Potato Chip Intake Increases Ascorbic Acid Levels and Decreases Reactive Oxygen Species in SMP30/GNL Knockout Mouse Tissues

Potato chips (PC) contain abundant amounts of the free radical scavenger ascorbic acid (AA) due to the rapid dehydration of potato tubers (Solanum tuberosum) that occurs during frying. To evaluate the antioxidant activity of PC, this study examined reactive oxygen species (ROS) levels in tissues from SMP30/GNL knockout (KO) mice that cannot synthesize AA and determined AA and ROS levels after the animals were fed 20 and 10% PC diets for 7 weeks. Compared with AA-sufficient mice, AA-depleted SMP30/GNL KO mice showed high ROS levels in tissues. SMP30/GNL KO mice fed a PC diet showed high AA and low ROS levels in the brain, heart, lung, testis, soleus muscle, plantaris muscle, stomach, small intestine, large intestine, eyeball, and epididymal fat compared with AA-depleted mice. The data suggest that PC intake increases AA levels and enhances ROS scavenging activity in tissues of SMP30/GNL KO mice, which are a promising model for evaluating the antioxidant activity of foods

Increase in TBARS in livers from <i>Lepr^db/dbSmp30^Y/−</i> mice.

<p>(A) Triglyceride, (B) Cholesterol, (C) Phospholipid and (D) TBARS content in livers from the four experimental groups. Lane 1, <i>Lepr^db/+Smp30^Y/+</i> mice. Lane 2, <i>Lepr^db/+Smp30^Y/−</i> mice. Lane 3, <i>Lepr^db/dbSmp30^Y/+</i> mice. Lane 4, <i>Lepr^db/dbSmp30^Y/−</i> mice. ^†<i>P</i><0.01 and ^§<i>P</i><0.001 <i>versus Lepr^db/+Smp30^Y/+</i>, ^¶<i>P</i><0.001 <i>versus Lepr^db/+Smp30^Y/−</i>, ^**<i>P</i><0.05 and ^††<i>P</i><0.001 <i>versus Lepr^db/dbSmp30^Y/+</i>. Values are given as means ± SEM of five animals.</p

Increase in endoplasmic reticulum (ER) stress in livers from <i>Lepr^db/dbSmp30^Y/−</i> mice.

<p>(A) Spliced XBP1 mRNA expression, (B) Phosphorylated eIF2α protein and (C) CHOP protein levels in livers from the four experimental groups. Values are given as means ± SEM of five animals. ^*<i>P</i><0.05, ^†<i>P</i><0.01 and ^§<i>P</i><0.001 <i>versus Lepr^db/+Smp30^Y/+</i>, ^#<i>P</i><0.05 <i>versus Lepr^db/+Smp30^Y/−</i>, ^**<i>P</i><0.05 <i>versus Lepr^db/dbSmp30^Y/+</i>.</p

Altered hepatic expression of lipid/lipoprotein metabolism-related genes in <i>Lepr^db/dbSmp30^Y/−</i> mice.

<p>Gene expression levels of (A) <i>ACC</i>, (B) <i>FAS</i>, (C) <i>SREBP1c</i>, (D) <i>SREBP2</i>, (E) <i>HMGCoAR</i>, (F) <i>PPAR</i>α, (G) <i>MCAD</i>, (H) <i>MTP</i>, (I) <i>ApoB100</i>, (J) <i>LDLR</i> (K) <i>VLDLR</i>, and (L) <i>CD36</i> in the livers. Lane 1: <i>Lepr^db/+Smp30^Y/+</i>, lane 2: <i>Lepr^db/+Smp30^Y/−</i>, lane 3: <i>Lepr^db/dbSmp30^Y/+</i> and lane 4: <i>Lepr^db/dbSmp30 ^Y/−</i> mice. mRNA for each gene was measured using real time RT-PCR and normalized to β-actin. The values from <i>Lepr^db/+ Smp30^Y/+</i> mice were assigned a relative value of 1.0. Values are given as means ± SEM of five animals. ^*<i>P</i><0.05, ^†<i>P</i><0.01 and ^§<i>P</i><0.001 <i>versus Lepr^db/+Smp30^Y/+</i>, ^#<i>P</i><0.05, ^‡<i>P</i><0.01 and ^¶<i>P</i><0.001 <i>versus Lepr^db/+Smp30^Y/−</i>, ^**<i>P</i><0.05 <i>versus Lepr^db/dbSmp30^Y/+</i>.</p

Establishment of <i>Lepr^db/dbSmp30^Y/−</i> mice.

<p>(A) Generation of <i>Lepr^db/dbSmp30^Y/−</i> mice. F1 hybrid mice (in green boxes) were crossed to produce the experimental <i>Lepr^db/+Smp30^Y/+</i>, <i>Lepr^db/+Smp30^Y/−</i>, <i>Lepr^db/dbSmp30^Y/+</i> and <i>Lepr^db/dbSmp30^Y/−</i> mice (in red boxes). (B) Appearance of <i>Lepr^db/dbSmp30^Y/−</i> mice at 24 weeks of age. (C) Western blot analysis of SMP30 protein levels in livers from each experimental group at 24 weeks of age. (D) Vitamin C concentration in livers from each experimental group of mice at 24 weeks of age. Values are given as means ± SEM of five animals.</p

Physiological, blood and biochemical parameters in four experimetal groups of mice.

*<p><i>P</i><0.05,</p>†<p><i>P</i><0.01 and</p>§<p><i>P</i><0.001 <i>versus Lepr^db/+Smp30^Y/+</i>.</p>#<p><i>P</i><0.05,</p>‡<p><i>P</i><0.01 and</p>¶<p><i>P</i><0.001 <i>versus Lepr^db/+Smp30^Y/−</i>.</p>**<p><i>P</i><0.05 <i>versus Lepr^db/dbSmp30^Y/+</i>.</p><p>Values are given as means ± SEM of five animals.</p

Primer sequences for use in real-time quantitative RT-PCR.

<p>Primer sequences for use in real-time quantitative RT-PCR.</p