Effects of serotonergic agents on plasma prolactin levels in pyridoxine-deficient adult male rats

Plasma concentration of prolactin was significantly reduced in pyridoxine-deficient as compared to control (pyridoxine-supplemented) adult male rats. Administration of pyridoxine to deficient rats resulted in a significant increase in plasma prolactin. The reduction in plasma prolactin in pyridoxine-deficient rats corresponded with the significantly reduced hypothalamic contents of pyridoxal phosphate and serotonin in pyridoxine-deficient rats. Plasma prolactin concentrations were also measured in response to serotonergic agents in both groups of rats. The administration of the 5HT_1A agonist (8-hydroxy 2-n-dipropylamino tetralin) resulted in a significant increase in plasma prolactin and that of the specific 5HT_1A antagonist spiroxatrine had the opposite effect. The results suggest that the hypothalamic serotonergic regulation of prolactin release is impaired in pyridoxine deficiency.     

Functional and metabolic consequences of vitamin B-6 deficiency in the rat heart

The cardiac functional and metabolic consequences of pyridoxine deficiency were studied in rats maintained on a pyridoxine-deficient diet for 10 weeks. Because food intake was diminished in the pyridoxine-deficient rats, a second group of animals was fed a diet restricted to the intake of the pyridoxine-deficient animals. The inotropic response (developed pressure) to an isoproterenol or Ca2+ concentration response curve was measured simultaneously with high energy phosphate levels using a modified Langendorf apparatus and 31P nuclear magnetic resonance spectroscopy. The inotropic response to Ca2+ and isoproterenol was significantly decreased relative to controls in both the food-deprived and the pyridoxine-deficient groups. Developed pressure after adrenergic stimulation was significantly less in the pyridoxine-deficient than in the food-deprived animals. Phosphocreatine and ATP levels were maintained and did not differ among the control, pyridoxine-deficient, and food-deprived groups during isoproterenol and Ca2+ stress, implying that the diminished inotropy was not due to an abnormality in generation of high energy phosphate levels.     

Supplementation of orotic acid to the casein, but not to egg protein, soy protein, or wheat gluten diets, increases serum ornithine carbamoyltransferase activity

Effects of dietary supplementation of orotic acid to a diet containing the casein protein were compared with diets containing egg protein, soy protein, or wheat gluten on lipid levels in the liver and serum and activities of ornithine carbamoyltransferase (OCT) and alanine aminotransferase in the serum of rats. We found that supplementation of orotic acid to each diet increased the contents of the liver total lipids, triacylglycerol, and phospholipids compared with those not supplemented. The contents of liver total lipids, triacylglycerol, cholesterol, and phospholipids in rats fed the casein diet were significantly higher than those of rats fed the other three diets when orotic acid was supplemented. The levels of triacylglycerol, cholesterol, and phospholipids in the serum of rats fed the casein diet were markedly decreased by addition of orotic acid. The supplementation of orotic acid significantly increased the activities of both serum OCT and alanine aminotransferase in rats fed the casein diet, but not in rats fed the other diets. In conclusion, liver lipid accumulation induced by dietary orotic acid depends on the type of dietary protein. The enhancement of serum OCT activity may result from liver lipid accumulation in rats fed the casein diet supplemented with orotic acid, demonstrating hepatic damage.     

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 ovariectomy on duodenal calcium transport in the rat: altered ability to adapt to low-calcium diet

Studies were undertaken to determine whether ovariectomy (ovx) would alter the ability of female rats to adapt to low dietary Ca intake by exhibiting an in duodenal active Ca transport. Intact and ovx female rats were fed diets containing 1.5, 0.50, or 0.02% Ca prior to measuring active Ca transport using everted duodenal sacs in vitro. In some experiments, ovx animals were pair-fed to intact animals of the same age consuming the same diet. When ovx animals were allowed to eat ad lib, we found that both growth rate and duodenal active Ca transport increased relative to age-matched, intact controls. However, when growth of ovx animals was maintained at the control rate by pair-feeding, ovx per se did not affect intestinal active Ca transport. Ovx did not alter circulating levels of 1,25-dihydroxyvitamin D (1,25(OH)2D). We found that intact females responded to the low-Ca (0.02%) diet with increased circulating 1,25(OH)2D levels and increased intestinal active Ca transport. Ovx animals exhibited the same increase in circulating concentrations of 1,25(OH)2D in response to low-Ca diet, but did not demonstrate increased duodenal active Ca transport. When ovx animals consumed the diet ad lib, they became larger and exhibited higher Ca transport rates than intact animals fed the high-Ca diet, but there was no difference in Ca transport between ovx animals fed diets containing different Ca contents. The results of these experiments demonstrate that in female rats, the ability to adapt to altered dietary Ca intake is dependent on intact ovarian function and is not necessarily directly related to circulating concentrations of 1,25(OH)2D.     

Effect of lysine and threonine deficient and supplement rice diets on lipids of hepatic smooth and rough endoplasmic reticulum of rats

Effect of feeding lysine and threonine deficient and supplemented rice diets to rats for fifteen days has been studied on the lipids of hepatic smooth (SER) and rough endoplasmic reticulum. The deficient diet reduced protein and phospholipids of SER where as it increased triglycerides contents of both SER and RER compared to rats fed the supplemented diet.     

Lipid metabolism in fatty liver of lysine- and threonine-deficient rats

Rats were fed a low protein diet deficient in and supplemented with lysine and threonine. Liver lipids contained more lecithin, sphingomyelin, and free fatty acids, and less amino phospholipids in the deficient rats. No variations in fatty acid composition of choline- and ethanolamine-containing phospholipids were found; only palmitic acid was increased in the serine-containing phospholipids of the deficient animals. The incorporation of acetate-(14)C into phospholipids, but not into other liver lipids, was lower in deficient rats. In the plasma of deficient rats the concentration of esterified fatty acids and phospholipids was lower, of free fatty acids higher, than in the controls. The fatty acid composition of depot fat differed from that of liver neutral fat both in deficient and supplemented animals. The results presented establish that multiple metabolic defects resulting from lysine and threonine deficiency accompany the fatty liver. The design of the experiments does not permit conclusions to be drawn regarding the causal relationship between the various alterations in lipid metabolism and the fatty liver.     

PYRIDOXINE DEFICIENCY AND DEVELOPMENT OF THE CENTRAL NERVOUS SYSTEM IN THE RAT

Pyridoxine (vitamin B₆) deficiency was produced in rats during the period of development of the central nervous system. The levels of pyridoxal phosphate and y-amino-butyric acid in whole brains of these rats were determined, together with the activities of glutamate decarboxylase (EC 4.1.1.15) and γ-aminobutyrate aminotransferase (EC 2.6.1.19). The lowered contents of pyridoxal phosphate and γ-aminobutyrate in the brains confirmed the existence of pyridoxine deficiency. The activity of the glutamate decarboxylase holo-enzyme was decreased, whereas the activity of the apoenzyme was increased. However, there appeared to be no difference in the activity of γ-aminobutyrate aminotransferase. Concomitantly, some electrophysiological parameters, such as EEG and auditory evoked potentials, were analysed. The EEG of pyridoxine-deficient animals showed spike activity, presumably indicative of the existence of seizures in many of the deficient rats. Evoked potentials presented abnormalities in their latency, wave form and response to repetitive stimuli, but the extent to which they were affected depended upon the intensity of the deficiency.     

Effects of dietary selenium and tocopherol on glutathione peroxidase and superoxide dismutase activities in rat phagocytes

Glutathione peroxidase activities (GSH-Px) of peritoneal exudate polymorphonuclear neutrophils, pulmonary alveolar macrophages, and peritoneal exudate macrophages of rats depleted of dietary selenium for four to six weeks were markedly lower than the corresponding activities in rats fed the same diet supplemented with 0.5 ppm selenium as sodium selenite. GSH-Px in phagocytes from selenium-supplemented rats adequate or deficient in tocopherol status did not differ significantly. In selenium deficient animals, the residual GSH-Px of polymorphonuclear neutrophils and peritoneal macrophages, but not of alveolar macrophages were slightly higher in tocopherol-deficient rats than in tocopherol-supplemented animals. Superoxide dismutase activities of each cell type were comparable and were not significantly affected by dietary selenium or tocopherol.     

Effect of dietary protein and calorie deficiency on tryptophan levels in the developing rat brain

The pattern of development of brain tryptophan in the rat was studied in the progeny of mothers fed a 7.5% protein diet ad lib., a 20% protein diet ad lib. and those fed a 20% protein diet pair-fed with mothers who received the 7.5% protein. The pattern of development was similar in all three groups. Starting with a high brain tryptophan content at birth, all animals showed a progressive reduction during the next 3 weeks. However, tryptophan levels at birth were several fold higher in the brains of pups born to mothers receiving either the low protein diet fed ad lib. or those born to mothers who received the 20% protein diet in restricted amounts. From the 14th day after birth, tryptophan concentration of brain in undernourished pups was significantly lower until the 35th day. The implications of this finding are discussed.     

Effects of different supplements to low protein and poor quality protein diets on performance and brain enzymes in the albino rat

Groups of albino rats were fed low and high protein diets and the former group was fed with different supplements. The supplements used were niacin, pyridoxine and glutamic acid. A low protein diet was found to decrease the activities of l -glutamate-NAD-oxidoreductase and l -glutamate-1-carboxy-lyase in the cerebrum; this confirmed the results of previous work in this laboratory. Addition of glutamic acid to a low protein diet was found to reverse the effects of a low protein diet to some extent. Groups of animals were fed kodri (Paspalum scorbiculatum), a millet deficient in lysine, with or without lysine itself or foodstuffs rich in it, e.g. moth bean (Phaseolus aconitifolius Jacq.), peas (Pisum sativuni) and skim milk powder. When combined, the groups fed on the lysine or lysine-source supplemented diets were found to perform better in a water maze on the basis of the relative ease with which they could reverse a previous learned pattern. They also had higher activities of l -glutamate-NAD-oxidoreductase and l -glutamate-1-carboxy-lyase than groups with no lysine or lysine source added. There was no significant difference between the groups receiving the different lysine supplements.     

Effects of Sterylglycosides from Soybean on Lipid Indices in the Plasma,Liver, and Feces of Rats

The effects of soybean oil (SOO, control), soybean lecithin (SOL), and of sterylglycocides (STG) and phospholipids (PL) fractionated from SOL on lipid indices in the plasma, liver, and feces were examined for male Wistar rats fed with diets containing these lipids for 3 weeks. The body weight gain and liver weight decreased or tended to be reduced in the animals given the diet containing a 5% STG mixture (STGM) compared with the values in the other dietary groups. The plasma lipid concentration in general declined in the rats fed with the diets supplemented with 5% SOL, STGM, or the PL mixture (PLM), and with 1% of STGM, acylated STG (ASTG), or non-acylated STG (NSTG). The triacylglycerol level was significantly depressed in the rats fed with the diets including 1 or 5% of STGM, ASTG, or NSTG when compared to the level of the SOO—fed animals. The total cholesterol and triacylglycerol contents in the liver were lower in the rats provided with the diets containing 5% of SOL, PC, or PLM than in the SOO- or STGM-diet-fed animals. The rats given the diets supplemented with 1 or 5% of STGM, ASTG, or NSTG had a decreased content of liver triacylglycerol compared with the content of the SOO—fed animals. The amounts of total lipids and total cholesterol excreted into the feces were higher in the rats fed with the diets supplemented with 5% SOL, or with 1% of STGM, ASTG, or NSTG, or especially with 5% STGM than in the SOO—fed animals. The present results suggest that STG suppressed the absorption of cholesterol and fatty acids in the intestines.     

Effect of Thyroid Hormone and Sex Difference on Liver Histidase Activity of Young Rats Fed a Histidine Imbalanced Diet

Histidase (l-histidine ammonia-lyase EC 4.3.1.3) activity of thyroidectomized rats was higher than that of intact animals. The levels of protein bound iodine (PBI) in plasma of rats fed a basal diet were higher than those of an imbalanced diet group under ad libitum condition, while if the food intake of a basal diet group was restricted to that of the imbalanced diet group, the levels of PBI of a paired fed group were practically the same as those of the imbalanced diet ad libitum group. Histidase activity of paired fed rats was twice as high as that of ad libitum fed animals, and was about 60% of that of the imbalanced ones. Thyroxine did not affect histidase activity in vitro.

Neither sex difference nor castration affected the activity of histidase of young rats fed the imbalanced diet.     

Effects of dietary pyridoxine on immune responses in abalone, Haliotis discus hannai Ino

A feeding experiment was conducted to investigate the effects of dietary pyridoxine (PN) on the immune responses of abalone, Haliotis discus hannai Ino. Purified diets supplemented with 0, 40, 800 mg PN kg(-1) or 80 mg kg(-1) of 4-deoxypyridoxine (PN antagonist) were fed to adult abalone (initial weight 45.77 +/- 0.25 g; initial shell length 68.02 +/- 0.78 mm) for 90 days. The air-dried brown kelp, Laminaria japonica, was used as a control diet. Each diet was fed to three replicate groups of abalone in a recirculation system using a completely randomised design. The results showed that weight gain ratio (WGR) of the abalone generally increased with the level of dietary PN supplementation though no significant differences were found among the treatments (P > 0.05). Phagocytic and phenoloxidase activities were significantly higher in abalone fed diets supplemented with 800 mg PN kg(-1) than those fed the PN-free diet or the one with 4-deoxypyridoxine (P < 0.05). Agglutination titre and respiratory burst activity were significantly higher in abalone fed diets supplemented with 40 mg PN kg(-1) than those fed the PN-free diet or the one with 4-deoxypyridoxine (P < 0.05). There were no significant differences in immunological characteristics between the abalone fed the diet containing 40 mg PN kg(-1) and those fed the diet containing 800 mg PN kg(-1) (P > 0.05). L. japonica resulted in significantly lower agglutination titre, respiratory burst and phagocytic activities than the artificial diets supplemented with 40 or 800 mg PN kg(-1) (P < 0.05). Total haemocyte count (THC), serum protein concentration, and the activities of lysozyme and acid phosphatase were not significantly affected by the dietary treatments (P > 0.05). These results demonstrate that dietary deficiency of pyridoxine suppresses the immune functions in H. discus hannai, and further investigations are needed to optimise the dietary level of this vitamin for maintaining the best immune responses in abalone.     

Pyridoxine deficiency and cytotoxicity of T lymphocytes in vitro.

The effect of pyridoxine deficiency on the proliferation and cytotoxicity of BALB/c mouse lymphocytes stimulated in vitro with irradiated spleen cells from C3H mice was studied. Cytotoxicity was measured by Na⁵¹CrO₄ release from L cells which have the same histocompatibility loci as C3H mouse cells. Pyridoxal-5′-phosphate (PLP) content in the spleen and liver of pyridoxine-deficient animals was determined with Escherichia coli B/1 t7A apotryptophanase. Maintenance of animals on a pyridoxine-deficient diet for 1 to 3 weeks affected neither proliferation of lymphocytes in vitro nor their cytotoxicity. Lymphocytes from mice fed a pyridoxine-deficient diet for 5 to 6 weeks had a reduced capacity to respond to foreign lymphoid cells in vitro. The Cytotoxicity of these lymphocytes was also significantly decreased. PLP, but not pyridoxal, added directly to the medium in vitro partially restored the impaired functions of T lymphocytes.     

The effects of dietary supplementation with butyrate and polyhydroxybutyrate on the digestive capacity and intestinal morphology of Pacific White Shrimp (Litopenaeus vannamei)

This study evaluated dietary supplementation with sodium butyrate and polyhydroxybutyrate (PHB) on the enzymatic activity, in vitro nutrient digestibility, and intestinal morphology of Pacific white shrimp (Litopenaeus vannamei). The treatments were: shrimp fed diet supplemented with 2% butyrate, shrimp fed diet supplemented with 2% PHB, and shrimp fed unsupplemented diet. Shrimp fed with PHB-supplemented diet showed higher values of intestinal protease, trypsin, chymotrypsin, and amylase. Shrimp fed with butyrate-supplemented diet showed higher intestinal lipase than unsupplemented shrimp. Butyrate increased hepatopancreatic protease, trypsin, and chymotrypsin activity and in vitro protein digestibility. Shrimp fed with PHB-supplemented diet and butyrate had higher digestibility of polysaccharides and lipids. Shrimp fed with PHB-supplemented diet presented increase in the length, width, and perimeter of intestinal villi. Animals fed with both diets retained overall integrity of their intestinal mucous membrane. The findings show that dietary supplementation with PHB and butyrate can alter intestinal morphology and could improve the digestive capacity of L. vannamei.     

Diet affects resting, but not basal metabolic rate of normothermic Siberian hamsters acclimated to winter

We examined the effect of different dietary supplements on seasonal changes in body mass (m_b), metabolic rate (MR) and nonshivering thermogenesis (NST) capacity in normothermic Siberian hamsters housed under semi-natural conditions. Once a week standard hamster food was supplemented with either sunflower and flax seeds, rich in polyunsaturated fatty acids (FA), or mealworms, rich in saturated and monounsaturated FA. We found that neither of these dietary supplements affected the hamsters' normal winter decrease in m_b and fat content nor their basal MR or NST capacity. NST capacity of summer-acclimated hamsters was lower than that of winter-acclimated ones. The composition of total body fat reflected the fat composition of the dietary supplements. Resting MR below the lower critical temperature of the hamsters, and their total serum cholesterol concentration were lower in hamsters fed a diet supplemented with mealworms than in hamsters fed a diet supplemented with seeds. These results indicate that in mealworm-fed hamsters energy expenditure in the cold is lower than in animals eating a seed-supplemented diet, and that the degree of FA unsaturation of diet affects energetics of heterotherms, not only during torpor, but also during normothermy.     

Effects of excess dietary phenylalanine on composition of cerebral lipids

Abstract— Concentrations in whole rat brains of lipids (total lipids, phospholipids, galactolipids, cholesterol, plasmalogens) and of proteolipid protein were not altered after feeding for 2 and 6 weeks of diets containing 5 per cent excess l -phenylalanine. After 2 weeks of diet with 7 per cent excess l -phenylalanine there was a slight reduction (5–10 per cent) in the concentrations in whole brain of cholesterol and galactolipids. No significant effects were noted in cerebral hemispheres after 3 weeks of diets with 7 per cent excess l -phenylalanine. In the 5 and 7 per cent supplemented groups of animals, the total amounts of the various lipids were initially reduced to levels which were within 10 per cent of those in diet-matched controls. The results for rats indicate that after 3 weeks of age only very moderate effects on accumulation of cerebral lipids can be produced by excess dietary l -phenylalanine fed at the most toxic levels of supplementation, while lower levels of dietary supplementation are without effect. The results suggest further that the more mature brain is resistant to alteration of deposition of myelin lipids by high levels of phenylalanine.     

Free Amino Acid Contents of Plasma and Urine,and Liver Enzyme Activities in Rats Fed High Glycine Diets

The contents of plasma free amino acids, the amounts of urinary excreted amino acids and urea, and the activities of liver serine dehydratase, glutamic-oxalacetic transaminase and glutamic-pyruvic transaminase were determined in weanling rats fed ad libitum a 10% casein diet (control), a 10% casein diet containing 7% glycine and 10% casein diets containing 7% glycine supplemented with 1.4% L-arginine and/or 0.9% L-methionine for 14 days.

The remarkable increase of glycine and the moderate increase of serine in the plasma of animals fed excess glycine diets were observed. The amount of excreted glycine in the urine of animals fed the excess glycine diet supplemented with L-arginine and L-methionine was much greater than that of animals given the excess glycine diet. Urinary excreted urea of rats fed the excess glycine diet was a little greater and that of rats fed the excess glycine diet supplemented with L-arginine and L-methionine was much greater than the control. Liver serine dehydratase activity of animals given the excess glycine diets with or without L-arginine was higher than the control and the highest activity was observed in the liver of animals fed the excess glycine diet containing L-arginine and L-methionine. The activity of liver glutamic-oxalacetic transaminase of rats fed the excess glycine diet containing L-arginine and L-methionine was a little higher than that of rats given the other diets. Liver glutamic-pyruvic transaminase activity was a little higher in animals given the excess glycine diets with or without L-arginine and further higher in animals fed the excess glycine diet containing L-arginine and L-methionine than the control.     

Dietary oxidized cholesterol decreases expression of hepatic microsomal triglyceride transfer protein in rats

The aim of this study was to compare the effects of dietary oxidized cholesterol and pure cholesterol on plasma and very low density lipoprotein (VLDL) lipids and on some parameters of VLDL assembly and secretion in rats fed two different dietary fats. Four groups of male growing Sprague-Dawley rats were fed diets containing pure or oxidized cholesterol (5 g/kg diet) with either coconut oil or salmon oil as dietary fat (100 g/kg diet) for 35 days. Rats fed oxidized cholesterol supplemented diets had significantly lower concentrations of triglycerides and cholesterol in plasma and VLDL than rats fed pure cholesterol supplemented diets irrespective of the type of fat. In addition, rats fed oxidized cholesterol supplemented diets had significantly lower relative concentrations of microsomal triglyceride transfer protein messenger ribonucleic acid (mRNA) than rats fed pure cholesterol supplemented diets. In contrast, hepatic lipid concentrations and the relative concentration of apolipoprotein B mRNA were not influenced by the dietary factors investigated. Parameters of hepatic lipogenesis (relative mRNA concentration of sterol regulatory element binding protein-1c and activity of glucose-6-phosphat dehydrogenase) were significantly reduced by feeding fish oil compared to coconut oil, but were not affected by the type of cholesterol. In conclusion, the data of this study suggest, that dietary oxidized cholesterol affects VLDL assembly and/or secretion by reducing the synthesis of MTP but not by impairing hepatic lipogenesis or synthesis of apolipoprotein B.