We recorded the auditory brainstem responses of rats fed a thiamin-deficient diet. The interpeak latencies between waves I and III, as well as those between waves I and IV, were significantly prolonged from day 24, while the latency of wave I was prolonged on day 26 of the thiamin-deficient diet. These delayed responses were corrected in 2 to 4 days after the initiation of daily intraperitoneal thiamin injections from day 32. The rats that were fed the thiamin-deficient diet, and then sacrificed on day 32, showed a decrease of total thiamin levels in the brain (26% of the level in control rat brains). Based on these results, we emphasize the value of the auditory brainstem response to detect thiamin deficiency.
The influences of vitamin E deficiency on compression injury of the rat spinal cord associated with ischemia were investigated. Growing rats were divided into two groups and given a diet containing either 2 IUD 100g or less than 0.1 IUD 100g of α-tocopherol acetate, respec-tively, for 6-8 weeks before experiments. Motor disturbances induced by spinal cord injury were found to be enhanced by vitamin E deficiency. The spinal cord blood flow (SCBF) was reduced by compression and subse-quently increased transiently and then decreased gradually in both groups, but the level was lower in the vitamin E-deficient group than in the control group. After injury, the vitamin E-deficient group showed lower recov-eries than the control group in the amplitude and latency of spinal cord evoked potentials and greater pathological changes of the spinal cord, such as bleeding and edema. The increase in the level of TBA-reactive substances in the spinal cord after injury increased with decrease in the dietary level of vitamin E. These results suggest that vitamin E may have a protective effects against ischemic spinal cord injury by its antioxidant effect.
Ascorbic acid (AsA) is known to be required for the syn-thesis of carnitine. The present study was designed to clarify the effect of AsA on the carnitine synthesis and lipid metabolism in guinea pigs. The animals were divided into four groups, and fed AsA-free diets for three weeks. Each group was supplemented with AsA in the following doses; high-AsA group, 100mg AsA/day/animal; control group, 5mg AsA/ day/animal; AsA-deficient group, 0.1mg AsA/day/animal; pair-fed group, 5mg AsA/day/animal. The pair-fed group was restricted to the amount of diet consumed by the AsA-deficient group. Tissue carnitine levels of the AsA-deficient group were significantly lower than not only the control group but the pair-fed group. Total cholesterol and phospholipid levels in plasma of the AsA-deficient group were found to be similar to those of the pair-fed group; however, plasma triglyceride levels were significantly higher than that of the pair-fed group. Furthermore, there was an inverse relationship between tissue AsA and plasma triglyceride levels. We concluded that carnitine synthesis and triglyceride metabolism in guinea pigs may be impaired by the decrease of tissue AsA level rather than by the insufficient food intake. It is suggested that tissue carnitine level altered by tissue AsA content affects plasma triglyceride level.
The enzyme activities, which are influenced by the vitamin C level in tissues, were measured to evaluate the vitamin C activity of erythorbic acid (ErA) in guinea pigs administered ErA. Guinea pigs were divided into two groups: animals in one group (control group) were administered 1, 5, and 100mg/day ascorbic acid (ASA) and those in the other group (supplemented group) were administered 1, 5, 20, and 100mg/day ErA for 16 days. At the end of the experimental period, they were sacrificed, blood was collected, and their livers were removed. The activities of liver aniline hydroxylase, of liver acid phosphatase, and of serum alkaline phosphatase, and the content of liver cytochrome P-450 were assayed. The activities of aniline hydroxylase and serum alkaline phosphatase and the content of liver cytochrome P-450 of the guinea pigs administered 1 mg ErA were lower than those of the guinea pigs admin-istered 1 mg AsA. However, the enzymeactivities and liver cytochrome P-450 content in the guinea pigs administered 5mg or more of ErA were similar in level to those in the guinea pigsadministered 5mg AsA. These results suggested that administration of a considerably high amount of ErA to guinea pigs showed a similar vitamin C activity to that of AsA, which might suggest that vitamin C activity of ErA may be more than one-twentieth that of AsA, as has been generally believed.
We investigated the role of thyroxine on bone growth in energy deficient rats. Rats were fed a normal diet and injected with saline, or a low-energy diet and injected with saline or 0.1, 1, or 5μg/100g BW of thyroxine for 22 days. Thyroxine injections decreased body weight gain but did not affect bone length and width. The epiphyseal growth plate was thinner and the activities of bone alkaline and acid phosphatase in energy deficient and 5μg/100g BW thyroxine injected animals were lower than that of the other treatment groups. Serum total thyroxine and triiodothyronine concentrations were increased but somatomedin C concentration was decreased by injecting with 5μg/100g BW of thyroxine in energy deficient rats.
In our previous report, we have described morphological changes in hepatocytes, e.g., enlargement of mitochondria and a change in the lamellar formation of rough endoplasmic reticulum, produced by short-term feeding of a protein-free diet to rats. In order to examine whether or not these morphological changes in the subcellular organella are accompanied by any functional and compositional changes, we mea-sured the P/O ratio and respiratory rate of mitochondria, and the phos-pholipid fatty acids of the mitochondrial and microsomal membranes in the liver of rats fed a protein-free diet for a short period. Feeding rats the protein-free diet for 4 days or 27-28 days had no effect on the rate of hepatic mitochondrial oxygen consumption (State 3 respiration). The diet significantly decreased the P/O ratio on the 4th day, but did not affect it on the 27-28th days. The decreased P/O ratio observed on the 4th day returned to the control level after overnight refeeding of a 20% casein diet. Main compositional changes induced by feeding rats the protein-free diet for 2 days were significant decreases in the phospholipid/protein ratios of the total liver and mitochondrial inner membrane, a tendency of an increase in the ratio of phosphatidylcholine (PC) to total phospholipids in the mitochondrial outer membrane, a significant decrease and a tendency of decrease in the arachidonate/linoleate ratio in the phosphatidyletha-nolamine (PE) and PC, respectively, in the mitochondrial outer mem-brane. Some of these results were discussed in relation to the morpho-logical changes in mitochondria and rough endoplasmic reticulum pro-duced by short-term feeding of the protein-free diet which we previ-ously reported.
O-β-D-Galactopyranosyl-(1→ 4)-O-β-D-galactopyranosyl-(1→4)-D-glucopyranose (designated as 4'GL) is produced from lactose by Cryptococcus laurentii. The influence of chronic ingestion of 4'GL on body weight gain, organ weight, serum lipids, and liver lipids was investigated in rats. The body weight gains of the 5 % and 10% 4'GL-diet groups were higher than that of the control group. Food intake and fecal dry weight were significantly increased (p<0.05) by 4'GL feeding. The 4'GL diet produced a significant increase (p<0.01) in the wet weight and contents of both the cecum and the colon. However, no significant increase was observed in the weight of the stomach, small intestine, liver, or other organs. The effects of 4'GL on serum and liver lipid levels were not observed in this experiment. The digestion of 4'GL was measured in vitro using the artificial gastric juice, α-amylase of human saliva, α-amylase of hog pancreas, and mucosa of rat intestine. 4'GL was not hydrolyzed by these enzymes. Long-term ingestion of 4'GL did not cause any induction of 4'GL hydrolyzing enzyme activity in the rat small intestine.
In earlier experiments in our laboratory, a lectin from the Kintoki bean (Phaseolus vulgaris) was found to have not only erythrocyte agglutinating activity but also toxicities for mice and rats, including growth inhibitory activity and even lethal activity. A number of studies on legume lectins have been carried out in other laboratories as well. But relatively little attention has been paid to lectins from non-leguminous foods. In the present study, we chose Taro tuber as a source of non-leguminous lectins and prepared two types of Taro tuber lectin. One was crude lectin precipitated with ammonium sulfate from the aqueous extract and the other was pure lectin isolated as we described previously. The two were compared with regards to the antinutritional functions in mice. The daily doses were 100mg for either intact or autoclaved crude lectin, which was a maximum amount available to give to mice in 1ml, and 30mg for the pure lectin which was equivalent to 100mg of the crude lectin in hemagglutinating activity. Control mice were given 1ml of water and the experiment was conducted for 6 days. Growth retardation was found in the mice given either lectin, but no significant difference was found in the weight increase between the control group and the auto-claved lectin group. For 3 days during the experimental period, physical activity was measured as an index of vigor of mice. The activities of the crude lectin and the pure lectin groups leveled down to 62.9 and 64.2% of that of thecontrol group, respectively. No apparent difference was observed in the tissue weights among the groups at the end of the experiment. Protein efficient ratio (PER) values indicated worse effi-ciency of protein utilization in the lectin groups. Enzyme activities of sucrase, leucine aminopeptidase, and particularly of alkaline phosphatase were lower in the small intestine of the experimental groups. These results indicate that Taro tuber lectin has toxicity inhibiting regular biological functions in the intestine of mice, leading to growth retardation. Since Taro tuber lectin is more resistant to heat treatment than legume lectins, the present results suggest a need for care in cooking Taro tuber.
Platelet aggregation was measured using platelet rich plasma prepared from rats fed oryzanol in the control diet and those fed oryzanol in a l per cent cholesterol diet (HCD). Oryzanol with the control diet did not alter platelet aggregation induced by ADP and collagen. On the other hand, oryzanol fed along with HCD significantly inhibited platelet aggregation induced by ADP and totally inhibited aggregation induced by collagen.