Reprod. Nutr. Dev. 43 (2003) 409-418
DOI: 10.1051/rnd:2003037

Soybean impairs Na ⁺-dependent glucose absorption and Cl ^- secretion in porcine small intestine

Gaëlle Boudry^a, Jean-Paul Lallès^a, Charles Henri Malbert^a, Marie Louise Grondahl^b, Martin Andreas Unmack^b and Erik Skadhauge<sup>b

a</sup>  Unité Mixte de Recherche sur le Veau et le Porc, INRA, Domaine de la Prise, 35590 St-Gilles, France
^b  Department of Anatomy and Physiology, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark

(Received 18 February 2003; accepted 6 July 2003)

Abstract
Recent evidence indicates that soybean, which is widely used in animal nutrition, could directly alter intestinal ion and nutrient transport. However, the mechanisms involved are still unknown. The aim of the study was to investigate the effect of three differently treated soybean products on the glucose and Cl ^- transport capacity in porcine small intestine by the Ussing chamber technique. Jejunal and ileal piglet epithelial tissues were pre-incubated with extracts of raw soybean flour (RSF), heated soybean flour (HSF), or ethanol heat-treated soybean protein concentrate (SPC). The Na ⁺-dependent glucose co-absorption capacity was then measured as an increase in the shortcircuit current (I ) after luminal addition of D-glucose. The effect of the soybean products on cAMP-dependent Cl ^- secretion was measured as the increase in I after the addition of the phosphodiesterase inhibitor, theophylline, while nervous regulation of Cl ^- secretion was investigated by the addition of the enteric neurotransmitters; 5-hydroxytryptamine (5-HT), substance P and vasoactive intestinal polypeptide (VIP). Incubation with RSF and HSF induced a 30% decrease of the Na ⁺-dependent glucose absorption capacity in the jejunum. The effect was similar for RSF in the ileum. Theophylline-induced secretion was decreased by 30% after incubation with RSF, HSF and SPC but only in the jejunum. 5-HT-, substance P- and VIP-induced secretion were not altered by incubation with soybean extracts except in the HSF-incubated where the substance P-induced secretion was significantly reduced. In conclusion, soybean contains ethanol-sensitive heat-insensitive compounds impairing Na ⁺-dependent glucose absorption in the jejunum and ileum, and ethanol- and heat-insensitive compounds causing an acute impairment of cAMP-dependent jejunal secretion.

Key words: soybean / Ussing chambers / intestinal secretion / glucose absorption / nutrition / electrolyte transport

Correspondence and reprints: Gaëlle Boudry boudry@st-gilles.rennes.inra.fr

© INRA, EDP Sciences 2003