In silico and in vivo experiment of soymilk peptide (tetrapeptide - FFYY) for the treatment of hypertension

Enzyme-Treated Soymilk (ETS) was produced from Commercial Soymilk (CSM) with the treatment of proteinase PROTIN SD-NY10 (Bacillus amyloliquefaciens). Previously, we have isolated novel peptides from ETS but data related to isolated-peptides are scant. In this study, bio-informatics and in vivo analysis of isolated-peptides showed strong binding affinity to the active site of the Angiotensin Converting Enzyme (ACE). Among four peptides, tetrapeptide Phe-Phe-Tyr-Tyr (FFYY) showed strong binding affinity and inhibitory activity to the ACE-enzyme (binding affinity -9.5 Kcal/mol and inhibitory concentration of 1.9 µM respectively) as well as showed less toxicity compared to other peptides. The animal experiment revealed that single oral dose of FFYY (80 µg/kg body weight/day) effectively ameliorates the systolic, diastolic and mean blood pressure in the spontaneously hypertensive rat (SHR) model. Chronic oral administration of FFYY (80 µg/kg body weight/day for 3 weeks) reduced the systolic blood pressure elevation and ACE activity without any adverse side effects on the physiological and biological parameters of SHR. In conclusion, both in silico and in vivo experiments of soymilk-isolated FFYY peptide showed a promising option as a potential alternative for hypertension treatment without adverse side effects on SHR.

Analysis of Genetic Polymorphism of Bitter Taste Receptor TAS2R38 and TAS2R46, and Its Relationship with Eating and Drinking Habits in Japanese ToMMo Subjects

Human type 2 taste receptor (TAS2R) genes encode bitter-taste receptors that are activated by various bitter ligands. It has been said that TAS2R38 may detect bitter substances and then suppress their intake by controlling gustatory or digestive responses. The major haplotypes of TAS2R38 involve three non-synonymous, closely-linked single-nucleotide polymorphisms (SNPs), leading to three amino acid substitutions (A49P, V262A and I296V) and resulting in a PAV or AVI allele. The allele frequency of AVI/PAV was 0.42/0.58 in this study. The genotype frequency distributions of TAS2R38 were 18.32%, 46.95% and 33.95% for AVI/AVI, AVI/PAV and PAV/PAV, respectively, and were in Hardy-Weinberg equilibrium. Five haplotype combinations of minor alleles were identified: AVI/AAV, AVI/AVV, AAI/PAV, AVI/PVV, AVI/AAI, with corresponding frequencies of 0.49%, 0.10%, 0.10%, 0.05%, 0.05%, respectively, in 2,047 Japanese Tohoku Medical Megabank Organization (ToMMo) subjects (2KJPN). The 16 subjects with these minor alleles were excluded from the questionnaire analysis, which found no significant differences among the major TAS2R38 genotypes (AVI/AVI, AVI/PAV and PAV/PAV) in the intake frequency of cruciferous vegetables or in the frequency of drinking alcohol. This result differs from previous data using American and European subjects. This is the first study to analyze the relationship between TAS2R38 genotype and the eating and drinking habits of Japanese subjects. It was also shown that there were no relationships at all between the genetic polymorphism of TAS2R46 and the phenotypes such as clinical BMI, eating and drinking habits among the 3 genotypes of TAS2R46 (∗/∗, ∗/W, W/W) at position W250∗ (∗stop codon).

Effect of vitamin K3 supplementation on immunoglobulin G concentration in colostrum of periparturient Holstein dairy cows

This study was to examine the effects of dietary vitamin K (VK) 3 supplementation on immune-related substances in milk, oxidative stress indices in plasma and VK1, and menaquinone 4 (MK-4) in plasma and milk in periparturient dairy cows. Forty healthy perinatal Holstein-Friesian dairy cows were used in this study. Twenty-one animals were randomly selected and categorized into the VK3 supplemented (50 mg/day/head as VK3) group; the remaining 19 were categorized into the control group. On day 3 after calving, blood and milk were sampled, and their chemical components were determined. The VK3 supplemented group had significantly higher menaquinone 4 levels in plasma and milk on day 3 postpartum than the control group. In addition, there was a significant increase in the immunoglobulin G (IgG) level in milk. VK3 may be absorbed from the gastrointestinal tract and converted to MK-4, the biologically active form of VK, in the mammary gland and other tissues. It was thought that the increase in MK-4 level in plasma and milk induced an increase in the concentration of IgG in milk. VK3 supplementation to periparturient dairy cows may contribute to the production of colostrum with high concentrations of IgG and MK-4.

Effects of dietary vitamin K3 supplementation on vitamin K1 and K2 (menaquinone) dynamics in dairy cows

The effect of dietary vitamin K₃ (VK3) on ruminant animals is not fully investigated. The aim of this study was to examine the effects of dietary VK3 on lactation performance, rumen characteristics, and VK1 and menaquinone (MK, or VK2) dynamics in the rumen, plasma, and milk of dairy cows. Eight Holstein dairy cows in late lactation periods were used in two crossover trials including a control (nontreatment) and a 50 or 200 mg/day (d) VK3 supplementation group. After 14 days, plasma, ruminal fluid, and milk were sampled and their VK1 and MKs contents were measured using fluorescence-high-performance liquid chromatography (HPLC). Milk production was unchanged after feeding 50 mg/day VK3 but marginally decreased after feeding 200 mg/day VK3. The molar ratio of propionate in ruminal fluid was significantly increased on feeding 200 mg/day VK3. Additionally, MK-4 concentrations significantly increased in both plasma and milk after VK3 feeding (50 and 200 mg/day). In ruminal fluid, MK-4 concentrations increased after 200 mg/day VK3 feeding. These results suggest that VK3 may be a good source of MK-4, the biologically active form of VK, in Holstein dairy cows during their late lactation periods. This study provides a basis for understanding the physiological role of VK in dairy cows.

Geranylgeraniol Inhibits Lipopolysaccharide-Induced Inflammation in Mouse-Derived MG6 Microglial Cells via NF-κB Signaling Modulation

Persistent inflammatory reactions in microglial cells are strongly associated with neurodegenerative pathogenesis. Additionally, geranylgeraniol (GGOH), a plant-derived isoprenoid, has been found to improve inflammatory conditions in several animal models. It has also been observed that its chemical structure is similar to that of the side chain of menaquinone-4, which is a vitamin K₂ sub-type that suppresses inflammation in mouse-derived microglial cells. In this study, we investigated whether GGOH has a similar anti-inflammatory effect in activated microglial cells. Particularly, mouse-derived MG6 cells pre-treated with GGOH were exposed to lipopolysaccharide (LPS). Thereafter, the mRNA levels of pro-inflammatory cytokines were determined via qRT-PCR, while protein expression levels, especially the expression of NF-κB signaling cascade-related proteins, were determined via Western blot analysis. The distribution of NF-κB p65 protein was also analyzed via fluorescence microscopy. Thus, it was observed that GGOH dose-dependently suppressed the LPS-induced increase in the mRNA levels of Il-1β, Tnf-α, Il-6, and Cox-2. Furthermore, GGOH inhibited the phosphorylation of TAK1, IKKα/β, and NF-κB p65 proteins as well as NF-κB nuclear translocation induced by LPS while maintaining IκBα expression. We showed that GGOH, similar to menaquinone-4, could alleviate LPS-induced microglial inflammation by targeting the NF-kB signaling pathway.

Fermented rice bran supplementation attenuates chronic colitis-associated extraintestinal manifestations in female C57BL/6N mice

Patients with inflammatory bowel disease (IBD) have higher incidence of extraintestinal manifestations (EIM), including liver disorders, sarcopenia, and neuroinflammation. Fermented rice bran (FRB), generated from rice bran (RB), is rich in bioactive compounds, and exhibits anti-colitis activity. However, its role in EIM prevention is still unclear. Here, for the first time, we investigated whether EIM in female C57Bl/6N mice is attenuated by FRB supplementation. EIM was induced by repeated administration of 1.5% dextran sulfate sodium (DSS) in drinking water (4 d) followed by drinking water (12 d). Mice were divided into 3 groups-control (AIN93M), 10% RB, and 10% FRB. FRB ameliorated relapsing colitis and inflammation in muscle by significantly lowering proinflammatory cytokines Tnf-α and Il-6 in serum and advanced glycation end product-specific receptor (Ager) in serum and muscle when compared with the RB and control groups. As FRB reduced aspartate aminotransferase levels and oxidative stress, it might prevent liver disorders. FRB downregulated proinflammatory cytokine and chemokine transcripts responsible for neuroinflammation in the hippocampus and upregulated mRNA expression of G protein coupled receptors (GPRs), Gpr41 and Gpr43, in small and large intestines, which may explain the FRB-mediated protective mechanism. Hence, FRB can be used as a supplement to prevent IBD-associated EIM.

The Role of Vitamin K in Cholestatic Liver Disease

Vitamin K (VK) is a ligand of the pregnane X receptor (PXR), which plays a critical role in the detoxification of xenobiotics and metabolism of bile acids. VK₁ may reduce the risk of death in patients with chronic liver failure. VK deficiency is associated with intrahepatic cholestasis, and is already being used as a drug for cholestasis-induced liver fibrosis in China. In Japan, to treat osteoporosis in patients with primary biliary cholangitis, VK₂ formulations are prescribed, along with vitamin D₃. Animal studies have revealed that after bile duct ligation-induced cholestasis, PXR knockout mice manifested more hepatic damage than wild-type mice. Ligand-mediated activation of PXR improves biochemical parameters. Rifampicin is a well-known human PXR ligand that has been used to treat intractable pruritus in severe cholestasis. In addition to its anti-cholestatic properties, PXR has anti-fibrotic and anti-inflammatory effects. However, because of the scarcity of animal studies, the mechanism of the effect of VK on cholestasis-related liver disease has not yet been revealed. Moreover, the application of VK in cholestasis-related diseases is controversial. Considering this background, the present review focuses on the effect of VK in cholestasis-related diseases, emphasizing its function as a modulator of PXR.

Volatile compounds of black cumin (Nigella sativa L.) seeds cultivated in Bangladesh and India

The compositional analysis of volatile compounds of Nigella sativa L. seeds obtained from India and Bangladesh was carried out in this study. Apart from the proportion of volatile compounds, the chemical composition of seeds from both sources were similar. The major volatile compounds in Bangladesh seeds were p-cymene (36.35%), thymoquinone (29.77%), α-thujene (12.40%), carvacrol (2.85%), β-pinene (2.41%), limonene (1.64%), methyl linoleate (1.33%) and sabinene (1.18%), contribution of these is 87.93% of the total volatile oil. On the other hand, the major volatile compounds in Indian seeds were p-cymene (41.80%), α-thujene (13.93%), thymoquinone (10.27%), methyl linoleate (4.02%), carvacrol (3.65%), β-pinene (2.96%), d-limonene (2.11%), 4,5-epoxy-1-isopropyl-4- methyl-1-cyclohexene (1.80%), sabinene (1.50%) and 4-terpineol (1.22%); contribution of these were 83.24% of the total volatile oil. In both seeds, p-cymene, thymoquinone, and α-thujene were the major components. Importantly, N. sativa seeds of Bangladesh contained almost 3-fold thymoquinone compared to Indian seeds. In conclusion, the seeds from Bangladesh contain a higher amount of terpene ketones (29.86%) represented by thymoquinone in comparison to Indian seeds (10.61%); on the other hand, Indian seeds contained a higher amount of terpene hydrocarbons (63.18%) mainly p-cymene, compared to Bangladesh seeds (54.53%). This is the first study to report detailed compositional analysis and comparison of Nigella sativa L. seeds from Bangladesh and India.

Beneficial Effects of Vitamin K Status on Glycemic Regulation and Diabetes Mellitus: A Mini-Review

Type 2 diabetes mellitus is a chronic disease that is characterized by hyperglycemia, insulin resistance, and dysfunctional insulin secretion. Glycemic control remains a crucial contributor to the progression of type 2 diabetes mellitus as well as the prevention or delay in the onset of diabetes-related complications. Vitamin K is a fat-soluble vitamin that plays an important role in the regulation of the glycemic status. Supplementation of vitamin K may reduce the risk of diabetes mellitus and improve insulin sensitivity. This mini-review summarizes the recent insights into the beneficial effects of vitamin K and its possible mechanism of action on insulin sensitivity and glycemic status, thereby suppressing the progression of diabetes mellitus.

Supplementation with Fermented Rice Bran Attenuates Muscle Atrophy in a Diabetic Rat Model

Fermented rice bran (FRB), a prospective supplement, has been proven to ameliorate certain medical conditions. However, its nutraceutical effect on muscle atrophy has never been investigated. The present study aimed to evaluate the effect of FRB on muscle atrophy in a streptozotocin (STZ)-induced diabetic rat model. Three groups of Sprague-Dawley rats, namely the control, STZ, and FRB groups, were treated as follows. The diabetic groups (STZ and FRB) were injected intraperitoneally with STZ (40 mg/kg BW), whereas the control group was injected with the vehicle. The STZ and control groups were fed the AIN93M diet, and the FRB group was fed 10% of FRB based on the AIN93M diet. The diabetic groups had reduced muscle size compared to the control group; however, these changes were alleviated in the FRB group. Moreover, the FRB group had a significantly lower expression of FBXO32/Atrogin-1 and TRIM63/MuRF1 (p < 0.05) due to blocked NF-κB activation. In conclusion, the anti-inflammatory effect of FRB may be beneficial for ameliorating muscle atrophy in diabetic conditions.

The Effect of Liver Hydrolysate on Chronic Ethanol-Induced Hepatic Injury in Normal Rats

The mechanism underlying the improvement in hepatic function by liver hydrolysate (LH) after ethanol-induced hepatic injury is unclear. Therefore, we investigated the effects of LH administration on chronic ethanol-induced hepatic injury in normal rats and the mechanism underlying the improvement of its symptoms by LH. LH attenuated liver damage and reduced oxidative stress after chronic ethanol-induced hepatic injury in normal rats. LH treatment reduced hepatic injury biomarkers of plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT). LH treatment also decreased levels of 8-hydroxy-deoxyguanosine (8-OHdG) as oxidative stress marker. LH may prove beneficial to prevent the liver damage of chronic ethanol, at least in part, by alleviating oxidative stress.

Menaquinone-4 Suppresses Lipopolysaccharide-Induced Inflammation in MG6 Mouse Microglia-Derived Cells by Inhibiting the NF-κB Signaling Pathway

The overactivation of microglia is known to trigger inflammatory reactions in the central nervous system, which ultimately induce neuroinflammatory disorders including Alzheimer's disease. However, increasing evidence has shown that menaquinone-4 (MK-4), a subtype of vitamin K2, can attenuate inflammation in the peripheral system. Whereas it was also observed at high levels within the brain, its function in this organ has not been well characterized. Therefore, we investigated the effect of MK-4 on microglial activation and clarified the underlying mechanism. Mouse microglia-derived MG6 cells were exposed to lipopolysaccharide (LPS) either with or without MK-4 pretreatment. Cell responses with respect to inflammatory cytokines (Il-1β, Tnf-α, and Il-6) were measured by qRT-PCR. We further analyzed the phosphorylation of TAK1, IKKα/β, and p65 of the NF-κB subunit by Western blotting. We observed that in LPS-induced MG6 cells, MK-4 dose-dependently suppressed the upregulation of inflammatory cytokines at the mRNA level. It also significantly decreased the phosphorylation of p65, but did not affect that TAK1 and IKKα/β. Furthermore, the nuclear translocation of NF-κB in LPS-induced MG6 cells was inhibited by MK-4. These results indicate that MK-4 attenuates microglial inflammation by inhibiting NF-κB signaling.

Menaquinone-4 Amplified Glucose-Stimulated Insulin Secretion in Isolated Mouse Pancreatic Islets and INS-1 Rat Insulinoma Cells

Vitamin K2 is indispensable for blood coagulation and bone metabolism. Menaquinone-4 (MK-4) is the predominant homolog of vitamin K2, which is present in large amounts in the pancreas, although its function is unclear. Meanwhile, β-cell dysfunction following insulin secretion has been found to decrease in patients with type 2 diabetes mellitus. To elucidate the physiological function of MK-4 in pancreatic β-cells, we studied the effects of MK-4 treatment on isolated mouse pancreatic islets and rat INS-1 cells. Glucose-stimulated insulin secretion significantly increased in isolated islets and INS-1 cells treated with MK-4. It was further clarified that MK-4 enhanced cAMP levels, accompanied by the regulation of the exchange protein directly activated by the cAMP 2 (Epac2)-dependent pathway but not the protein kinase A (PKA)-dependent pathway. A novel function of MK-4 on glucose-stimulated insulin secretion was found, suggesting that MK-4 might act as a potent amplifier of the incretin effect. This study therefore presents a novel potential therapeutic approach for impaired insulinotropic effects.

Adenosine and adenosine-5'-monophosphate ingestion ameliorates abnormal glucose metabolism in mice fed a high-fat diet

Background

We have previously reported that ingestion of adenosine (ADN) and adenosine-5′-monophosphate (AMP) improves abnormal glucose metabolism in the stroke-prone spontaneously hypertensive rat model of non-obesity-associated insulin resistance. In this study, we investigated the effect of ADN and AMP ingestion on glucose metabolism in mice with high-fat diet-induced obesity.

Methods

Seven-week-old C57BL/6 J mice were administered distilled water (as a control), 10 mg/L ADN, or 13 mg/L AMP via their drinking water for 14 or 25 weeks, during which they were fed a high-fat diet. Oral glucose tolerance test (OGTT) was conducted on 21-week-old mice fasted for 16 h. Insulin tolerance test (ITT) was performed on 22-week-old mice fasted for 3 h. Blood and muscle were collected for further analysis of serum parameters, gene and protein expression levels, respectively.

Results

Glucose metabolism in the ADN and AMP groups was significantly improved compared with the control. OGTT and ITT showed that ADN and AMP groups lower than control group. Furthermore, phosphorylation of AMP-activated protein kinase (AMPK) and mRNA levels of genes involved in lipid oxidation were enhanced in the skeletal muscle of ADN- and AMP-treated mice.

Conclusion

These results indicate that ingestion of ADN or AMP induces activation of AMPK in skeletal muscle and mitigates insulin resistance in mice with high-fat diet-induced diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12906-018-2367-6) contains supplementary material, which is available to authorized users.

Orexigenic action of oral zinc: metabolomic analysis in the rat hypothalamus

We previously reported an orexigenic action of oral zinc administration in male Sprague-Dawley (SD) rats during an early stage of feeding with a zinc-deficient diet, without decreased zinc concentrations in tissues. The overall conclusion was that orally but not intraperitoneally administered zinc stimulates food intake in short-term zinc-deficient-diet fed rats. We here investigate the mechanism of the orexigenic action of zinc using GC-MS/MS-targeted metabolomic analysis in the rat hypothalamus. Four-week-old, male SD/Slc rats were used, and after 2 days of feeding with a zinc-deficient diet, 3 mg of ZnSO₄ in 5 mL saline solution were administered to each rat either orally or intraperitoneally. Three hours after administration, the rats were sacrificed and the hypothalamus were excised and analyzed. We found that the oral administration group showed increased concentrations of 3-aminopropanoic acid (β-alanine), hypotaurine, dopamine, and biotin. In light of metabolomic analysis of these results, we indicate directions for further research.

Zinc deficiency causes delayed ATP clearance and adenosine generation in rats and cell culture models

Zinc deficiency causes myriad pathophysiological symptoms, but why distinct phenotypes are generated by zinc deficiency remains unclear. Considering that several ectoenzymes involved in purinergic signaling through extracellular adenine-nucleotide hydrolysis possess zinc ions in their active sites, and disorders in purinergic signaling result in diverse diseases that are frequently similar to those caused by zinc deficiency, herein we examine whether zinc deficiency affects extracellular adenine-nucleotide metabolism. Zinc deficiency severely impairs the activities of major ectoenzymes (ENPP1, ENPP3, NT5E/CD73, and TNAP), and also strongly suppresses adenine-nucleotide hydrolysis in cell-membrane preparations or rat plasma, thereby increasing ATP and ADP levels and decreasing adenosine levels. Thus, zinc deficiency delays both extracellular ATP clearance and adenosine generation, and zinc modulates extracellular adenine-nucleotide metabolism. Since the finely tuned balance between extracellular adenine nucleotides and adenosine is critical for purinergic signaling, these findings provide a novel insight into why zinc deficiency results in diverse symptoms.

Taka-aki Takeda et al. find that zinc deficiency impairs adenine nucleotide metabolism in both cell and rat models leading to delays in extracellular ATP clearance and adenosine generation. The results show that zinc deficiency affects purinergic signaling and may explain why zinc deficiency in humans results in diverse symptoms.

Effects of Vitamin K₂ on the Expression of Genes Involved in Bile Acid Synthesis and Glucose Homeostasis in Mice with Humanized PXR

Pregnane X receptor (PXR) is a nuclear receptor activated by various compounds, including prescribed drugs and dietary ingredients. Ligand-specific activation of PXR alters drug metabolism and affects many other physiological conditions. Species-specific ligand preference is a considerable challenge for studies of PXR function. To increase translational value of the results of mouse studies, humanized mouse model expressing human PXR (hPXR) has been developed. Menaquinone-4 (MK-4), one of vitamin K₂ analogs prescribed in osteoporosis, is a PXR ligand. We hypothesized that MK-4 could modulate the physiological conditions endogenously influenced by PXR, including those that have not been yet properly elucidated. In the present study, we investigated the effects of a single oral treatment with MK-4 on hepatic gene expression in wild-type and hPXR mice by using quantitative RT-PCR and DNA microarray. MK-4 administration altered mRNA levels of genes involved in drug metabolism (Abca3, Cyp2s1, Sult1b1), bile acid synthesis (Cyp7a1, Cyp8b1), and energy homeostasis (Aldoc, Slc2a5). Similar mRNA changes of CYP7A1 and CYP8B1 were observed in human hepatocarcinoma HepG2 cells treated with MK-4. These results suggest that MK-4 may modulate bile acid synthesis. To our knowledge, this is the first report showing the effect of MK-4 in hPXR mice.

Genotyping Analysis of Bitter-Taste Receptor Genes TAS2R38 and TAS2R46 in Japanese Patients with Gastrointestinal Cancers

Type-2 bitter-taste receptors (TAS2Rs) are important for the evaluation of food quality and the nutritional control in animals. Mutations in some TAS2Rs including TAS2R38 are known to increase susceptibility to various diseases. However, the involvement of TAS2Rs in cancers has not been well understood. We conducted a pilot study by genotyping two TAS2R genes, TAS2R38 and TAS2R46, in Japanese cancer patients diagnosed with the following types of cancer: biliary tract cancer, hepatocellular carcinoma, pancreatic cancer, colorectal cancer and gastric cancer. We selected the two TAS2Rs because they carry virtually non-functional alleles in human populations. We found that cancer risk is not associated with any TAS2R46 genotypes since there were no significant differences in genotype frequencies between cancer patients and controls. On the other hand, we confirmed that phenylthiocarbamide (PTC) non-tasters homozygous (AVI/AVI) for TAS2R38 were more frequent among Japanese cancer patients than those among controls as suggested in a previous study. The AVI/AVI genotype was therefore considered to increases cancer risk. In contrast, we also found that homozygous (PAV/PAV) PTC tasters are less frequent among cancer patients, suggesting that the PAV/PAV is a cancer resistant genotype that decreases cancer risk. Genotype frequencies for heterozygous AVI/PAV genotype were not significantly different between the two groups. It is suggested that the risk and resistance of cancers is antagonistically controlled by the two TAS2R38 alleles, PAV and AVI, rather than by the AVI allele alone.

A novel function of geranylgeraniol in regulating testosterone production

Isoprenoids play widely differing roles in various physiological processes in animals and plants. Geranylgeraniol (GGOH) is an isoprenoid found in plants, and is an important metabolic derivative in the isoprenoid/cholesterol synthesis pathway. Earlier studies focused on GGOH's ability to improve the side effects of bisphosphonate therapy by regulating the mevalonate pathway. More recently, the mevalonate pathway-independent effects of GGOH have been described, including anti-inflammatory, anti-tumorigenic, and neuroprotective activities. It is noteworthy that GGOH regulates the steroidogenesis pathway in testis-derived I-10 tumor cells. Testosterone is a hormone produced via steroidogenesis in testicles and plays a role in fetal development and the male reproductive system. GGOH enhanced testosterone and progesterone (its precursor) levels in I-10 cells by activating adenylate cyclase via cAMP/PKA signaling, without altering phosphodiesterase activity. These findings highlight the potential benefits of GGOH as a therapeutic agent for low testosterone levels, such as late-onset hypogonadism in men.

Dietary tryptophan alleviates dextran sodium sulfate-induced colitis through aryl hydrocarbon receptor in mice

Ulcerative colitis is the typical progression of chronic inflammatory bowel disease. Amino acids, particularly tryptophan, have been reported to exert a protective effect against colitis induced by dextran sodium sulfate (DSS), but the precise underlying mechanisms remain incompletely clarified. Tryptophan metabolites are recognized to function as endogenous ligands for aryl hydrocarbon receptor (Ahr), which is a critical regulator of inflammation and immunity. Thus, we conducted this study to investigate whether dietary tryptophan supplementation protects against DSS-induced colitis by acting through Ahr. Female wild-type (WT) and Ahr-deficient (knockout; KO) mice (10-12 weeks old) were divided into four groups and fed either a control or 0.5% tryptophan diet. The tryptophan diet ameliorated DSS-induced colitis symptoms and severity in WT mice but not in KO mice, and the diet reduced the mRNA expression of Il-6, Tnfα, Il-1β and the chemokines Ccl2, Cxcl1 and Cxcl2 in the WT groups. Furthermore, Il-22 and Stat3 mRNA expression in the colon was elevated in WT mice fed with the tryptophan diet, which mainly protected epithelial layer integrity, and Ahr also modulated immune homeostasis by regulating Foxp3 and Il-17 mRNA expression. These data suggest that tryptophan-containing diet might ameliorate DSS-induced acute colitis and regulate epithelial homeostasis through Ahr. Thus, tryptophan could serve as a promising preventive agent in the treatment of ulcerative colitis.

Properties of Zip4 accumulation during zinc deficiency and its usefulness to evaluate zinc status: a study of the effects of zinc deficiency during lactation

Systemic and cellular zinc homeostasis is elaborately controlled by ZIP and ZnT zinc transporters. Therefore, detailed characterization of their expression properties is of importance. Of these transporter proteins, Zip4 functions as the primarily important transporter to control systemic zinc homeostasis because of its indispensable function of zinc absorption in the small intestine. In this study, we closely investigated Zip4 protein accumulation in the rat small intestine in response to zinc status using an anti-Zip4 monoclonal antibody that we generated and contrasted this with the zinc-responsive activity of the membrane-bound alkaline phosphatase (ALP). We found that Zip4 accumulation is more rapid in response to zinc deficiency than previously thought. Accumulation increased in the jejunum as early as 1 day following a zinc-deficient diet. In the small intestine, Zip4 protein expression was higher in the jejunum than in the duodenum and was accompanied by reduction of ALP activity, suggesting that the jejunum can become zinc deficient more easily. Furthermore, by monitoring Zip4 accumulation levels and ALP activity in the duodenum and jejunum, we reasserted that zinc deficiency during lactation may transiently alter plasma glucose levels in the offspring in a sex-specific manner, without affecting homeostatic control of zinc metabolism. This confirms that zinc nutrition during lactation is extremely important for the health of the offspring. These results reveal that rapid Zip4 accumulation provides a significant conceptual advance in understanding the molecular basis of systemic zinc homeostatic control, and that properties of Zip4 protein accumulation are useful to evaluate zinc status closely.

Geranylgeraniol enhances testosterone production via the cAMP/protein kinase A pathway in testis-derived I-10 tumor cells

Testosterone levels in men decrease with age; this decline has been linked to various diseases and can shorten life expectancy. Geranylgeraniol (GGOH) is an isoprenoid found in plants that plays an important role in several biological processes; however, its role in steroidogenesis is unknown. Here, we report that GGOH enhances the production of testosterone and its precursor progesterone in testis-derived I-10 tumor cells. GGOH induced protein kinase A (PKA) activity and increased cAMP levels and was found to regulate cAMP/PKA signaling by activating adenylate cyclase without altering phosphodiesterase activity. GGOH also stimulated mRNA and protein levels of steroidogenic acute regulatory protein, a downstream effector in the cAMP/PKA pathway. These results demonstrate that GGOH enhances steroidogenesis in testis-derived cells by modulating cAMP/PKA signaling. Our findings have potential applications for the development of therapeutics that increase testosterone levels in aging men.

Fermented barley extract supplementation ameliorates metabolic state in stroke-prone spontaneously hypertensive rats

We studied the effects of fermented barley extract P (FBEP) in stroke-prone spontaneously hypertensive rats (SHRSP). Male 10-week-old SHRSP were divided into three groups that were fed: an AIN-93M diet (control), a low dose of FBEP (4 g/kg; FBEP1), and a high dose of FBEP (20 g/kg; FBEP2) for three weeks. Hypertension was significantly improved by the use of FBEP supplementation. The FBEP diet improved plasma triglyceride, insulin sensitivity, enhanced plasma catalase, and superoxide dismutase activities, and decreased plasma 8-hydroxy-2'-deoxyguanosine levels. In addition, the FBEP diet upregulated hepatic antioxidative genes and modulated Nrf2 protein levels in the liver. Furthermore, a single oral dose of FBEP (2 g/kg body weight) was able to lower blood pressure in SHRSP. In conclusion, our data suggest that increased expression of hepatic antioxidative genes and modulation of Nrf2 may play a role in the regulation of metabolic diseases in SHRSP consuming a FBEP diet.

Impact of fasting time on hepatic lipid metabolism in nutritional animal studies

Many animal studies on improvement of lipid metabolism, using dietary components, fast the animals on the final day of the feeding. Although fasting has a significant impact on lipid metabolism, its time-dependent influence is not fully understood. We examined the effects of several fasting times on lipid metabolism. Rats fed with a semisynthetic diet for 2 wk were killed after 0 (9:00 am), 6 (7:00 am-1:00 pm), 9 (0:00 am-9:00 am), and 13 h (8:00 pm-9:00 am) of fasting. Compared to the 0 h group, marked reduction of liver weight and hepatic triacylglycerol content was observed in the 9 and 13 h groups. Activities of hepatic enzymes involved in fatty acid synthesis gradually decreased during fasting. In contrast, drastic time-dependent reduction of gene expression, of the enzymes, was observed. Expression of carnitine palmitoyltransferase mRNA was higher in the fasting groups than in the 0 h group. Our study showed that fasting has a significant impact on several parameters related to lipid metabolism in rat liver.

Identification and evaluation of anti-inflammatory compounds from Kaempferia parviflora

The rhizome of Kaempferia parviflora has been used in traditional Thai medicine. In this study, we identified and compared specific compounds from the hexane extract of K. parviflora with those from other Zingiberaceous plants by using gas chromatography–mass spectrometry. We identified 5,7-dimethoxyflavone (DMF), 5-hydroxy-3,7,3′,4′-tetramethoxyflavone (TMF), estimated 3,5,7-trimethoxyflavone, 5-hydroxy-7,4′-dimethoxyflavone, 3,5,7,4′-tetramethoxyflavone, and investigated their anti-inflammatory effects in rat basophilic leukemia (RBL-2H3) cells stimulated with an IgE antigen or a calcium ionophore. We found that DMF and TMF more potently inhibited antigen-induced degranulation than did nobiletin, a well-known anti-inflammatory agent. In addition, compared to RBL-2H3 cells stimulated with a calcium ionophore, those treated with DMF and TMF showed more marked inhibition of the degranulation and the production and mRNA expression of inflammatory mediators. These results suggest that DMF and TMF inhibit an early step in the high-affinity IgE receptor signaling cascade rather than intracellular calcium release and protein kinase C activation.

Behavioral analysis of Drosophila transformants expressing human taste receptor genes in the gustatory receptor neurons

Transgenic Drosophila expressing human T2R4 and T2R38 bitter-taste receptors or PKD2L1 sour-taste receptor in the fly gustatory receptor neurons and other tissues were prepared using conventional Gal4/UAS binary system. Molecular analysis showed that the transgene mRNAs are expressed according to the tissue specificity of the Gal4 drivers. Transformants expressing the transgene taste receptors in the fly taste neurons were then studied by a behavioral assay to analyze whether transgene chemoreceptors are functional and coupled to the cell response. Since wild-type flies show strong aversion against the T2R ligands as in mammals, the authors analyzed the transformants where the transgenes are expressed in the fly sugar receptor neurons so that they promote feeding ligand-dependently if they are functional and activate the neurons. Although the feeding preference varied considerably among different strains and individuals, statistical analysis using large numbers of transformants indicated that transformants expressing T2R4 showed a small but significant increase in the preference for denatonium and quinine, the T2R4 ligands, as compared to the control flies, whereas transformants expressing T2R38 did not. Similarly, transformants expressing T2R38 and PKD2L1 also showed a similar preference increase for T2R38-specific ligand phenylthiocarbamide (PTC) and a sour-taste ligand, citric acid, respectively. Taken together, the transformants expressing mammalian taste receptors showed a small but significant increase in the feeding preference that is taste receptor and also ligand dependent. Although future improvements are required to attain performance comparable to the endogenous robust response, Drosophila taste neurons may serve as a potential in vivo heterologous expression system for analyzing chemoreceptor function.

Administration of biotin prevents the development of insulin resistance in the skeletal muscles of Otsuka Long-Evans Tokushima Fatty rats

Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for type 2 diabetes mellitus. In the present study, we investigated whether pharmacologic doses of biotin have the potential to abate insulin resistance in the skeletal muscles of OLETF rats. OLETF rats (34 weeks of age) were divided into 2 groups and given distilled water (OLETF-control group) or distilled water containing 3.3 mg L(-1) of biotin (OLETF-biotin group) for 8 weeks. At the end of experimental period, the OLETF-control rats developed severe hyperglycemia and hyperinsulinemia, whereas the OLETF-biotin rats showed significantly smaller responses to oral glucose tolerance test than the OLETF-control rats. The glucose uptake in the hind limbs of the rats was significantly higher in the OLETF-biotin group than in the OLETF-control group. Biotin administration increased the glucose transporter type 4 (GLUT4) protein content in the total membrane fraction but had little effect on the GLUT4 content in the plasma membrane fraction. These results indicate that administration of a pharmacological dose of biotin prevents the development of insulin resistance in the skeletal muscles of OLETF rats presumably via an increase in GLUT4 protein expression but not via GLUT4 translocation.

Novel effect of adenosine 5'-monophosphate on ameliorating hypertension and the metabolism of lipids and glucose in stroke-prone spontaneously hypertensive rats

The aim of the study was to investigate the effects of adenosine 5'-monophosphate (AMP) in stroke-prone spontaneously hypertensive rats (SHRSP). Male rats (10 weeks old) were divided into three groups: a control group fed an AIN-93 M diet and two others fed supplemental AMP (17.5 and 87.5 mg/kg diet) for 3 weeks. AMP effectively improved hypertension, plasma triglyceride, and HDL-cholesterol, glucose, kidney function parameters, hepatic lipid, enhances plasma nitric oxide, and plasma adiponectin accompanied by the up-regulation of mRNA expression levels of the hepatic adiponectin receptor 2. Single and chronic oral administration of AMP affected the hepatic mRNA expression levels of genes involved in β-oxidation, fatty acid synthesis, and AMP-activated protein kinase. Furthermore, a single oral dose of AMP (40 mg/kg body weight) improved hypertension and hyperglycemia in SHRSP. In conclusion, AMP displays a novel effect in ameliorating metabolic-related diseases in SHRSP and could be beneficial as a functional food.

Menaquinone-4 enhances testosterone production in rats and testis-derived tumor cells

Background

Vitamin K is essential for the posttranslational modification of various Gla proteins. Although it is widespread in several organs, including the testis, the function of vitamin K in these organs is not well characterized. In this study, we investigated the function of vitamin K in the testis and analyzed its role in steroidogenesis.

Methods

Eight-week-old male Wistar rats were fed a diet supplemented with menaquinone-4 (MK-4, 75 mg/kg diet), one of the predominant K₂ vitamins present in the testis, for 5 weeks. In vivo testosterone levels of the rats' plasma and testes were measured by enzyme-linked immunosorbent assay, and in vitro testosterone levels of testis-derived tumor cells (I-10 cells) maintained in Ham's F-10 medium with 10% fetal bovine serum were measured following treatment with MK-4 (0 to 100 μM) at several time points. Testosterone and cellular protein levels were analyzed with respect to their effects on steroidogenesis.

Results

Testosterone levels in the plasma and testes of MK-4-fed rats were significantly increased compared to those of control rats, with no obvious differences in plasma luteinizing hormone levels. Secreted testosterone levels from I-10 cells were elevated by MK-4, but not by vitamin K₁, in a dose-dependent manner independent of cAMP treatment. Western blot analysis revealed that expression of CYP11A, the rate-limiting enzyme in steroidogenesis, and phosphorylation levels of protein kinase A (PKA) and the cAMP response element-binding protein were all stimulated by the presence of MK-4. Enhancement of testosterone production was inhibited by H89, a specific inhibitor of PKA, but not by warfarin, an inhibitor of γ-glutamylcarboxylation.

Conclusions

MK-4 stimulates testosterone production in rats and testis-derived tumor cells via activation of PKA. MK-4 may be involved in steroidogenesis in the testis, and its supplementation could reverse the downregulation of testosterone production in elders.

Zinc as an appetite stimulator - the possible role of zinc in the progression of diseases such as cachexia and sarcopenia

Zinc is required by humans and animals for many physiological functions, such as growth, immune function, and reproduction. Zinc deficiency induces a number of physiological problems, including anorexia, growth retardation, dermatitis, taste disorder, and hypogonadism. Although it is clear that zinc deficiency produces specific and profound anorexia in experimental animals, the connection between zinc deficiency and anorexia is less certain. We were the first to show that orally, but not intraperitoneally, administered zinc rapidly stimulates food intake through orexigenic peptides coupled to the afferent vagus nerve using rats during early-stage zinc deficiency without decreased zinc concentrations in plasma and tissues. We confirmed that a zinc-sufficient diet containing zinc chloride acutely stimulated food intake after short-term zinc deprivation. We also found that orally administered zinc sulfate increased the expression of NPY and orexin mRNA after administration. Using vagotomized rats, we tested whether the increase in food intake after oral administration of zinc was mediated by the vagus nerve. In sham-operated rats, the oral administration of zinc stimulated food intake, whereas zinc and saline administrations did not exhibit differing effects in vagotomized rats. We conclude that zinc stimulates food intake in short-term zinc-deficient rats through the afferent vagus nerve with subsequent effects on hypothalamic peptides associated with food intake regulation. In this review, we describe recent research investigating the roles of zinc as an appetite stimulator in food intake regulation, along with research about hypothalamus, ghrelin, leptin and zinc receptor, and clinical application about anorexia nervosa, cachexia and sarcopenia. The article also presents some promising patents on zinc.

Regulation of blood pressure and glucose metabolism induced by L-tryptophan in stroke-prone spontaneously hypertensive rats

BACKGROUND

Amino acids have been reported to act as modulators of various regulatory processes and to provide new therapeutic applications for either the prevention or treatment of metabolic disorders. The purpose of the present study is to investigate the effects of single oral dose administration and a continuous treatment of L-tryptophan (L-Trp) on the regulation of blood pressure and glucose metabolism in stroke-prone spontaneously hypertensive rats (SHRSP).

METHODS

First, male 9-week-old SHRSP were administered 100 mg L-Trp·kg-1 body weight in saline to the L-Trp group and 0.9% saline to the control group via a gastric tube as a single oral dose of L-Trp. Second, three groups of SHRSP were fed an AIN-93M-based diet supplemented with L-tryptophan (L-Trp) (0, 200, or 1000 mg·kg-1 diet) for 3 weeks as continuous treatment of L-Trp.

RESULTS

Single oral dose administration of L-Trp improved blood pressure, blood glucose, and insulin levels. Blood pressure, blood glucose, and insulin levels improved significantly in the L-Trp treatment groups. The administration of L-Trp also significantly increased plasma nitric oxide and serotonin levels.

CONCLUSION

L-Trp by both single oral dose administration and continuous treatment improves glucose metabolism and blood pressure in SHRSP.

Reduction of blood pressure by soybean saponins, renin inhibitors from soybean, in spontaneously hypertensive rats

The effect of commercial purified soybean saponin on renin activity and blood pressure was investigated. Soybean saponin significantly inhibited human renin in vitro with IC(50)=59.9 µg/ml. Orally administered soybean saponin at 80 mg/kg of body weight per day to spontaneously hypertensive rats for 8 weeks significantly decreased the blood pressure.

Vitamin K suppresses the lipopolysaccharide-induced expression of inflammatory cytokines in cultured macrophage-like cells via the inhibition of the activation of nuclear factor κB through the repression of IKKα/β phosphorylation

Vitamin K is essential for blood coagulation and bone metabolism in mammals. This vitamin functions as a cofactor in the posttranslational synthesis of γ-carboxyglutamic acid (Gla) from glutamic acid residues. However, other functions of vitamin K have been reported recently. We previously found that vitamin K suppresses the inflammatory reaction induced by lipopolysaccharide (LPS) in rats and human macrophage-like THP-1 cells. In this study, we further investigated the mechanism underlying the anti-inflammatory effect of vitamin K by using cultures of LPS-treated human- and mouse-derived cells. All the vitamin K analogues analyzed in our study exhibited varied levels of anti-inflammatory activity. The isoprenyl side chain structures, except geranylgeraniol, of these analogues did not show such activity; warfarin did not interfere with this activity. The results of our study suggest that the 2-methyl-1,4-naphtoquinone ring structure contributes to express the anti-inflammatory activity, which is independent of the Gla formation activity of vitamin K. Furthermore, menaquinone-4, a form of vitamin K₂, reduced the activation of nuclear factor κB (NFκB) and inhibited the phosphorylation of IKKα/β after treatment of cells with LPS. These results clearly show that the anti-inflammatory activity of vitamin K is mediated via the inactivation of the NFκB signaling pathway.

Absorption and effectiveness of orally administered low molecular weight collagen hydrolysate in rats

Collagen, a major extracellular matrix macromolecule, is widely used for biomedical purposes. We investigated the absorption mechanism of low molecular weight collagen hydrolysate (LMW-CH) and its effects on osteoporosis in rats. When administered to Wistar rats with either [(14)C]proline (Pro group) or glycyl-[(14)C]prolyl-hydroxyproline (CTp group), LMW-CH rapidly increased plasma radioactivity. LMW-CH was absorbed into the blood of Wistar rats in the peptide form. Glycyl-prolyl-hydroxyproline tripeptide remained in the plasma and accumulated in the kidney. In both groups, radioactivity was retained at a high level in the skin until 14 days after administration. Additionally, the administration of LMW-CH to ovariectomized stroke-prone spontaneously hypertensive rats increased the organic substance content and decreased the water content of the left femur. Our findings show that LMW-CH exerts a beneficial effect on osteoporosis by increasing the organic substance content of bone.

The nucleosomal binding protein NSBP1 is highly expressed in the placenta and modulates the expression of differentiation markers in placental Rcho-1 cells

We report that NSBP1, a nucleosome binding protein that affects the structure of chromatin, is highly expressed in mouse placenta. In Rcho-1 cells, which recapitulate the differentiation of trophoblast giant cells of living placenta, NSBP1 expression is linked to differentiation. Disregulation of NSBP1 protein levels, by either siRNA treatment or by overexpression, alters the expression of several members of the prolactin gene family without affecting the levels of several transcription factors involved in placental differentiation. Our studies identify NSBP1 as a nucleosome binding protein that modulates the expression of prolactin gene family members most likely by inducing changes in chromatin structure.

Adenosine, an identified active component from the Driselase-treated fraction of rice bran, is effective at improving metabolic syndrome in stroke-prone spontaneously hypertensive rats

In the present study, we isolated and identified an active component from the Driselase-treated fraction and investigated its effect by acute and chronic oral administration on hypertension, lipid, and glucose metabolism in stroke-prone spontaneously hypertensive rats. The active component was identified as adenosine and improves hypertension after single oral administration. Rats who were 10 weeks old were divided into control and adenosine groups and were administered water or water with adenosine (10 mg/L), respectively, for 3 weeks. Hypertension and plasma lipid, nitric oxide, insulin, leptin, adiponectin levels, and glucose metabolism were significantly improved in the adenosine group. The mRNA expression levels of genes involved in lipid and glucose metabolism were altered in the adenosine group. Single oral administration of adenosine (10 mg/kg body weight) improved hypertension and plasma triglyceride, glucose, and nitric oxide levels 2 h after administration. In conclusion, oral acute and chronic administration of adenosine are beneficial and improve the metabolic syndrome-related disease parameters.

Orally administered zinc increases food intake via vagal stimulation in rats

We investigated the role of zinc in food intake regulation using rats during early-stage zinc deficiency without decreased zinc concentrations in plasma and tissues. Plasma, liver, and hypothalamic zinc concentrations were not affected in male Sprague-Dawley rats fed a zinc-deficient (Zn-Def) diet for 3 d compared with the pair-fed control group, which was fed a zinc-sufficient diet to the intake of the Zn-Def diet. Zinc sulfate at a dose of 19 micromol/kg body weight was orally or intraperitoneally (i.p.) administered to rats fed a Zn-Def diet for 3d and food intake was measured. We found that zinc stimulated food intake after oral but not i.p. administration. The mRNA expression of neuropeptide Y (NPY) and orexin in the hypothalamus significantly increased 3 h after oral but not i.p. administration of zinc. Pretreatment with an antagonist for the NPY Y(1) receptor or the orexin OX(1) receptor blocked orexigenic activity after oral administration of zinc. The stimulation of food intake by oral administration of zinc was abolished by vagotomy. Taken together, orally administered zinc may stimulate food intake via orexigenic peptides coupled to the afferent vagal stimulation in rats after short-term treatment with a Zn-Def diet.

Novel effects of a single administration of ferulic acid on the regulation of blood pressure and the hepatic lipid metabolic profile in stroke-prone spontaneously hypertensive rats

We studied the effects of a single oral administration of ferulic acid (FA) on the blood pressure (BP) and lipid profile in stroke-prone spontaneously hypertensive rats (SHRSP). Male 12-week-old SHRSP were administered FA (9.5 mg/kg of body weight) and distilled water as the control (C) (1 mL) via a gastric tube. The hypotensive effect of FA was observed at the lowest value after 2 h administration. A decrease in the angiotensin-1-converting enzyme (ACE) activity in the plasma corresponded well with the reduction of BP. Plasma total cholesterol and triglyceride levels were lower after 2 h administration. The mRNA expression of genes involved in lipid and drug metabolism was downregulated in the FA group. These results suggest that oral administration of FA appears beneficial in improving hypertension and hyperlipidemia.

Decreased expression of carbonic anhydrase isozyme II, rather than of isozyme VI, in submandibular glands in long-term zinc-deficient rats

We previously reported that in rats, long-term Zn deficiency significantly reduced taste sensitivity and total carbonic anhydrase (CA) activity in the submandibular gland. We therefore investigated the effects of Zn deficiency on salivary secretion and the expressions of CA isozymes (II and VI) in the rat submandibular gland, since those isozymes are thought to be related to taste sensation and salivary secretion. Male Sprague–Dawley rats, age 4 weeks, were divided into three groups (Zn-def, low-Zn and pair-fed, that were fed a diet containing 2·2, 4·1 or 33·7 mg Zn/kg, respectively, for 42 d). Northern blot analysis indicated that Zn deficiency reduced CA II mRNA expression in the submandibular gland without reducing CA VI mRNA expression. In Western blot analysis, Zn deficiency significantly reduced CA II (erythrocyte CA) protein expression in the submandibular gland without reducing CA VI protein expression. Salivary secretion was lower in the Zn-def group than in the pair-fed group. These results suggest that decreased CA isozyme II expression underlies the decreased CA activity previously reported in the submandibular gland in Zn-def rats, and this may reduce regular salivary secretion.