Protein source in a high‐protein diet modulates reductions in insulin resistance and hepatic steatosis in <i>fa/fa</i> Zucker rats

Wojcik, Jennifer L; Devassy, Jessay G.; Wu, Yinghong; Zahradka, Peter; Taylor, Carla G.; Aukema, Harold M.

doi:10.1002/oby.21312

Cited by 25 publications

(28 citation statements)

References 39 publications

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“…This is in line with a cross-sectional analysis showing an increased risk of overweight and obesity in women consuming a greater proportion of energy from protein (Murtaugh et al 2007). However, as previously reported in these rats, the HP diets resulted in higher lean mass (Wojcik et al 2016), consistent with studies indicating that one of the benefits of HP diets is their effect on sparing fat free mass during weight loss , Claessens et al 2009).…”

Section: Discussionsupporting

confidence: 91%

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Mixed compared with single-source proteins in high-protein diets affect kidney structure and function differentially in obesefa/faZucker rats

Devassy

Wojcik

Ibrahim

et al. 2017

Appl. Physiol. Nutr. Metab.

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Questions remain regarding the potential negative effects of dietary high protein (HP) on kidney health, particularly in the context of obesity in which the risk for renal disease is already increased. To examine whether some of the variability in HP effects on kidney health may be due to source of protein, obese fa/fa Zucker rats were given HP (35% of energy from protein) diets containing either casein, soy protein, or a mixed source of animal and plant proteins for 12 weeks. Control lean and obese rats were given diets containing casein at normal protein (15% of energy from protein) levels. Body weight and blood pressure were measured, and markers of renal structural changes, damage, and function were assessed. Obesity alone resulted in mild renal changes, as evidenced by higher kidney weights, proteinuria, and glomerular volumes. In obese rats, increasing the protein level using the single, but not mixed, protein sources resulted in higher renal fibrosis compared with the lean rats. The mixed-protein HP group also had lower levels of serum monocyte chemoattractant protein-1, even though this diet further increased kidney and glomerular size. Soy and mixed-protein HP diets also resulted in a small number of damaged glomeruli, while soy compared with mixed-protein HP diet delayed the increase in blood pressure over time. Since obesity itself confers added risk of renal disease, an HP diet from mixed-protein sources that enables weight loss but has fewer risks to renal health may be advantageous.

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Section: Discussionsupporting

confidence: 91%

“…We have previously reported that an HP diet composed of mixed proteins (compared to single protein sources of casein or soy protein) was more effective in reducing insulin resistance and hepatic steatosis independent of weight loss in the obese fa/fa Zucker rat (Wojcik et al 2016).…”

Section: Introductionmentioning

confidence: 98%

Mixed compared with single-source proteins in high-protein diets affect kidney structure and function differentially in obesefa/faZucker rats

Devassy

Wojcik

Ibrahim

et al. 2017

Appl. Physiol. Nutr. Metab.

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“…There was no difference in fasting plasma glucose between lean or obese animals or between dietary treatments. These findings are supported by studies in humans [55,56], which have demonstrated that long-term high-protein diets have little effect on fasting plasma glucose levels, as well as in animal studies [57]. Although we did not collect postprandial data in this study, Bernard et al [58] have shown that an amino acid mixture (high in the BCAA leucine) can improve glucose tolerance and decrease insulin resistance in obese, Zucker rats in an acute setting.…”

Section: Discussionsupporting

confidence: 55%

A High-Protein Diet Reduces Weight Gain, Decreases Food Intake, Decreases Liver Fat Deposition, and Improves Markers of Muscle Metabolism in Obese Zucker Rats

French

Dridi²,

Shouse

et al. 2017

Nutrients

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A primary factor in controlling and preventing obesity is through dietary manipulation. Diets higher in protein have been shown to improve body composition and metabolic health during weight loss. The objective of this study was to examine the effects of a high-protein diet versus a moderate-protein diet on muscle, liver and fat metabolism and glucose regulation using the obese Zucker rat. Twelve-week old, male, Zucker (fa/fa) and lean control (Fa/fa) rats were randomly assigned to either a high-protein (40% energy) or moderate-protein (20% energy) diet for 12 weeks, with a total of four groups: lean 20% protein (L20; n = 8), lean 40% protein (L40; n = 10), obese 20% protein (O20; n = 8), and obese 40% protein (O40; n = 10). At the end of 12 weeks, animals were fasted and euthanized. There was no difference in food intake between L20 and L40. O40 rats gained less weight and had lower food intake (p < 0.05) compared to O20. O40 rats had lower liver weight (p < 0.05) compared to O20. However, O40 rats had higher orexin (p < 0.05) levels compared to L20, L40 and O20. Rats in the L40 and O40 groups had less liver and muscle lipid deposition compared to L20 and L40 diet rats, respectively. O40 had decreased skeletal muscle mechanistic target of rapamycin complex 1 (mTORC1) phosphorylation and peroxisome proliferator-activated receptor gamma (PPARγ) mRNA expression compared to O20 (p < 0.05), with no difference in 5′ AMP-activated protein kinase (AMPK), eukaryotic translation initiation factor 4E binding protein 1 (4EBP1), protein kinase B (Akt) or p70 ribosomal S6 kinase (p70S6K) phosphorylation. The data suggest that high-protein diets have the potential to reduce weight gain and alter metabolism, possibly through regulation of an mTORC1-dependent pathway in skeletal muscle.

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“…However, no significant differences were found for systolic or diastolic blood pressure in other meta-analyses comparing HP diets to LP [7,39]. It is thought that HP consumption is responsible for higher intake of sodium hence subsequent hypertension but there is no valid data to support this claim [49,50]. In the Omni Heart study a HP diet (25% energy as HP, 48% as carbohydrate) compared with a high carbohydrate diet (15% energy as protein, 58%…”

Section: Hp Diets and Healthmentioning

confidence: 99%

Linoleic acid derived oxylipins are elevated in kidney and liver and reduced in serum in rats given a high-protein diet

Islam

Ravandi

Aukema

2018

The Journal of Nutritional Biochemistry

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High protein (HP) diets are often used as a means to reduce obesity, but their long-term effects remain unclear. In vitro studies suggest the involvement of a subset of oxylipins in the tissue response to HP diets. To examine the role of these bioactive lipids in vivo, normal adult male Sprague Dawley rats were provided isocaloric diets with LP (low protein, 8% protein by weight), NP (normal protein, 14%) or HP (50%) diets for 2 weeks, and targeted lipidomic analysis of oxylipins in kidney (cortex and medulla), liver and serum was performed by HPLC-MS/MS. The main group of oxylipins affected by the HP diet was the oxylipins derived from linoleic acid (LA), many of which were elevated in kidney (particularly the medulla) and liver, but reduced in serum of rats provided the HP compared to NP or LP diets. A smaller proportion of other n-6 fatty acid derived oxylipins were lower in kidney and higher in liver, and none were affected in serum, by HP feeding. Few n-3 oxylipins were affected by protein level. In liver only, the oxylipin product to substrate ratios of the soluble epoxide hydrolase enzyme were higher in LP fed rats. Differences between cortex and medulla oxylipins suggest relatively higher cortex activity of 5- and 8-lipoxygenase and cytochrome P450 hydroxylase, and higher medulla cyclooxygenase and 12- and 15-lipoxygenase activity. Further studies are needed to elucidate the physiological effects of the changes in these novel oxylipins in response to short-term dietary HP.

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Protein source in a high‐protein diet modulates reductions in insulin resistance and hepatic steatosis in fa/fa Zucker rats

Cited by 25 publications

References 39 publications

Mixed compared with single-source proteins in high-protein diets affect kidney structure and function differentially in obesefa/faZucker rats

Mixed compared with single-source proteins in high-protein diets affect kidney structure and function differentially in obesefa/faZucker rats

A High-Protein Diet Reduces Weight Gain, Decreases Food Intake, Decreases Liver Fat Deposition, and Improves Markers of Muscle Metabolism in Obese Zucker Rats

Linoleic acid derived oxylipins are elevated in kidney and liver and reduced in serum in rats given a high-protein diet

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