The mRNA and protein expression of ruminal MCT1 is increased by feeding a mixed hay/concentrate diet compared with hay &amp;lt;i&amp;gt;ad libitum&amp;lt;/i&amp;gt; diet (Short Communication)

J Kuzinski,M Röntgen

doi:10.5194/aab-54-280-2011

Abstract

Abstract. In this study the protein and mRNA expression of Monocarboxylate transporter 1 (MCT1) was evaluated in rumen epithelial cells (REC) obtained from sheep fed hay ad libitum (control, h diet, n=4) or a mixed hay/concentrate diet (h/c diet, n=4) for two weeks. REC were isolated via fractionated trypsination and three groups consisting of fractions 3 to 5=G1, fractions 6 to 8=G2, and fractions 9 and 10=G3 were formed. Using an anti-basal cytokeratin antibody and flow cytometric analysis, the proportion of REC originating from the stratum basale (SB) was determined for each group. In addition, MCT1 mRNA and protein expression was determined by qRT-PCR and Western blot, respectively. Feeding the h/c diet led to a 299±93 % elevation of the number of SB cells known to express the MCT1 protein. This is accompanied by an increased MCT1 mRNA (1.8 to 2.2-fold) and protein (1.3-fold) expression. Thus, an increased number of MCT1 expressing cells and upregulation of ruminal MCT1 protein seem to be components of rumen epithelium functional adaptation to high energy diet.

Highlights

In the ruminant, short-chain fatty acids (SCFA) produced by the anaerobic microbial fermentation of carbohydrates cover up to 80 % of the energy requirements of these animals (Siciliano-Jones & Murphy 1989, Bergmann 1990)
The product obtained corresponded to the calculated base number (206 bp) of the sequence produced by the primers
In rumen epithelial cells (REC) obtained from h-fed sheep the concentration of Monocarboxylate transporter 1 (MCT1) mRNA decreased from 0.43±0.14 pg per pg S18 mRNA in G1 to 0.23±0.06 pg per pg S18 mRNA in G3 (Figure 2B)

Summary

Introduction

Short-chain fatty acids (SCFA) produced by the anaerobic microbial fermentation of carbohydrates cover up to 80 % of the energy requirements of these animals (Siciliano-Jones & Murphy 1989, Bergmann 1990). Its absorption is known to occur by passive diffusion of undissociated acids and include the apical uptake of SCFA anions in exchange for bicarbonate (Kramer et al 1996, Gäbel & Sehested 1997). Following uptake into rumen epithelial cells (REC), SCFA butyrate are metabolized to hardly membrane-permeant ketone bodies, namely acetoacetate and ß-hydroxybutyrate (BHB). The transport of these metabolites from rumen epithelium to the blood is facilitated by a large-conductance anion channel in the basolateral membrane (Stumpff et al 2009) and by the Monocarboxylate transporter 1 (MCT1). MCT1 possesses an important role in transepithelial transfer of nutrients and in rumen pH regulation (Müller et al 2002, Gäbel & Aschenbach 2006, Kirat et al 2005, Kirat et al 2006)

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Results

Conclusion