Impacts of diarrhea on the immune system, intestinal environment, and expression of PGRPs in New Zealand rabbits.

Yang Chen,Xinsheng Wu,Lin Mu,Yulai Pan,Bohao Zhao,Yuwei Wu,Shuaishuai Hu,Cigen Zhu

doi:10.7717/peerj.4100

Yang Chen, Xinsheng Wu + Show 6 more

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https://doi.org/10.7717/peerj.4100

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Journal: PeerJ	Publication Date: Nov 27, 2017
Citations: 12	License type: CC BY 4.0

Affiliation: Yangzhou University, Model Animal Research Center

Abstract

Diarrhea is a syndrome of digestive disorders in young rabbits and may lead to secondary infections resulting in reduced immunity and higher mortality in baby rabbits, with serious impacts on rabbit farming. In this study, we investigated the effects of diarrhea on the health of baby rabbits in terms of intestinal mucosal development, immune function, and intestinal microbial diversity. We found that the duodenal villus length and the villus/crypt ratio in rabbits with diarrhea were significantly reduced compared with those in healthy rabbits (P < 0.01). Rabbits with diarrhea had significantly lower concentrations of acetic acid (P < 0.05), higher pH levels (P < 0.05), and higher levels of ammonia nitrogen (P < 0.01) in the cecum. Moreover, diarrhea in baby rabbits led to significantly reduced levels of total serum protein (P < 0.05) and markedly increased levels of alkaline phosphatase, urea nitrogen, TNF-α, and IL-6 (P < 0.05). Transcriptional analysis of peptidoglycan recognition proteins (PGRPs, including PGLYRP-1, PGLYRP-2, and PGLYRP-3) using real-time PCR revealed that diarrhea induced the upregulation of PGRPs in the cecum and duodenum. Furthermore, through pyrosequencing of the 16S rRNA V4 region in cecum samples, we found that the total number and diversity of microbes were not significantly different between healthy rabbits and those with diarrhea, though there were noticeable differences in the prevalences of Clostridium, Roseburia, and Alistipes. Our results will contribute to a better understanding of the pathological mechanisms of diarrhea in young rabbits.

Highlights

Diarrhea is a common disease in rabbits, especially in weaned baby rabbits, in which it has the highest incidence among all diseases (Beltz, Rosales & Morales, 2005)
Histological analysis revealed that the density of duodenal villi in rabbits with diarrhea was lower than that in the healthy rabbits, and the morphology of the diarrheal duodenum was not intact (Fig. 3)
Crypt depth was not significantly different between the two groups (Table 2). These results indicate that diarrhea leads to severe damage to the duodenal structure in rabbits

Summary

Introduction

Diarrhea is a common disease in rabbits, especially in weaned baby rabbits, in which it has the highest incidence among all diseases (Beltz, Rosales & Morales, 2005) It causes a disturbance in the intestinal microflora and sometimes death, resulting in considerable losses to the rabbit farming industry (Pascual, 2001). There are 109–1010 Bacteroides in every gram of cecal content in an adult rabbit, whereas the total amount of Bifidobacteria, Clostridium, Streptococcus, and Enterobacter is 1010–1012 CFU/g (De Blas & Wiseman, 2010) These microorganisms participate in the metabolism of urea, ammonia, and peptides, as well as in the hydrolysis of fibers by secreting digestive enzymes or through their own metabolism, producing volatile fatty acids (VFA), amino acids, and vitamins. The sequences of PGLYRP-1, PGLYRP-2, and PGLYRP-3 have been determined through homology searching of the NCBI and Ensembl databases, yet their functions in rabbit diarrhea have not been documented

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