Effects of dietary fructan on cecal enzyme activities in rats

In this study, we have attempted to determine the effects of dietary fructose polymers (fructan), high molecular-weight β-(2,6)-linked levan, and low-molecular-weight β-(2,1)-linked inulin, on two intestinal enzymes (β-glucuronidase and β-glucosidase). As a preliminary experiment, when intestinal microflora were cultured in anaerobic media harboring levan or its oligosaccharides, bacterial cell growth was observed in the levanoligosaccharide-supplemented media, but not in the levan-supplemented media, indicating that levan’s size is important for the utilization by intestinal bacteria of levan as an energy source. In our animal study, the intake of a levan-rich diet was determined to significantly attenuate the activity of the harmful enzyme β-glucuronidase, but did not affect the activity of β-glucosidase.     

Influence of serotonin on some serum enzyme activities in rats

The serotonin injected intraperitoneally in rats (20 mg/Kg of body weight) modifies some seric enzymatic activities (LDH, alpha-HBDH and CPK) at different times from the injection (30, 60, 90 min.), acting probably on membrane permeability and on intracellular metabolism.     

Effects of oral L-arginine supplementation on blood pressure and asymmetric dimethylarginine in stress-induced preeclamptic rats

This study was carried out to elucidate the role of asymmetric dimethylarginine (ADMA) and nitric oxide (NO) in preeclampsia development, and to investigate the effect of L-arginine supplementation in rats. Preeclampsia was induced in pregnant rats using a stress model. L-arginine was administered orally and ADMA, urinary nitrate, and protein levels were measured on the 20th day of pregnancy. Compared with the group of rats that are normally pregnant, the levels of blood pressure (BP), protein excretion, and ADMA were significantly increased in preeclampsia which returned to normal levels following the supplementation of L-arginine. Both group of rats had similar urine nitrate levels. Arginine-ADMA-NO pathway is affected in preeclampsia. L-arginine supplementation decreased hypertension (HT), proteinuria, and ADMA levels indicating that taking L-arginine may be beneficial in preeclampsia treatment.     

Synergistic action of olive oil supplementation and dietary restriction on serum lipids and cardiac antioxidant defences

Caloric intake is higher than recommended in many populations. Therefore, enhancing olive oil intake alone may not be the most effective way to prevent cardiovascular diseases. The purpose of the present study was to analyse the association of olive oil and dietary restriction on lipid profile and myocardial antioxidant defences. Male Wistar rats (180-200 g, n = 6) were divided into 4 groups: control ad libitum diet (C), 50% restricted diet (DR), fed ad libitum and supplemented with olive oil (3 mL/(kg x day)) (OO), and 50% restricted diet and supplemented with olive oil (DROO). After 30 days of treatments, OO, DR, and DROO groups had increased total cholesterol and high-density lipoprotein cholesterol concentrations. DR and DROO animals showed decreased low-density lipoprotein cholesterol. DROO had the lowest low-density lipoprotein cholesterol concentration. Total lipids and triacylglycerols were raised by dietary restriction and diminished by olive oil. OO rats had higher myocardial superoxide dismutase and lower catalase and glutathione peroxidase activities than C rats. DR and DROO showed enhanced cardiac superoxide dismutase, catalase, and glutathione peroxidase activities from the control. Olive oil supplementation alone improved the lipid profile but was more effective when coupled with dietary restriction. There was a synergistic beneficial action of dietary restriction and olive oil on serum lipids and myocardial antioxidant defences.     

Effects of an alpha-glucosidase inhibitor, acarbose, on blood glucose and serum lipids in streptozotocin-induced diabetic rats

Effects of either a single dose or a long-term administration of an alpha-glucosidase inhibitor, acarbose, on blood glucose, cholesterol concentrations in serum lipoprotein fractions, triglycerides and free fatty acids were examined in streptozotocin-induced diabetic rats. In experiment 1, starch loading tests were performed with or without adding acarbose. The addition of acarbose (0.75 mg per kg of body weight or over) significantly reduced the elevation of blood glucose levels. In experiment 2, the animals were divided into three groups: Group A fed on a control diet, Group B fed on a diet containing 5 mg acarbose in 100 g of diet and Group C fed on a diet containing 20 mg acarbose in 100 g of diet. The food intake in Group C was significantly reduced by 22% as compared to Group A, while the food intake in Group B showed no change. The high dose of acarbose showed a tendency to lower fasting blood glucose levels, but the difference was statistically insignificant. However, postprandial glucose levels in Group C at each period examined and in Group B at 30 days were significantly lower than the counterparts in Group A. Acarbose caused a dose-dependent decrease in serum total cholesterol levels and HDL-cholesterol: total cholesterol ratios were elevated in Group B and C. Serum triglyceride levels in Group B and C were extremely lower than those in Group A on and after 20 days. These results indicate that the addition of acarbose to the diet induces a decrease in postprandial blood glucose levels and simultaneously causes an improvement in lipid metabolism of streptozotocin-induced diabetic rats.     

Effects of oral zinc and magnesium supplementation on serum thyroid hormone and lipid levels in experimentally induced diabetic rats

This study was designed to investigate the effects of oral zinc and magnesium supplementation on serum thyroid hormone and lipid levels in alloxan-induced diabetic rats. Thirty-two albino male rats, weighing 234±34 g, were divided into four experimental groups (control, diabetic, diabetic+zinc supplemented and diabetic+ magnesium supplemented). The experiment lasted for 60 d. The first 45 d of the experiment was the supplementation and last 15 d was the supplementation and diabetes-inducing period. Diabetic+zinc-supplemented and diabetic+magnesium-supplemented groups were given orally (by adding in their drinking water) 227 mg/L of zinc and 100 mg/kg body weight (bw) of magnesium, respectively throughout the experiment. Control and diabetic groups served as controls and did not receive zinc or magnesium supplementation. Diabetic, diabetic+zinc-supplemented, and diabetic+magnesium-supplemented groups were given a daily injection (ip) of 100 mg/kg bw of alloxan for 15 d starting on d 46 of the experiment. The control group was only injected with the same volume of isotonic NaCl as the diabetic group received. At the end of the of the experiment, rats in all four groups were fasted for 12 h and blood samples were taken from the heart under ether anesthesia for the determination of thyroid hormone, glucose, total cholesterol, and triglyceride concentrations. It was found that serum glucose, total cholesterol, and triglyceride concentrations were higher and serum T3 and T4 concentrations were lower in diabetic rats than those in the control group. Zinc supplementation did not change any parameter in diabetic rats. However, magnesium supplementation decreased the elevated total cholesterol and triglyceride concentrations of the diabetic rats to the control level. It was concluded that oral magnesium supplementation might decrease the diabetes-induced disturbances of lipid metabolism.     

Biochemical responses of healthy subjects during dietary supplementation with L-arginine

Dietary supplements of L-arginine, a substrate for nitric oxide synthases, may promote formation of nitric oxide and thus may be of clinical benefit. However, the optimal level of L-arginine supplementation is unclear. The objective of this study was to evaluate the response of healthy individuals to increasing doses of L-arginine (as free acid). Twelve healthy subjects were recruited and instructed to take L-arginine for 1-week periods at daily doses of 3, 9, 21, and 30 g. At baseline and at the end of each week, 24-hour urine and fasting blood samples were collected, and weight, diastolic blood pressure, and systolic blood pressure were recorded. Samples were analyzed for L-arginine, L-citrulline, glycine, L-lysine, L-ornithine, asymmetric dimethy L-arginine, symmetric dimethy L-arginine, glucose, insulin (serum), creatinine, cGMP (urine), and total nitrates (serum and urine). Ten subjects reported adverse side effects at initial L-arginine doses of 21 g/day (five subjects) or 30 g/day (five subjects), respectively. Blood pressure and weight did not change during the supplementation period. Of the individual biochemical measures, only L-arginine, glycine, and L-ornithine concentrations changed significantly. The mean concentration of L-arginine reached a peak during supplementation at 9 g/d; however, individuals differed markedly in their response. Availability of L-arginine, relative to that of asymmetric dimethy L-arginine, increased significantly at both 9 g/day and 21 g/day. Mean values indicate that supplementation with 9 g/day of L-arginine, a dose associated with minimal adverse side effects, is sufficient to increase circulating L-arginine concentrations. However, subjects varied widely in their responses, indicating that L-arginine supplementation needs to be tailored to individuals.     

南瓜多糖对糖尿病大鼠血糖和血脂的影响

目的：研究南瓜多糖对糖尿病大鼠血糖和血脂的影响。方法：Wistar大鼠腹腔注射四氧嘧啶后。将成模的糖尿病大鼠根据血糖和体重随机分为糖尿病组、消渴丸组和南瓜多糖组,同时设立正常对照组,并分别给予蒸馏水、消渴丸和南瓜多糖灌胃,每周测量体重一次,四周后测定空腹血糖、血清总胆固醇、甘油三酯、高密度脂蛋白、低密度脂蛋白和游离脂肪酸的含量。结果：糖尿病组大鼠体重下降,血糖显著升高,甘油三酯、总胆固醇、低密度脂蛋白和游离脂肪酸含量显著增加,而高密度脂蛋白含量显著降低;补充南瓜多糖和消渴丸后,体重逐渐增加,血糖显著下降,总胆固醇、甘油三酯、低密度脂蛋白和游离脂肪酸含量显著降低,高密度脂蛋白含量显著升高,并且南瓜多糖的降糖降脂效果优于消渴丸。结论：南瓜多糖能增加体重,降低糖尿病大鼠血糖、血脂,对糖尿病及其并发症有一定的作用。     

Effects of benfluorex-vitamin C supplementation on cutaneous capillaries of diabetic rats

The ultrastructural changes on capillaries of the dermis in diabetic and benfluorex-vitamin C treated diabetic rats have been investigated. Three groups of 21 Wistar albino rats were used in the examination: control, diabetes, and benfluorex-vitamin C treated diabetic rats. Diabetes was induced by injection of streptozotocin. The streptozotocin-induced group was treated for 21 days with vitamin C and benfluorex, of which antidiabetic and antihyperlipidemic effects were experimentally proved. Samples taken from the skin of rats' legs were examined under transmission electron microscopy. Swollen endothelial cells, narrowed capillary lumens, a thickened basement membrane, and fusion of mitochondrial cristae in the capillaries of diabetic rat dermis were seen. In the benfluorex-vitamin C treated group, contrary to the diabetic group, neither signs of degeneration in endothelial cells nor a significant difference with the control group with regard to capillary structure were observed. Amelioration in capillaries appears to be due to benfluorex and vitamin C treatment in diabetes.     

Effects of antenatal,postpartum and post-weaning melatonin supplementation on blood pressure and renal antioxidant enzyme activities in spontaneously hypertensive rats

Although melatonin lowers blood pressure in spontaneously hypertensive rats (SHR), its effect following antenatal and postpartum supplementation on the subsequent development of hypertension in SHR pups remains unknown. To investigate this, SHR dams were given melatonin in drinking water (10 mg/kg body weight/day) from day 1 of pregnancy until day 21 postpartum. After weaning, a group of male pups continued to receive melatonin till the age of 16 weeks (Mel-SHR), while no further melatonin was given to another group of male pups (Maternal-Mel-SHR). Controls received plain drinking water. Systolic blood pressure (SBP) was measured at 4, 6, 8, 12 and 16 weeks of age, after which the kidneys were collected for analysis of antioxidant enzyme profiles. SBP was significantly lower till the age of 8 weeks in Maternal-Mel-SHR and Mel-SHR than that in the controls, after which no significant difference was evident in SBP between the controls and Maternal-Mel-SHR. SBP in Mel-SHR was lower than that in controls and Maternal-Mel-SHR at 12 and 16 weeks of age. Renal glutathione peroxidase (GPx) and glutathione s-transferase (GST) activities, levels of total glutathione and relative GPx-1 protein were significantly higher in Mel-SHR. GPx protein was however significantly higher in Mel-SHR. No significant differences were evident between the three groups in the activities of superoxide dismutase, catalase and glutathione reductase. In conclusion, it appears that while antenatal and postpartum melatonin supplementation decreases the rate of rise in blood pressure in SHR offspring, it however does not alter the tendency of offspring of SHR to develop hypertension.     

Influence of dietary lipids on intestinal bile acid absorption

The enterohepatic circulation and the inability of upper small intestine to actively absorb bile acid are physiological adaptations for maintaining adequate bile acid concentrations in the intestinal lumen for use in lipid digestion and absorption. Certain lipids inhibit bile acid absorption suggesting a possible role of lipids in this scheme. Using isolated intestinal villi preparations of hamster ileum, experiments were conducted to assess the degree of inhibition of bile acid absorption by lipids of various classes and to determine the possible mechanism of inhibition. At an initial bile acid concentration of 10.0 mM, triolein significantly reduced villus uptake of taurocholic acid by 50% and cholic acid by 38%. This inhibition was similar to the degree of inhibition produced by oleic acid (58 and 48%, respectively). Likewise, representative medium-chain and short-chain triglycerides inhibited taurocholic acid uptake by 35 and 39%, respectively. Results show that triglycerides as well as oleic acid inhibit ileal bile acid uptake. Neither oleic acid nor triolein altered bile acid uptake when micelles were absent from incubation solutions. Furthermore, lipids did not alter absorption of a nonmicelle-forming bile acid, taurodehydrocholic acid. These data imply that dietary lipids in general may inhibit intestinal bile acid absorption. Oleic acid significantly reduced the intermicellar bile acid concentration from 8.9 +/- 0.2 mM to 3.9 +/- 0.2 mM while tributyrin, tricaprylin, and triolein had no effect. Results from these studies suggest that the mechanism of inhibition appears to be an enhancement of micelle formation. We speculate that this mechanism may be an additional mechanism for maintaining adequate luminal bile acid concentrations and may be the pathophysiologic mechanism contributing to bile acid malabsorption in cystic fibrosis.     

Effects of dietary lactose and purified diet on intestinal microflora of rats

In the rats fed on lactose-containing purified diet (PDL), bifidobacteria remarkably increased in number in both the jejunum and cecum as compared with those fed on control diet (PD) or conventional diet (NMF). Besides, lactobacilli, streptococci, staphylococci, and Escherichia coli increased in number in the jejuna and/or ceca of rats fed on PDL as compared with those fed on PD. The incidence and numbers of Lactobacillus species were remarkably different between the rats fed on PDL and those on any of the other diets. Indole-producing Bacteroides spp. were rarely isolated from the PDL-fed rats. The cecum was markedly enlarged in the PDL rats and reduced in the PD rats as compared with that in the NMF animals.     

Effects of dietary selenium supplementation on parasitemia,anemia and serum proteins of Trypanosoma brucei brucei infected rats

Trypanosomosis has been associated with immunosuppression, anemia and oxidative damage while selenium possesses both immunostimulatory and antioxidative effects. This study was designed to assess the effect of dietary selenium supplementation on parasitemia, anemia, survival pattern and serum protein profiles of trypanosome-infected rats. Twenty five rats, divided into five groups (A–E) of 5 each, were treated as follows: 4, 8 and 16 ppm (ppm) of selenium in their feed, respectively throughout the experimental period and were infected with Trypanosoma brucei brucei on day 14 post supplementation, infected not supplemented and the negative control. Supplementation at 4 and 8 ppm increased the packed cell volume (PCV) and hemoglobin (Hb) concentration on day 7 of supplementation (PS) when compared with the unsupplemented groups. Following infection on day 14 PS, the PCV, Hb of 16 ppm and infected not supplemented groups were significantly (P < 0.05) lower than other groups on days 28 and 35 PS. Supplementation did not lead to significant (P > 0.05) changes on the total protein, albumin and globulin by day 14 PS. Infection, however, caused significant (P > 0.05) decrease in the total protein and albumin from day 28. The supplementation did not significantly (P > 0.05) increase the pre-patent period but caused a significant reduction in the parasitemia levels and increased survival intervals. Dietary selenium supplementation, from the results, may show promise in the management of African trypanosomosis as the supplementation was able to: reduce anemia and parasitemia and increase survival intervals of trypanosome infected rats.     

A protein-free diet alters small intestinal architecture and digestive enzyme activities in rats

The consequences of feeding a protein-free (PF) diet, as compared to casein, on gut characteristics were studied in slightly energy-restricted rats fed similar amounts of feed for 10 d. The weight and pH of fresh digesta in the stomach were lower (P = 0.045 and P = 0.016). However, the weight of fresh digesta in the other segments and gut tissue weight were not significantly affected by the diet (P > 0.05). Small intestinal crypt depth, width and area were reduced by 13, 23 and 37%, respectively (P = 0.011, P = 0.004 and P = 0.001), and villus width tended to be smaller (P = 0.057), with the PF diet. Villus height to crypt depth ratio was also lower with the PF diet in the duodenum and ileum, respectively (P < 0.05). Finally, the specific activities of alkaline phosphatase and aminopeptidase N were reduced by 36 to 38% at different sites of the small intestine in the rats fed the PF diet (P < 0.05). In conclusion, chronic consumption of a protein-free diet altered the intestinal villus-crypt architecture and enzyme activities in rats.     

Effects of dietary nutrients on lipogenic enzyme and mRNA activities in rat liver during induction

By feeding a carbohydrate diet (without protein) to fasted rats, malic enzyme mRNA activity in the liver was increased to the level in rats fed a carbohydrate and protein diet, whereas the enzyme activity itself was increased to 60% of that level. It appears that malic enzyme mRNA activity was increased by dietary carbohydrate, while dietary protein contributed to an increase in the translation of mRNA. In the animals fed carbohydrate without protein, glucose-6-phosphate dehydrogenase mRNA activity increased to 50% of the level in rats fed the carbohydrate and protein diet, whereas the enzyme activity increased to only 25%. By feeding a protein diet (without carbohydrate), glucose-6-phosphate dehydrogenase activity increased to 65% of the level in rats fed both carbohydrate and protein. This enzyme induction appears to be more dependent on protein than carbohydrate. With the carbohydrate diet, acetyl-CoA carboxylase was induced up to the level in the carbohydrate and protein diet group, whereas fatty acid synthetase was induced to only 33%. Acetyl-CoA carboxylase induction appears to be carbohydrate dependent. On the other hand, isotopic leucine incorporation studies showed that the magnitudes of the enzyme inductions caused by the dietary nutrients should be ascribed to the enzyme synthesis rates rather than the degradation. By fat feeding, the mRNA activities of malic enzyme and glucose-6-phosphate dehydrogenase were markedly decreased along with the enzyme induction. Fat appears to reduce these enzyme inductions before the translation of mRNA.