Both butyrate incubation and hypoxia upregulate genes involved in the ruminal transport of SCFA and their metabolites

• Published in: Journal of animal physiology and animal nutrition Vol. 99; no. 2; pp. 379 - 390
• Main Authors: Dengler, F, Rackwitz, R, Benesch, F, Pfannkuche, H, Gäbel, G
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Science 01.04.2015; Blackwell Publishing Ltd; Wiley Subscription Services, Inc
• Subjects: acyl coenzyme A; adenoma; anaerobic conditions; Animals; Biological Transport; butyrates; Butyric Acid - pharmacology; electrophysiology; extrusion; Fatty Acids, Volatile - metabolism; Female; gene expression; gene expression regulation; Gene Expression Regulation - drug effects; genes; glucose transporters; HIF 1α; hypoxia; MCT; messenger RNA; metabolites; mRNA expression; NFκB; Oxygen - administration & dosage; Oxygen - pharmacology; PPARα; prostaglandin synthase; protein expression; quantitative polymerase chain reaction; reverse transcriptase polymerase chain reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; Rumen - drug effects; Rumen - metabolism; rumen epithelium; Sheep - physiology; short chain fatty acids; signal transduction; Tissue Culture Techniques; transcription factor NF-kappa B; Up-Regulation; HIF 1α; NFκB; PPARα; protein expression; MCT; mRNA expression
• ISSN: 0931-2439; 1439-0396
• DOI: 10.1111/jpn.12201

Butyrate modulates the differentiation, proliferation and gene expression profiles of various cell types. Ruminal epithelium is exposed to a high intraluminal concentration and inflow of n‐butyrate. We aimed to investigate the influence of n‐butyrate on the mRNA expression of proteins involved in the transmembranal transfer of n‐butyrate metabolites and short‐chain fatty acids in ruminal epithelium. N‐butyrate‐induced changes were compared with the effects of hypoxia because metabolite accumulation after O₂depletion is at least partly comparable to the accumulation of metabolites after n‐butyrate exposure. Furthermore, in various tissues, O₂depletion modulates the expression of transport proteins that are also involved in the extrusion of metabolites derived from n‐butyrate breakdown in ruminal epithelium. Sheep ruminal epithelia mounted in Ussing chambers were exposed to 50 mM n‐butyrate or incubated under hypoxic conditions for 6 h. Electrophysiological measurements showed hypoxia‐induced damage in the epithelia. The mRNA expression levels of monocarboxylate transporters (MCT) 1 and 4, anion exchanger (AE) 2, downregulated in adenoma (DRA), putative anion transporter (PAT) 1 and glucose transporter (GLUT) 1 were assessed by RT‐qPCR. We also examined the mRNA expression of nuclear factor (NF) κB, cyclooxygenase (COX) 2, hypoxia‐inducible factor (HIF) 1α and acyl‐CoA oxidase (ACO) to elucidate the possible signalling pathways involved in the modulation of gene expression. The mRNA expression levels of MCT 1, MCT 4, GLUT 1, HIF 1α and COX 2 were upregulated after both n‐butyrate exposure and hypoxia. ACO and PAT 1 were upregulated only after n‐butyrate incubation. Upregulation of both MCT isoforms and NFκB after n‐butyrate incubation could be detected on protein level as well. Our study suggests key roles for MCT 1 and 4 in the adaptation to an increased intracellular load of metabolites, whereas an involvement of PAT 1 in the transport of n‐butyrate also seems possible.