Takamitsu Tsukahara

Voluntary Running Exercise Alters Microbiota Composition and Increases n-Butyrate Concentration in the Rat Cecum

The effects of voluntary wheel-running exercise on cecal microbiota and short-chain fatty acid production were investigated in rats. The microbiota composition was notably different between the exercised and sedentary rats. Furthermore, the exercised rats showed a significantly higher n-butyrate concentration than the sedentary rats. This alteration of the cecal microbial environment may contribute to the beneficial effect of exercise on gastrointestinal disorders.

Activating Transcription Factor 3 Constitutes a Negative Feedback Mechanism That Attenuates Saturated Fatty Acid/Toll-Like Receptor 4 Signaling and Macrophage Activation in Obese Adipose Tissue

Obese adipose tissue is markedly infiltrated by macrophages, suggesting that they may participate in the inflammatory pathways that are activated in obese adipose tissue. Evidence has suggested that saturated fatty acids released via adipocyte lipolysis serve as a naturally occurring ligand that stimulates Toll-like receptor (TLR)4 signaling, thereby inducing the inflammatory responses in macrophages in obese adipose tissue. Through a combination of cDNA microarray analyses of saturated fatty acid–stimulated macrophages in vitro and obese adipose tissue in vivo, here we identified activating transcription factor (ATF)3, a member of the ATF/cAMP response element-binding protein family of basic leucine zipper-type transcription factors, as a target gene of saturated fatty acids/TLR4 signaling in macrophages in obese adipose tissue. Importantly, ATF3, when induced by saturated fatty acids, can transcriptionally repress tumor necrosis factor-α production in macrophages in vitro. Chromatin immunoprecipitation assay revealed that ATF3 is recruited to the region containing the activator protein-1 site of the endogenous tumor necrosis factor-α promoter. Furthermore, transgenic overexpression of ATF3 specifically in macrophages results in the marked attenuation of proinflammatory M1 macrophage activation in the adipose tissue from genetically obese KKAy mice fed high-fat diet. This study provides evidence that ATF3, which is induced in obese adipose tissue, acts as a transcriptional repressor of saturated fatty acids/TLR4 signaling, thereby revealing the negative feedback mechanism that attenuates obesity-induced macrophage activation. Our data also suggest that activation of ATF3 in macrophages offers a novel therapeutic strategy to prevent or treat obesity-induced adipose tissue inflammation.

Effects of chronic social defeat stress on MAP kinase cascade.

Chronic psychological and social stress can cause psychiatric disorders in humans. In this study, we analyzed the mitogen-activated protein kinase (MAPK) cascade in the hippocampus of chronically socially defeated rats. The rats that were subjected to social defeat every day for 5 weeks showed physiological and behavioral changes, including a reduced rate of weight gain, enlarged adrenal glands, and increased immobility in the forced swim test without concomitant changes in locomotor activity in the open field test. Altered body weight and enlarged adrenal glands are typical symptoms of human depression. Prolonged immobility in the forced swim test indicates behavioral despair, a well-established index of depression. Because the MAPK cascade plays a pivotal role in depression, we quantified the expression of these molecules in the hippocampus of chronically defeated rats using western blot analysis. We found that phospho-MAPK kinases 1/2 (MEK1/2) and phospho-extracellular signal-regulated kinases 1/2 (ERK1/2) were decreased, whereas MAPK phosphatase-1 (MKP-1) was increased in the hippocampus of chronically defeated rats compared to the control group. These results were consistent with findings in depressed patients and other animal models of depression. In conclusion, our findings suggest that chronic psychosocial stress in Wistar rats induced depression-like behavior and downregulated the MAPK cascade in the hippocampus.

Improvement of bone strength and dermal thickness due to dietary edible bird's nest extract in ovariectomized rats.

Oral administration of edible bird’s nest extract (EBNE) improved bone strength and calcium concentration in the femur of ovariectomized rats. Dermal thickness was also increased by EBNE supplementation, whereas EBNE administration did not affect the serum estradiol concentration. These results suggest that EBNE is effective for the improvement of bone loss and skin aging in postmenopause all women.

Postnatal changes in the expression of genes for cryptdins 1–6 and the role of luminal bacteria in cryptdin gene expression in mouse small intestine

Although there have been many fascinating studies on cryptdins, the information for each cryptdin isoform was not completely provided. In this study, the postnatal changes in the gene expression of cryptdin 1-6 were evaluated, and the patterns of change were compared between conventional and germ-free mice. Two patterns of postnatal change were observed: gene expression of cryptdins 1, 3 and 6 increased gradually, and that of cryptdins 2 and 5 increased rapidly. Gene expression of cryptdin 4 increased gradually in the ileum but rapidly in the jejunum. Conventional mice showed significantly higher gene expression for all isoforms than germ-free mice. Interestingly, the difference in the gene expression for cryptdin 2, 4 and 5 between the jejunum and ileum seemed to be increased by the presence of the luminal bacteria. The results indicate that cryptdin isoforms develop differently depending on the isoform type, and that the gene expression of all cryptdin isoforms was affected by the presence of the luminal bacteria.

Oral administration of Lactobacillus plantarum Lq80 and Megasphaera elsdenii iNP-001 induces efficient recovery from mucosal atrophy in the small and the large intestines of weaning piglets.

Weaning causes atrophy of intestinal mucosa and a drop of IgA protection in piglets which increases vulnerability to pathogenic infections. Probiotic lactobacilli may support recovery from such weaning stresses. Butyrate-produce bacteria may support the growth of colonic mucosa. Megasphaera elsdenii, a lactate-utilizing butyrate producer, may help butyrate production particularly when combined with lactobacilli. Weaned piglets (Experiment 1: 20 days old, Experiment 2: 28 days old) were orally dosed once a day with either (L) 10(10) (cell/dose) L. plantarum Lq80, or (LM) 10(10) (cell/dose) Lq80 with 10(9) (cell/dose) M. elsdenii iNP-001. Lq80 was contained in capsules resistant to gastric digestion. M. elsdenii was contained in capsules resistant to gastric and intestinal digestion. An untreated control (C) was also prepared. After 2 weeks of administration, L. plantarum enhanced the recovery from the villous atrophy in both experiments. The rectal and colonic IgA tended to be higher in L and LM than in C in Experiment 1. Colonic butyrate was higher in LM than in the others in Experiment 1. The thickness of the colonic mucosa was greater in LM than in the others in Experiment 1. In early weaned piglets, the effects of L. plantarum and M. elsdenii were clear.

The amount of secreted IgA may not determine the secretory IgA coating ratio of gastrointestinal bacteria

It is reported that some, but not all, bacteria in human faeces are coated with secretory immunoglobulin A (S-IgA). We evaluated the proportion of S-IgA-coated bacteria to total intestinal bacteria (S-IgA coating ratio) in the gastrointestinal tract of two different strains of mice supplied by two different suppliers. The S-IgA coating ratio was significantly different in each gastrointestinal segment and between mouse suppliers. The amount of non-bacteria-bound IgA (free IgA) in each gastrointestinal segment indicated that this difference in the S-IgA coating ratio might not be due to the amount of secreted IgA. Furthermore, immunoblotting analysis revealed that only a small amount of IgA (<5% to free-IgA) was used for the coating. This indicates that, although sufficient S-IgA was secreted to coat the entire intestinal population of bacteria, only some part of the bacteria were coated with S-IgA. This study suggests that the amount of luminal S-IgA may not determine the S-IgA coating ratio, and that the amount of IgA coating intestinal commensal bacteria is very small.

Effects of animal or plant protein diets on cecal fermentation in guinea pigs (Cavia porcellus), rats (Rattus norvegicus) and chicks (Gallus gallus domesticus).

Monogastric herbivores such as the guinea pig depend on energy supply from enteric fermentation as short-chain fatty acids (SCFA) corresponding to 30-40% of their maintenance energy requirements. They evolved specific digestive system to adapt their indigenous microflora to plant polysaccharides fermentation. No information has been available about the adaptability of microbial fermentation in hindgut of the monogastric herbivorous to an animal protein diet. We investigated if the guinea pig can fully retrieve energy of an animal protein diet by hindgut fermentation compared with a plant protein diet. For comparison, we also studied two omnivores. End products of in vitro cecal fermentation (SCFA, ammonia and gases) were measured to judge how well an animal protein diet could be fermented. The animal protein diet resulted in the less intensive fermentation with increased feed intake and volume of cecal contents than the plant protein diet only in guinea pigs. This may be due to a limited capacity of the hindgut microflora to adapt to the substrate rich in animal protein. We also found that chick cecal contents produced methane at higher emission rate than ruminants.

Improved Isolation Methods for Mucosal Leukocytes from Small and Large Intestines in Rats

We optimized the isolation protocol for intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs) from the rat small intestine, and LPLs from even the rat large intestine. The major population of IELs in the small intestine was considered to be from the villus epithelia. The cytotoxicity of mucosal leukocytes was comparable among isolated fractions from both the small and large intestines, regardless of the population differences. Further analyses of the cells collected from other lymphoid tissues demonstrated that CD161+ cells selectively accumulated in the intestinal lamina propria and did not recirculate through the lymph ducts. Our modified isolation protocol enables the collection of mucosal immune cells from the rat intestines without any deterioration of cell function and could contribute to a better understanding of dietary influences on the mucosal immune system.

Effects of chronic social defeat stress on peripheral leptin and its hypothalamic actions

BackgroundSuppression of body weight and symptom of anorexia are major symptoms of depression. Recently, we reported that chronic social defeat stress (CSDS) induced suppression of body weight gain and anorexic feeding behavior in rats. These abnormalities were the result of disrupted malonyl-coenzyme A (CoA) signaling pathway in the hypothalamus. However, the condition of peripheral leptin and its hypothalamic downstream signal molecules which regulate hypothalamic malonyl-CoA level in the CSDS-exposed rats (CSDS rats) is still unknown.ResultsCSDS rats showed suppressed body weight gain and food intake. The weight of the CSDS rats’ epididymal white adipose tissues was decreased when compared to the control rats. The plasma cholesterol concentration was decreased significantly in the CSDS rats compared to the control rats (P < 0.05). The plasma glucose concentration was slightly decreased in the CSDS rats compared to the control rats (P < 0.1). The expression of leptin mRNA in epididymal white adipose tissues and the plasma leptin concentration were decreased in CSDS rats. Furthermore, the phosphorylation of the hypothalamic downstream signals of leptin, including extracellular signal-regulated kinase 1/2 (ERK1/2) and signal transducer and activator of transcription 3 (STAT3), was decreased in CSDS rats.ConclusionsOur results indicated that decreased peripheral leptin expression in CSDS rats could down-regulate the hypothalamic downstream signaling pathways of leptin while suppressed food intake. These data indicate that CSDS induces the down-regulation of hypothalamic AMPK following the elevation of hypothalamic malonyl-CoA levels and is independent of peripheral leptin and glucose.