Consumption of Japanese Yam Improves Lipid Metabolism in High-Cholesterol Diet-Fed Rats

Abstract

SummaryWe investigated the effects of dietary Japanese yam (Dioscorea japonica Thunb.) on lipid metabolism. Male Wistar rats (6 wk old) were fed a high-cholesterol diet for 6 wk and then supplemented with 26% of Japanese yam or 0.5% of its constituent diosgenin for a further 4 wk of high-cholesterol feeding (C6-J4 and C6-D4 groups, respectively). In the C6-J4 group, body weight gains significantly decreased, but skeletal muscle fiber sizes in quadriceps significantly increased compared with the other groups. Furthermore, Japanese yam supplementation resulted in the reduction of triglyceride contents in their liver, quadriceps, and intra-abdominal visceral fat. Diosgenin supplementation resulted in an increase in the numbers of skeletal muscle fibers and decrease in the fat accumulations in liver and of the lipid contents in quadriceps. Although quadriceps cholesterol contents decreased concomitantly with increased serum HDL-cholesterol in both the groups, fecal bile acid, fecal cholesterol contents, and fecal weight were higher in the C6-J4 group than in the C6-D4 group. Meanwhile, we demonstrated that Japanese yam inhibited micellar cholesterol solubility in vitro in a concentration-dependent manner. These results suggest that Japanese yam is more effective than diosgenin in reducing fat accumulation and improving cholesterol metabolism during chronic consumption of a high-cholesterol diet.

Equine chorionic gonadotropin drives the transcriptional profile of immature cumulus‐oocyte complexes and in vitro‐produced blastocysts of superstimulated Nelore cows

“…In cumulus cells, a striking impact on gene expression was not observed, unlike found in oocytes samples. CPT1B , an enzyme required for the net transport of long‐chain fatty acyl‐CoAs from the cytoplasm into the mitochondria to for β‐oxidation fate, and VCAN , an extracellular matrix proteoglycan and a key biomarker of pregnancy outcome (Gebhardt, Feil, Dunning, Lane, & Russell, ; Kusano, Tsujihara, Masui, Kozai, & Takeuchi, ; Russell, Doyle, Ochsner, Sandy, & Richards, ; Wathlet et al, ; Xu, Chen, Zhang, Wei, & Cao, ),were upregulated in the FSH/eCG group. Furthermore, we found that NDUFA1 , a mitochondrial antioxidant enzyme that is expressed in response to oxidative and endoplasmic reticulum stresses, that was upregulated in human cumulus cells from oocytes yielding low‐quality embryos and from oocytes failing in fertilization (Liu et al, ), and was 300‐fold downregulated in the FSH/eCG group.…”

Diosgenin Supplementation Prevents Lipid Accumulation and Induces Skeletal Muscle-Fiber Hypertrophy in Rats

“…We examined whether dietary Dio ameliorated lipid metabolism and altered skeletal muscle structure in the rats chronically fed a high-cholesterol (Chol) diet. It was shown that supplementation with Dio for 4 wk resulted in a slight increase in serum high-density lipoprotein (HDL)-Chol and fecal bile acid levels, and in a decrease in the size of lipid droplets in the liver (8). While these results indicated that Dio slightly improved lipid metabolism in rats regularly ingesting a high-Chol diet, we were unable to clarify the role of dietary Dio.…”

“…Following acclimatization, rats were randomly divided into three groups of six animals: control (CTL), high-Chol diet (Chol), and high-Chol Dio-supplemented diet (Chol1 Dio) groups. Rats in the CTL group were fed standard rodent chow, while those in the Chol group were fed high-Chol diets containing 0.5% Chol and 0.125% sodium cholate for 6 wk (Table 1) as previously described (8). The Chol1Dio group was fed a high-Chol diet supplemented with 0.5% Dio (Tokyo Chemical Industry Co., Ltd., Japan) for 6 wk.…”

“…Measurements of lipid components in blood and tissues. Blood, feces, and liver tissues were processed as previously described (8). Briefly, blood was centrifuged at 1,700 3g for 10 min (KUBOTA 5200, Japan) after sitting at room temperature for 30 min, and supernatants were collected.…”

“…Observations of skeletal muscle and liver tissues. Left quadriceps and liver tissues were fixed in a 4% paraformaldehyde phosphate buffer solution as previously described (8), and histological sections were examined and photographed under a microscope after staining with hematoxylin and eosin (H&E). Image analyses were performed using Image J software.…”