Jejunum Of Sheep Research Articles

X-ray absorption spectroscopy of copper and iron in sheep digesta

BackgroundThe bioavailable supply of copper to ruminants has long been problematic. Complexities in supply exist due to interactions with other dietary elements in the rumen, most notably with iron or molybdenum in combination with sulphur, which can result in copper binding preventing its absorption. The molybdenum-sulphur-copper interaction has been extensively studied over the years. However, very little is known about the iron-sulphur-copper interaction, especially its mode of action in the gastrointestinal tract. MethodsIn the present work digesta from the rumen and jejunum of sheep fed a high copper, sulphur and iron diet was analysed using X-ray absorption spectroscopy (XAS). ResultsX-ray absorption fine structure (XAFS) and X-ray absorption near edge structure (XANES) indicated that all of the copper and iron had changed in bonding in the rumen and that the oxidation state of the elements had been reduced into a mix of Fe2+ & Fe3+ and Cu+ with some Cu0. ConclusionThe copper compounds were most likely to be thiol co-ordinated in line with Cu+ chemistry. Changes to the copper compounds took place in the jejunum, although thiols were still highly favoured the possible existence of a copper-iron-sulphur complex which also included oxygen and chloride was also observed. This possibly has some resemblance to the crystal structure of bornite.

Histological characteristics of the jejunum wall of sheep of the Edilbaev breed

On the basis of the Department of Animal Anatomy of the St. Petersburg State University of Veterinary Medicine, we examined 10 corpses of sheep of the Edilbaevsky breed aged one year and older. The cadaverous material for the study was samples of the jejunum of sheep of the Edilbaev breed. In the course of the study, histological and morphological data were obtained and processed, as well as features of the histostructures of the jejunum wall of sheep of the Edilbaev breed in postnatal ontogenesis were revealed. In our study, a complex of traditional histological methods and staining was used: hematoxylin-eosin and Masson trichrome. Violations of the trophism of the jejunum can lead to incomplete development of the organism as a whole, and in rare cases to a fatal outcome, leading to economically unprofitable situations in sheep farms. The lean book of sheep is a segment of the small intestine, in which not only band, wall digestion is carried out, but also the absorption of a large part of nutrients, micromacroelements, vitamins and water, as well as the area where diseases such as inversion and intussusceptions of the intestine are most common. As a result of the study, it was concluded that the walls of the jejunum of sheep of the Edilba breed aged one year and older have a similar structure with a similar type of digestive system in other ruminants. Morphometric data have been established, in particular, the thickness of the intestinal membranes, the thickness and height of the villi, the depth of the crypts in this breed of sheep, which may vary from a certain load of the digestive apparatus.

Menthol stimulates calcium absorption in the rumen but not in the jejunum of sheep

Stimulation of Ca2+ absorption can counteract hypocalcemia at the onset of lactation. The plant bioactive lipid compound (PBLC) menthol is an agonist for nonselective cation channels of the transient receptor potential (TRP) family. It acutely stimulated Ca2+ absorption in ruminal epithelia of nonadapted animals ex vivo and caused higher plasma Ca2+ concentrations in cows and sheep in vivo. To elucidate the pathway by which menthol feeding increases plasma Ca2+ level, the present study aimed to investigate the long-term dose-dependent effects of dietary menthol-rich PBLC on Ca2+ absorption and mRNA abundances of TRP channels in both rumen and jejunum. Twenty-four growing Suffolk sheep were equally distributed to a Con, PBLC-L, and PBLC-H group, which received 0, 80, and 160 mg/d of a menthol-rich PBLC. After 4 wk, ruminal and jejunal epithelia were analyzed for mRNA abundances of TRPA1, TRPV3, TRPV5-6, and TRPM6-8 genes. The Ca2+ flux rates and electrophysiological properties of epithelia from rumen and mid-jejunum were measured in Ussing chambers in the presence and absence of mucosal Na+. Acute changes in Ca2+ flux rates were measured after mucosal application of 50 µM menthol. Ruminal epithelia had quantifiable transcripts of TRPV3 = TRPM6 >TRPM7 >TRPA1 with no difference among feeding groups. Jejunum had quantifiable transcripts of TRPM7 >TRPA1 ≥ TRPM6 ≥ TRPV6 >TRPV5, where TRPA1, TRPV5, and TRPV6 tended to decrease linearly with increasing PBLC dose. Absorptive net flux of Ca2+ was detected only in the rumen, whereas jejunum showed a high passive permeability to Ca2+. Net flux rates of Ca2+ in the rumen increased in a quadratic manner (highest in PBLC-L animals) and were systematically decreased with the omission of mucosal Na+. Short-circuit current increased in both PBLC feeding groups compared with Con only in the rumen. Acute application of menthol-stimulated mucosal-to-serosal and net Ca2+ flux rates only in ruminal epithelia with higher stimulation in PBLC-fed animals. We conclude that Ca2+ transport is mainly active and transcellular in the rumen. It most likely involves TRPV3 that can be stimulated by menthol. Pre-feeding of menthol-rich PBLC enhances ruminal Ca2+ absorption and sensitizes it to acute stimulation by menthol. By contrast, intestinal Ca2+ absorption is not sensitive to menthol stimulation. Menthol could be used as a tool to enhance ruminal Ca2+ absorption and to prevent hypocalcemia in dairy cows.

Expression of corticotropin releasing factor (CRF) in the enteric nervous system of the jejunum of sheep

 Corticotropin releasing factor (CRF), a 41-amino acid neuropeptide widely distributed in the mammalian central nervous system, has been shown to influence several gastrointestinal functions. Recent studies show that CRF released locally from enteric nerves may also underlie alterations in gut function. In this study, immunohistochemisty was applied to demonstrate the presence of CRF in the jejunum of sheep. Using double immunohistochemical staining the co-localization of CRF with vasoactive intestinal peptide (VIP), galanin, tyrosine hydroxylase (TH), neuropeptide Y (NPY) and substance P (SP) was evaluated. The presence of CRF was detected in myenteric neurons (3.6 ± 0.9%) as well as in submucous neurons (10.5 ± 1.2%). In the ovine jejunum different numbers of CRF-expressing nerve fibres were detected in myenteric ganglia, submucous ganglia, circular smooth muscle layer, lamina muscularis mucosae and between mucosal glands. None of the CRF-positive enteric neurons and CRF-positive nerve fibres exhibited the presence of TH. CRF-immunoreactive (IR) myenteric neurons widely co-expressed VIP and/or NPY. A minor population of CRF-IR myenteric neurons additionally co-stored SP. Galanin was not present in CRF-IR myenteric neurons. The presence of VIP was observed in the vast majority of CRF-positive submucous neurons. Moderate numbers of CRF-IR sumbucous neurons co-expressing galanin or NPY were also found. The presence of SP in CRF-positive submucous neurons was noted only incidentally. In the circular smooth muscle layer CRF-IR/VIP-IR, CRF-IR/NPY-IR as well as CRF-IR/SP-IR nerve fibres were present. In the mucosal layer of the ovine jejunum CRF-IR nerve fibres co-stored additionally VIP, galanin, NPY or SP. This present study provides for the first time evidence that CRF present in different subclasses of enteric neurons may influence certain activities of the ovine jejunum. Co-localization studies indicate that VIP, galanin, SP and NPY functionally co-operate with CRF in the jejunum of the sheep.  

Developmental control of the Nlrp6 inflammasome and a substrate, IL-18, in mammalian intestine

The inflammasome is a multiprotein complex whose formation is triggered when a NOD-like receptor binds a pathogen ligand, resulting in activated caspase-1, which converts certain interleukins (IL-1β, IL-18, and IL-33) to their active forms. There is currently no information on regulation of this system around the time of birth. We employed transcript profiling of fetal rat intestinal and lung RNA at embryonic days 16 (E16) and 20 (E20) with out-of-sample validation using quantitative RT-PCR. Transcript profiling and quantitative RT-PCR demonstrated that transcripts of core components of the NOD-like receptor Nlrp6 inflammasome (Nlrp6, Pycard, Caspase-1) and one of its substrates, IL-18, were increased at E20 compared with E16 in fetal intestine and not lung. Immunohistochemistry demonstrated increased Pycard in intestinal epithelium. Western blotting demonstrated that IL-18 was undetectable at E16, clearly detectable at E20 in its inactive form, and detectable postnatally in both its inactive and active form. Dramatic upregulation of IL-18 was also observed in the fetal sheep jejunum in late gestation (P = 0.006). Transcription factor binding analysis of the rat array data revealed an overrepresentation of nuclear transcription factor binding sites peroxisome proliferator-activated receptor γ (PPAR-γ) and retinoid X receptor-α and chicken ovalbumin upstream promoter transcription factor 1 in the region 1,000 bp upstream of the transcription start site. Rosiglitazone, a PPAR-γ agonist, more than doubled levels of NLRP6 mRNA in human intestinal epithelial (Caco2) cells. These observations provide the first evidence, to our knowledge, linking activity of PPAR-γ to expression of a NOD-like receptor and adds to a growing body of evidence linking pattern recognition receptors of the innate immune system and intestinal colonization.

Mechanisms of intestinal phosphate transport in small ruminants.

In order to study the localization and mechanisms of intestinal phosphate transport in sheep and goats, unidirectional inorganic phosphate (Pi) flux rates across isolated stripped epithelial tissues were measured in vitro by applying the Ussing-chamber technique. In the first experiment the tissues were obtained from animals which had been kept on an adequate dietary P supply. In the second experiment the animals had either been kept on an adequate Ca and P supply or were Ca- and/or P-depleted. Significant net Pi absorption was measured in all segments of the small intestine and in the proximal colon of sheep and in the duodenum and jejunum of goats. Since the experiments were carried out in the absence of any electrochemical gradient, this clearly indicates the presence of active mechanisms for Pi transport in the intestinal tract of small ruminants. In sheep jejunum, reduction of mucosal Na concentration to 1.8 mM or serosal application of ouabain (0.1 mM) resulted in significant decreases of net Pi absorption of the same order of magnitude, indicating that about 65% of active Pi transport in sheep jejunum is mediated by a Na-dependent active transport mechanism. The mechanism for the remaining Na(+)-independent active Pi transport has not yet been identified. Dietary P depletion caused hypophosphataemia and induced a significant stimulation of net Pi absorption in goat duodenum and jejunum. This increase was independent of dietary Ca supply and was not associated with increased plasma calcitriol concentrations. This suggests substantial differences in hormonal regulation of Pi transport in small ruminants in comparison with single-stomached species.

Effect of vasoactive intestinal polypeptide (VIP) on the net movement of electrolytes and water and glucose absorption in the jejunal loop of sheep.

The effect of vasoactive intestinal polypeptide (VIP) on glucose absorption and the net movement of electrolytes and water in the jejunum of sheep was investigated using a Thiry-Vella loop. Intraluminal perfusion of glucose solution (10 mM) containing NaCl (149 mM) and PEG (1 mg/ml) was done at 1 ml/min and the outflow solution was collected every ten minutes. After a 30 min control period. VIP was infused into the jugular vein for 30 min at rates of 10, 30, 100, 300 and 1,000 pmol/kg/hr. In the control period, water, sodium, chloride and glucose were absorbed, while bicarbonate and potassium were secreted. VIP decreased water absorption at 10 and 30 pmol/kg/hr and converted to secretion at over 100 pmol/kg/hr in a dose-dependent manner. Sodium flux changed to secretion only at 1,000 pmol/kg/hr, but chloride flux remained absorptive even at the highest dose. Bicarbonate secretion was stimulated dose-dependently by VIP. Potassium secretion was also increased at all doses, though this response was not dose-dependent. The net glucose absorption was not altered by VIP at any dose. Our findings indicate that VIP stimulates the jejunal secretion of water, sodium, potassium and bicarbonate and that VIP does not inhibit glucose absorption when the secretion of luminal fluid is accelerated by VIP in the jejunal loop of sheep.

Expression of lactase-phlorizin hydrolase in sheep is regulated at the RNA level.

Lactase-phlorizin hydrolase (LPH) is expressed on the intestinal brush border and is responsible for the hydrolysis of lactose, the chief sugar in mammalian milk. The enzyme activity of LPH peaks soon after birth in most mammals and declines to much lower levels before adolescence. The molecular basis of this pattern of expression has not been clearly established. We have measured relative amounts of LPH mRNA in intestine from sheep with ages across a developmental spectrum, including third trimester fetal lambs, newborn lambs and adult sheep. LPH mRNA levels in the jejunum decline approximately 50-fold between infancy and adulthood, in parallel with the reduction in both lactase specific activity and immunologically reactive lactase protein expression in sheep jejunum. LPH mRNA is present in high concentration in the duodenum of newborn lambs, but steadily declines by day 34 and is dramatically reduced in adults. Because the changes in LPH mRNA, protein, and enzymic activity are generally parallel, we conclude that the developmental regulation of LPH in sheep is probably mediated primarily at the mRNA level.

Inhibition of sulphate and selenate transport in sheep jejunum by oxalate and other dicarboxylate anions.

SummaryThe influence of oxalate on mucosal sulphate, selenate and selenite uptake in the sheep mid‐jejunum was investigated. Oxalate significantly inhibited sulphate and selenate uptake, whereas mucosal uptake of selenite and L‐leucine was not affected. Thus, the effect of oxalate on sulphate and selenate uptake appears to be specific. Besides oxalate, the dicarboxylate anions oxaloacetate and fumarate also significantly reduced mucosal sulphate uptake.The results suggest that oxalate and dicarboxylate anions with a similar structure competitively inhibit mucosal sulphate and selenate uptake by sheep mid‐jejunum.ZusammenfassungHemmung der Sulfat‐ und Selenataufnahme im Jejunum des Schafes durch Oxalat und andere Dicarboxylatanionen: Es wurde der Einfluß von Oxalat auf die Aufnahme von Sulfat, Selenat und Selenit in die Mucosa des mittleren Jejunums von Schafen untersucht. Oxalat führte zu einer signifikanten Hemmung der Sulfat‐ sowie der Selenataufnahme. Dagegen wurden die Selenit‐ und Leucinaufnahme nicht beeinflußt. Somit scheint der Effekt von Oxalat auf die Sulfat‐ bzw. Selenataufnahme spezifisch zu sein. Neben Oxalat führten auch die Dicarboxylat‐Anionen Oxalacetat und Fumarat zu einer signifikanten Reduktion der mucosalen Sulfataufnahme.Die Ergebnisse weisen auf eine kompetitive Hemmung der Sulfat‐ bzw. Selenataufnahme im mittleren Jejunum des Schafes durch Oxalat und strukturell ähnliche Dicarboxylat‐Anionen hin.

Uptake of selenate and selenite by isolated intestinal brush border membrane vesicles from pig, sheep, and rat

Selenate and selenite uptakes by isolated intestinal brush border membrane vesicles (BBMV) from pig, sheep, and rat were investigated. Selenate uptake into jejunal and ileal, but not duodenal, BBMV from pig was stimulated by an inwardly directed transmembrane Na(+) gradient (Na out (+) >Na in (+) ). Selenate transport into rat ileal and sheep jejunal BBMV was also enhanced in the presence of a Na(+) gradient. Unlike selenate uptake, selenite uptake was not Na(+) dependent, neither in pig small intestine nor in sheep jejunum and rat ileum. Uptake of selenate represented real uptake into the vesicular lumen, whereas selenite uptake was a result of an extensive binding of(75)Se to the membranes. Thiosulfate at a 250-fold concentration of selenate completely inhibited Na(+)-dependent selenate uptake into pig jejunal BBMV. Furthermore, Na(+)-dependent sulfate uptake was totally inhibited in the presence of a 250-fold selenate concentration. The results clearly show that selenate transport across the BBM of pig jejunum and ileum, sheep jejunum, and rat ileum is partially energized by a transmembrane Na(+) gradient. Moreover, it is concluded from the results that there exists a common transport mechanism for sulfate and selenate in the BBM. The extensive binding of(75)Se from(75)Se-labeled selenite to the membranes could be from a spontaneous reaction of selenite with membrane-associated SH groups.

A biochemical study of experimental Johne's disease: II. An in vitro study of L-histidine uptake by sheep intestinal mucosa

Mucosal scrapings were obtained from two sites, in the jejunum and ileum of sheep, which had been experimentally infected with Mycobacterium johnei. The “active” uptake of L-histidine into the mucosa of the ileum was increased in infected animals when compared with healthy controls whereas in the jejunum the uptake was decreased. The “active” uptake was abolished by the addition of 0·2 m m 2:4 dinitrophenol to the incubation medium and passive uptake was similar in the infected and control groups. The predilection site of infection is the jejunum of the sheep where there is decreased absorption. The increased absorption lower down the intestine, in the ileum, may compensate for the decreased absorption in the jejunum.

The metabolism of the small intestine: Glycolysis in the mucosa of the small intestine of the sheep

1.1. Between 78–119 per cent of the glycolytic activity of homogenates of the mucosa from the jejunum of sheep was recovered in the particle-free supernatant fraction.2.2. High rates of l-lactate formation were obtained with glucose 6-phosphate as substrate; these were about two to three times those with fructose or glucose. Some l-glycerol 3-phosphate was formed from all three substrates.3.3. There was an increase in the specific activities of supernatant fractions with the age of the sheep over the period of 194 days investigated.4.4. It was not possible, in two experiments, to demonstrate any effects of different diets on the glycolytic activity of the jejunum.