Molecular characterisation of carbohydrate digestion and absorption in equine small intestine.
Abstract: Dietary carbohydrates, when digested and absorbed in the small intestine of the horse, provide a substantial fraction of metabolisable energy. However, if levels in diets exceed the capacity of the equine small intestine to digest and absorb them, they reach the hindgut, cause alterations in microbial populations and the metabolite products and predispose the horse to gastrointestinal diseases. We set out to determine, at the molecular level, the mechanisms, properties and the site of expression of carbohydrate digestive and absorptive functions of the equine small intestinal brush-border membrane. We have demonstrated that the disaccharidases sucrase, lactase and maltase are expressed diversely along the length of the intestine and D-glucose is transported across the equine intestinal brush-border membrane by a high affinity, low capacity, Na+/glucose cotransporter type 1 isoform (SGLT1). The highest rate of transport is in duodenum > jejunum > ileum. We have cloned and sequenced the cDNA encoding equine SGLT1 and alignment with SGLT1 of other species indicates 85-89% homology at the nucleotide and 84-87% identity at the amino acid levels. We have shown that there is a good correlation between levels of functional SGLT1 protein and SGLT1 mRNA abundance along the length of the small intestine. This indicates that the major site of glucose absorption in horses maintained on conventional grass-based diets is in the proximal intestine, and the expression of equine intestinal SGLT1 along the proximal to distal axis of the intestine is regulated at the level of mRNA abundance. The data presented in this paper are the first to provide information on the capacity of the equine intestine to digest and absorb soluble carbohydrates and has implications for a better feed management, pharmaceutical intervention and for dietary supplementation in horses following intestinal resection.
Publication Date: 2002-07-16 PubMed ID: 12117106DOI: 10.2746/042516402776249209Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article focuses on the molecular mechanisms of carbohydrate digestion and absorption in the equine small intestine. The study posits that the digestion and absorption of dietary carbohydrates in a horse’s small intestine, when done efficiently, can provide a substantial fraction of the animal’s energy required for metabolism.
Study Objective and Methodology
- The main objective of the study was to understand the mechanisms, properties, and locations of carbohydrate digestive and absorptive functions in the equine small intestine.
- The researchers set out to determine this at a molecular level, focusing on the small intestinal brush-border membrane of the horse.
- The study involved evaluating expression levels of certain digestive enzymes and a specific transport protein in different sections of the small intestine.
Key Findings
- The enzymes sucrase, lactase, and maltase which break down certain types of sugars were found to be expressed at varying levels along the length of the intestine.
- The study revealed that D-glucose is moved across the equine intestinal brush-border membrane via a Na+/glucose cotransporter type 1 isoform (SGLT1), which has high affinity but low capacity.
- The rate of transport of glucose was the highest in the duodenum, followed by the jejunum and the ileum.
Additional Research and Implications
- The researchers cloned and sequenced the cDNA encoding equine SGLT1. Comparison with SGLT1 sequences from other species pointed to an 85-89% similarity at the nucleotide level, and 84-87% similarity at the amino acid level.
- They also found that the amount of functional SGLT1 protein correlated with the abundance of SGLT1 mRNA along with the length of the small intestine.
- This suggests that glucose absorption primarily occurs in the proximal intestine in horses maintained on traditional grass-based diets. It also indicates that SGLT1 expression is regulated at the mRNA level along the length of the intestine.
- The data from this study provides the first insights on the capacity of the equine intestine to digest and absorb soluble carbohydrates. This information could potentially aid better feed management, and contribute to the development of pharmaceuticals and diet supplementation for horses, especially following intestinal resection.
Cite This Article
APA
Dyer J, Fernandez-Castaño Merediz E, Salmon KS, Proudman CJ, Edwards GB, Shirazi-Beechey SP.
(2002).
Molecular characterisation of carbohydrate digestion and absorption in equine small intestine.
Equine Vet J, 34(4), 349-358.
https://doi.org/10.2746/042516402776249209 Publication
Researcher Affiliations
- Department of Veterinary Preclinical Sciences, University of Liverpool, UK.
MeSH Terms
- Amino Acid Sequence
- Animal Feed
- Animal Nutritional Physiological Phenomena
- Animals
- Blotting, Northern / veterinary
- Dietary Carbohydrates / metabolism
- Dietary Carbohydrates / pharmacokinetics
- Digestion
- Disaccharidases / metabolism
- Gastrointestinal Diseases / diagnosis
- Gastrointestinal Diseases / veterinary
- Gastrointestinal Transit
- Glucose / metabolism
- Horse Diseases / diagnosis
- Horses / physiology
- Intestinal Absorption
- Intestinal Mucosa / enzymology
- Intestine, Small / metabolism
- Membrane Glycoproteins / chemistry
- Membrane Glycoproteins / genetics
- Membrane Glycoproteins / metabolism
- Microvilli / enzymology
- Microvilli / metabolism
- Molecular Sequence Data
- Monosaccharide Transport Proteins / chemistry
- Monosaccharide Transport Proteins / genetics
- Monosaccharide Transport Proteins / metabolism
- Nutritive Value
- RNA, Messenger / metabolism
- Sequence Alignment / veterinary
- Sequence Homology, Amino Acid
- Sodium-Glucose Transporter 1
- Species Specificity
Citations
This article has been cited 11 times.- Stang FL, Bjerregaard R, Müller CE, Ergon Å, Halling M, Thorringer NW, Kidane A, Jensen RB. The effect of harvest time of forage on carbohydrate digestion in horses quantified by in vitro and mobile bag techniques.. J Anim Sci 2023 Jan 3;101.
- Gandarillas M, Keim JP, Gapp EM. Associative Effects between Forages and Concentrates on In Vitro Fermentation of Working Equine Diets.. Animals (Basel) 2021 Jul 26;11(8).
- Cappai MG, Taras A, Biggio GP, Dimauro C, Gatta D, Cossu I, Cherchi R, Pinna W. NEFA, BHBa, UREA and Liver Enzyme Variation in the Bloodstream of Weaned Foals up to 18 Months of Age.. Animals (Basel) 2021 Jun 11;11(6).
- Marciniak S, Mughal MR, Godfrey LR, Bankoff RJ, Randrianatoandro H, Crowley BE, Bergey CM, Muldoon KM, Randrianasy J, Raharivololona BM, Schuster SC, Malhi RS, Yoder AD, Louis EE Jr, Kistler L, Perry GH. Evolutionary and phylogenetic insights from a nuclear genome sequence of the extinct, giant, "subfossil" koala lemur Megaladapis edwardsi.. Proc Natl Acad Sci U S A 2021 Jun 29;118(26).
- De Palo P, Maggiolino A, Albenzio M, Casalino E, Neglia G, Centoducati G, Tateo A. Survey of biochemical and oxidative profile in donkey foals suckled with one natural and one semi-artificial technique.. PLoS One 2018;13(6):e0198774.
- Hewetson M, Sykes BW, Hallowell GD, Tulamo RM. Diagnostic accuracy of blood sucrose as a screening test for equine gastric ulcer syndrome (EGUS) in adult horses.. Acta Vet Scand 2017 Mar 11;59(1):15.
- Gao K, Zheng C, Wang T, Zhao H, Wang J, Wang Z, Zhai X, Jia Z, Chen J, Zhou Y, Wang W. 1-Deoxynojirimycin: Occurrence, Extraction, Chemistry, Oral Pharmacokinetics, Biological Activities and In Silico Target Fishing.. Molecules 2016 Nov 23;21(11).
- Poulsen SB, Fenton RA, Rieg T. Sodium-glucose cotransport.. Curr Opin Nephrol Hypertens 2015 Sep;24(5):463-9.
- Lacombe VA. Expression and regulation of facilitative glucose transporters in equine insulin-sensitive tissue: from physiology to pathology.. ISRN Vet Sci 2014;2014:409547.
- Batchelor DJ, Al-Rammahi M, Moran AW, Brand JG, Li X, Haskins M, German AJ, Shirazi-Beechey SP. Sodium/glucose cotransporter-1, sweet receptor, and disaccharidase expression in the intestine of the domestic dog and cat: two species of different dietary habit.. Am J Physiol Regul Integr Comp Physiol 2011 Jan;300(1):R67-75.
- Dyer J, Al-Rammahi M, Waterfall L, Salmon KS, Geor RJ, Bouré L, Edwards GB, Proudman CJ, Shirazi-Beechey SP. Adaptive response of equine intestinal Na+/glucose co-transporter (SGLT1) to an increase in dietary soluble carbohydrate.. Pflugers Arch 2009 Jun;458(2):419-30.
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