Regions Of Rat Small Intestine Research Articles

Targeted delivery of chitosan nanoparticles to Peyer’s patch using M cell-homing peptide selected by phage display technique

This study is aimed to develop an efficient oral vaccine carrier which specifically targets the follicle-associated epithelium region of Peyer’s patch (PP). M cell-homing peptide was selected by the phase display technique and its targeting efficiency was validated using chitosan nanoparticles (CNs) conjugated with the discovered peptide. A phage clone encoding CKSTHPLSC (CKS9) peptide sequence was selected by analysis of comparative superiority in transcytosis efficacy across the M cell layer in vitro and in vivo among the candidates. CKS9 was chemically conjugated to water-soluble chitosan (WSC) and the CKS9-immobilized chitosan nanoparticles (CKS9-CNs) were prepared by ionic gelation of CKS9-WSC with tripolyphosphate, yielding spherical nanoparticles around 226.2 ± 41.9 nm. The targeting ability of CKS9-CNs to the M cell and to the PP regions of rat small intestine was investigated by in vitro transcytosis assay and closed ileal loop assay, respectively, and was visualized by fluorescence-microscopy analysis. CKS9-CNs were transported more effectively across the M cell model and accumulated more specifically into PP regions in comparison with CNs, indicating that CKS9 peptide prominently enhanced the targeting and transcytosis ability of CNs to PP regions. These results suggest that the CKS9-CNs could be used as a new carrier for oral vaccine delivery.

Premicellar taurocholate enhances calcium uptake from all regions of rat small intestine

Background/Aims: The specific components of bile, which is necessary for normal calcium absorption, are unknown. We have previously shown that Ca2+ is bound with high affinity by premicellar taurocholate. The current studies examined the effects of taurocholate on intestinal calcium transport. Methods: Intestinal Ca2+ uptakes were measured from proximal, mid, and distal small intestinal segments perfused with solutions containing 45 CaCl2 (0.1–1 mmol/L), taurocholate (0–10 mmol/L), trihydroxymethylaminomethane buffer (pH 7), phenolsulfonpthalein (nonabsorbable marker), and NaCl (total ionic strength, 0.16 mol/L) for four randomized perfusion periods. In other studies, the proximal small intestine was divided into two equal segments and perfused with either 45CaCl2 or 45CaCl2 plus taurocholate (2.5–5 mmol/L). Calcium absorption was measured from the difference in uptake and calcium concentration retained in mucosa. Finally, effects of taurocholate on Ca2+ uptake across isolated brush border membrane vesicles were measured. Results: Premicellar taurocholate produced an approximately 1.7–2-fold enhancement (P < 0.01) in Ca2+ uptake in all regions, with lesser contributions from micellar taurocholate. These effects resulted in a net increase in calcium absorption. Premicellar taurocholate also significantly increased calcium uptake across brush border vesicles. Conclusions: Premicellar taurocholate significantly enhances calcium uptake into, and absorption across, enterocytes. The mechanisms remain to be experimentally verified.

Neural mediation of cholera toxin-induced mucin secretion in the rat small intestine

We examined the role of enteric nerves in cholera toxin (CT)-induced mucin secretion in proximal and distal regions of rat small intestine. Stimulation of intestinal loops with 120 micrograms (1.5 mumol) CT using an in vitro open-loop model resulted in an approximately four-fold increase in luminal mucin content over unstimulated controls in both regions of the gut. Prior treatment of loops with tetrodotoxin had no effect on the amount of mucin released in response to CT. However, permanent destruction of primary sensory afferent nerves by neonatal treatment of rats with capsaicin reduced the mucin response to CT to baseline levels in both regions. In normal animals, atropine resulted in approximately 40% inhibition of mucin secretion in both the proximal and distal small intestine. The atropine-sensitive secretory response appears to be a component of the capsaicin-sensitive response. These results suggest that choleraic mucin secretion is mediated primarily by a capsaicin-sensitive neurogenic pathway involving local activation of sensory nerves, which may then elicit mucin secretion through interaction with cholinergic nerves.

Premicellar taurocholate enhances ferrous iron uptake from all regions of rat small intestine

Inorganic iron is virtually insoluble at the pH of small intestinal contents. This severe solubility limitation has been partly overcome by intraluminal substances that bind and solubilize iron, thus increasing availability for absorption. While several dietary ligands capable of solubilizing Fe2+ in intestinal lumen have been described, an endogenous binding ligand has not been previously described. It has recently been shown that certain trihydroxy bile acids (taurocholate and glycocholate) show high-affinity premicellar and low-affinity micellar Fe2+-binding properties, resulting in the formation of soluble Fe2+-bile salt complexes. It was hypothesized that this binding would increase the intraluminal pool of soluble iron, increase delivery of soluble iron to mucosal carriers, and thus enhance intestinal Fe2+ uptake. As a first step toward testing this hypothesis, the effect of taurocholate on Fe2+ uptake from all regions of in vivo rat small intestine is reported. It is shown that taurocholate, at premicellar concentrations, produces a marked, stepwise increase in Fe2+ uptake from all regions of small bowel, with little further increase above the critical micellar concentration. Enhancement of intestinal Fe2+ uptake is a newly described effect, and potential physiological function, of premicellar bile salts.

Effect of fasting on Na-K-ATPase activity in rat small intestinal mucosa.

The effect of fasting on mucosal Na-K-ATPase activity in various regions of rat small intestine was investigated. Fasting (17--48 h) was associated with a consistent decrease in specific and total activity of Na-K-ATPase in the jejunum, the levels tending to rise more distally. No effect on the specific activities of Mg-ATPase or alkaline phosphatase was found. Fasting was also associated with incresed adrenocortical activity and with decreases in mucosal mass, protein content, and histological dimensions of the jejunum, no similar changes being found in the distal small intestine. Glucose ingestion prevented the decrease in jejunal enzyme activity associated with fasting and elevated levels in the mid and terminal small intestine of fed animals. These effects suggest that Na-K-ATPase activity in small intestinal mucosa may be, in part, inducible.

Resistance of intestinal triglyceride transport capacity in the rat to adaptation to altered luminal environment

Previous studies have shown that the transmucosal transport capacity for tiolein is slower in distal compared with proximal regions of rat small intestine. The effect of altered luminal conditions on the relative capacities for [14C]triolein transport through different regions of intestinal wall were examined by determining the net accumulation of 14C-lipid in the mucosa during maximal steady [14C]triolein absorption. The high 14C-lipid accumulation in distal mucosa was not reduced after direct distal infusion of oleic acid and monolein for 7 days before challenge (substrate induction). No decrease in distal intestinal lipid accumulation was found 1 month after removal of the proximal 40% of intestine beyond the duodenum. Conversely, alteration of the luminal environment in the proximal intestine by 3 days of starvation or by ileal resection did not increase the tissue 14C-lipid concentration in this region during maximal [14C]triolein challenge. When proximal and distal segments were exchanged without reduction in intestinal length, by jejunoileal transposition, major 14C-lipid accumulation still occurred in originally distal segments during 3 hr of [14C]triolein infusion 1 month later. Mucosal synthesis of triglyceride was equally efficient in jejunum and ileum, suggesting that the intrinsic differences in proximal and distal lipid accumulation during maximal rate transport were related to a relatively limited capacity for chylomicron synthesis or secretion in the distal intestine.

Relations of weak-electrolyte transport and acid-base metabolism in rat small intestine in vitro

The jejunal and ileal regions of rat small intestine in vitro exhibit different patterns of weak-electrolyte transport and acid-base metabolism. The jejunal pattern of weak-electrolyte transport is net transport of weak acids M yields S and of weak bases S yields M (M, mucosal; S, serosal), and the pattern of acid-base metabolism is luminal acidification and serosal alkalinization. In the absence of sodium or in the presence of metabolic inhibitors, weak-electrolyte transport and serosal alkalinization are inhibited, but luminal acidification is not inhibited. The ileal pattern of weak-electrolyte transport is the opposite of that of the jejunum and may be associated with the presence of a luminal alkalinization process observed in this region. In the absence of chloride the ileal patterns of weak-electrolyte transport and acid-base metabolism become similar to those of the jejunum. It is suggested that these observations support a previously proposed model for weak-electrolyte transport in the intestine consisting of a series three-compartment system in which the pH of the intermediate compartment is greater than that of the bulk phases.

The hydrolysis of dipeptides by different regions of rat small intestine

Research Article| November 01 1960 The hydrolysis of dipeptides by different regions of rat small intestine G. B. Robinson; G. B. Robinson 1Department of Medical Biochemistry and Pharmacology, The Medical School, Birmingham 15 Search for other works by this author on: This Site PubMed Google Scholar B. Shaw B. Shaw 1Department of Medical Biochemistry and Pharmacology, The Medical School, Birmingham 15 Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1960) 77 (2): 351–356. https://doi.org/10.1042/bj0770351 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation G. B. Robinson, B. Shaw; The hydrolysis of dipeptides by different regions of rat small intestine. Biochem J 1 November 1960; 77 (2): 351–356. doi: https://doi.org/10.1042/bj0770351 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1960 CAMBRIDGE UNIVERSITY PRESS1960 Article PDF first page preview Close Modal You do not currently have access to this content.