Supplemental zinc reduced intestinal permeability by enhancing occludin and zonula occludens protein-1 (ZO-1) expression in weaning piglets.
The present study was carried out to evaluate the pharmacological effect of Zn in diarrhoea in relation to intestinal permeability. Seventy-two weaning piglets, aged 24 d, were allocated to three dietary treatments: (1) control diet without supplemental Zn; (2) control diet supplemented with 2000 mg Zn/kg from ZnO; (3) control diet supplemented with 2000 mg Zn/kg from tetrabasic zinc chloride (TBZC). At the end of a 14 d experiment period, piglets were weighed, feed consumption was measured, and mucosal barrier function was determined using the lactulose/mannitol test. Expression of mucosal tight junction protein was measured at RNA and protein level. Inclusion of TBZC or ZnO in the diet significantly increased average daily gain (P < 0.01) and average daily feed intake (P < 0.05), while leading to reduced feed conversion ratio (P < 0.05) and faecal scores (P < 0.01). TBZC reduced urinary lactulose:mannitol ratios of weaning piglets (P < 0.05), while dietary supplementation with ZnO tended to reduce urinary lactulose:mannitol ratios (P = 0.061). ZnO or TBZC significantly enhanced the mRNA and protein expression of occludin (P < 0.05) and zonula occludens protein-1 (ZO-1) (P < 0.05) in the ileal mucosa. Piglets fed the TBZC-supplemented diet had a higher level of occludin than pigs fed the ZnO-supplemented diet (P < 0.05). The results indicate that Zn supplementation decreased faecal scores and the reduction was accompanied by reduced intestinal permeability, which was evident from the reduced urinary lactulose:mannitol ratios and increased expression of occludin and ZO-1. Therefore, the protective effect of pharmacological levels of dietary Zn in reducing diarrhoea might, at least partly, be associated with reduced intestinal permeability.
Zhang
Bingkun
B
State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, People's Republic of China.
Guo
Yuming
Y
D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D019587:Dietary Supplements / Q000706:statistics & numerical data; D007422:Intestines / Q000187:drug effects / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics*; D062793:Occludin; D010750:Phosphoproteins / Q000235:genetics; D013552:Swine; D015032:Zinc / Q000494:pharmacology*
D008565:Membrane Proteins; D062793:Occludin; D010750:Phosphoproteins; D015032:Zinc