[14C] Menaquinone-4 was administered orally once daily at a dose of 4 mg/kg for ten days to female rats of different ages to determine its blood and tissue distribution with particular attention to its distribu-tion in bone. Animals aged 10 and 30 months were either ovariectomized or sham-operated as a control, and young rats aged 7 weeks were used as untreated controls. Blood concentrations of radioactivity at 24h after each dose during repeated administration increased daily and approached a steady state byy the seventh dose. Higher concentrations of radioactivity in blood (plasma) were observed in older animals than in the younger ones, but there was little difference between ovariectomized rats (OVX rats) and sham-operated rats (Sham rats). In tissue samples collected at 1.5h after administration, the liver, adipose tissue, spleen and adrenals showed higher concentrations of radioactivity than the other organs and the plasma. In bone tissues, the bone marrow (BM) and cancellous tissue (CT) of the femur showed radioactivity concentrations which were higher than that in the plasma, and these increased during repeated administration. Finally, at 24h after the last dose, the concentrations of radioactivity in bone tissues of older animals (BM, 5, 807.2ng eq/g; CT, 5, 264.8ng eq/g in OVX rats aged 10 months and BM, 11, 479.3ng eq/g; CT, 4, 023.0ng eq/g in OVX rats aged 30 months) were several times higher than those in younger animals (BM, 2, 771.6ng eq/g; CT, 890.2ng eq/g in 7-week-old untreated rats). The values in OVX rats were also higher than those in Sham rats. Furthermore, micro autoradiography studies of femur sections from OVX rats indicated that [14C] Menaqui-none-4 localized in cancellous tissue where bone is known to be actively remodelled. The concentrations of radioactivity in cancellous tissue and bone marrow of OVX rats aged 10 and 30 months were comparable to the pharmacologically effective concentrations of Menaquinone-4 (10-6-10-5 M) in in vitro studies on bone formation. These findings suggest that orally administered Menaquinone-4 distributes specifically into the bone tissues of ovariectomized rats and this is consistent with its effect as a therapeutic agent for osteoporosis.
Long chain alkylcobalamins and long chain acyl-cyanoco-balamins, two types of hydrophobic derivatives of vitamin B12, were synthesized. It was shown by TLC and determination of the partition coefficient between organic and aqueous phases that the hydrophobicity of alkylcobalamins and acyl-cyanocobalamins increased with the chain length of the alkyl or acyl group introduced into cobalamin. Long chain alkylcobalamins were easily converted to aquacobalamin by photoirradia-tion, but the first-order rate constant of photolysis decreased with the length of an alkyl group. Long chain acyl-cyanocobalamins were gradu-ally hydrolyzed to cyanocobalamin in neutral or alkaline solution with the pseudo-first order rate constant increasing with the pH of the solution. Stabilization of acyl-cyanocobalamins toward hydrolysis was achieved by introducing a methyl group into the α-position of an acyl group. All the long chain alkylcobalamins tested supported the growth of Escherichia coli 215, a cobalamin- or L-methionine-auxotroph, and Lactobacillus leichmannii, although their activity as cobalamin was at most 28% and 15% that of cyanocobalamin for E. coli 215 and L. leichmannii, respectively.
Male mice of three strains, C57BL, DBA and C3H/He, were fed on commercial food with 10% (v/v) ethanol solution as drinking liquid ad libitum for eighty days, and the changes in the activities of enzymes in the metabolic pathway of ethanol in the liver were examined. C57BL and C3H/He mice showed a preference for drinking the 10% (v/v) ethanol solution, while DBA mice did not. The ethanol intake g/g of body weight of C3H/He mice showed the highest value among all three strains and that of C57BL mice tended to show higher value than that of DBA mice. The liver weights of C57BL and C3H/He mice increased significantly following chronic ethanol administration, but that of DBA did not. The cytosolic enzyme alcohol dehydrogenase (ADH) showed no changes in any of the strains following chronic ethanol administration. The microsomal ethanol-oxidizing system (MEOS) of C57BL mice exhibited approximately 2-fold higher activity compared to that of DBA and C3H/He mice but did not increase in any strain following chronic ethanol administration. However, the microsomal aniline hydroxylase activity in the liver increased significantly in C57BL and C3H/He mice following chronic administration of ethanol. The microsomal cytochrome P-450 content also tended to slightly increase in the same strains of mice. It seemed that cytochrome P-450IIE1 was induced in the liver microsomes of these strains. Total aldehyde dehydrogenase (A1DH) activities together with high-Km A1DH activity increased markedly in the microsomes of C57BL mice and tended to increase in C3H/He mice, while it did not change in DBA mice following chronic ethanol administration. In the mitochondria of C57BL, total A1DH activities increased slightly and high-Km A1DH activities tended to increase. These mitochondrial A1DH activities of C3H/He and DBA mice tended to increase following chronic ethanol administration. The cytosolic A1DH activity showed no changes in any strain of mice following chronic ethanol administration. It seemed that in the microsomes, the activities of enzymes related to oxidation of ethanol increased in C57BL and C3H/He mice, which tended to consume a large amount of ethanol, and did not in DBA mice which tended to consume a small amount of it. It seemed that the increases in activities of enzymes related to oxidation of acetaldehyde in the microsomes and in the mitochondria were responsible for the strain difference.
Two-experiments were conducted to clarify the effect of calcitonin (CT) on growth, muscle protein breakdown, plasma corticos-terone (CTC) concentration and urinary calcium excretion in young growing rats treated with CTC. Rats received hormonal treatments for 6 days (Experiment 1) or 24h (Experiment 2). Dose levels of CTC were 10mg and 5mg/ 100g body weight/day in experiment 1 and 2, respectively, and that of CT was 100m unit/100g body weight/day in both experiments. Muscle protein degradation was evaluated by urinary Nτ methylhistidine excretion. CT increased 24-h urinary calcium excretion but not 6-day calcium excretion. CTC markedly inhibited growth, accelerated muscle protein degradation and increased calcium excretion in both experiments. However, very interestingly, CT minimized CTC-induced muscle proteo-lysis, and normalized the CTC-induced decrease in urinary calcium excretion. Furthermore, CT decreased the CTC-induced increase in the plasma CTC concentration. The present observations indicate that CT reduces CTC-induced muscle protein breakdown by reducing the plasma CTC concentration and that increased urinary calcium excretion due to CT treatment may also play a role in reducing CTC-induced muscle protein breakdown.
Nutritional encephalomalacia (NE) in broiler chicken is considered as a peroxidative dysfunction caused by vitamin E-deficient diets. A feeding experiment was performed to investigate the consequences of feeding different fats in combination with increasing amounts of vitamin E on liver lipid peroxidation and plasma prostanoid pattern. Newly hatched chicks from hens on a vitamin E-poor diet were fed with either mainly linolenic, linoleic or oleic acid-rich oils in a vitamin E-deficient (5ppm) basic diet. The animals were supplemented with vitamin E on three levels (0, 20 or 120ppm). On appearance of the first symptoms of NE after 8 days post-hatching, the animals were examined. Typical symptoms with a high incidence only occurred in the group fed linoleic acid and 5 ppm vitamin E. Plasma prostanoids and microsomal alkane production in liver as a measure of endogenous lipid peroxidation were determined. The dietary conditions affected plasma prostaglandin E2 and thromboxane A2, but not prostacyclin. However, it seems unlikely that the prostanoids are involved in the pathogenesis of NE. Liver lipid peroxidation increased in vitamin E deficiency. The level of alkanes depended on the type of fat supplied. The consequences of the different dietary fats in combination with vitamin E deficiency on peroxidative metabolism of broiler chickens are evident, indicating that a high level of oxidative stress is imposed by the linoleic acid-rich fat.
The effects of spinach leaf protein concentrate (SPPC) on serum and liver lipid concentrations and on serum free amino acid concentrations were examined in rats fed a cholesterol-free diet contain-ing 2 and 10% fats. The serum total cholesterol, triacylglycerol and phospholipid concentrations in the rats fed an SPPC diet containing 2% corn oil were significantly lower than those of the rats fed a corresponding casein diet. When 10% corn oil or lard was used, the serum cholesterol-lowering effect of the SPPC became insignificant, but the serum and liver triacylglycerol concentrations were kept at significantly lower levels. Both the amounts of fecal neutral steroids and bile acids were significantly higher in the rats fed the SPPC than those of the casein-fed rats. The concentrations of serum threonine, serine, glutamine, glycine, cystine, and isoleucine were significantly higher in the rats fed the SPPC diet contain-ing 2% corn oil compared with those of the control rats, but when the dietary fat was raised to 10%, only glycine showed a higher serum concentration. These results indicate that the SPPC has a stronger cho-lesterol-lowering effect at a lower dietary fat level, 2%, and the activity is partly due to the inhibition of intestinal absorption of cholesterol and bile acid, and partly due to an increase in the concentration of some of the serum amino acids.