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Evaluation of glucose tolerance and intestinal luminal membrane glucose transporter function in horses with equine motor neuron disease

Nikkie A. BendersMedicine Section, Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, the Netherlands.
Present address is Dierenartsencentrum Heerlen, Sittarderweg 79b, 6412 CC Heerlen, the Netherlands.

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Jane DyerEpithelial Function and Development Group, Department of Veterinary Preclinical Sciences, School of Veterinary Medicine, University of Liverpool, Liverpool L69 7ZJ, UK.

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Inge D. WijnbergMedicine Section, Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, the Netherlands.

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Soraya P. Shirazi-BeecheyEpithelial Function and Development Group, Department of Veterinary Preclinical Sciences, School of Veterinary Medicine, University of Liverpool, Liverpool L69 7ZJ, UK.

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Johannes H. van der KolkMedicine Section, Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, the Netherlands.

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Abstract

Objective—To confirm whether the plasma glucose concentration curve obtained during oral glucose tolerance tests (OGTTs) in horses with equine motor neuron disease (EMND) is decreased, compared with that obtained in clinically normal horses, and determine whether that decrease is a result of defective glucose metabolism or intestinal glucose transport dysfunction.

Animals—8 horses with EMND and 44 matched control horses.

Procedure—Electromyography and OGTTs were performed in all 8 affected horses and 10 control horses. Intravenous GTTs (IVGTTs) were performed in 6 affected horses and another 11 control horses. The activity and levels of jejunal luminal membrane glucose transporter (Na+/glucose cotransporter isoform 1 [SGLT1]) were measured in 2 affected horses and 23 control horses.

Results—In horses with EMND, generalized neuropathy was detected via quantitative electromyography; the mean increase in plasma glucose concentration during the OGTT was significantly decreased, compared with the value in control horses. During the IVGTT, the mean increase in plasma glucose concentration was significantly lower than that of control horses. The activity and levels of SGLT1 in 2 affected horses were similar to those of control horses. Diagnosis of EMND was confirmed postmortem in all affected horses.

Conclusions and Clinical Relevance—Data suggest that the decreased plasma glucose curve obtained in horses with EMND during OGTTs (compared with control horses) is a result of overall enhanced glucose metabolism or abnormalities in the facilitated glucose transporters; definitive identification of the underlying mechanisms could aid in the development of appropriate treatments of EMND in horses. (Am J Vet Res 2005;66:93–99)

Abstract

Objective—To confirm whether the plasma glucose concentration curve obtained during oral glucose tolerance tests (OGTTs) in horses with equine motor neuron disease (EMND) is decreased, compared with that obtained in clinically normal horses, and determine whether that decrease is a result of defective glucose metabolism or intestinal glucose transport dysfunction.

Animals—8 horses with EMND and 44 matched control horses.

Procedure—Electromyography and OGTTs were performed in all 8 affected horses and 10 control horses. Intravenous GTTs (IVGTTs) were performed in 6 affected horses and another 11 control horses. The activity and levels of jejunal luminal membrane glucose transporter (Na+/glucose cotransporter isoform 1 [SGLT1]) were measured in 2 affected horses and 23 control horses.

Results—In horses with EMND, generalized neuropathy was detected via quantitative electromyography; the mean increase in plasma glucose concentration during the OGTT was significantly decreased, compared with the value in control horses. During the IVGTT, the mean increase in plasma glucose concentration was significantly lower than that of control horses. The activity and levels of SGLT1 in 2 affected horses were similar to those of control horses. Diagnosis of EMND was confirmed postmortem in all affected horses.

Conclusions and Clinical Relevance—Data suggest that the decreased plasma glucose curve obtained in horses with EMND during OGTTs (compared with control horses) is a result of overall enhanced glucose metabolism or abnormalities in the facilitated glucose transporters; definitive identification of the underlying mechanisms could aid in the development of appropriate treatments of EMND in horses. (Am J Vet Res 2005;66:93–99)