Kyoichi Osada

Effect of Dietary Purified Xanthohumol from Hop (Humulus lupulus L.) Pomace on Adipose Tissue Mass, Fasting Blood Glucose Level, and Lipid Metabolism in KK-Ay Mice

We previously showed that xanthohumol-rich hop extract (XRHE, ~18% xanthohumol) exerts anti-obesity effects in rats fed a high-fat diet through regulation of fatty acid metabolism. In this study, we examined the effects of dietary purified xanthohumol from XRHE (PX, ~91.9% xanthohumol) in KK-Ay mice in order to understand the anti-obesity effects of xanthohumol alone because XRHE contains 82% unknown compounds. Dietary consumption of PX significantly inhibited an increase in the visceral fat weight of mice compared to those fed control diet without PX. Plasma leptin level was significantly lower in the PX-fed group than in the control group. Dietary PX lowered hepatic fatty acid synthesis by down-regulation of SREBP1c mRNA expression in the liver. On the other hand, fatty acid β-oxidation in the liver was promoted by dietary PX through the up-regulation of PPARα mRNA expression. Moreover, the fecal levels of fatty acids and carbohydrates increased by dietary PX. PX inhibited lipase or α-amylase activity in vitro. Thus, we found that PX may exert anti-obesity effects through the regulation of lipid metabolism and inhibition of intestinal fat and carbohydrate absorption, and that xanthohumol alone may exert anti-obesity effects.

Ezetimibe reduced hepatic steatosis induced by dietary oxysterols in nonhuman primates

Oxidized cholesterol (oxysterols) plays an important and multifaceted role in lipid metabolism. Here we examined whether dietary oxysterols accelerate hepatic lipid accumulation and inflammation in nonhuman primates. We also examined the effect of the Niemann–Pick C1‐like1 inhibitor, ezetimibe (Ez). Macaca fascicularis (5‐year‐old males) were fed either regular cholesterol + high‐fat diet (control‐HFD) or oxysterols + high‐fat diet (ox‐HFD; with 0.015% of oxysterols cholesterol) for 24 weeks. Compared with control‐HFD, ox‐HFD did not affect plasma lipid levels, but it did affect hepatic lipid levels [total cholesterol, 40.9 mg·g−1 (ox‐HFD) versus 3.2 (control‐HFD) mg·g−1; triglycerides, 28.0 (ox‐HFD) versus 5.7 (control‐HFD) mg·g−1]. Ox‐HFD increased lipid accumulation as well as recruitment of inflammatory cells when compared to control‐HFD. We then examined the effects of Ez, 0.2 mg·kg−1·day−1 for 12 weeks. In addition to a significant reduction in dyslipidemia, Ez alleviated biochemical and pathological aspects of steatosis. Dietary oxysterols aggravate steatosis in nonhuman primates. Treatment with Ez may be a novel therapeutic approach to NAFLD by alleviating dyslipidemia.

Effects of eicosapentaenoic acid and docosahexaenoic acid on anxiety-like behavior in socially isolated rats

Abstract The effects of fish oil for improving mental health have been reported. The present study was undertaken to compare the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on anxiety-like behavior using a rat model. Experimental diets enriched in EPA or DHA as glycerides were prepared. Rats were exposed to social isolation stress and fed the experimental diet for 14 days. The results of behavioral tests revealed that rats fed the EPA-enriched diet exhibited less anxiety-like behavior than rats fed the control or DHA-enriched diets. Furthermore, EPA suppressed anxiety-like behavior only in socially isolated rats. The increase in EPA contents in the brain phospholipid fraction by feeding EPA-enriched diet was more significant than that of DHA by feeding DHA-enriched diet. These results suggest that dietary EPA is more anxiolytic than DHA in rats exposed to social isolation stress and is effective in increasing EPA content in brain membranes. This study revealed that EPA has a stronger inhibitory effect on anxiety-like behaviors than DHA in rats under stress.