Urinary excretion of nicotinamide and its metabolites in mouse, guinea pig, and hamster with a pharmacological amount of nicotinamide or N¹-methylnicotinamide (MNA) was investigated to compare them with those of rat. In mouse, nicotinamide N-oxide was the most abundant metabolite, accounting for 35% of urinary excretion of nicotinamide and its metabolites, and followed by N¹-methyl-2-pyridone-5-carboxamide (2-Pyr), 20%; nicotinamide, 18%; MNA, 16%; and N¹-methyl-4-pyridone-3-carboxamide (4-Pyr), 11%. In guinea pig, 2-Pyr was the most abundant metabolite, accounting for 80% of urinary excretion, and was followed by MNA, 11%; nicotinamide, 3%; 4-Pyr, 3%; and nicotinamide N-oxide, 3%. In hamster, nicotinamide was the most abundant metabolite, accounting for 44%, and followed by 2-Pyr, 21%; nicotinamide N-oxide, 15%; MNA, 10%; and 4-Pyr, 10%. Urinary excretion of nicotinic acid and nicotinuric acid was not detected in mouse, guinea pig, and hamster. When a pharmacological amount of nicotinamide was intraperitoneally injected into mouse, the excretion of nicotinamide N-oxide increased to 79.7% of the nicotinamide metabolites, while those of MNA (4.9%), 2-Pyr (11.2%), and 4-Pyr (6.3%) decreased. Nicotinic acid and nicotinuric acid were again not detected. When a pharmacological amount of nicotinamide was intraperitoneally injected into guinea pig and hamster, the deamidated metabolites nicotinic acid and nicotinuric acid occupied significant percentages of the nicotinamide metabolites: 50.4% and 26.3%, respectively, in guinea pig; and 7.7% and 79.5%, respectively, in hamster. The ratio of 2-Pyr to 4-Pyr excretion did not change when nicotinamide or MNA was locaded into mouse, guinea pig, and hamster. From these results, the catabolism of nicotinamide in rodent is discussed.

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The effect of la-hydroxycholecalciferol (1α-OH-D₃) admin-istration on Mg metabolism in sheep was studied. Three wethers were in tramuscularly injected with 0.2μg/kg body weight of lα-OH-D₃ for 3 days. Plasma Mg concentration was decreased and plasma Ca concentration was increased by la-OH-D₃ administration. However, the duration of hypomagnesemia was shorter than that of the increment in the plasma Ca concentration. The administration of lα-OH-D₃ increased apparent Ca absorption and urinary Ca excretion. However, apparent absorption and urinary excretion of Mg was not changed by lα-OH-D₃ administration. The amount of glomerular filtrated Mg was reduced concomitantly with the reduction of plasma Mg concentration and glomerular filtration rate when lα-OH-D3 was injected. The tubular reabsorption of Mg tended to be suppressed and the ratio of reabsorbed to filtrated Mg was significantly lowered by 1α-OH-D₃ administration. These results suggested that the stimulation of urinary Mg excretion might not be one of the major factors inducing hypomagnesemia although 1α-OH-D₃ suppressed reabsorption of Mg in the renal tubule

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The effects of sulfur-containing amino acids (SAA) and potassium (K) on urinary excretion and retention of calcium (Ca) of 27 young Japanese women were studied. A basal diet low in protein level (50g per day) was fortified by meat or soy protein isolate (SPI) to a protein level of 100g per day, and effects of addition of apple to these high protein diets, and addition of SAA and/or potassium (K) to the high SPI diet, especially on urinary Ca excretion, were studied. The addition of meat which increased protein intake to 100g caused the increase in apparent absorption and urinary excretion of Ca with increased excretion of urinary sulfur (S), phosphate, ammonia, and titratable acids (TA), whereas addition of SPI did not. The addition of apple to high meat diet decreased absorption and urinary excretion of Ca. Urinary Ca, S, K, ammonia, and TA excretion increased by the addition of SAA to high SPI diet in a manner similar to the meat diet. Consequently, SAA-supplemented diet had a significantly negative effect on Ca retention. In SPI+SAA, K diet period, urinary K excretion markedly increased, and increments in urinary Ca, ammonia, and TA excretion were reversed. These changes observed in SPI+SAA, K diet period were similar to those by adding apple to meat diet without any effect on Ca absorption. The results suggest that the hypercalciuria induced by high meat diet is mainly caused by high content of SAA and may be reversed by the ingestion of K-rich foodstuffs, and soy protein does not induce hypercalciuria because of it contains less SAA than animal protein.

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Hypercholesterolemia due to feeding of polychlorinated biphenyls (PCB) and due to feeding of high cholesterol was compared. Rats in control group were fed a 25% casein diet, and those in PCB group or cholesterol group were fed the 25% casein diet supplemented with 0.03% PCB or 1% cholesterol and 0.25% cholic acid, respectively. Lipo-protein mass (d<1.21g/ml) was higher 1.9- and 1.3-fold in rats fed PCB and cholesterol, respectively, as compared with controls. In rats fed PCB, protein, cholesterol, and phospholipid in the lipoprotein fraction markedly increased. Cholesterol-feeding resulted in the increase in pre-β-lipoprotein cholesterol, while PCB-feeding increased α-lipoprotein cholesterol and slightly slow migrated pre-β-lipoprotein cholesterol. PCB-treated rats had more apolipoprotein A-I in the lipoprotein fraction than control and cholesterol-fed rats. The data demonstrated that hyperlipoproteinemia induced by PCB is a novel α-lipoproteinemia and a useful model for investigating metabolism of high density lipoprotein.

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To clarify whether nicotine stimulates the sympathetic nervous system (SNS) and thermogenesis in brown adipose tissue (BAT) and whether it promotes the resting metabolic rate (RMR), with resulting mitigation of obesity, we measured norepinephrine (NE) turnover (an indicator of SNS activity), guanosine-5'-diphosphate (GDP) binding (a thermogenic indicator), oxygen consumption in BAT, and RMR in monosodium-L-glutamate (MSG) obese and saline control mice after 2 weeks treatment with nicotine. Nicotine significantly increased NE turnover, GDP binding, oxygen consumption in BAT, and RMR, and significantly reduced body weight in MSG obese mice as well as in control mice without affecting food intake. These results suggest that nicotine stimulates NE turnover and thermogenesis in BAT, and promotes RMR, all of which contribute to the mitigation of obesity.

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Male ExHC (exogenous hypercholesterolemic) rats were either prematurely weaned at 17 days of age or allowed to nurse until 35 days of age. The prematurely weaned rats were either fed a diet containing cholestyramine or cholestyramine-free diet until 35 days of age. Cholestyramine supplementation markedly increased fecal bile acid excretion and modified the composition. After giving a stock diet for 7 weeks, all rats received a cholesterol-enriched diet for 9 weeks. The serum cholesterol level in later time was not affected by early dietary manipulation. The activity of hepatic cholesterol 7α-hydroxylase and fecal bile acid excretion at the end of the cholesterol challenge decreased in the cholestyramine-pretreated group, when compared to the normally weaned group. Fecal excretion and the ratio of the secondary (deoxycholic and lithocholic acids) to the primary (cholic and chenodeoxycholic acids) bile acids significantly decreased in the early cholestyramine-treated group. These results suggest that a modification of bile acid metabolism in early life may strongly influence the hepatic and possibly colonic bile acid metabolism in later life, when challenged with a high-cholesterol diet.

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Raw beans, c.v. Carioca 80, were fractionated into tegu-ment (FRO), dialyzable solids (FR1), water-soluble (FR3) and salt-soluble (FR2, FR5) protein-rich fractions, and the insoluble residue (FR4). Each of these fractions was used at a level of 8% (w/w) in the preparation of balanced diets for rats with casein as the primary source of protein. The protein contributed by each fraction substituted an equivalent amount of casein to maintain total dietary protein at 10%. Tryptophan and sulfur amino acids were supplemented to the levels of these amino acids in a 10% casein diet. The bean fractions decreased rat growth, diet efficiency ratio, protein digestibility and utilization. Autoclaving the bean fractions (121°C, 30min) prior to being mixed in the diets did improve growth, protein digestibility and utilization, but the values encountered were still significantly lower than those determined for the 10% casein diet. The differences between the casein and the mixed casein-bean protein diets could not be explained on the basis of amino acid scores.

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Administration of Embelin, an experimental antifertility agent, to male rats (20mg/kg body wt/day, daily for 15 and 30 days), caused an elevation in the uptake of D-glucose, L-alanine, L-leucine, and calcium in the small intestinal segments. An increase was also noted in the intestinal brush border membrane (BBM)-associated enzymes, sucrase, lactase, maltase, alkaline phosphatase, and leucine aminopeptidase in both the intestinal homogenates and partially purified BBM preparations, particularly after 30-day administration of the drug. Embelin treatment also caused a significant increase in the microsomal glucose-6-phosphatase and the cytosolic enzyme, lactate dehydrogenase. In the Embelin-treated animals BBM-associated total lipids, phospholipids, cholesterol, triacyl-glycerol, unesterified fatty acids, ganglioside-sialic acids as well as the cholesterol/phospholipids molar ratio showed a considerable increase. All these changes in the Embelin-treated animals were restored back to the normal or near normal biochemical makeup when the drug therapy was withdrawn and the animals were allowed to recover for another 15 and 30 days, respectively.

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The effects of Spirulina platensis on lipoprotein lipase activity and hepatic triglyceride lipase activity in post-heparin plasma were studied in fructose-induced hyperlipidemic rats. Male Wistar rats aged 3 weeks old (body weight, 54g) were fed on the high-fructose diet (68%) or the high-fructose diets containing Spirulina at the level of 5, 10, and 15%, respectively, for 4 weeks. The dietary hyperlipidemia caused by the high-fructose diet was improved by Spirulina feeding, accompanied by a significant increase in the lipoprotein lipase activity in post-heparin plasma.

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To clarify the effect of caffeine on brown adipose tissue (BAT) thermogenesis, we measured guanosine-5'-diphosphate (GDP) binding, a thermogenic indicator of BAT, and oxygen consumption in BAT mitochondria as well as BAT temperature and resting metabolic rate (RMR) in mice. Intraperitoneal injection of caffeine (60mg/kg) sig-nificantly elevated BAT temperature with less effect on core temperature, and increased significantly GDP binding and oxygen consumption in BAT mitochondria, and RMR. These results suggest that caffeine activates BAT thermogenesis, which may contribute to the increase of RMR.

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