Reducing the dietary omega-6:omega-3 utilizing α-linolenic acid; not a sufficient therapy for attenuating high-fat-diet-induced obesity development nor related detrimental metabolic and adipose tissue inflammatory outcomes.

To examine the effect of manipulating the omega-6:omega-3 (1∶1, 5∶1, 10∶1, and 20∶1) utilizing only α-linolenic and linoleic acid within a clinically-relevant high-fat diet (HFD) composed of up to seven sources of fat and designed to be similar to the standard American diet (MUFA∶PUFA of 2∶1, 12% and 40% of calories from saturated and total fat, respectively) on body composition, macrophage polarization, inflammation, and metabolic dysfunction in mice.Diets were administered for 20 weeks. Body composition and metabolism (HOMA index and lipid profile) were examined monthly. GC-MS was utilized to determine the eicosapentaenoic acid (EPA):arachidonic acid (AA) and the docosahexaenoic acid (DHA):AA in AT phospholipids. Adipose tissue (AT) mRNA expression of chemokines (MCP-1, Fetuin-A, CXCL14), marker genes for M1 and M2 macrophages (CD11c and CD206, respectively) and inflammatory markers (TNF-α, IL-6, IL-1β, TLR-2, TLR-4, IL-10, GPR120) were measured along with activation of NFκB, JNK, and STAT-3. Macrophage infiltration into AT was examined using F4/80 immunohistochemistry.Any therapeutic benefit produced by reducing the omega-6:omega-3 was evident only when comparing the 1∶1 to 20∶1 HFD; the 1∶1 HFD resulted in a lower TC:HDL-C and decreased AT CXCL14 gene expression and AT macrophage infiltration, which was linked to a higher EPA:AA and DHA:AA in AT phospholipids. However, despite these effects, and independent of the omega-6:omega-3, all HFDs, in general, led to similar levels of adiposity, insulin resistance, and AT inflammation.Reducing the omega-6:omega-3 using α-linolenic acid is not an effective therapy for attenuating obesity and type II diabetes mellitus development

Figure 3

<p>Epididymal AT gene expression of (A) chemokines and (B) macrophage markers (n = 10). Diets not sharing a common letter differ significantly from one another (P≤.05). Representative images of (C) H&E and F4/80 staining of epididymal AT (20x).</p

Fasting metabolic panel assessed incrementally (age 8, 12, 16, 20, and 24 weeks) throughout the course of the study (n = 10).

<p>Values not sharing a common letter differ significantly over time within the group (P≤.05). Values not sharing a common symbol differ significantly among groups within the given week (P≤.05).</p

Figure 4

<p>Representative epididymal AT western blots of (A) phosphorylated (Thr183/Tyr185) and total JNK, phosphorylated p65 (Ser536) and total NFκB, and phosphorylated (Tyr705) and total STAT3. Epididymal AT gene expression of (B) inflammatory markers (n = 10). Diets not sharing a common letter differ significantly from one another (P≤.05).</p

Figure 2

<p>Influence of diets on (A) weekly mean body weight, (B) fat pad weights (retroperitoneal, mesentery, epididymal), and (C) adipocyte size at sacrifice (n = 10). Diets not sharing a common letter differ significantly from one another (P≤.05). ^*Significantly different from AIN-76A Mod (ages 6–24 weeks: all HFDs) ^#Significantly different from 20:1 (11 weeks of age: 10:1, 12 weeks of age: 5:1) (P≤.05).</p

Diet composition of treatment diets.

<p>SFAs, Saturated Fatty-Acids; MCSFAs, Medium-Chain Saturated Fatty Acids; LCSFAs, Long-Chain Saturated Fatty Acids; USFAs, Unsaturated Fatty Acids; MUFAs, Monounsaturated Fatty Acids; PUFAs, Polyunsaturated Fatty Acids.</p

Body composition of mice assessed at baseline (4 weeks of age) and incrementally (age 8, 12, 16, 20, and 24 weeks) throughout the course of the study (n = 10).

<p>Values not sharing a common letter differ significantly over time within the given diet (P≤.05). Values not sharing a common symbol differ significantly among diet within the given week (P≤.05).</p

A Low Dose of Dietary Quercetin Fails to Protect against the Development of an Obese Phenotype in Mice

<div><p>The purpose of this study was to examine the effect of a 40% high-fat diet (HFD) supplemented with a dietary attainable level of quercetin (0.02%) on body composition, adipose tissue (AT) inflammation, Non-Alcoholic Fatty-Liver Disease (NAFLD), and metabolic outcomes. Diets were administered for 16 weeks to C57BL/6<i>J</i> mice (n = 10/group) beginning at 4 weeks of age. Body composition and fasting blood glucose, insulin, and total cholesterol concentrations were examined intermittently. AT and liver mRNA expression (RT-PCR) of inflammatory mediators (F4/80, CD206 (AT only), CD11c (AT only) TLR-2 (AT only), TLR-4 (AT only), MCP-1, TNF-α, IL-6 (AT only), and IL-10 (AT only)) were measured along with activation of NFκB-p65, and JNK (western blot). Hepatic lipid accumulation, gene expression (RT-PCR) of hepatic metabolic markers (ACAC1, SREBP-1, PPAR-γ), protein content of Endoplasmic Reticulum (ER) Stress markers (BiP, phosphorylated and total EIF2α, phosphorylated and total IRE1α, CHOP), and hepatic oxidative capacity were assessed (western blot). Quercetin administration had no effect at mitigating increases in visceral AT, AT inflammation, hepatic steatosis, ER Stress, decrements in hepatic oxidative capacity, or the development of insulin resistance and hypercholesterolemia. In conclusion, 0.02% quercetin supplementation is not an effective therapy for attenuating HFD-induced obesity development. It is likely that a higher dose of quercetin supplementation is needed to elicit favorable outcomes in obesity.</p></div