to C-ZL. Melatonin improved nephropathy of ZDF rats and modulated their mitochondrial dynamics by reducing expression of Drp1 fission marker and increasing that of fusion markers, Mfn2 and Opa1. Furthermore, melatonin ameliorated mitochondrial dysfunction by increasing respiratory control index and electron transfer chain complex IV activity. In addition, it lowered mitochondrial oxidative status. Our findings show that melatonin supplementation improves nephropathy likely via modulation of the mitochondrial fission/fusion balance and function in ZDF rats.

Type 2 diabetes progression: A regulatory network approach.

In order to elucidate central elements underlying type 2 diabetes, we constructed a regulatory network model involving 37 components (molecules, receptors, processes, etc.) associated to signaling pathways of pancreatic beta-cells. In a first approximation, the network topology was described by Boolean rules whose interacting dynamics predicted stationary patterns broadly classified as health, metabolic syndrome, and diabetes stages. A subsequent approximation based on a continuous logic analysis allowed us to characterize the progression of the disease as transitions between these states associated to alterations of cell homeostasis due to exhaustion or exacerbation of specific regulatory signals. The method allowed the identification of key transcription factors involved in metabolic stress as essential for the progression of the disease. Integration of the present analysis with existent mathematical models designed to yield accurate account of experimental data in human or animal essays leads to reliable predictions for beta-cell mass, insulinemia, glycemia, and glycosylated hemoglobin in diabetic fatty rats.

Metalloproteins and apolipoprotein C: candidate plasma biomarkers of T2DM screened by comparative proteomics and lipidomics in ZDF rats

BackgroundEarly diagnosis of type 2 diabetes mellitus (T2DM) is still difficult. Screening of plasma biomarkers has great significance of optimizing diagnosis and predicting the complications of T2DM.MethodsWe used a special diet, Purina #5008, to induce diabetes in Zucker leptin receptor gene-deficient rats (fa/fa) to establish Zucker diabetic fatty (ZDF) rats, simulating the early stage of T2DM. The differentially expressed proteins (DEP) and lipids (DEL), as potential biomarkers, were screened to compare the plasma expression levels in ZDF rats and their basic diet-fed wild-type controls (fa/+) by Tandem Mass Tags (TMT) and liquid chromatography-tandem mass spectrometry.ResultsThese two groups had different plasma proteins and lipids profiles consisting of 84 DEPs and, 179 DELs identified in the positive ion mode and 178 DELs in the negative ion mode, respectively. Enrichment analysis of these different indicators showed that oxidative stress, insulin resistance and metabolic disorders of glycan and lipid played an important role in generating the difference. Some markers can be used as candidate biomarkers in prediction and treatments of T2DM, such as ceruloplasmin, apolipoprotein C-I, apolipoprotein C-II and apolipoprotein C-IV.ConclusionThese plasma differences help to optimize the diagnosis and predict the complications of T2DM, although this remains to be verified in the crowd. Trace elements related-metalloproteins, such as ceruloplasmin, and lipid metabolism and transport-related apolipoprotein C are expected to be candidate biomarkers of T2DM and should be given more attention.

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.

482-P: The GLP-1 Receptor Agonist Liraglutide Improves Glomerular Filtration Rate, Renal Inflammation, and Fibrosis in the Type 2 Diabetic SDT Fatty Rat

The Glucagon-Like Peptide 1 (GLP-1) receptor agonist liraglutide (LIRA) may reduce the rate of development and progression of diabetic kidney disease in type 2 diabetic patients. To evaluate its impact on kidney function, we evaluated the effects of LIRA on glomerular filtration rate (GFR), in both the hyperfiltration and GFR decline phases in the Spontaneously Diabetic Torii (SDT) fatty rat, a preclinical model of type 2 diabetes. SDT fatty male rats were treated subcutaneously, once daily with vehicle or LIRA 0.4mg/kg for 10 weeks. To measure the effects of LIRA on glomerular hyperfiltration, rats were injected with FITC-sinistrin at 4 weeks of treatment to measure GFR. After 5 weeks of treatment, rats underwent unilateral nephrectomy and were put on a 0.3% salt diet to induce a GFR decline for the last weeks of treatment, then GFR was measured at 10 weeks of treatment. Urine biochemistry and kidney histology analysis were also performed. Compared with vehicle, LIRA resulted in significant body weight loss and lower body weight. LIRA also reduced blood glucose levels significantly by up to ∼20%, as expected. During the hyperfiltration phase, LIRA attenuated hyperfiltration, with a 19% lower GFR vs. vehicle (vehicle: 21 ± 1.1 mL/min/kg; LIRA: 17.1 ± 1.0 mL/min/kg, p&amp;lt;0.05 vs. vehicle). In vehicle treated animals, unilateral nephrectomy and 0.3% salt diet induced a major reduction (-56%) in GFR, as expected. After 10 weeks of treatment, LIRA markedly attenuated this GFR decline (vehicle: 9.3 ± 0.5 mL/min/kg; LIRA: 13.3 ± 0.9 mL/min/kg, p&amp;lt;0.001 vs. vehicle). In line with the benefits observed on GFR, LIRA lowered urine albumin to creatinine ratio both in the hyperfiltration and GFR decline phases. Moreover, histology analysis showed that LIRA significantly reduced kidney inflammation and fibrosis scores, as compared with vehicle. In conclusion, LIRA shows significant benefits on GFR, renal inflammation and fibrosis in the SDT fatty rat model. Disclosure F. Briand: Employee; Self; Physiogenex. Stock/Shareholder; Self; Physiogenex. M. Shinohara: None. E. Brousseau: Employee; Self; Physiogenex. Y. Kageyama: None. T. Sulpice: Employee; Self; Physiogenex. Stock/Shareholder; Self; Physiogenex.