Satoshi Innami

Administration of beta-carotene Suppresses Lipid Peroxidation in Tissues and Improves the Glucose Tolerance Ability of Streptozotocin-Induced Diabetic Rats

The present study attempted to examine the antioxidative effect of dietary beta-carotene (BC) on lipid peroxidation (LPO) in the streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley (SD) rats were fed on the AIN76 standard diet with or without 0.1% BC. On the 21st day after introduction of these diets, STZ was intraperitoneally injected in half the subjects of both groups. All animals were sacrificed seven days after the STZ injection. Glucose tolerance and thiobarbituric acid reactive substance (TBARS) in the tissues or serum were measured. Body weight gain in the BC + STZ group was significantly higher than that in the STZ group (p < 0.05). Blood glucose and TBARS concentrations of the liver, pancreas, and serum in the BC + STZ group were significantly lower than those in the STZ group. The blood insulin concentration in the BC + STZ group was significantly higher than that in the STZ group. The hepatic and serum beta-carotene concentrations in the BC + STZ group were significantly lower than those in the BC group. Moreover, the synthesis and oxidation of glutathione (GSH) in the BC + STZ group were reduced when compared to the STZ group. These results suggest that the administration of beta-carotene suppresses the elevation of LPO and reduces the symptoms of diabetes mellitus (DM) in the STZ-induced diabetic rats.

Jew's mellow leaves (Corchorus olitorius) suppress elevation of postprandial blood glucose levels in rats and humans.

The study was performed to explore the suppressive effect of Jews mellow leaves (JML) on postprandial blood glucose levels in rats and humans. A soluble dietary fiber (SDF) was extracted from the freeze-dried JML powder. An elevation of the postprandial blood glucose level in rats given 1% or 2% JML-SDF solution orally together with 20% glucose solution was significantly suppressed as compared with that observed in the control rats given only glucose solution. When seven healthy young male adults ingested 225 mL of JML mixed juice containing 15 g of freeze-dried powder with 75 g of glucose in the fasting state in the morning, the elevation of the postprandial blood glucose level was significantly suppressed as compared with the control subjects. The diffusion rate of glucose and the permeation rate of glucose in the cultured Caco-2 cells were both significantly reduced by the addition of appropriate amounts of JML-SDF when compared to the controls. These results indicate that the effective substance in JML for suppressing blood glucose elevation is a kind of mucilaginous SDF. The mechanism by which this suppression occurs may be largely attributable to the delayed absorption of glucose from the intestinal membrane in the upper digestive tract by viscous SDF.

Dietary fiber suppresses elevation of uric acid and urea nitrogen concentrations in serum of rats with renal dysfunction induced by dietary adenine.

This study was conducted to examine the effects of several kinds of dietary fiber (DF) with different physical properties on the elevation of uric acid and urea nitrogen concentrations in serum of rats induced by dietary adenine. DF decreased an uptake of 14C-labeled adenine in the rat jejunum in vitro, but the reduction varied with the physical property of DF. Male Wistar rats (3 weeks old) were fed a diet with or without a 0.4% adenine and a 5% DF (cellulose, chitin, chitosan, or xanthan gum) for 20 days. Feeding of adenine in the fiber-free group elevated the concentrations of uric acid, creatinine, and urea nitrogen in serum, but decreased the excretions of these compounds into urine and increased the amounts of 2,8-dihydroxyadenine (2,8-DHA) in kidney and urine. The test DF was found to suppress the elevation of uric acid, creatinine, and urea nitrogen concentrations in serum induced by dietary adenine, and to mitigate the decreased excretions of these compounds into urine and the increased retention of 2,8-DHA in kidney and urine. This phenomenon was remarkable in the xanthan gum group. These results suggest that DF suppresses the elevation of uric acid and urea nitrogen concentrations in serum by attenuating the absorption of dietary adenine.

Effects of a Partially Hydrolyzed Curdlan on Serum and Hepatic Cholesterol Concentration, and Cecal Fermentation in Rats

A significant reduction was observed for serum and hepatic cholesterol concentrations in the rats fed diet containing a 5% partially hydrolyzed curdlan (PHCD), whereas only the hepatic cholesterol concentration was decreased in the curdlan (CD)-fed rats. The cecal contents in the CD group contained a significantly larger amount of short-chain fatty acids, but not those in the PHCD group. CD, but not PHCD, significantly increased the population of cecal bifidobacteria. From the in vitro fermentation test with cecal contents from cellulose powder (CP) and CD-fed rats, PHCD proved to be easily fermented by both cecal contents; incidentally CD was more susceptible to the cecal contents from CD-fed rats than to those from CP-fed rats. These results suggest that PHCD is involved in the modulation of lipid metabolism and intestinal microflora through a different manner from the native CD in rats.

Influence of dietary krill on iron absorption in growing rats.

オキアミ摂取がラットの消化管からの鉄吸収や鉄栄養に関係する血液性状に与える影響を成長期のwistar系雄ラットを用いて検討した。実験飼料は凍結乾燥生オキアミと煮熟オキアミをいずれも20%と30%タンパク質の2段階レベルで添加したものを調製, 対照として, これらオキアミ飼料に等しいレベルのタンパク質と鉄を含むカゼイン飼料を調製した。これらの飼料を4週間投与後, 体重増加量, 血球数, ヘモグロビン濃度 (Hb), 血清鉄濃度 (SI) 等を測定した結果, 等しいタンパク質レベルについて比較するとき, これらの値は両種のオキアミ群では対照群より低く, とくに煮熟オキアミ群では著定い低下を示した。実験期の最後の9日間の見かけの鉄吸収率は, 生オキアミ群と対照群は比較的似ていたが, 煮熟オキアミ群では負の値を示し, 鉄吸収の著しい阻害作用のあることが推定された。この鉄吸収阻害と甲殻の関係を見るため, 大正エビの生甲殻と煮熟甲殻の乾燥粉末を各10%添加した飼料と濾紙粉末添加の対照飼料を3週間投与した各群のHb, SIを比較した。生甲殻と対照群では差は認められなかったが, 煮熟甲殻群ではSI, Hbは対照群より低い傾向を示した。これらの結果から, オキアミ中には鉄の吸収を阻害する成分が存在するらしいが, それは甲殻である可能性が強く, 加熱処理により活性化されるものと推定されたた。

On Mechanism of “Konjac” Mannan Metabolism by Gastrointestinal Bacteria

こんにゃく粉がカロリー源としてどの程度動物の成長に利用されるかを知るための第一段階として, 米でんぷんの一部をこんにゃく粉で置き換え, pair feeding methodを用いて15%および30%こんにゃく粉混入群を米でんぷん群と比較した結果, 体重増加では両者とも米でんぷん群よりやや劣る程度で, あまり著しい差はみられなかったが, 腹部の膨満がみられたので剖見したところ, 消化管 (内容物共) の重量が大きく, いわゆる見掛けの体重増のあることが判明した。そこで終体重から消化管の重量を差引いた値からさらに初体重を引いたものを仮に真の成長量と考えて比較検討した結果, こんにゃく粉の混入の多くなるに従い, 成長量は劣るがある程度ネズミの成長に効果のあることがうかがわれた。しかしその程度がどのくらいかについては判然としなかった。一方こんにゃく粉炭水化物の消化率は97～99%であって, 井上が人間で得られた成績にほぼ等しい結果を得た。