Lectin binding profile on the small intestine of 5-week old pigs in response to the use of chlortetracycline as a growth promotant, and under gnotobiotic conditions

¹ Departments of Biology and Microbiology, South Dakota State University, Brookings, SD-57007, USA; Center for Infectious Disease Research and Vaccinology (CIDRV), South Dakota State University, Brookings, SD-57007, USA
² Departments of Biology and Microbiology, South Dakota State University, Brookings, SD-57007, USA
³ Animal and Range Sciences, South Dakota State University, Brookings, SD-57007, USA
⁴ Animal and Range Sciences, South Dakota State University, Brookings, SD-57007, USA; Center for Infectious Disease Research and Vaccinology (CIDRV), South Dakota State University, Brookings, SD-57007, USA
⁵ Veterinary Science, South Dakota State University, Brookings, SD-57007, USA; Center for Infectious Disease Research and Vaccinology (CIDRV), South Dakota State University, Brookings, SD-57007, USA
⁶ Departments of Biology and Microbiology, South Dakota State University, Brookings, SD-57007, USA; Veterinary Science, South Dakota State University, Brookings, SD-57007, USA; Center for Infectious Disease Research and Vaccinology (CIDRV), South Dakota State University, Brookings, SD-57007, USA

^* To whom correspondence should be addressed. E-mail: radhey.kaushik{at}sdstate.edu.

	Abstract

Antibiotics have traditionally been used for growth promotion in the pork industry; however, their use in animal feed has recently been limited because of human health concerns. The intestinal microbiota plays an important role in mediating many physiological functions such as digestion and animal growth. It was hypothesized that use of antibiotics as growth promotants and subsequent variations in intestinal microbiota induce significant changes in the intestinal glycoconjugate composition, which ultimately affects animal growth and disease susceptibility. The aim of this study was to characterize the lectin binding profiles on the ileum of weanling pigs in response to the absence of intestinal microbiota, and to the use of the antibiotic chlortetracycline as growth promotant. Eighteen half-sib piglets obtained by cesarean section were divided into three groups (n = 6) and maintained as control, antibiotic-fed and gnotobiotic piglets until 5-wk of age. The glycoconjugate composition on the ileal tissues was examined by lectin histochemistry. Lycopersicon esculentum lectin (LEL), Jacalin, Pisum sativum agglutinin (PSA), Lens culinaris agglutinin (LCA) and Sambucus nigra lectin (SNA) showed significant differences (P < 0.05) in binding intensities on the dome and villous epithelium between the groups. Griffonia simplicifolia lectin I (GSL-1), Glycine maxi agglutinin (SBA) and Arachis hypogea agglutinin (PNA) exhibited differences (P < 0.05) between treatment groups in lectin binding on goblet cells. Triticum vulgaris agglutinin (WGA), PSA and LCA showed significant differences (P < 0.05) in binding intensities on dome, corona and follicular regions of ileum among different groups of animals. Overall, ileal tissues from gnotobiotic piglets expressed significantly weaker (P < 0.05) lectin binding for many lectins compared with control and antibiotic groups. This suggests that the intestinal microbiota plays an important role in the expression of sugar moieties in the intestine. Lectins LCA, Phaseolus vulgaris Leucoagglutinin (PHA-L) and Maackia amurensis lectin II (MAL) showed significant differences (P < 0.05) in lectin bindings between control and antibiotic-fed piglets. This indicates that chlortetracycline as a growth promotant induces biologically relevant changes in the lectin binding profile of the ileum. These findings will help in further understanding the role of gut microbiota and mechanisms of action of antibiotics as growth promotants in pigs.

Key Words: Chlortetracycline, gnotobiotic, growth promotant, intestinal microbiota, lectins, pigs