Effects of soybean agglutinin on intestinal barrier permeability and tight junction protein expression in weaned piglets

Abstract

This study was developed to provide further information on the intestinal barrier permeability and the tight junction protein expression in weaned piglets fed with different levels of soybean agglutinin (SBA). Twenty-five weaned crossbred barrows (Duroc × Landrace × Yorkshire) were selected and randomly allotted to five groups, each group with five replicates. The piglets in the control group were not fed with leguminous products. 0.05, 0.1, 0.15 and 0.2% SBA was added to the control diet to form four experimental diets, respectively. After the experimental period of 7 days (for each group), all the piglets were anesthetized with excess procaine and slaughtered. The d-lactic acid in plasma and the Ileal mucosa diamine oxidase (DAO) was analyzed to observe the change in the intestinal permeability. The tight junction proteins occludin and ZO-1 in the jejunum tissue distribution and relative expression were detected by immunohistochemistry and Western Blot. The results illustrated that a high dose of SBA (0.1-0.2%) could increase the intestinal permeability and reduce piglet intestinal epithelial tight junction protein occludin or ZO-1 expression, while low dose of SBA (0.05% of total diet) had no significant affects. The contents of DAO, d-lactic acid, occludin or ZO-1, had a linear relationship with the SBA levels (0-0.2%) in diets. The high dose SBA (0.1-0.2%) could increase the intestinal permeability and reduce piglet intestinal epithelial tight junction protein occludin or ZO-1 expression, while low dose of SBA (0.05% of total diet) had no affects.

Keywords: ZO-1; intestinal permeability; occludin; piglets; soybean agglutinin; tight junction.

Figure 1

Linear correlations between DAO activity and SBA levels. n = 5; y = −27.57x + 11.49; R² = 0.577; P < 0.001.

Figure 2

Linear correlations between contents of d-lactic acid and SBA levels. n = 5; y = 2.77x + 2.03; R² = 0.517; P < 0.001.

Figure 3

Location of tight junction protein ZO-1 and Occludin in jejunum of weaned piglets. Immunohistochemistry staining (magnification 100×) represents control group and 0.2% SBA group.

Figure 4

Expression of tight junction protein Occludin and ZO-1 in jejunum of weaned piglets. The tight junction protein Occludin and ZO-1 from jejumun was analyzed by Western-Blot (A), and statistically calculated (B). The β-actin is housekeeping protein. The data represents different groups.

Figure 5

Linear correlations between occludin relative band density and SBA levels. n = 5; y = −2.42x + 0.82; R² = 0.715; P < 0.001.

Figure 6

Linear correlations between ZO-1 relative band density and SBA levels. n = 5; y = −1.54x + 0.76; R² = 0.592; P < 0.001.