Lean Zucker Rats Research Articles

Feeding of Hermetia illucens Larvae Meal Attenuates Hepatic Lipid Synthesis and Fatty Liver Development in Obese Zucker Rats.

The present study tested the hypothesis that dietary insect meal from Hermetia illucens (HI) larvae attenuates the development of liver steatosis and hyperlipidemia in the obese Zucker rat. To test the hypothesis, a 4-week trial with male, obese Zucker rats (n = 30) and male, lean Zucker rats (n = 10) was performed. The obese rats were assigned to three obese groups (group O-C, group O-HI25, group O-HI50) of 10 rats each. The lean rats served as a lean control group (L-C). Group L-C and group O-C were fed a control diet with 20% casein as protein source, whereas 25% and 50% of the protein from casein was replaced with protein from HI larvae meal in the diets of group O-HI25 and O-HI50, respectively. The staining of liver sections with Oil red O revealed an excessive lipid accumulation in the liver of group O-C compared to group L-C, whereas liver lipid accumulation in group O-HI25 and O-HI50 was markedly reduced compared to group O-C. Hepatic concentrations of triglycerides, cholesterol, C14:0, C16:0, C16:1, C18:0, C18:1, the sum of total fatty acids and hepatic mRNA levels of several genes associated with lipid synthesis and plasma concentration of cholesterol were markedly higher in group O-C than in group L-C, but lower in group O-HI50 than in group O-C (p < 0.05). In conclusion, partial replacement of casein by HI larvae meal attenuates liver steatosis and dyslipidemia in obese Zucker rats. This suggests that HI larvae meal serves as a functional food protecting from obesity-induced metabolic disorders.

PS-BPB06-1: GLOMERULAR HEMODYNAMIC CHANGES WITH SGLT2 INHIBITION IN TYPE 2 DIABETIC RATS USING IN VIVO IMAGING

Background and aim: Clinical trials have shown that sodium-glucose co-transporter 2 inhibitor (SGLT2i) not only reduce the risk of heart failure and cardiovascular events in people with type 2 diabetes, but also inhibit DKD progression. Improvement of glomerular hyperfiltration via tubuloglomerular feedback (TGF) is considered to be one of the possible pathways for renal protection with SGLT2i in DKD. However, the mechanisms responsible for kidney protection, especially in the setting of T2D, remain incompletely understood. In previous work, we established a method for measuring single nephron GFR (SNGFR) in mice using in vivo imaging and found that the adenosine/adenosine A1 receptor (A1aR) pathway is central for tubuloglomerular feedback (TGF) signaling and the pathogenesis of glomerular hyperfiltration in animal models of type 1 diabetes (Kidokoro K. et al. Circulation 2019). The mechanism of development of glomerular hyperfiltration, and improvement of glomerular hyperfiltration by SGLT2i may, however, be different in type 1 vs type 2 diabetes and related DKD. However, the detailed regulatory mechanism of GFR have not yet been elucidated in DKD related to T2D. Methods: 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; 10 mg/kg, gavage) for 120 minutes, which generated the following three groups: SGLT2i group, SGLT2i + adenosine A1 receptor (A1aR) antagonist (8-cyclopentyl-1,3-dipropylxanthine, 1 mg/kg) group, and insulin group. Results: SNGFR, afferent and efferent arteriole diameter were significantly increased in ZDF compared to ZL, with greater afferent vs. efferent dilatation. SGLT2i treatment resulted in correction of afferent arteriole vasodilation, with post-SGLT2i diameter that was comparable to baseline levels (p &gt; 0.05). Post-SGLT2i SNGFR was also similar compared to baseline levels. Changes in efferent arteriole diameter were not significant. The inhibitory effect on hyperfiltration by SGLT2i was abolished by the concomitant use of an A1aR antagonist. In contrast, urinary sodium and urinary glucose in SGLT2 inhibitor group increased significantly regardless of adenosine A1 receptor antagonist use. In response to SGLT2i, urinary adenosine and PGE2 increased significantly (p &gt; 0.05), while urine NOx did not change. Conclusion: Regulation of afferent arteriolar tone with SGLT2i is dependent on adenosine/ A1aR signaling an experimental model of T2D related hyperfiltration, regardless of ARB use.

Transcriptomic and proteomic pathways of diabetic and non-diabetic mitochondrial transplantation

Reduced mitochondrial function increases myocardial susceptibility to ischemia–reperfusion injury (IRI) in diabetic hearts. Mitochondrial transplantation (MT) ameliorates IRI, however, the cardioprotective effects of MT may be limited using diabetic mitochondria. Zucker Diabetic Fatty (ZDF) rats were subjected to temporary myocardial RI and then received either vehicle alone or vehicle containing mitochondria isolated from either diabetic ZDF or non-diabetic Zucker lean (ZL) rats. The ZDF rats were allowed to recover for 2 h or 28 days. MT using either ZDF- or ZL-mitochondria provided sustained reduction in infarct size and was associated with overlapping upregulation of pathways associated with muscle contraction, development, organization, and anti-apoptosis. MT using either ZDF- or ZL-mitochondria also significantly preserved myocardial function, however, ZL- mitochondria provided a more robust long-term preservation of myocardial function through the mitochondria dependent upregulation of pathways for cardiac and muscle metabolism and development. MT using either diabetic or non-diabetic mitochondria decreased infarct size and preserved functional recovery, however, the cardioprotection afforded by MT was attenuated in hearts receiving diabetic compared to non-diabetic MT.

Urine trace element disorder along with renal function injury in vitamin D deficient diabetic rats and intervention effect of 1α,25-dihydroxyvitamin D3.

Trace element metabolism disorders are often secondary to disorders of glucose metabolism in diabetes. Although 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] could ameliorate abnormal glucose metabolism in the development of diabetes, the effect on trace element metabolism is unclear. The objective of this study was to evaluate the influence of 1,25(OH)2D3 on urinary excretions of trace elements in Zucker diabetic fatty (ZDF) rats. At 6 weeks of age, male ZDF (n = 40) rats were subdivided into four groups: diabetic model (ZDF), low-dose (ZDF + VL, 2 μg/kg⋅bw), middle-dose (ZDF + VM, 8 μg/kg⋅bw) and high-dose (ZDF + VH, 16 μg/kg⋅bw) 1,25(OH)2D3 groups. Another 10 Zucker lean (ZL) rats served as a control group. All rats were given vitamin D deficient Purina #5008 chow and the intervention groups were given the corresponding dose of 1,25(OH)2D3 by gavage on alternate days for 7 weeks. Microalbuminuria (MALB) and urinary creatinine concentration were detected by a biochemical autoanalyzer. Urine trace element concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS) and were corrected by urinary creatinine. Throughout the intervention phase, MALB, UACR and urinary creatinine levels in the ZDF group were significantly higher than those in the ZL group, and showed a gradual increase with the prolongation of the intervention time. These changes were reversed in a dose-dependent manner after 1,25(OH)2D3 intervention (P < 0.05). Correspondingly, most of the urinary trace element excretions in the ZDF rats were significantly increased compared with the ZL group, and 1,25(OH)2D3 intervention significantly reduced the urinary copper (Cu), zinc (Zn), selenium (Se) and molybdenum (Mo) levels in the ZDF rats (P < 0.05), especially in the medium and high dose groups. 1,25(OH)2D3 had improvement effects on urinary Cu, Zn, Se, and Mo excretions in ZDF rats, suggesting that it may be related to the reduction of diabetic renal impairment and renal oxidative damage.

Contribution of calcium dysregulation to impaired coronary artery contraction in Zucker diabetic fatty rats.

Diabetic coronary artery injury is closely associated with Ca2+ dysregulation, although the underlying mechanism remains unclear. This study explored the role and mechanism of Ca2+ handling in coronary artery dysfunction in type 2 diabetic rats. Zucker diabetic fatty (ZDF) rats were used as the type 2 diabetes mellitus model. The contractility of coronary artery rings induced by KCl, CaCl2 , 5-HT and U46619 was significantly lower in ZDF rats than in Zucker lean rats. Vasoconstriction induced by 5-HT and U46619 was greatly inhibited by nifedipine. However, in the presence of 1μM nifedipine or in the Ca2+ -free KH solution containing 1μM nifedipine, there was no difference in the vasoconstriction between Zucker lean and ZDF rats. Store-operated calcium channels (SOCs) were not involved in coronary vasoconstriction. The downregulation of contractile proteins and the upregulation of synthesized proteins were in coronary artery smooth muscle cells (CASMCs) from ZDF rats. Metformin reversed the reduction of vasoconstriction in ZDF rats. Taken together, L-type calcium channel is important for regulating the excitation-contraction coupling of VSMCs in coronary arteries, and dysregulation of this channel contributes to the decreased contractility of coronary arteries in T2DM.

Replenishment of vitamin A for 7 days partially restored hepatic gene expressions altered by its deficiency in rats.

We investigated the effects of vitamin A (VA) status on metabolism of Zucker rats with different genders and genotypes, and of short-term refeeding of a VA sufficient (VAS) diet on VA deficient (VAD) animals. First, male and female Zucker lean (ZL) and fatty (ZF) rats at weaning were fed a VAD or VAS diet for 8 weeks. Second, male VAD ZL rats were fed a VAS diet for 3 (VAD-VAS3d) or 7 (VAD-VAS7d) days. The body weight (BW), blood parameters, and hepatic expressions of genes for metabolism were determined. VA deficiency reduced BW gain in ZL and ZF rats of either gender. VAD ZL rats had lower plasma glucose, insulin, and leptin levels than VAS ZL rats. VAD-VAS3d and VAD-VAS7d rats had higher plasma glucose, insulin, and leptin levels than that in the VAD rats. The hepatic mRNA levels of Gck, Cyp26a1, Srebp-1c, Igf1, Rarb, Rxra, Rxrg, Pparg, and Ppard were lowered by VA deficiency. Refeeding of the VAS diet for 3 days restored the Gck and Cyp26a1 expressions, and for 7 days restored the Gck, Cyp26a1, Igf1, and Rxrb expressions significantly. The 7-day VA replenishment partially restored the hepatic gene expressions and metabolic changes in VAD ZL rats.

Effects of salvianolic acid A on intestinal microbiota and lipid metabolism disorders in Zucker diabetic fatty rats

Salvianolic acid A (SalA) is the main water-soluble component isolated from Salvia miltiorrhiza. This study explored the influences of SalA on intestinal microbiota composition and lipid metabolism in Zucker diabetic fatty (ZDF) rats. The 6-week-old male ZDF rats were treated with distilled water (N = 10) and low dose (SalA 0.5 mg/kg/d, N = 10), medium dose (SalA 1 mg/kg/d, N = 10), and high dose (SalA 2 mg/kg/d, N = 10) of SalA, with the male Zucker lean normoglycemic rats of the same week age as controls (given distilled water, N = 10). The blood glucose, body weight, and food intake of rats were examined. After 7 and 8 weeks of continuous administration, oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed, respectively. Serum fasting insulin (FINS), total cholesterol (TC), triglyceride (TG), and free fatty acid (FFA) were determined. Liver tissues were stained using hematoxylin–eosin (HE) and oil red O staining. Fecal samples were analyzed by 16S rRNA gene sequencing. Small intestinal tissues were stained using HE and immunohistochemistry. The tight junction proteins (ZO-1/Occludin/Claudin-1) and serum levels of LPS/TNF-α/IL-6 were evaluated. SalA reduced insulin resistance, liver injury, serum FFA, liver TC and TG levels in ZDF rats, and improved lipid metabolism. After SalA treatment, intestinal microbiota richness and diversity of ZDF rats were promoted. SalA retained the homeostasis of intestinal core microbiota. SalA reduced intestinal epithelial barrier damage, LPS, and inflammatory cytokines in ZDF rats. Overall, SalA can sustain intestinal microbiota balance and improve the lipid metabolism of ZDF rats.

Effects of Isoprenaline on ventricular myocyte shortening and Ca2+ transport in the Zucker rat

Obesity is an important risk factor for diabetes mellitus (DM) which is a major global health problem. Electro-mechanical dysfunction has been extensively described in diabetic heart and cardiovascular complications are an important cause of mortality and morbidity in diabetic patients. ObjectivesTo examine the effects of Isoprenaline (ISO) in obesity and diabesity on ventricular myocyte shortening and Ca2+ transport in Zucker fatty (ZF), Zucker diabetic fatty (ZDF) in comparison to Zucker lean (ZL) rats. MethodsMyocyte shortening and intracellular Ca2+ were investigated with video imaging and fluorescence photometry, respectively. ResultsThe amplitude of Isoprenaline stimulated shortening was significantly (p < 0.05) decreased in ZDF and ZF compared to ZL myocytes. The amplitude of Isoprenaline stimulated Ca2+ transient was also significantly (p < 0.05) reduced in ZF compared to ZL and modestly reduced in ZDF compared to ZL myocytes. Mean Isoprenaline stimulated time to peak along with time to half relaxation of shortening were unchanged in ZDF and ZF compared to ZL myocytes. Mean Isoprenaline stimulated time to peak Ca2+ transient was significantly shortened in ZF compared to ZL myocytes. Time to half decay of the Ca2+ transient was considerably prolonged in ZDF compared to ZL myocytes. Amplitude of Isoprenaline stimulated caffeine-evoked Ca2+ transients were significantly reduced in ZDF and ZF in comparison to ZL myocytes. ConclusionIsoprenaline was less effective at generating an increase in the amplitude of shortening in ZDF and ZF in comparison to ZL myocytes and defects in Ca2+ signaling, and in particular SR Ca2+ transport, might partly underlie these abnormalities.

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.

Effects of Obesity and Diabesity on Ventricular Muscle Structure and Function in the Zucker Rat.

(1) Background: Cardiovascular complications are a leading cause of morbidity and mortality in diabetic patients. The effects of obesity and diabesity on the function and structure of ventricular myocytes in the Zucker fatty (ZF) rat and the Zucker diabetic fatty (ZDF) rat compared to Zucker lean (ZL) control rats have been investigated. (2) Methods: Shortening and intracellular Ca2+ were simultaneously measured with cell imaging and fluorescence photometry, respectively. Ventricular muscle protein expression and structure were investigated with Western blot and electron microscopy, respectively. (3) Results: The amplitude of shortening was increased in ZF compared to ZL but not compared to ZDF myocytes. Resting Ca2+ was increased in ZDF compared to ZL myocytes. Time to half decay of the Ca2+ transient was prolonged in ZDF compared to ZL and was reduced in ZF compared to ZL myocytes. Changes in expression of proteins associated with cardiac muscle contraction are presented. Structurally, there were reductions in sarcomere length in ZDF and ZF compared to ZL and reductions in mitochondria count in ZF compared to ZDF and ZL myocytes. (4) Conclusions: Alterations in ventricular muscle proteins and structure may partly underlie the defects observed in Ca2+ signaling in ZDF and ZF compared to ZL rat hearts.

Super-Resolution Ultrasound Imaging Provides Quantification of the Renal Cortical and Medullary Vasculature in Obese Zucker Rats: A Pilot Study.

Obesity is a risk factor of chronic kidney disease (CKD), leading to alterations in the renal vascular structure. This study tested if renal vascular density and tortuosity was quantifiable in vivo in obese rats using microbubble-based super-resolution ultrasound imaging. The kidneys of two 11-week-old and two 20-week-old male obese Zucker rats were compared with age-matched male lean Zucker rats. The super-resolution ultrasound images were manually divided into inner medulla, outer medulla, and cortex, and each area was subdivided into arteries and veins. We quantified vascular density and tortuosity, number of detected microbubbles, and generated tracks. For comparison, we assessed glomerular filtration rate, albumin/creatinine ratio, and renal histology to evaluate CKD. The number of detected microbubbles and generated tracks varied between animals and significantly affected quantification of vessel density. In areas with a comparable number of tracks, density increased in the obese animals, concomitant with a decrease in glomerular filtration rate and an increase in albumin/creatinine ratio, but without any pathology in the histological staining. The results indicate that super-resolution ultrasound imaging can be used to quantify structural alterations in the renal vasculature. Techniques to generate more comparable number of microbubble tracks and confirmation of the findings in larger-scale studies are needed.

Diet Containing Soy Protein Concentrate With Low and High Isoflavones for 9 Weeks Protects Against Non-alcoholic Fatty Liver Steatosis Using Obese Zucker Rats.

Non-alcoholic fatty liver disease (NAFLD), is one of the main liver diseases in the US and the world which often is related to obesity. Previously, we reported short- and long-term consumption of soy protein isolate diet with high isoflavones can reduce liver steatosis in the male and female obese Zucker rat model. However, the effects of high vs. low soy isoflavones on NAFLD is less known. The objectives of the present study were to examine the role of isoflavones levels in soy protein concentrate diets on protection against NAFLD in an obese rat model. Forty-two 6-week old lean (L, n = 21) and obese (O, n = 21) Zucker rats were randomly assigned to 1 of 3 dietary groups: casein diet (C = control), soy protein concentrate with low isoflavones (LIF), or soy protein concentrate with high isoflavones (HIF) for 9 weeks. Rats were weighed twice weekly. After 9 weeks, rats were sacrificed and samples of livers were taken for histopathological analysis. Serums were collected to measure ALT and AST levels. Results indicate that obese rats gained significantly more weight than lean rats for all three diet groups (P < 0.001). No significant difference in body weight between LC, LLIF and LHIF was noted. However, the OLIF and OHIF rats gained significantly more weight than OC rats (P < 0.001). Liver steatosis scores were significantly greater in obese rats compared to lean rats (P < 0.001). The OLIF and OHIF-fed rats had significantly reduced steatosis scores than OC rats (P = 0.013 and P < 0.001, respectively). The serum ALT levels were significantly greater in OC, OLIF and OHIF compared to LC, LLIF and LHIF, respectively (P < 0.001, P < 0.001, and P = 0.011). AST serum levels were greater in OC and OLIF compared to LC and LLIF, respectively (P = 0.001 and P = 0.022). In summary, we found that soy protein concentrate with isoflavones protects against liver steatosis and the protection is greater with a higher concentration of isoflavones.

Aerobic exercise training combined or not with okra consumption as a strategy to prevent kidney changes caused by metabolic syndrome in Zucker rats.

The complications of Metabolic Syndrome (MetS) include kidney disease, and most dialysis patients are diagnosed with MetS. The benefit of exercise training (ET) for MetS treatment is already well defined in the literature, but the antidiabetic and antihyperlipidemic benefits of okra (O) have been discovered only recently. The aim of this study was to evaluate the effects of O and/or ET supplementation on renal function and histology; serum urea and creatinine value; inflammation (IL-6, IL-10, TNF-α) and oxidative stress in renal tissue. For this, 32 Zucker rats (fa/fa) were randomly separated into four groups of 8 animals each: Metabolic Syndrome (MetS), MetS + Okra (MetS + O), MetS + Exercise Training (MetS + ET), and MetS + Exercise Training and Okra (MetS + ET + O), and 8 Zucker lean (fa/+) rats comprised the Control group (CTL). Okra was administered by orogastric gavage 2x/day (morning and night, 100 mg/kg) and ET performed on the treadmill, at moderate intensity, 1h/day, 5x/week for 6 weeks. Although the renal function was not altered, the animals with MetS showed greater fibrotic deposition accompanied by a worse stage of renal injury, in addition to increased kidney weight. Although all interventions were beneficial in reducing fibrosis, only ET combined with O was able to improve the degree of renal tissue impairment. ET improved the anti-inflammatory status and reduced nitrite levels, but the combination of ET and O was more beneficial as regards catalase activity. Okra consumption alone did not promote changes in inflammatory cytokines and oxidative stress in the kidney. In conclusion, ET combined or not with O seems to be beneficial in preventing the progression of renal disease when renal function is not yet altered.

Effects of 8 Weeks Feeding Diet with Low and High Isoflavones Soy Protein Concentrate on Serum Isoflavones in Non-alcoholic Fatty Liver Disease (NAFLD) Rat Model

ObjectivesTo examine the effects of 8 weeks feeding of low and high isoflavones levels in soy protein concentrate on the total serum isoflavones in a NAFLD obese rat model.Methods42 six-week old lean (L, n = 21) and obese (O, n = 21) Zucker rats were randomly assigned to 1 of 3 dietary groups: casein diet (C = control), soy protein with low isoflavones (LIF), or soy protein with high isoflavones (HIF) for 8 weeks (n = 7 rats/group). Rats were weighed twice weekly. After 8 weeks, all rats were sacrificed and serum for total isoflavones (genistein, daidzein and equol) were measured using a validated UPLC-MS/MS method and quantified utilizing stable-labeled internal standards.ResultsObese rats gained significantly more weight (P < 0.0001) than lean rats for all three diet groups. There was no detectable serum IF for both LC and OB groups. The mean ± SD for LIF vs HIF serum total IF (uM) for genistein were; (0.11 + 0.04 vs 2.55 + 1.04; p < 0.001), daidzein (0.07 + 0.02 vs 1.14 + 0.45; p < 001) and equol (0.07 + 0.03 vs 1.84 + 0.8; p < 0.001). For OLIF vs OHIF serum genistein were; (0.22 + 0.08 vs 3.69 + 1.52; p < 0.001), daidzein (0.12 + 0.04 vs 1.58 + 0.70; p < 001) and equol (0.06 + 0.03 vs 2.40 + 0.7; p < 0.001). Comparing serum genistein LLIF vs OLIF; p < 0.05 for Daidzein p < 0.05 and equol p = 0.86.ConclusionsHigh isoflavones soy protein concentrate compared to low isoflavones increased serum genistein and daidzein but had no effects on serum equol in a NAFLD rat model.Funding SourcesThis project is support USDA #12889791 to RH.

Diet Containing Soy Protein Concentrate with Low and High Isoflavones for 18 Weeks Protects Against Non-alcoholic Fatty Liver Diseases

ObjectivesTo examine the role of isoflavones levels in soy protein diets on protection against NAFLD in an obese rat model.Methods42 six-week old lean (L, n = 21) and obese (O, n = 21) Zucker rats were randomly assigned to one of 3 dietary groups after one week of acclimation: casein diet (C = control), soy protein with low isoflavones (LIF), or soy protein with high isoflavones (HIF) for 18 weeks (n = 7 rats/group). Rats were weighed twice weekly. After 18 weeks, rats were sacrificed and livers were weighted and samples were taken for histopathological analysis. The steatosis was semiquantitated as a score of 0 to 4 in each case based on relative degree of steatosis within hepatocytes: (0) no steatosis; (1) <25%; (2) 25–50%; (3) >50–75% and (4) >75%. Serums were collected to measure alanine aminotransferase (ALT) and aspartate aminotransferase (AST) using VetScan VS@ profile.ResultsObese rats gained significantly more weight than lean rats for all three diet groups, with no significant difference between obese OLIF vs. OHIF groups. Obese rats (OC) had a significant (P < 0.0001) increased liver steatosis scores and liver weight compared to lean rats (LC). The OHIF and OLIF-fed rats significantly (P < 0.0001) lowered the steatosis scores and liver weight compared to OC (p < 0.0001). However, there were no significant differences between for steatosis score or liver weight for OLIF vs. OHIF. There were no significant differences in either AST or ALT levels between any combination of diet group.ConclusionsWe found that soy protein concentrate protects against liver steatosis and protection is greater with a higher concentration of isoflavones.Funding SourcesThis project is support USDA #12889791 to RH.

Feeding Obese Zucker Rats With Soy Protein Concentrate With High Isoflavones Compared to Low Isoflavones Leads to a Significant Reduction of Serum Tumor Necrosis Factor-α

ObjectivesSoy isoflavones have been proposed to be the functional compounds that mediate the health benefits of soy-rich foods. This study was designed to investigate whether level of isoflavone content (high or low) of soy protein concentrate diet would affect serum TNF-α concentration in an obese Zucker rat model. Methods42 six-week old lean (L, n = 21) and obese (O, n = 21) Zucker rats were randomly assigned to one of 3 dietary groups after one week of acclimation: casein diet (C = control), soy protein with low isoflavones (LIF), or soy protein with high isoflavones (HIF) for 18 weeks (n = 7 rats/group). Rats were weighed twice weekly. After 18 weeks, rats were sacrificed and serum samples were collected. Serum TNF-α concentrations were determined by ELISA and compared between groups. ResultsAt the end of 18 weeks of dietary treatment, obese rats gained significantly more weight than lean rats in all three diet groups. In lean rats, there were no significant differences in body weight or serum TNF-α concentration between any diet groups (C, LIF, or HIF). In contrast, in obese rats, both LIF and HIF groups had significantly higher body weight compared to control group. While O-LIF and O-HIF groups did not differ in body weight, O-HIF group had significantly lower serum TNF-α concentration, suggesting a decreased level of systemic inflammation compared to O-LIF group. ConclusionsHIF soy protein diet significantly decreased serum TNF-α concentration in obese Zucker rats compared to LIF soy protein diet independent of body weight. Isoflavones may be responsible for the observed anti-inflammatory effect. Because systemic inflammation contributes to the etiology of a plethora of diseases, soy isoflavones may exert their many health benefits partially through downregulating systemic inflammation. Funding SourcesThis project is support USDA #12,889,791 to RH.

Temporal and Region‐Specific Tau Protein Hyper‐Phosphorylation in the Brain Coincides with the Development of Impaired Baroreflex Control of Arterial Pressure and Spatial Learning in Male Obese Zucker Rats

Obesity and other traits of metabolic syndrome (MetS) are recognized risk factors for the development of neurodegenerative diseases such as Alzheimer’s Disease (AD) and related dementias. Emerging evidence indicates pathophysiologies common to MetS and AD, such as obesity, hypertension, insulin resistance, and impaired glycemic control, occur with development of tauopathies and cognitive decline. Male obese Zucker rats (OZRs), a hyperphagic genetic model of MetS, develop these deleterious traits with predictable ages of onset and time courses. Juvenile OZRs display prominently elevated triglycerides and insulin compared to age‐matched lean Zucker rats (LZRs). By 12‐14 weeks of age although fasting glucose is still comparable in OZRs and LZRs, with access to food the OZRs exhibit chronic, marked hyperglycemia. At this age male OZRs also become hypertensive with impaired short‐term control of arterial pressure by baroreflexes, which are improved by treatments that normalize blood glucose. We hypothesized that young adult male OZRs would develop age‐dependent expression of markers of neurodegeneration in medulla and hippocampus coincident with deficits in functions related to these brain regions. Cohorts of age‐matched male OZRs and LZRs underwent cognitive testing using the Morris water maze (MWM). At 18‐19 weeks, the escape latencies and path lengths were comparable in male OZRs and LZRs (n=12/group). In contrast, at 28 weeks of age, OZRs (n=16) exhibited a greater than 2‐fold higher escape latency and significantly longer path lengths (p&lt;0.05) in the acquisition and retention phases of the MWM compared to age‐matched LZRs (n=15), suggesting the emergence of impaired spatial learning ability in the OZRs. The 18‐19‐week‐old male OZRs exhibited tau hyper‐phosphorylation (S396 and S199,and S202) in the medulla, but the expressions of these markers in the hippocampus were comparable in OZRs and LZRs (n=6/group) at this age. In contrast, 27‐28‐week‐old OZRs (n=6) exhibited tau hyperphosphorylation at S396in hippocampus as well as medulla compared to LZRs (n=6). Our data suggest that changes in tau phosphorylation in male OZRs occur in a temporal and spatial manner coincident with changes in brain function in these regions. In male OZRs, earlier manifestation in the medulla occurred with impaired short‐term regulation of arterial pressure by the medulla. Later manifestation of tau hyperphosphorylation in hippocampus coincided with deficits in spatial learning. Understanding mechanisms by which these histological, physiological, and behavioral changes occur in male OZRs may provide important insights into connections between the development of MetS and AD‐related dementias in humans to yield improved early‐stage interventions.

Reduction in the Dietary VA Status Prevents Type 2 Diabetes and Obesity in Zucker Diabetic Fatty Rats.

We hypothesized that the vitamin A (VA) status regulates type 2 diabetes (T2D) development in Zucker diabetic fatty (ZDF) rats. Zucker Lean and ZDF rats at weaning were fed a VA deficient with basal fat (VAD-BF, no VA and 22.1% fat energy), VA marginal with BF (VAM-BF, 0.35 mg retinyl palmitate (RP)/kg), VA sufficient with BF (VAS-BF, 4.0 mg RP/kg), VAD with high fat (VAD-HF, 60% fat energy), VAM-HF or VAS-HF diet for 8 weeks, including an oral glucose tolerance test (OGTT) at week 7.5. The hepatic mRNA and proteins levels were determined using real-time PCR and Western blot, respectively. The VAD-BF/HF and VAM-BF/HF diets prevented peripheral hyperglycemia and attenuated obesity in ZDF rats, which occurred in the presence of the VAS-BF/HF diets. This lowered VA status reduced venous blood hyperglycemia, hyperinsulinemia and hyperlipidemia, and improved OGTT and homeostasis model assessment for insulin resistance results in ZDF rats. The expression levels of key hepatic genes for glucose and fat metabolism were regulated by VA status and dietary fat contents. An interaction between VA and HF condition was also observed. We conclude that the reduction in the dietary VA status in both BF and HF conditions prevents T2D and obesity in ZDF rats.

Systemic Administration of Tempol, a Superoxide Dismutase Mimetic, Augments Upper Airway Muscle Activity in Obese Zucker Rats.

Obstructive sleep apnea (OSA) is characterized by repetitive partial/complete collapse of the pharynx during sleep, which results in apnea/hypopnea leading to arterial oxygen desaturations and arousals. Repetitive apnea/hypopnea-arousal episodes cause hypoxia/reoxygenation cycles, which increase free radical generation and oxidative stress that cause motor/sensory nerve impairments and muscle damage. We hypothesize that antioxidants may protect and/or reverse from oxidative stress-induced damage in OSA patients. To understand the acute protective effects of antioxidants on respiratory muscles, we studied the systemic effects of a membrane permeable superoxide dismutase mimetic, Tempol, on genioglossus (EMGGG) and diaphragmatic (EMGDIA) electro-myographic activities, hypoglossal motoneuron (HMN) nerve activity and cardiorespiratory parameters (mean arterial blood pressure, heart rate) in adult isoflurane-anesthetized obese Zucker rats (OZR) and age-matched lean Zucker rats (LZR). Tempol dose-dependently (1–100 mg/kg) increased EMGGG without changing EMGDIA in OZR and LZR. Tempol increased respiratory rate and tidal volume in OZR and LZR. Tempol (1–25 mg/kg) dose-dependently increased HMN nerve activity in healthy Sprague Dawley rats. Tempol (100 mg/kg) increased EMGGG output by 189% in OZR and 163% in LZR. With respect to mechanisms of effect, Tempol (100 mg/kg) did not augment EMGGG after bilateral HMN transection in Sprague Dawley rats. Although future studies are warranted, available data suggest that in addition to its antioxidant and antihypertensive properties, Tempol can selectively augment EMGGG through modulating HMN and this effect may prevent collapsibility and/or improve stability of the upper airway pharyngeal dilator muscles during episodes of partial and/or complete collapse of the upper airway in OSA human subjects.

Effects of acylated and nonacylated anthocyanins extracts on gut metabolites and microbiota in diabetic Zucker rats: A metabolomic and metagenomic study

Anthocyanins have been shown to have prebiotic properties. This study investigated the impact of nonacylated anthocyanins and acylated anthocyanins on fecal and cecal metabolites and colonic gut microbiota in diabetic state using 1H nuclear magnetic resonance (NMR) metabolomics and metagenomic sequencing. Zucker diabetic fatty rats fed with high-fat diet were gavaged with nonacylated anthocyanins extracted from bilberries (NAAB) or acylated anthocyanins extracted from purple potatoes (AAPP) at daily doses of 25 and 50 mg/kg body weight for 8 weeks. Lean Zucker rats fed with normal diet (ND) and high-fat diet (Con) were used as healthy controls groups. Binned NMR spectra and sequenced gene abundance were used for data analysis. Dysbiosis of colonic microbiota and gut metabolites in the diabetic rats were observed compared to the lean Zucker rats. Both anthocyanin extracts increased cecal sugar levels and the abundance of Peptostreptococcaceae sp. and decreased the abundance of Parabacteroides spp. in colon. In addition to the increased fecal short-chain fatty acids, AAPP decreased colonic Ruminococcus torques and Lachnospiraceae bacterium 4_1_37FAA abundances and increased oxidative phosphorylation. The anthocyanin extracts modulated the gut metabolism and microbiota in diabetes, with AAPP showing more regulatory and beneficial effects on diabetes.