Cinnamon bark oil and coconut oil emulsions modified small intestinal motility and barrier function in laying hens in an ex vivo experiment.

1. Plant extracts and oils are supplemented in diets for chickens due to their antimicrobial capacities; however, little information exists whether they influence intestinal motility and barrier function.2. The present study aimed to determine the effect of increasing levels of cinnamon bark oil (CBO; 0%, 0.038%, 0.076% and 0.151%) and coconut oil emulsions prepared with soy and sunflower lecithin on the contractile function of enteric wall muscles in the jejunum and ileum and jejunal barrier function in laying hens.3. For testing muscle contraction, mid-jejunal and ileal segments (n = 4 each per hen) from four laying hens were placed in a longitudinal orientation into isolated organ baths filled with Krebs buffer and fastened to force transducers. Muscle segments were induced to contract with acetylcholine and the effects of the oil emulsions on contraction were measured.4. For barrier function, distal jejunal pieces were stripped of serosa before mounting into Ussing chambers and recording changes in short-circuit current (ISC) and transepithelial tissue conductivity (GT) before and after addition of the respective emulsion.5. The CBO decreased the muscle tone, representing a relaxation of on average 36.2% and 42.6% for the jejunum and ileum, respectively, compared to before the addition (P < 0.001). Moreover, CBO linearly decreased the ISC and GT of the jejunal mucosa, indicating a greater absorption of anions and increased barrier function (P < 0.001). Only the coconut oil-sunflower lecithin emulsion relaxed the muscles, whereas both coconut oil-lecithin emulsions increased the ISC but reduced the GT of the jejunal mucosa, which suggested an increased cation absorption and decreased paracellular permeability, respectively (P < 0.05).6. In conclusion, CBO and coconut oil-lecithin emulsions showed the potential to increase jejunal barrier function, whereas CBO may be more efficacious to slow down digesta passage in the small intestine.

Toll-like receptor signaling for the induction of mucin expression by lipopolysaccharide in the hen vagina.

We previously reported that bacterial lipopolysaccharide (LPS), a ligand of Toll-like receptor 4 (TLR4), induced mucin mRNA to enhance the mucosal barrier in the hen vagina. The aim of this study was to determine the intracellular signaling molecules for that mucin induction, and the effect of molting and estrogen on their expression. The expression of TLR4, its adaptor molecules, and transcriptional factors in the vaginal mucosa of laying and molting hens treated with or without estradiol was examined by reverse-transcription PCR. The expression of mucin in the cultured mucosal tissue stimulated by LPS together with inhibitors of transcriptional factors was analyzed by quantitative reverse-transcription PCR. The expression of TLR4, its adaptor molecule, namely, myeloid differentiation factor 88 (MyD88) or Toll-interleukin 1 receptor domain-containing adaptor-inducing IFN-ß (TRIF), and transcriptional factors, namely, cFos and cJun, declined in molting hens compared with that in laying hens, and were upregulated by estradiol. In vagina of laying hens, mucin expression was upregulated by LPS, whereas it was suppressed by inhibitors of transcriptional factors, namely, ALLN (an inhibitor of IκB proteolysis), BAY-117085 (an NFκB inhibitor), U0126 [a mitogen-activated protein kinase (MAPK) inhibitor], and transhinone IIA [an activated protein 1 (AP-1) inhibitor]. These results suggest that a MyD88-dependent pathway downstream of TLR4 and transcriptional factors of NFκB and AP-1 participate in the induction of mucin expression by LPS in the vaginal mucosa. These signaling functions may decline during molting owing to the decline in the level of circulating estrogen. Such mucin expression system may play a role in the mucosal barrier against infection in the vaginal mucosa.

Induction of mucin expression by estrogen and lipopolysaccharide in the lower oviductal segments in hens.

Mucins play an essential role as mucosal barrier to prevent invasion of pathogens in the oviductal tissue of hens. The aim of this study was to determine the effect of estradiol and lipopolysaccharide (LPS) on the mucin expression in the lower oviductal segments (vagina and uterus) of hens. The mucosal tissues of the vagina and uterus were collected from White Leghorn laying and molting hens, and molting hens with or without intramuscular injection with 1 mg of estradiol-benzoate (EB) daily for 7 d. Part of these tissues was cultured in TCM-199 culture medium with or without LPS (10, 100, or 1,000 ng/mL) for 1.5 or 3 h. Mucin expression in the mucosa of laying, molting, and EB-treated molting hens (EB-group) and in those tissues cultured with or without LPS was analyzed by quantitative reverse-transcription PCR. Cultured tissues were also processed for paraffin sections and stained with Alcian blue (AB). In both the vagina and uterus, mucin expression and density of AB-positive mucopolysaccharide were reduced in molting hens compared with laying hens, and upregulated by EB. Mucin expression in the cultured vagina and uterus tissues of laying and molting hens was upregulated by LPS in a dose- and time-dependent manner. However, there was no response to LPS for induction of mucin in the tissues of EB-group hens. The mucin expression level in the vagina and uterus tissues stimulated by LPS was lower in the EB-group hens than in laying and molting hens, and that in the uterus was lower in the molting hens than in laying hens. These results suggest that mucin expression is stimulated by LPS in the vagina and uterus of laying and molting hens. Estrogen may upregulate mucin expression in those tissues in association with epithelial development, whereas it may suppress the response to LPS for mucin induction. The mucin expression caused by LPS may enhance mucosal barrier function and play a role in preventing infections by bacteria in the vagina and uterus.

Differences in the mucosal surface barrier formed by mucin in the lower oviductal segments between laying and molting hens.

The aim of this study was to determine the differences in the mucin expression that forms a mucosal surface barrier in the oviduct between laying and molting hens. The lower segments of oviducts (isthmus, uterus, and vagina) of White Leghorn laying and molting hens were collected. Localization and gene expression of mucosal mucin were analyzed by quantitative reverse-transcription PCR of mucin mRNA and mucin5AC immunohistochemistry. Sugar residues were localized by lectin (WGA or Jacalin) histochemistry. Expression of mucin mRNA was significantly declined in the lower oviductal segments in molting compared with laying hens. Immunoreactive-mucin5AC was localized in the mucosal epithelium and on the epithelial surface of laying hens, whereas it was reduced in molting hens. Substances positively stained by WGA and Jacalin were identified on the surface of the mucosal epithelium in the lower oviductal segments in laying and molting hens. These results suggest that mucin synthesis in the lower segments of the oviduct is reduced, although the existence of WGA- and Jacalin-positive sugars may be kept even in the molting phase. The reduction of mucin synthesis may result in a decline of mucosal barrier function in the molting phase.