Protein malnutrition promotes hepatic steatosis, decreases insulin-like growth factor (IGF)-I production and retards growth. To identify new molecules involved in such changes, we conducted DNA microarray analysis on liver samples from rats fed an isoenergetic low-protein diet for 8 h. We identified the fibroblast growth factor 21 gene (Fgf21) as one of the most strongly up-regulated genes under conditions of acute protein malnutrition (P<0·05, false-discovery rate<0·001). In addition, amino acid deprivation increased Fgf21 mRNA levels in rat liver-derived RL-34 cells (P<0·01). These results suggested that amino acid limitation directly increases Fgf21 expression. FGF21 is a polypeptide hormone that regulates glucose and lipid metabolism. FGF21 also promotes a growth hormone-resistance state and suppresses IGF-I in transgenic mice. Therefore, to determine further whether Fgf21 up-regulation causes hepatic steatosis and growth retardation after IGF-I decrease in protein malnutrition, we fed an isoenergetic low-protein diet to Fgf21-knockout (KO) mice. Fgf21-KO did not rescue growth retardation and reduced plasma IGF-I concentration in these mice. Fgf21-KO mice showed greater epididymal white adipose tissue weight and increased hepatic TAG and cholesterol levels under protein malnutrition conditions (P<0·05). Overall, the results showed that protein deprivation directly increased Fgf21 expression. However, growth retardation and decreased IGF-I were not mediated by increased FGF21 expression in protein malnutrition. Furthermore, FGF21 up-regulation rather appears to have a protective effect against obesity and hepatic steatosis in protein-malnourished animals.

Jerusalem artichoke (JA) has the potential to attenuate lipid disturbances and insulin resistance (IR), but the underlying mechanisms are not well understood. In the present study, we elucidated the physiological responses and mechanisms of JA intervention with a comprehensive transcriptome analysis. Wistar rats were fed a control diet, a 60 % fructose-enriched diet (FRU), or a FRU with 10 % JA (n 6–7) for 4 weeks. An oral glucose tolerance test was carried out on day 21. Liver samples were collected for biochemical and global gene expression analyses (GeneChip® Rat Genome 230 2.0 Array, Affymetrix). Fructose feeding resulted in IR and hepatic TAG accumulation; dietary JA supplementation significantly improved these changes. Transcriptomic profiling revealed that the expression of malic enzyme 1 (Me1), associated with fatty acid synthesis; decorin (Dcn), related to fibrosis; and cytochrome P450, family 1, subfamily a, polypeptide 2 (Cyp1a2) and nicotinamide phosphoribosyltransferase (Nampt), associated with inflammation, was differentially altered by the FRU, whereas dietary JA supplementation significantly improved the expression of these genes. We established for the first time the molecular mechanisms driving the beneficial effects of JA in the prevention of type 2 diabetes and non-alcoholic fatty liver disease. We propose that 10 % JA supplementation may be beneficial for the prevention of the onset of these diseases.

Lactoferrin (LF) is a multifunctional glycoprotein in mammalian milk. In a previous report, we showed that enteric-coated bovine LF tablets can decrease visceral fat accumulation, hypothesising that the enteric coating is critical to the functional peptides reaching the visceral fat tissue and exerting their anti-adipogenic activity. The aim of the present study was to assess whether ingested LF can retain its anti-adipogenic activity. We therefore investigated the effects of LF and LF treated with digestive enzymes (the stomach enzyme pepsin and the small intestine enzyme trypsin) on lipid accumulation in pre-adipocytes derived from the mesenteric fat tissue of male Sprague–Dawley rats. Lipid accumulation in pre-adipocytes was significantly reduced by LF in a dose-dependent manner and was associated with reduction in gene expression of CCAAT/enhancer binding protein delta, CCAAT/enhancer binding protein alpha and PPARγ as revealed by DNA microarray analysis. Trypsin-treated LF continued to show anti-adipogenic action, whereas pepsin-treated LF abrogated the activity. When an LF solution (1000 mg bovine LF) was administered by gastric intubation to Sprague–Dawley rats, immunoreactive LF determined by ELISA could be detected in mesenteric fat tissue at a concentration of 14·4 μg/g fat after 15 min. The overall results point to the importance of enteric coating for action of LF as a visceral fat-reducing agent when administered in oral form.

Recent transcriptomics studies on the effect of long-term or severe energy restriction (ER) have revealed that many genes are dynamically modulated by this condition in rodents. The present study was conducted to define the global gene expression profile in response to mild ER treatment. Growing rats were fed with reduced amount of diet (5–30 % ER) for 1 week or 1 month. Using DNA microarray analysis of the liver, seventy-two genes that were consistently changed through the different ER levels were identified. Many were related to lipid metabolism including genes encoding key enzymes such as carnitine palmitoyltransferase 1 and fatty acid synthase. Interestingly, a number of genes were altered even by 5 % ER for 1 week where no differences in weight gain were observed. The information obtained in the present study can be used as a valuable reference data source in the transcriptomics studies of food and nutrition in which subtle differences in food intake sometimes hinder appropriate interpretation of the data.

In the current situation where microarray data in the field of nutritional genomics (nutrigenomics) are accumulating rapidly, there is imminent need for an efficient data infrastructure to support research workflow. We have established a web-based, integrated database of the publications and microarray expression data in the field of nutrigenomics. The registered data include links to external databases such as PubMed of the National Center for Biotechnology Information and public microarray databases that contain Minimum Information About a Microarray Experiment-compliant microarray expression data. Using this database, all data sets created will be effectively utilized and shared with other researchers. This database is built on an open-source database system and is freely accessible via the World Wide Web (http://a-yo5.ch.a.u-tokyo.ac.jp/index.phtml</url).

The magnetic properties of Ce@C82 have been studied. The magnetic anisotropy of Ce@C82 was analyzed taking account of the crystal field of the interior C82 cage acting on Ce3+ ion. Results showed that the reduction of the susceptibility at low temperature was caused due to the antiferromagnetic coupling between Ce3+ ion and C82 cage. The magnetization measurement at several temperatures also supported the antiferromagnetic interaction at low temperature. The magnetic susceptibility larger than the calculated one was measured at higher temperatures due to the magnetic interaction between the metallofullerenes and between the particles in the crystal. The magnetization of some frozen Ce@C82 solutions was found to depend on the applied field magnitude. The dependence suggested that the magnetic anisotropy of Ce ion induced a torque to restrict the rotational motion of Ce@C82 by the field.

Effect of quantity and nutritional quality of dietary proteins on the content of mRNA of insulin-like growth factor-binding protein-1 (IGFBP-1) was studied in rat liver and kidney. IGFBP-1 mRNA content per unit RNA increased in liver and kidney of rats fed on a protein-free diet and in those of fasted rats compared with that in the rats fed on a casein diet. When rats were given a gluten diet for 7 d, IGFBP-1 mRNA content in liver did not change significantly but that in kidney increased considerably compared with that in those organs of the rats fed on the casein diet. Because IGFBP-1 mRNA has been demonstrated both in liver parenchymal and non-parenchymal cells (Takenaka et al. 1991), the effect of the protein-free diet on these two types of cells has been studied. An increase in IGFBP-1 mRNA content under protein deprivation was observed in both liver parenchymal and non-parenchymal cells, suggesting that these two types of cells are regulated in a similar mode as far as IGFBP-1 mRNA content is concerned. The physiological and nutritional significance of the previously stated results on protein anabolism are discussed when considered together with our previous observations on the plasma concentrations of IGF-1 (Takahashi et al. 1990) and IGFBP (Umezawa et al. 1991) and insulin-like growth factor-1 mRNA content in liver (Miura et al. 1991).

Effects of quantity and quality of dietary proteins on plasma immunoreactive insulin-like growth factor-1 (IGF-1) concentration, and content of IGF-1 mRNA in rat liver were investigated in rats. Plasma immunoreactive IGF-1 concentration in rats given a casein diet was higher than that in rats given a soya-bean-protein or protein-free diet. The IGF-1 mRNA content in liver was estimated by the Northern blot hybridization technique employing 32P-labelled rat IGF-1 complementary DNA (cDNA). At least four molecular species of IGF-1 mRNA of different molecular weight were found in rat liver. The sizes were 0·8–1·2, 2·0, 3·6–4·0 and 7·4 kb. Most of the mRNA species decreased in the livers of rats given a gluten diet (120 g gluten/kg diet) compared with rats given the casein diet. In particular, mRNA of 7·4 kb decreased markedly. When rats were fed on the protein-free diet, mRNA of all species decreased significantly. The estimated IGF-1 mRNA in the livers of rats fed on the gluten or protein-free diet was almost 0·4 of that of the rats given the casein diet. Feeding the soya-bean-protein diet did not result in a marked effect on the hepatic content of mRNA species of IGF-1. The results showed that liver IGF-1 mRNA content is sensitively regulated by quantity and nutritional quality of dietary proteins.

The effect of protein deprivation on plasma concentration of insulin-like growth factor-binding proteins (IGFBP) was studied in rats. A significant decrease in the concentration of IGFBP of molecular weight (mass) approximately 40 kDa was observed in protein-deprived rats. There was no prominent effect of protein deprivation on the concentration of IGFBP with molecular weights of about 30 kDa or 22–24 kDa. The binding capacity to plasma IGFBP of exogenously-added 125I-labelled insulin-like growth factor-1 (125I-IGF-1) was also studied. IGFBP of molecular weight about 30 and 22–24 kDa (the native form of this protein is presumed to be 29 kDa) in protein-deprived rat plasma bound more 125I-IGF-1 than those in protein-fed rat plasma. This suggested that these IGFBP in protein-deprived rat plasma are relatively unsaturated by endogenous IGF-1. The response of IGFBP to protein deprivation which was elucidated in the present investigations add further evidence to our previous assumption that IGFBP play an important role in protein nutrition.

The relations between the urinary excretion of acid-soluble peptide (ASP)-form amino acids, the rate of whole body protein synthesis and plasma immunoreactive insulin-like growth factor-1/somatomedin C concentration were investigated in rats. The urinary ASP-form leucine plus valine excretion correlated well with the rate of whole body protein synthesis and with the plasma immunoreactive insulin-like growth factor-1 concentration. The results provide further evidence for the hypothesis that urinary excretion of ASP is an excellent index of the status of protein metabolism in animals.

1. Nutritional factors affecting the urinary excretion of acid-soluble peptides (ASP) were studied in rats. The ratio, total urinary nitrogen: ASP-form leucine + valine was lowest in the rats fed on a protein-free diet and increased as retained N: absorbed N decreased. The ratio was not affected by dietary protein level when the level was below the National Research Council (1978) recommended requirement, but increased greatly when it exceeded the recommended requirement.

2. The excretion of ASP-form leucine + valine per kg body-weight was significantly lower in the protein- deficient rats than in those fed on protein-adequate diets. This variable decreased during the stage of rapid growth, but did not change as markedly after the onset of adolescence. It increased again when the rats became older. The patterns of change in the rate of excretion of ASP-form amino acids during growth and that of Nr-methylhistidine were different.

3. When labelled amino acids were injected into rats, the largest amount of the ASP-form label was excreted on the 1st day of injection. From the 2nd day the excretion of ASP-form label decreased exponentially.

4. The findings suggest that the rate of urinary excretion of ASP-form amino acids can be employed as an index of protein metabolism, particularly as a simple index of the assessment of the status of protein nutrition.