The Dynamic Distribution of Porcine Microbiota across Different Ages and Gastrointestinal Tract Segments

Metagenome of gut microbes has been implicated in metabolism, immunity, and health maintenance of its host. However, in most of previous studies, the microbiota was sampled from feces instead of gastrointestinal (GI) tract. In this study, we compared the microbial populations from feces at four different developmental stages and contents of four intestinal segments at maturity to examine the dynamic shift of microbiota in pigs and investigated whether adult porcine fecal samples could be used to represent samples of the GI tract. Analysis results revealed that the ratio of Firmicutes to Bacteroidetes from the feces of the older pigs (2-, 3-, 6- month) were 10 times higher compared to those from piglets (1-month). As the pigs matured, so did it seem that the composition of microbiome became more stable in feces. In adult pigs, there were significant differences in microbial profiles between the contents of the small intestine and large intestine. The dominant genera in the small intestine belonged to aerobe or facultative anaerobe categories, whereas the main genera in the large intestine were all anaerobes. Compared to the GI tract, the composition of microbiome was quite different in feces. The microbial profile in large intestine was more similar to feces than those in the small intestine, with the similarity of 0.75 and 0.38 on average, respectively. Microbial functions, predicted by metagenome profiles, showed the enrichment associated with metabolism pathway and metabolic disease in large intestine and feces while higher abundance of infectious disease, immune function disease, and cancer in small intestine. Fecal microbes also showed enriched function in metabolic pathways compared to microbes from pooled gut contents. Our study extended the understanding of dynamic shift of gut microbes during pig growth and also characterized the profiles of bacterial communities across GI tracts of mature pigs.     

The uptake of fluorescein-conjugated dextran 70,000 by the small intestinal epithelium of the young rat and pig in relation to macromolecular transmission into the blood

The macromolecular transmission from the intestinal lumen into the circulation, and its cessation (intestinal closure), were investigated in young rats and pigs in relation to the enterocytes ability to internalize macromolecules. After gavage feeding of FITC-labelled dextran 70,000 (FITC-dextran) and bovine serum albumin (BSA), the uptake of FITC-dextran into the enterocytes was examined by fluorescence microscopy, and the intestinal transmission of both markers was estimated from their blood serum concentrations. In both preclosure rats (14-days old) and piglets (newborn, unsuckled), high serum concentrations of the markers were correlated with the presence of highly fluorescent enterocytes. Although the transmission of the markers to the blood had ceased in postclosure suckling pigs (24-h old), the enterocytes showed a high fluorescence, indicating that the cellular uptake of FITC-dextran was still high. In the 6-days old piglets, only the distal part of the intestine showed uptake of FITC-dextran. In postclosure rats (21- and 30-days old) and in pigs 4-8 weeks old, no fluorescence in the enterocytes and only trace amounts of markers in the serum could be detected. These results reflect differences in the closure process between the species. In the rat, closure is likely to be due to a decrease in the endocytotic activity of the enterocytes, whereas closure in the pig is related to a cessation of the passage of internalized material into the blood (transcytosis).     

Precocious cessation of intestinal macromolecular transmission and sucrase development induced by insulin in adrenalectomized suckling rat.

1. The role of insulin in the regulatory mechanisms governing cessation of intestinal absorption of macromolecules and sucrase development was studied in the adrenalectomized suckling rat (ADX rat). 2. Intestinal absorption of bovine immunoglobulin (IgG) infused orally was dose-dependently suppressed to 35-75% in ADX rats repeatedly injected subcutaneously with insulin. 3. When insulin was administered orally, the IgG absorption was also suppressed. 4. Intestinal sucrase activity was also induced precociously by insulin administered subcutaneously and orally. 5. These results suggest that insulin plays a role in the maturation of suppression mechanisms for macromolecular transmission and sucrase development in the small intestine of the suckling rat.     

The role of insulin-like growth factors in small intestinal cell growth and development.

IGF-I and IGF-II receptors are expressed in the small intestine of mammalian species, as are the genes to synthesize both peptides. IGF binding proteins are also expressed in the intestine. IGF-I and IGF-II mRNA are highest in fetal and newborn tissues and decrease with age. IGF-I mRNA is present in the adult small intestine, and is associated with the submucosal regions and crypt cells. IGF-I and IGF-II receptor binding to the small intestine is higher in newborn animals and decreases with age. Both receptors are more concentrated in the crypt than villus regions, but IGF-II binding is higher than IGF-I in all regions. IGF-I receptors are associated with the submucosal region of the small intestine, whereas IGF-II receptors are more abundant in the mucosal cells. Administration of IGF-I either orally or by osmotic pump generally has no affect on small intestinal weight or length, but does increase mucosal cellularity. LR3-IGF-I administration by osmotic pump affects the small intestine similarly to IGF-I, although with a higher potency. In the few studies in which IGF-II was administered, increased gut mass was observed in adult rats, but not newborn rats or pigs. Significant effects on mucosal expression of disaccharidases was achieved with either oral or subcutaneous IGF-I or oral IGF-II. Administration of IGF in models of intestinal hypertrophy and atrophy are also reviewed.     

The neonatal Fc receptor is not required for mucosal infection by mouse mammary tumor virus.

The milk-borne mouse mammary tumor virus (MMTV) infects newborn mice via the intestine. Infection is initially restricted to Peyer's patches and later spreads to the epithelial cells of the mammary gland. The receptor that mediates uptake and transport of MMTV across the intestinal barrier has not yet been identified, The neonatal Fc receptor (nFcR), which is expressed by enterocytes during the first two weeks of life, is downregulated at weaning, and its disappearance correlates with the onset of intestinal resistance to MMTV. To test whether the nFcR mediates transport and allows infection, we foster nursed on infected MMTV mothers beta2 microglobulin-deficient (beta2m-deficient) newborn mice that are unable to express the nFcR at the surface of their enterocytes. Exposure of beta2m-deficient mice to milk-borne virus resulted in the deletion of peripheral blood T cells reactive to the superantigen encoded by MMTV. Since beta2m-deficient newborn mice are susceptible to MMTV infection despite the lack of the nFcR, we conclude that the nFcR is not required for MMTV transport.     

酶解乳蛋白对初生仔猪小肠组织学结构及隐窝细胞增殖的影响(英文)

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Characterization of a gastrointestinal tract microscale cell culture analog used to predict drug toxicity

The lining of the gastrointestinal (GI) tract is the largest surface exposed to the external environment in the human body. One of the main functions of the small intestine is absorption, and intestinal absorption is a route used by essential nutrients, chemicals, and pharmaceuticals to enter the systemic circulation. Understanding the effects of digestion on a drug or chemical, how compounds interact with and are absorbed through the small intestinal epithelium, and how these compounds affect the rest of the body is critical for toxicological evaluation. Our goal is to create physiologically realistic in vitro models of the human GI tract that provide rapid, inexpensive, and accurate predictions of the body's response to orally delivered drugs and chemicals. Our group has developed an in vitro microscale cell culture analog (µCCA) of the GI tract that includes digestion, a mucus layer, and physiologically realistic cell populations. The GI tract µCCA, coupled with a multi‐chamber silicon µCCA representing the systemic circulation, is described and challenged with acetaminophen. Proof of concept experiments showed that acetaminophen passes through and is metabolized by the in vitro intestinal epithelium and is further metabolized by liver cells, resulting in liver cell toxicity in a dose‐dependent manner. The µCCA response is also consistent with in vivo measurements in mice. The system should be broadly useful for studies on orally delivered drugs or ingestion of chemicals with potential toxicity. Biotechnol. Bioeng. 2009; 104: 193–205 © 2009 Wiley Periodicals, Inc.     

Preterm birth makes the immature intestine sensitive to feeding-induced intestinal atrophy

Preterm birth and formula feeding predispose to small intestinal dysfunction, which may lead to necrotizing enterocolitis (NEC). In piglets, we tested whether the physiological and environmental transitions occurring at birth affect the response of the immature intestine to enteral feeding. Pig fetuses (106 days gestation, term = 115 days) were prepared with esophageal feeding tubes and fed either sow's colostrum (n = 8) or infant formula (n = 7) in utero. After 24 h of oral feeding, the pig fetuses were delivered by cesarean section and their gastrointestinal morphology and function were compared with those of preterm newborn (NB) littermates that were not fed (n = 8) or fed colostrum (n = 7) or formula (n = 13) for 24 h after birth. Before birth, both colostrum and formula feeding resulted in marked increases in intestinal mass, brush-border enzyme activities, and plasma glucagon-like peptide 2 concentrations, to levels similar to those in NB colostrum-fed piglets. In contrast, NB formula-fed piglets showed reduced intestinal growth, decreased brush-border enzyme activities, and intestinal lesions, reflecting NEC. NB formula-fed pigs also showed impaired enterocyte endocytotic function and decreased antioxidative capacity, whereas brush-border enzyme mRNA levels were unaltered, relative to NB colostrum-fed pigs. Our results indicate that the feeding-induced growth and enzyme maturation of the immature intestine are not birth dependent. However, with a suboptimal diet (milk formula), factors related to preterm birth (e.g., microbial colonization and metabolic and endocrine changes) make the immature intestine sensitive to atrophy and development of NEC.     

The role of insulin in the intestinal absorption of glucose in the rat.

1. Acute pre-treatment with either mannoheptulose or streptozotocin--both compounds acting as powerful suppressors of insulin secretion--caused a significant decrease on the in vivo rate of intestinal glucose absorption following an intragastric [U-14C]glucose administration. 2. Mannoheptulose treatment also lowered the rate of whole-body oxidation of the administered tracer. 3. Insulin had no effect on the metabolic fate of [U-14C]glucose by isolated enterocytes. 4. However, the rate of glucose uptake, measured by the oxidation of [1-14C]glucose to 14CO2 in the presence of phenazine methosulphate, was decreased by insulin at concentrations of 50-200 munits/ml. 5. In addition, the rate of transport of [U-14C]glucose by brush-border membrane vesicles was also inhibited by insulin at high concentrations (100-1000 munits/ml). 6. This indicated that insulin acts by inhibiting glucose transport in isolated in vitro preparations. 7. Acute pre-treatment with either mannoheptulose or streptozotocin caused a significant decrease in the rate of gastric emptying, measured as the distribution of [3H]insulin along the gastrointestinal tract, following an intragastric glucose load. 8. It is concluded that insulin secretion modulates intestinal glucose absorption in vivo by enhancing gastric emptying in spite of the inhibitory effects of glucose transport observed with in vitro preparations.     

Germination and outgrowth of Bacillus subtilis and Bacillus licheniformis spores in the gastrointestinal tract of pigs

Aims: To determine if orally ingested Bacillus spores used as probiotics or direct‐fed microbial feed additives germinate and the vegetative cells grow in the gastrointestinal (GI) tract. Methods and Results: Three independent experiments were done to determine if spores of Bacillus licheniformis and Bacillus subtilis germinate and grow in the GI tract of pigs. After a 2 weeks spore‐feeding period, spores were detected in all segments of the GI tract. The lowest number of spores was found in the stomach, increasing in the small intestine to approx. 55% of the dietary inclusion. When spores were withdrawn from the feed, faecal excretion of spores reflected the dietary inclusion, but decreased gradually to the background level after 1 week. By containing spores in short, sealed pieces of dialysis membrane that were orally administered to the pigs, both the number of spores and vegetative cells could be determined by flow cytometry. Spores accounted for 72% of the total counts after 4–6 h in the stomach and proximal part of the small intestine. After 24 h, spores constituted only 12% of the total counts in the stomach, caecum, and mid‐colon. Less spores and more vegetative cells were detected after 24 h, but total counts increased only 2·14‐fold compared to time zero. Conclusions: The experiments showed that 70–90% of dietary‐supplemented Bacillus spores germinate in the proximal part of the pig GI tract, and that only limited outgrowth of the vegetative cell population occurs. The two Bacillus strains can temporarily remain in the GI system, but will be unable to permanently colonize the GI tract. Significance and Impact of the Study: A substantial population of growing vegetative cells in the GI tract is not a prerequisite for the mode of action of Bacillus feed additives and probiotics.     

Effects of the Oral Administration of Viable and Heat-Killed Streptococcus bovis HC5 Cells to Pre-Sensitized BALB/c Mice

Antimicrobial peptides have been suggested as an alternative to classical antibiotics in livestock production and bacteriocin-producing bacteria could be added to animal feeds to deliver bacteriocins in the gastrointestinal (GI) tract of ruminant and monogastric animals. In this study, viable (V) and heat-killed (HK) Streptococcus bovis HC5 cells were orally administered to pre-sensitized mice in order to assess the effects of a bacteriocin-producing bacteria on histological parameters and the immune response of the GI tract of monogastric animals. The administration of V and HK S. bovis HC5 cells during 58 days to BALB/c mice did not affect weight gain, but an increase in gut permeability was detected in animals receiving the HK cells. Viable and heat killed cells caused similar morphological alterations in the GI tract of the animals, but the most prominent effects were detected in the small intestine. The oral administration of S. bovis HC5 also influenced cytokine production in the small intestine, and the immune-mediated activity differed between V and HK cells. The relative expression of IL-12 and INF-γ was significantly higher in the small intestine of mice treated with V cells, while an increase in IL-5, IL-13 and TNF-α expression was only detected in mice treated with HK cells. Considering that even under a condition of severe challenge (pre-sensitization followed by daily exposure to the same bacterial immunogen) the general health of the animals was maintained, it appears that oral administration of S. bovis HC5 cells could be a useful route to deliver bacteriocin in the GI tract of livestock animals.     

Uptake, transport and regulation of JBP485 by PEPT1 in vitro and in vivo

Cyclo-trans-4-l-hydroxyprolyl-l-serine (JBP485) is a dipeptide with anti-hepatitis activity that has been chemically synthesized. Previous experiments in rats showed that JBP485 was well absorbed by the intestine after oral administration. The human peptide transporter (PEPT1) is expressed in the intestine and recognizes compounds such as dipeptides and tripeptides. The purposes of this study were to determine if JBP485 acted as a substrate for intestinal PEPT1, and to investigate the characteristics of JBP485 uptake and transepithelial transport by PEPT1. The uptake of JBP485 was pH dependent in human intestinal epithelial cells Caco-2. And JBP485 uptake was also significantly inhibited by glycylsarcosine (Gly-Sar, a typical substrate for PEPT1 transporters), JBP923 (a derivative of JBP485), and cephalexin (CEX, a β-lactam antibiotic and a known substrate of PEPT1) in Caco-2 cells. The rate of apical-to-basolateral transepithelial transport of JBP485 was 1.84 times higher than that for basolateral-to-apical transport. JBP485 transport was obviously inhibited by Gly-Sar, JBP923 and CEX in Caco-2 cells. The uptake of JBP485 was increased by verapamil but not by cyclosporin A (CsA) and inhibited by the presence of Zn²⁺ or the toxic metabolite of ethanol, acetaldehyde (AcH) in Caco-2 cells. The in vivo uptake of JBP485 was increased by verapamil and decreased by ethanol in vivo, which was consisted with the in vitro study. PEPT1 mRNA levels were enhanced after exposure of the cells to JBP485 for 24 h, compared to control. In conclusion, JBP485 was actively transported by the intestinal oligopeptide transporter PEPT1. This mechanism is likely to contribute to the rapid absorption of JBP485 by the gastrointestinal tract after oral administration.     

Carboxyl nonsteroidal anti-inflammatory drugs are efficiently glucuronidated by microsomes of the human gastrointestinal tract

Limited studies have been carried out on the biotransformation of carboxyl nonsteroidal anti-inflammatory drugs (NSAIDs) in the liver. However, the role of the intestine in NSAID metabolism has not been investigated. In this report, the contribution of UDP-glucuronosyltransferases (UGTs) in the human gastrointestinal (GI) tract from five donors to the glucuronidation of the NSAIDs, RS-ketoprofen, S-naproxen, RS- and S-etodolac, was investigated. UGT activity and, for some donors, mRNA levels were evaluated. All NSAIDs were glucuronidated throughout the GI tract; however, glucuronidation was low in stomach and duodenum as compared to the remainder of the intestine. RT-PCR analysis demonstrated that the UGT1A isoforms, UGT1A3, 1A8, and 1A10, and UGT2B7 were expressed in the GI tract. Human recombinant UGT1A3, 1A9, 1A10 and 2B7 were actively involved in the glucuronidation of all NSAIDs while UGT1A7 and the intestine-specific UGT1A8 had no glucuronidating activity towards those compounds. Despite interindividual variations in both the levels of mRNA and the distribution of activity through the intestine, UGTs in the GI tract may contribute significantly to the first pass metabolism of orally administered NSAIDs.     

Development of Novel Biodegradable Polymeric Nanoparticles-in-Microsphere Formulation for Local Plasmid DNA Delivery in the Gastrointestinal Tract

There is a critical need for development of novel delivery systems to facilitate the translation of nucleic acid-based macromolecules into clinically-viable therapies. The aim of this investigation was to develop and evaluate a novel nanoparticles-in-microsphere oral system (NiMOS) for gene delivery and transfection in specific regions of the gastrointestinal (GI) tract. Plasmid DNA, encoding for the enhanced green fluorescent protein (EGFP-N1), was encapsulated in type B gelatin nanoparticles. NiMOS were prepared by further protecting the DNA-loaded nanoparticles in a poly(epsilon-caprolactone) (PCL) matrix to form microspheres of less than 5.0 μm in diameter. In order to evaluate the biodistribution following oral administration, radiolabeled (¹¹¹In-labeled) gelatin nanoparticles and NiMOS were administered orally to fasted Balb/C mice. The results of biodistribution studies showed that, while gelatin nanoparticles traversed through the GI tract fairly quickly with more than 54% of the administered dose per gram localizing in the large intestine at the end of 2 h, NiMOS resided in the stomach and small intestine for relatively longer duration. Following oral administration of EGFP-N1 plasmid DNA at 100 μg dose in the control and test formulations, the quantitative and qualitative results presented in this study provide the necessary evidence for transfection potential of NiMOS upon oral administration. After 5 days post-administration, transgene expression in the small and large intestine of mice was observed. Based on these results, NiMOS show significant potential as novel gene delivery vehicle for therapeutic and vaccination purposes.     

Intestinal apolipoprotein A-IV gene expression in the piglet

Fetal, newborn, and suckling piglets were used to study the intestinal expression of the apoA-IV gene in the immature mammal. Swine apoA-IV (42 kD) was isolated from fat-fed piglet lipoprotein-deficient plasma by adsorption to Intralipid followed by preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and electroelution. Rabbit anti-swine apoA-IV antibodies were raised, and apoA-IV was immunoprecipitated from small intestinal homogenates after in vivo radiolabeling with [3H]leucine. ApoA-IV synthesis was expressed as a percentage of total protein synthesis from trichloroacetic acid-precipitable counts. Fetal (40 day gestation) whole small intestine synthesis was 2.1%. Postnatally, 2-day-old newborn piglets given high triglyceride and low triglyceride duodenal infusions, as well as bile diversion, were studied. Synthesis rates in jejunal mucosa in all groups were comparable to the fetal whole intestinal value except in the jejunum of the high-triglyceride group, where synthesis was increased sevenfold. In 1- to 2-week-old fasting, cream-fed, and bile-diverted piglets synthesis was again unchanged except in the fat-fed jejunum, where synthesis doubled. Ileal synthesis rates in newborn and suckling animals were lower than jejunal rates and did not increase with lipid absorption or decrease with bile diversion. Northern blot hybridization of intestinal RNA samples from the newborn groups with an authentic cross-hybridizing human apoA-IV cDNA probe revealed a 1.8 kb signal which was strongest in the high-triglyceride jejunal samples. Slot blot hybridization showed eightfold increased apoA-IV mRNA levels in high-triglyceride jejunal samples as compared to low-triglyceride and bile-diverted jejunum with no differences in beta actin mRNA abundance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Orally Administered Therapeutic Peptide Delivery: Enhanced Absorption Through the Small Intestine Using Permeation Enhancers

Peptide therapeutics (PTs) is generally regarded as highly effective macromolecule therapeutics at very low concentrations. The main issues surrounding the administration of PTs is guaranteeing that they are bioavailable, reach the desired therapeutic index and distribute throughout the body effectively. The oral administration, a non-invasive route, of PTs is considered a major complication due to inadequate oral absorption through biological membranes such as the small intestine epithelium due to presystemic proteolytic enzymatic activity. PTs bioavailability is further diminished in the systemic circulation due to low stability in the plasma and rapid excretion from the body. Many alternative routes can be considered non-invasive such as transdermal and nasal routes, but this review focuses on the oral route, specifically the small intestine region of the gastrointestinal tract. Although this region has the highest density of proteolytic enzymes, it contains tight junctions which have the lowest trans-epithelial electrical resistance throughout the body; thus paracellular transport of these large PTs can be achieved more readily. The use of a natural polysaccharide polymer, such as trimethyl chitosan (TMC), which enhances the bioavailability of these PTs through the small intestine, will also be discussed in great detail. TMC has been considered because it could potentially solve many of the mechanistic and chemical problems associated with oral therapeutic peptide administration. The safety of orally administered PTs through the small intestinal epithelium employing a polymer such as TMC is also discussed as this is a significant issue for regulatory bodies.     

Effectiveness of submicronized chitosan-coated liposomes in oral absorption of indomethacin

The plasma profile of indomethacin (IMC) after oral administration of IMC-loaded submicronized chitosan-coated liposomes (ssCS-Lip) was evaluated to reveal the effectiveness of the mucoadhesive function for improving the absorption of this poorly absorbable drug. The stomach and small intestine were removed from rats after 1, 2, and 4 hours of oral administration of submicron-sized liposomes (ssLip) or ssCS-Lip containing fluorescent dye, and the retentive properties were confirmed by measuring the amount of dye in each part of the gastrointestinal (GI) tract. Results showed that ssCS-Lip tended to be better retained in the upper part of the GI tract, compared with ssLip, at 1, 2, and 4 hours after administration, and was significantly better retained in the small intestine at 4 hours. The plasma profile and bioavailability of IMC after oral administration of both types of liposomes were improved, compared with oral administration of IMC solution. The maximum residence time of ssCS-Lip was significantly longer than those of ssLip. The extended plasma profile of ssCS-Lip was attributed to its prolonged retention in the upper region of the GI tract, and its delayed migration to the lower part of the intestine, the neutral pH of which is more soluble for IMC, an acidic drug. Therefore, the chitosan-coated ssLip, with its higher retention in the GI tract, is a promising drug carrier for the oral administration of poorly absorbed compounds.     

Effectiveness of submicronized chitosan-coated liposomes in oral absorption of indomethacin

The plasma profile of indomethacin (IMC) after oral administration of IMC-loaded submicronized chitosan-coated liposomes (ssCS-Lip) was evaluated to reveal the effectiveness of the mucoadhesive function for improving the absorption of this poorly absorbable drug. The stomach and small intestine were removed from rats after 1, 2, and 4 hours of oral administration of submicron-sized liposomes (ssLip) or ssCS-Lip containing fluorescent dye, and the retentive properties were confirmed by measuring the amount of dye in each part of the gastrointestinal (GI) tract. Results showed that ssCS-Lip tended to be better retained in the upper part of the GI tract, compared with ssLip, at 1, 2, and 4 hours after administration, and was significantly better retained in the small intestine at 4 hours. The plasma profile and bioavailability of IMC after oral administration of both types of liposomes were improved, compared with oral administration of IMC solution. The maximum residence time of ssCS-Lip was significantly longer than those of ssLip. The extended plasma profile of ssCS-Lip was attributed to its prolonged retention in the upper region of the GI tract, and its delayed migration to the lower part of the intestine, the neutral pH of which is more soluble for IMC, an acidic drug. Therefore, the chitosan-coated ssLip, with its higher retention in the GI tract, is a promising drug carrier for the oral administration of poorly absorbed compounds.     

Influence of obestatin on the histological development of the small intestine in piglets during the first week of postnatal life

Obestatin is a gastrointestinal peptide having wide-ranging effects on cell proliferation; however, its mechanism of action remains poorly understood. Thus, the aim of the study was to elucidate the effect of exogenous obestatin on the postnatal structural development of the small intestine. Seven-day-old piglets with an average BW of 1.56 ± 0.23 kg were divided into four groups (n = 10) that received intragastrically obestatin (2, 10 or 15 μg/kg BW) or vehicle. After a 6-day experimental period, morphological analysis of gastrointestinal tract and small intestine wall (mitosis and apoptosis indexes, histomorphometry of mucosa and muscularis layers) was performed. The study revealed a seemingly incoherent pattern of the histological structure of the small intestine among the experimental groups, suggesting that the effect of obestatin is both intestinal segment specific and dose dependent. Histomorphometric analysis of the small intestine showed that higher doses of obestatin seem to promote the structural development of the duodenum while simultaneously hindering the maturation of more distal parts of the intestine. Intragastric administration of obestatin increased the crypt mitotic index in all segments of the small intestine with the strongest pro-mitotic activity following the administration of obestatin at a dose of 10 and 15 μg/kg BW. The significant differences in the number of apoptotic cells in the intestinal villi among the groups were observed only in proximal jejunum and ileum. In conclusion, it seems that obestatin shows a broad-spectrum of activity in the gastrointestinal tract of newborn piglets, being able to accelerate its structural development. However, the varied effect depending on the intestinal segment or the concentration of exogenous obestatin causes that further research is needed to clarify the exact mechanism of this phenomenon.     

In vitro evaluation of the activity of microencapsulated carvacrol against Escherichia coli with K88 pili

Aims: The aim of the current study is to develop encapsulation of essential oils for oral delivery to the small intestine of pigs in order to retain their antimicrobial activity. Methods and Results: Carvacrol was used as a model essential oil and successfully encapsulated in microcapsules made from Ca‐alginate hydrogel using an emulsion–extrusion technology with high encapsulation efficiency. This encapsulation method did not compromise the antimicrobial activity when tested against Escherichia coli K88 in a culture medium, as well as in a simulated gastrointestinal model. In the simulated gastrointestinal model, <20% of encapsulated carvacrol was released in the simulated gastric fluid; the rest was nearly completely released in the intestinal fluid after 6 h of incubation. Conclusions: Encapsulation in Ca‐alginate microcapsules could effectively reduce the early absorption of carvacrol in the upper gastrointestinal tract after oral administration, therefore, retains its potential antibacterial activity for the small intestine. Significance and Impact of the Study: The developed encapsulation method is expected to be suitable for encapsulation of other essential oils. The results from this study would increase the likelihood of success in the application of essential oils as antimicrobial agents for controlling enteric diseases in pigs.