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FRB Effects in Tryptophan Levels, and SCFA

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And also, we checked the short-chain fatty acids in feces and colon. So lactic acid, acetic acid, butyric acid and propionic acid, every short chain fatty acid significantly increase in fermented rice bran group before DSS treatment in the feces and after DSS treatment also. Maybe these short-chain fatty acids suppress inflammation in DSS-induced colitis. And also, we measured mRNA levels of tight junction proteins and secretory mucin in large intestine. So tight junction proteins and mucin 2, mRNA levels were significantly higher, compared with non-FRB and the controlled. FRB, fermented rice bran feeding maybe protects infiltration of DSS and intestinal bacteria, and prevent colitis. And also, we measured one of the key molecules of the tryptophan and tryptophan metabolism in feces and plasma.
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Feces tryptophan level and tryptamine level is much higher in fermented rice bran treatment group. And also, serum tryptophan and tryptamine levels also significantly higher in both groups. These tryptophan and tryptophan metabolites tryptamine, are important, maybe important for prevention of the inflammation. Here is the summary of tryptophan metabolism. Tryptophan is actually one of the essential amino acid for the protein synthesis. On the other hand, this amino acid is metabolized into several compounds. Previously I showed you tryptophan metabolizes to serotonin. Maybe that is, after absorption, we created serotonin endogenously. And also, one of the Vitamin, niacin, also synthesized from the tryptophan. On the other hand, indole, tryptamine, indole-3-acetic acid is actually metabolized from the tryptophan by intestinal microflora.
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Kynurenine, tryptamine, indole acetic acid and indole aldehyde show ligand activity of aryl hydrocarbon receptor, AHR, and modulate gene expression. What is aryl hydrocarbon receptor? Aryl hydrocarbon receptor is a ligand dependent transcription factor. This receptor was first identified as the mediator responsible for the toxic compound, toxic environmental compound dioxin. In absence of the ligand AHR is complexed with heat shock protein 90 (HSP90) and XAP2 and retained in cytoplasm. After stimulation of ligand AHR is translocated into nucleus and creates formation of heterodimer and bind to xenobiotic responsive element (XRE) in certain genes and stimulates transcription of its target genes. In this case is the cytochrome P450 1A1/1A2. Like drug metabolism enzyme.
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So this transcription factor, AHR is an important transcription factor for the drug metabolism first time. But now, AHR also modulates several types of gene expression especially in immune function related gene. AHR regulates T cell differentiation suppression of macrophage activation stimulation of dendritic cells differentiation and inhibition of B cells differentiation The ligands of AHR including tryptophan metabolites, as I showed you, can modulate the expression of genes during inflammatory-response genes.

FRB has already shown protective effects in UC murine models. And the research team further found out that FRB could increase stool short-chain fatty acids (SCFA), which represents anti-inflammatory potential. Since tryptophan is the main active ingredient in FRB, the research team did also find out that serum tryptophan and its metabolite tryptamine also increase, suggesting that FRB could potentially modulate AhR(Aryl hydrocarbon receptor) via an increase of tryptophan.

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Agriculture and Nutrition

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