Youngju Song

EFFECTS OF SWIMMING EXERCISE AND SOYBEAN SUPPLEMENTATION ON THE IMMUNE FUNCTIONS OF RATS FED A HIGH‐FAT DIET

1 In the present study, the effects of swimming exercise and soybean supplementation on the immune functions of rats fed a high‐fat diet were examined. 2 Thirty‐four male rats were randomly divided into four groups: (i) HS, a high‐fat diet sedentary group (n = 8); (ii) HE, a high‐fat diet exercised group (n = 9); (iii) SS, a soybean diet sedentary group (n = 8); and (iv) SE, a soybean diet exercised group (n = 9). The high‐fat diet was composed of 35% carbohydrate, 20% protein and 35% fat. For the soybean diet, 3% crude soybean extract was substituted for the protein, carbohydrate and fat according to the energy content of the diet. In the exercise groups, rats swam for 60 min/day, 5 days/week for 4 weeks. 3 The subpopulation of CD4+ cells and the CD4+/CD8+ ratio did not differ significantly between the high‐fat diet and soybean diet groups. However, the subpopulation of CD8+ cells in the spleens of SS rats was significantly higher than that in the spleens of HS rats (P < 0.05). In addition, splenic interferon‐γ secretion in the SE group, with or without conconavalin A stimulation, was significantly increased compared with the SS group (P < 0.05 and P < 0.01, respectively). 4 These results show that regular endurance exercise training with soybean supplementation ameliorates splenic T cell‐mediated immunity.

Opuntia humifusa Supplementation Increased Bone Density by Regulating Parathyroid Hormone and Osteocalcin in Male Growing Rats

We investigated the effect of Opuntia humifusa (O. humifusa) supplementation on bone density and related hormone secretion in growing male rats. Sixteen six-week-old male Sprague-Dawley rats were randomly divided into two groups; control diet group (CG, n = 8), and experimental diet group (EG, n = 8). The rats in the CG were given a control diet and those in the EG were given 5% O. humifusa added to the control diet for eight weeks. The serum OC level of the EG was significantly higher than that of the CG, and the serum parathyroid hormone (PTH) level of EG was significantly lower than that of the CG. In addition, the femoral and tibial BMD of the EG were significantly higher values than those of the CG, and the tibial BMC of the EG was significantly higher than that of the CG. These results suggest that O. humifusa supplementation has a positive effect on bone density by suppressing PTH and increasing the OC level in growing male rats.

Effect of Opuntia humifusa Supplementation and Acute Exercise on Insulin Sensitivity and Associations with PPAR-γ and PGC-1α Protein Expression in Skeletal Muscle of Rats

This study examined whether Opuntia humifusa (O. humifusa), which is a member of the Cactaceae family, supplementation and acute swimming exercise affect insulin sensitivity and associations with PPAR-γ and PGC-1α protein expression in rats. Thirty-two rats were randomly divided into four groups (HS: high fat diet sedentary group, n = 8; HE: high fat diet acute exercise group, n = 8; OS: 5% O. humifusa supplemented high fat diet sedentary group, n = 8; OE: 5% O. humifusa supplemented high fat diet acute exercise group, n = 8). Rats in the HE and OE swam for 120 min. before being sacrificed. Our results indicated that serum glucose level, fasting insulin level and homeostasis model assessment of insulin resistance (HOMA-IR) in OS were significantly lower compared to those of the HS (p < 0.01, p < 0.05, p < 0.05). In addition, PPAR-γ protein expression in the OS and OE was significantly higher than that of the HS and HE, respectively (p < 0.05, p < 0.01). PGC-1α and GLUT-4 protein expressions in the OS were significantly higher compared to those of the HS (p < 0.05, p < 0.05). From these results, O. humifusa supplementation might play an important role for improving insulin sensitivity through elevation of PPAR-γ, PGC-1α, and GLUT-4 protein expression in rat skeletal muscle.

Effect of gamma-aminobutyric acid produced by Lactobacillus sakei B2-16 on diet and exercise in high fat diet-induced Obese rats

Effect of gamma-aminobutyric acid (GABA) produced by Lactobacillus sakei B2-16 on diet and acute swimming exercise was investigated in rats with high fat diet (HFD)-induced obesity. The body weight gain in the GABA+Exercise group was significantly (p<0.05) lower than in the HFD group. Combined treatment with GABA and exercise decreased the body weight gain by 25.6%, compared to the HFD group. On the other hand, neither GABA supplementation nor exercise alone significantly (p>0.05) influenced reduction in body weight gain, compared to the HFD group. The weights of abdominal and epididymal fat tissues and the liver in the GABA+Exercise group were significantly (p<0.05) lower than in the HFD group. The activity of citrate synthase was significantly (p<0.05) elevated in the soleus muscle by GABA supplementation. GABA contributes to reduction in body weight gain and fat tissue weight by increasing physical activity during exercise.

Effects of Opuntia humifusa Supplementation on Lipid Peroxidation and SOD Protein Expression in the Liver, Kidney, and Skeletal Muscle of Rats Fed a High-fat Diet

This study was conducted to investigate the effects of Opuntia humifusa supplementation on lipid peroxidation and superoxide dismutase (SOD) protein expression at resting state in various organs of rats fed a high-fat diet. Sixteen Sprague-Dawley male rats, 6 weeks of age, were randomly divided into two groups: a control diet group (CG, n=8) and an experimental diet group (EG, n=8). They were given a high-fat diet (CG) or a diet supplemented with 5% of O. humifusa (EG) or 8 weeks. The results showed that the malondialdehyde (MDA) levels of the kidney and the liver were significantly lower in the EG group than in the CG group (p<0.01). In addition, the MDA levels in the skeletal muscle of the EG group tended to be lower than those in the CG group, but this difference was not significant. The Cu, Zn-SOD protein expression in the kidney of the EG group was significantly increased compared with that of the CG group (p<0.01). The Mn-SOD protein expression in the skeletal muscle of the EG group was significantly increased compared with that of the CG group (p<0.01). These results suggest that O. humifusa supplementation has antioxidative properties, which are exerted in a specific organ manner, and that it inhibits the action of lipid peroxidation and the expression of SOD in rats fed a high-fat diet.

Serum levels of appetite-regulating hormones and pro-inflammatory cytokines are ameliorated by a CLA diet and endurance exercise in rats fed a high-fat diet.

[Purpose] This study examined whether conjugated linoleic acid (CLA) supplementation and endurance exercise affect appetite-regulating hormones and pro-inflammatory cytokines in rats. [Methods] Seven-week-old male Sprague-Dawley rats were divided randomly into the high-fat diet sedentary group (HS, n=8), the 1.0% CLA supplemented high-fat diet sedentary group (CS, n=8), and the 1.0% CLA supplemented high-fat diet exercise group (CE, n=8). Rats in the CE group swam 60 min/day, 5 days/week for 4 weeks. [Results] Leptin and insulin levels in the CS and CE groups were significantly lower than those in the HS group (p<0.001), whereas leptin (p<0.01) and insulin (p<0.05) levels decreased significantly in the CE compared to those in the CS group. Interleukin (IL)-1β (p<0.001) and IL-6 (p<0.01) levels in the CS and CE groups decreased significantly compared to those in the HS group. Leptin (IL-1β: r=0.835, p<0.001), IL-6 (r=0.607, p<0.05), insulin (IL-1β: r=0.797, p<0.01), and IL-6 (r=0.827, p<0.01) levels were positively related with pro-inflammatory cytokine levels. [Conclusion] Endurance exercise may play an important role during CLA supplementation of rats on a high-fat diet.

Kudzu Leaf Extract Suppresses the Production of Inducible Nitric Oxide Synthase, Cyclooxygenase-2, Tumor Necrosis Factor-Alpha, and Interleukin-6 via Inhibition of JNK, TBK1 and STAT1 in Inflammatory Macrophages

Kudzu (Pueraria montana var. lobata (Willd.) Sanjappa & Pradeep) is a perennial leguminous vine, and its root and flower have been used for herbal medicine in Asia for a long time. Most dietary flavonoids are reported to be concentrated in its root, not in its aerial parts including leaves. In this study, we investigated whether kudzu leaf and its major constituent, robinin (kaempferol-3-O-robinoside-7-O-rhanmoside) possessed anti-inflammatory activity. To test this hypothesis, we used peritoneal macrophages isolated from BALB/c mice and stimulated the cells with lipopolysaccharide (LPS) or LPS plus interferon (IFN)-γ. Compared with kudzu root extract, its leaf extract was more potent in inhibiting the production of inducible nitric oxide synthase (iNOS), cyclooxygenase-2, tumor necrosis factor-α, and interleukin-6. Kudzu leaf extract decreased LPS-induced activation of c-Jun N-terminal kinase (JNK) and TANK-binding kinase 1(TBK1) with no effects on nuclear factor-κB and activator protein 1 transcriptional activity. Also, kudzu leaf extract inhibited LPS/IFN-γ-induced signal transducer and activator of transcription 1 (STAT1) activation partly via an altered level of STAT1 expression. Robinin, being present in 0.46% of dry weight of leaf extract, but almost undetected in the root, decreased iNOS protein involving modulation of JNK and STAT1 activation. However, robinin showed no impact on other inflammatory markers. Our data provide evidence that kudzu leaf is an excellent food source of as yet unknown anti-inflammatory constituents.

Antioxidative effect of CLA diet and endurance training in liver and skeletal muscles of rat

The purpose of this study is to investigate the effects of conjugated linoleic acid (CLA) supplementation and endurance exercise on the oxidative/anti-oxidative status in rat liver and skeletal muscles. Sprague-Dawley male rats were randomly divided into HS (high-fat diet sedentary group, n = 8), CS group (CLA supplemented sedentary group, n = 8), and CE group (CLA supplemented exercise group, n = 8). For CLA supplementation, 1.0% CLA was substituted for dietary fat. For endurance exercise, the rats swam for 60 min a day, 5 days a week for 8 weeks. The MDA content, Cu, Zn-SOD and Mn-SOD expression in the soleus muscle (SOM) of the CE group improved significantly compared to the HS (p < 0.01) and CS groups (p < 0.05). Moreover, Mn-SOD expression in both the SOM and extensor digitorum longus muscle (EDL) of the CS were enhanced significantly compared to the HS (p < 0.05). From these results, it was suggested that CLA supplementation under the endurance exercise condition may improve the oxidative status by decreasing the MDA content via potential scavenging of Cu,Zn-SOD, and Mn-SOD protein in red muscle, respectively. Therefore, our study demonstrated long-term endurance exercise with CLA supplementation plays a crucial role for maintenance of antioxidative properties in the skeletal muscle of rat.

Opuntia humifusa Supplementation Reduces Fat Weight by Increasing PPAR-γ and PGC-1α Protein Expression in the Skeletal Muscle of Rats

This study was conducted to investigate the effects of supplementation with Opuntia humifusa on the expression of peroxisome proliferator-activated receptor-delta (PPAR-δ), peroxisome proliferator-activated receptor-gamma (PPAR-γ) and peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1α) in the skeletal muscle of rats fed a high-fat diet. Sixteen Sprague-Dawley male rats at 6 weeks of age were randomly divided into 2 groups: a control diet group (CG, n=8) and an experimental diet group (EG, n=8). The rats were fed a high-fat diet (CG) or a high-fat diet supplemented with 5% O. humifusa (EG) for 8 weeks. The results showed that the abdominal fat pad and epididymal fat pad weights were significantly lower in the EG than in the CG (p＜0.01). In the blood, serum glucose, triglycerides, and total cholesterol in the EG group were lower than in the CG (p＜0.01). The expression of PPAR-γ and PGC-1α protein in the skeletal muscle of the EG was increased compared with that of the CG (p＜0.05). These results indicate that 8 weeks of O. humifusa supplementation lowers serum glucose and triglyceride levels and suppresses weight gain by reducing fat weight through an increase in the expression of PPAR-γ and PGC-1α in the muscle tissue of rats.