Mid Jejunum Research Articles

Influence of Chronic Alcohol Intake on Intestinal Taurine and Antipyrine Transport in Pregnant Rats

Taurine is a nonessential amino acid that plays a critical role in development. However, biosynthetic capacity is almost negligible in the fetus and must be supplied by the mother. Therefore, when maternal taurine status is depressed during gestation, fetal tissue taurine concentrations can also be compromised. In the present study, the effect of chronic alcohol intake on the intestinal transport of taurine during pregnancy has been investigated by an in vitro technique that allows measurement of the unidirectional influx of the amino acid across the intact rat mid jejunum. The influence of alcohol intake on the passive component of the intestinal transport was also investigated with antipyrine, a model compound for passive diffusion. For chronic alcohol treatment, the rats were fed a liquid diet containing ethanol (36% of calories) or an isocaloric diet (pair-fed control) for 5 weeks before and during pregnancy. The animals were sacrificed at 21 days of gestation. Results from the kinetic analysis revealed that chronic ethanol treatment significantly decreases the maximum transport (Jm) of taurine, without modifying the Michaelis-Menten constant (Km), but enhances its diffusion component (ka) compared with that of controls. At the same time, this treatment significantly increased the passive diffusion of antipyrine. These results indicate that although chronic ethanol inhibits the active transport of taurine, passive diffusion is significantly increased. However, because of the predominant passive component in the intestinal absorption of taurine, an overall enhancement in the absorption of this amino acid is observed in alcohol-fed rats. The biological and practical implications of our results are discussed.

EFFECTS OF DIETARY DEPRIVATION ON SMALLAND LARGE INTESTINAL ION TRANSPORT IN THE MOUSE

The aim of this work is to investigate the effects of nutritional levels on the secretory functions of the small and large intestine in the mouse. The study was carried out on male swiss strain adult mice (of approximate 700) weighing 2040 gr. Mice starvedfor 48h refed after 48h starvation allowing themfood ad lib. Mice were also undernourishedfor 4d with 50% (3grlper mouselper day) of the fed control adult daily food intake. Experimental data was collectedfrom mice smaIl (midjejunum and proximal ileum) and large intestine (proximal, mid and distal colon). In mid jejunum and proximal Ueum, funetionaIly distinct differences were observed by their bioelectric properties [i.e potential difference (PD.), tissue resistance (R) and basal short-circiuit current (Isc)). These were altered by changes in nutritional status in the mid jejunum, while those of the proximal ileum remained unchanged. Three functionaIly distinet eolonie segments (proximal, mid and distal) were identified by their bioeleetrie properties (P.D., R and basal Ise) which varied along the eolon. These properties were altered by changes in nuıritional status. When stimulated to secrete the 48h starved mid jejunum and proximal ileum did not exhibit a hypersecretory response to the Ca2+ acting secretory agonists (bethaneehol, 5-HT) and DbeAMP. In the eolon, after 48h starvation bethaneehol aetivated a higher eleetrogneic seeretion that in the fed controls. The response of the distal colon to bethaneehol was biphasic. In the proximal and mid colon, in the case of food deprivation, cye/ic nue/eotide acting secretory agonists (DbcAMP, theophylline) did not aetivate a hypersecretory response compared to the fed colons. In the starved proximal colon, atropine potentiared 5-HT-indueed inerease in Ise and this was significantly larger than that in thefed. In the sma// and large intestine, CI. replaeement by glueonate in vitro, indicated that the basa i and eholinergie secretagogue stimulated seeretion were mainly carried by the C]- ion. In the ease of starvation, in the sma// intestine in vivo, the basal and bethanechol-stimulated fluid transport eonflrmed the lack of secretion obtained in vitro. In the colon, however, the in vivo results did not confirm the hypersecretion induced by bethanechol in vitro.

In Vitro Release and Intestinal Absorption of Physostigmine Salicylate from Submicron Emulsions

The in vitro release of physostigmine salicylate (PS) from a submicron emulsion and an aqueous solution was studied using the dialysis bag method. These formulations were then perfused to various locations along the rat small intestine (proximal, mid, and distal jejunum), and two lengths (10 and 55 cm). The disappearance of PS from the luminal compartment and its appearance in the blood compartment was monitored. In the in vitro drug release from emulsion experiments, a biphasic appearance of PS in the sink solution was observed, suggesting a possible sustained release from the emulsion. However, absorption data from perfusion studies did not correlate with this in vitro observation. No significant difference was found in absorption from emulsion versus solution in the mid jejunum where PS absorption was maximal. The difference between the two liquid formulations was observed only in those intestinal segments where the absorption was relatively low [absorption rate values of 4.6 ± 0.86 and 9.98 ± 2.04 (log%/min) × 10−3 in the proximal and distal parts of the small intestine, respectively, as compared with 14.0 ± 1.2-14.8 ± 1.1 (log%/min) × 10−3 in the mid jejunum]. In the distal part of the rat small intestine, PS was absorbed significantly better from solution than from the submicron emulsion. Cholinesterase activity in blood samples collected after intestinal perfusion with emulsion or solution revealed lower enzyme activity following emulsion administration.

Neutral and Acidic Goblet Cell Concentrations in the Small Intestine of the Unweaned Pig

Concentrations of Alcian blue (AB+) and periodic acid-Schiff (PAS+) staining goblet cells on small intestinal villi and in intestinal glands of unweaned pigs were determined. Samples from the distal duodenum, mid jejunum, and distal jejunum were taken from 7 pigs from each of 4 litters at ages 9, 18, 24, 27, 30, 33 and 36 days. The only concentration differences between litters were observed in the mid-jejunal villi AB+ staining goblet cells (p = 0.03) so that litter origin of piglets was basically nonexistent. Concentrations of goblet cells increased with age on the villous AB+ and PAS+ cells in the duodenum and in the mid jejunum (p less than 0.03). No other differences in goblet cell concentrations were observed.

Distribution of peptide YY in the gastrointestinal tract of the rat, dog, and monkey

The objective of this study was to characterize the distribution and concentration of peptide YY (PYY) in the gastrointestinal tract of the rat, dog, and monkey. In the rat, the greatest concentration of PYY was detected in the ileum and colon. The concentrations of PYY in the ileum and colon were 72 ± 49 and 768 ± 180 ng/g tissue, respectively. In the dog, PYY was found primarily in extracts of the mucosal layer of the ileum and colon, with smaller amounts in the distal jejunum. The concentration of PYY in the mucosal layers of the canine distal jejunum was 113 ± 25 ng/g tissue, proximal jejunum 302 ± 56, mid jejunum 507 ± 151, distal ileum 691 ± 184, and colon 1706 ± 774 ng/g tissue. In the monkey gastrointestinal tract, PYY was detected predominantly in mucosal extracts of the jejunum, ileum, and colon. The concentration of PYY in the mucosal layer extract of the jejunum was 92 ± 23, ileum 615 ± 127, and colon 1013 ± 243 ng/g tissue.

325 DEVELOPMENT OF INTESTINAL SUCRASE ACTIVITY: INTER ACTION OF THYROID AND ADRENAL HORMONES

Administration of exogenous thyroid hormones precociously increase intestinal sucrase activity (SA) in suckling rats. To differentiate the effects of thyroid and adrenal hormones on SA, intact suckling Sprague-Dawley rats were given TSH (0.5U) bid or water subcutaneously from day 14 until sacrifice on day 18. Results are shown below (x+SEM). Serum T4 and corticosterone (CS) as well as SA in the jejunum (J), mid-jejunum (MJ) and ileum (I) were all significantly increased in intact TSH treated rats.Sucklings were then adrenalectomized (ADX) on day 14 and given TSH (0.5 or 1.0U) bid or water subcutaneously until sacrifice on day 18. No significant differences in SA were found between ADX sucklings given TSH(1 or 2U/day) and ADX controls given water only.In the absence of the adrenal glands, physiologic elevation of endogenous thyroid hormones by TSH does not alter the maturational time course of intestinal sucrase activity.

Use of differential interference contrast microscopy to determine cell renewal times in mouse intestine.

Pieces of mouse mid jejunum have been cleared in glycerin and examined by differential interference contrast microscopy at low powers of magnification. The position and number of crypts and villi can be determined in the same specimen using this technique. The calculated value for crypt/villus ratio 4.53 +/- 0.99 (mean +/- SD) is less than a previously published value obtained using indirect techniques. A revised estimate of cell renewal time, based on this newly determined value for crypt/villus ratio, is 45 h. This agrees with earlier estimates derived from entirely different methods of analysis. The general usefulness of this form of light microscopy in helping one appreciate some three-dimensional problems in mucosal architecture is emphasized.

Gastrointestinal responses to graded levels of cellulose feeding in conventional and germ-free mice.

Conventional (CV) and germ-free (GF) mice were fed on a semi-synthetic diet containing graded levels of cellulose (0, 5, 15 and 30%), and thereafter the length and wet weight of intestine, the morphology of mid-jejunum epithelium and the turnover of mid-jejunum epithelial cells were determined. The following results were obtained. enlarged stomachs were observed in CV mice fed on a non-cellulose or 30% cellulose diet, but there were no differences found among the four dietary groups in GF mice. On the other hand, no effect of intestinal bacteria was observed, at least with regard to caecum weight, since the responses of caecum wet weight to the graded cellulose intake in CV mice were similar to those in GF mice. The responses of intestine length to graded cellulose intake differed between CV and GF mice, indicating that intestinal bacteria may modify the length of intestine in some way. Marked differences were observed in the responses of villus length to graded levels of cellulose between CV and GF mice. That is, in CV mice there was a gradual increase in villus length as cellulose content increased, whereas in GF mice there was a marked decrease in villus length. In the CV mice, graded levels of dietary cellulose had no effect on the epithelial cell turnover. On the other hand, in the GF mice it was observed that the greater the amount of dietary cellulose, the faster the turnover rate becomes. As a result, dietary cellulose would enhance the turnover rates of jejunal epithelial cells only in the absence of intestinal bacteria.

Lipid digestion in the sheep: effect of bile and pancreatic juice on the lipids of intestinal contents.

The effect of bile and pancreatic juice on the pattern of lipids in the intestinal digesta of the sheep has been examined using animals suitably prepared with chronic intestinal fistulæ. The major lipid of digesta collected anterior to the common bile duct was the free fatty acid fraction composed mainly of palmitic and stearic acids. Digesta collected immediately posterior to the common bile duct contained, in addition, polyunsaturated fatty acids and lecithin, indicating that these lipids originated in the mixed secretions of bile and pancreatic juice. In the mid jejunum the major phospholipid was lysolecithin derived from the hydrolysis of lecithin by pancreatic enzymes. In the duodenum and jejunum the free fatty acids were associated mainly with the particulate matter of digesta, but in the ileum the free fatty acids were more evenly distributed between the particulate and aqueous phases. Negligible amounts of monoglyceride were present in digesta of the small intestine. Diversion of bile and pancreatic juice from the intestine resulted in the disappearance of lysolecithin and a decrease in the content of unsaturated fatty acids in the digesta of the jejunum. The digestion of lipids in the sheep intestine is discussed in relation to the possible role of bile and pancreatic juice. It is suggested that a major function of pancreatic juice is to provide, by interaction with biliary lecithin, the lysolecithin required for optimum micelle formation and lipid absorption.

The effect of prostaglandins on gastrointestinal serotonin in the rat.

Abstract J.H. THOMPSON and M. ANGULO, The effect of prostaglandins on gastrointestinal serotonin in tht rat , European J. Pharmacol. 4 (1968) 224–227. Total serotonin levels were measured spectrophotofluorometrically in the stomach fundus (SF), pyloric antrum (PA) and mid-jejunum (MJ) of adult male Sprague-Dawley rats (200–380 g) following injection of prostaglandins (PG) e 1 and E 2 . PGE 1 100 μg/kg IV did not significantly effect MJ serotonin levels at various time periods from 0.5–60.0 minutes. Furthermore, PGE 1 in doses of 10–900 μg/kg SC did not significantly effect total MJ serotonin levels 30 minutes after injection. PGE 1 and PGE 2 in doses of 200 μg/kg SC were without effect on serotonin levels in SF, PA and MJ. Similar results were obtained following a 60 minute subcutaneous infusion of PGE 1 1 μg/kt/min. It is concluded that the gastric secretory depression and smooth muscle stimulation produced by PG are not mediated via the release of serotonin.

The effect of nicotine on intestinal serotonin levels

Total mucosal serotonin from the stomach fundus (SF), pyloric antrum (PA), mid jejunum (MJ) and ascending colon (AC) of the rat was partially depleted in vivo by a ‘smoking dose’ (100 μg/kg) of nicotine hydrogen tartrate intravenously. Maximal depletion occurred as follows: SF 43% at 15 sec, PA 41% at 20 sec, MJ 45% at 30 sec and AC 34% at 15 sec. These were highly significant ( P < 0.001). Recovery was apparent in 10–30 min. Intraperitoneal nicotine gave similar results, however, due to delayed drug absorption the depleting effect occurred later (60–300 sec), was of smaller magnitude (average 30%), and was of a longer duration (20–60 min).