The objective of the present study was to analyze the activation and expression patterns of upstream and downstream factors of PGC-1α to determine whether antioxidant (AO) supplementation inhibits mitochondrial biogenesis in skeletal muscles as an adaptation to endurance training, as well as to analyze changes in endurance capacity based on such findings. For this objective, 24 male Sprague-Dawley (SD) rats were allocated into 4 groups (vehicle-sedentary, V-Sed; vehicle-exercise, V-EX; antioxidant-sedentary, AO-Sed; antioxidant-exercise, AO-EX) of 6 rats each. The rats were then treated with vitamin C (500 mgkg−1 body weightd−1) or a placebo for 8 wk, and a swimming program was implemented in some rats during the last 4 wk of this period. Immediately after the last training session, blood was collected from the tail of each rat, and TBARS was measured to test the effect of vitamin C as an AO. As a result, increased oxidative stress from exercise was inhibited by vitamin C supplementation. Analysis of whether reduced oxidative stress by vitamin C supplementation also inhibited mitochondrial biogenesis within skeletal muscles showed that phosphorylation of p38 MAPK and AMPK, along with levels of PGC-1α, NRF-1, mtTFA, and mitochondrial electron transport enzymes, increased after endurance training in spite of vitamin C supplementation. Moreover, running time, distance, and total work increased significantly in the exercise group as compared to those in the sedentary group, regardless of vitamin C supplementation. These results indicate that mitochondrial biogenesis and endurance capacity increase as a result of endurance training, regardless of AO supplementation.
Vitamin D deficiency/insufficiency is currently considered to be a re-emerging public health problem globally. This study was designed to determine the prevalence of vitamin D deficiency and insufficiency and to investigate its trend from 2001 to 2013 in a longitudinal study of Iranian adults. This study was part of a population-based, longitudinal ongoing study of Iranian healthy adults aged 35 y and older at baseline. Serum vitamin D level was assessed in a sub-sample of 370 subjects, who were apparently healthy at the time of recruitment in 2001 and were free from MetS, in three phases (2001, 2007 and 2013) during the 12-y study period. Adjusted prevalence and trend of vitamin D deficiency were calculated. Mean serum vitamin D levels increased over the time of the study (52.12, 54.27 and 62.28 nmol/L, respectively) and the prevalence of vitamin D deficiency decreased (30.5, 27.0 and 24.4, respectively). However, the prevalence of vitamin D insufficiency did not change over this time period. The risk of vitamin D deficiency decreased significantly in 2007 [OR: 0.73 (95% CI: 0.53, 0.99)] and 2013 [OR: 0.50 (95% CI: 0.36, 0.70)] compared to the baseline. The present study demonstrated some improvement in serum vitamin D levels, while the prevalence of vitamin D inadequacy was still high. Considering the possible health consequences of vitamin D deficiency, there is an urgent need for developing population-wide strategies, such as supplementation and fortification, to prevent or control vitamin D deficiency.
Coffee polyphenols (CPPs) derived from coffee beans have beneficial effects on blood pressure and vascular endothelial function. In addition, CPPs suppress ultraviolet light induced erythema. However, the effects of CPPs on dry skin and cutaneous vascular function have not been clarified. We investigated the effects of CPPs on dry skin and the recovery rate (RR) of skin temperature after a cold-stress test as a measure of vascular function in subjects with visible scaliness in a double-blind, placebo-controlled, randomized study. The subjects were divided into two groups, the CPP group and the Placebo group. In the CPP group, the subjects ingested a beverage containing 297.8 mg CPPs every day for 4 wk. The degree of skin dryness was assessed quantitatively using a Visioscan to evaluate skin scaliness and smoothness. A subjective evaluation using a visual analog scale (VAS) of skin smoothness was also used. As a result, the scaliness and smoothness of cheek skin was significantly improved after 4 wk in the CPP group compared to the Placebo group. The improvements of the VAS score on ‘skin smoothness’ and the RR were also observed in the CPP group but the difference was not statistically significant. However, when the CPP group was divided into subgroups of high RR and low RR, the improvement of the RR was significant in the low RR subgroup. In conclusion, our results suggest that CPPs improve skin scaliness and play a role in cutaneous blood flow regulation after cold stress.
Nutrition knowledge is necessary for individuals to adopt appropriate dietary habits, and needs to be evaluated before nutrition education is provided. However, there is no tool to assess general nutrition knowledge of adults in Japan. Our aims were to determine the validity and reliability of a general nutrition knowledge questionnaire for Japanese adults. We developed the pilot version of the Japanese general nutrition knowledge questionnaire (JGNKQ) and administered the pilot study to assess content validity and internal reliability to 1,182 Japanese adults aged 18-64 y. The JGNKQ was further modified based on the pilot study and the final version consisted of 5 sections and 147 items. The JGNKQ was administered to female undergraduate Japanese students in their senior year twice in 2015 to assess construct validity and test-retest reliability. Ninety-six students majoring in nutrition and 44 students in other majors who studied at the same university completed the first questionnaire. Seventy-five students completed the questionnaire twice. The responses from the first questionnaire and both questionnaires were used to assess construct validity and test-retest reliability, respectively. The students in nutrition major had significantly higher scores than the students in other majors on all sections of the questionnaire (p=0.000); therefore, the questionnaire had good construct validity. The test-retest reliability correlation coefficient value of overall and each section except “The use of dietary information to make dietary choices” were 0.75, 0.67, 0.67, 0.68 and 0.61, respectively. We suggest that the JGNKQ is an effective tool to assess the nutrition knowledge level of Japanese adults.
Studies have suggested that the consumption of green tea reduces the risk of cardiovascular diseases. Although epigallocatechin gallate (EGCG) is the best studied active substance characteristic of green tea, previous results on EGCG do not appear sufficient to explain completely the mechanism of cardiovascular protection by green tea. Therefore, we investigated the effect of three different tea cultivars, “Yabukita,” “Sofu,” and “Sunrouge,” which have characteristic flavonoid compositions, on the nitric oxide (NO) production and the related protein expression in the aorta of spontaneously hypertensive rats (SHRs) fed a high-salt diet. As a result, the reduction of urinary NO metabolite (NOx) levels, which reflect whole-body NO production, caused by the high-salt diet were significantly prevented by all three tea infusions. The improvement of NOx reduction in the tea-intake groups was unlikely to be caused by the changes in oxidative damage. On the other hand, as a partial effect, only “Yabukita” or “Sofu” increased the expression of the soluble guanylate cyclase, a receptor for NO, in the thoracic aorta. In the present study, the differences in the composition of these three cultivars led to partially different effects on NO signaling in SHRs, suggesting the physiological significance of subdominant ingredients besides EGCG.
Milk basic protein (MBP) comprises a group of basic whey proteins and is effective in preventing bone loss by promoting bone deposition (bone formation) and suppressing withdrawn (bone resorption). We previously revealed the bone protective effects of MBP during life phases involving excessive bone resorption, such as in adults and postmenopausal women, and in animal models (ovariectomized rats and mice). However, it was unclear whether MBP increases bone mass during the growth stage, when there is more bone formation than resorption. We therefore investigated the effect of MBP supplementation on bone mass in 6-wk-old mice provided water supplemented with MBP [0.01%, 0.1%, 1.0% (w/w)] or deionized water (control) ad libitum for 10 wk. Analysis by micro-computerized tomography showed that MBP significantly increased tibia cortical bone mineral density and femur trabecular bone volume to tissue volume compared with mice provided deionized water. Next, the function of MBP in bone remodeling (bone formation and resorption) was evaluated using an in vitro system and the results demonstrated that MBP directly promoted osteoblast proliferation and inhibited osteoclastogenesis. Moreover, the plasma level of insulin-like growth factor-1 was increased by MBP supplementation, suggesting that MBP indirectly promoted osteoblast proliferation/differentiation. These effects enhance bone formation and/or inhibit bone resorption, resulting in increased bone mass in growing mice.
Previous studies have shown that the short-term intake of a high-fat diet (HFD) impairs glucose metabolism. In this study, we investigated the influences of pre-exercise HFD intake for 3 d on post-exercise glycogen repletion in skeletal muscle in ICR mice. Mice received either an HFD (57% kcal from fat, 23% kcal from carbohydrate; HFD group) or standard laboratory chow (13% kcal from fat, 60% kcal from carbohydrate; Con group) for 3 d before exercise. Mice performed treadmill running at 25 m/min for 60 min and were orally administered a glucose (2 mg/g body weight) solution immediately after and at 60 min after exercise. A negative main effect of pre-exercise HFD intake was observed for skeletal muscle glycogen concentration from the pre-exercise phase to 120 min of post-exercise recovery (p<0.01). Blood glucose concentration in the HFD group was significantly higher than in the Con group at 120 min after exercise (p<0.01). No significant difference was observed in plasma insulin concentration. There were no significant between-group differences in the phosphorylation state of Akt Thr308, AMPK Thr172, AS160 Thr642, or glycogen synthase Ser641 or in glucose transporter 4 protein levels during post-exercise recovery. Our results suggest that the intake of a pre-exercise HFD for 3 d affects post-exercise glycogen repletion in skeletal muscle without impairing the insulin signaling cascade.
Caffeine is a methylxanthine derived from plant foods such as coffee beans and tea leaves, and has multiple biological activities against physiological response and several diseases. Although there are some reports about the direct effect of caffeine against anti-lipid accumulation in vitro, the effect of caffeine on lipid accumulation in adipocytes through stimulating intestinal epithelial cells is unknown. Since direct treatment with caffeine to 3T3-L1 cells did not affect lipid accumulation, we determined whether caffeine-stimulated intestinal epithelial Caco-2 cells influence the lipid accumulation in 3T3-L1 adipocytes. Caco-2 cells were cultured on a transwell insert with or without caffeine for 24 h. Subsequently, the basolateral component of the Caco-2 cell culture on the transwell was collected and termed caffeine-conditioning medium (CCM). When 3T3-L1 adipocytes were incubated with CCM, CCM decreased lipid accumulation and suppressed gene expression of proliferator activated receptor (PPAR) γ and CCAAT/enhancer binding protein (C/EBP) α in 3T3-L1 adipocytes. Furthermore, CCM decreased the expression of C/EBPβ and C/EBPδ at the protein level, but not at the mRNA level. We observed that a proteasome inhibitor, MG132, inhibited CCM-caused down-expression of C/EBPβ and C/EBPδ proteins, and that CCM promoted the ubiquitination level of C/EBPβ and C/EBPδ proteins. Protein microarray analysis showed caffeine suppresses the secretion of inflammatory cytokines, interleukin-8 and plasminogen activator inhibitor-1 from Caco-2 cells. These results suggest that caffeine indirectly suppresses lipid accumulation in 3T3-L1 adipocytes through decreasing secretion of inflammatory cytokines from Caco-2 cells.
Insulin resistance reduces insulin-induced muscle protein synthesis and accelerates muscle protein degradation. Ginseng ingestion has been reported to improve insulin resistance through the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. We hypothesized that panaxatriol (PT) derived from ginseng in combination with aerobic exercise (EX) may further promote protein synthesis and suppress protein degradation, and subsequently maintain muscle mass through the amelioration of insulin resistance. KKAy insulin-resistant mice were divided into control, panaxatriol only (PT), exercise only (EX), and EX+PT groups. EX and EX+PT ran on the treadmill for 45 min at 15 m/min 5 d/wk for 6 wk. PT and EX+PT groups were fed a standard diet containing 0.2% PT for 6 wk. Homeostasis model assessment for insulin resistance (HOMA-R) values was significantly improved after exercise for 6 wk. Moreover, EX+PT mice showed improved HOMA-R as compared to EX mice. p70S6K phosphorylation after a 4 h fast was significantly higher in EX than in the non-exercise control, and it was higher in EX+PT mice than in EX mice. Atrogin1 mRNA expression was significantly lower in EX than in the non-exercise control, and was significantly lowered further by PT treatment. EX and EX+PT mice showed higher soleus muscle mass and cross-sectional area (CSA) of the soleus myofibers than control animals, with higher values noted for both parameters in EX+PT than in EX. These results suggest that aerobic exercise and PT ingestion may contribute to maintain skeletal muscle mass through the amelioration of insulin resistance.
Tocotrienols (T3s) and tocopherols (Tocs) are both members of the vitamin E family. It is known that δ-tocotrienol (δ-T3) has displayed the most potent anti-cancer activity amongst the tocotrienols. On the other hand, γ-tocopherol (γ-Toc) is reported to have a protective effect against prostate cancer. Therefore, we investigated whether the combination of γ-Toc and δ-T3 could strengthen the inhibitory effect of δ-T3 on prostate cancer cell growth. In this study the effect of combined δ-T3 (annatto T3 oil) and γ-Toc (Tmix, γ-Toc-rich oil) therapy was assessed against human androgen-dependent prostate cancer cells (LNCaP). We found that combined treatment of δ-T3 (10 μM) and γ-Toc (5 μM) resulted in reinforced anti-prostate cancer activity. Specifically, cell cycle phase distribution analysis revealed that in addition to G1 arrest caused by the treatment with δ-T3, the combination of δ-T3 with γ-Toc induced G2/M arrest. Enhanced induction of apoptosis by the combined treatment was also observed. These findings indicate that combination of δ-T3 and γ-Toc significantly inhibits prostate cancer cell growth due to the simultaneous cell cycle arrest in the G1 phase and G2/M phase.