Studies on 5'-nucleotidase histochemistry. III. 5'-Nucleotidase activity in smooth muscle cells of the rat's gastrointestinal tube.

The distribution pattern of histochemically detectable 5'-nucleotidase (5'-Nase) activity is described in smooth muscle cells of the rat's gastrointestinal tube (esophagus, stomach, small intestine, large intestine). Both, light and electron microscopic methods are used. Faint positive 5'-Nase activity is observed on smooth muscle cells of the lamina muscularis mucosae in the thoracal esophagus whereas it is completely absent from smooth muscle cells of the abdominal esophagus and the stomach. In the small and large intestine strong positive 5'-Nase reaction is found on smooth muscle cells of the lamina muscularis mucosae and the innermost part of the lamina muscularis externa. In the circular and longitudinal layer of the lamina muscularis externa a slight increase in 5'-Nase activity is observed from the proximal to the distal segments. The reaction product is restricted to the outer cell surface of smooth muscle cells. In the small intestine the strong enzymatic activity in the innermost part of the muscularis externa is found to be localized at small and dense muscle cells (sd-cells). Common morphological and histochemical characteristics of sd-cells and smooth muscle cells of the lamina muscularis mucosae are emphasized. Hypothetical functions e.g. uptake of precursors of nucleosidephosphates, possible functional connection to a high glycogen content, correlation between 5'-Nase activity and proliferation capacity and local vasodilatory effect are discussed.     

黄喉拟水龟消化道的组织学观察

观察黄喉拟水龟消化道的组织结构.采用常规石蜡切片和HE染色方法对黄喉拟水龟的消化道进行观察.除了口咽腔以外,消化道的管壁是由粘膜层、粘膜下层、肌肉层和外膜组成;各部分的主要区别在于粘膜层,食道和大肠的是复层柱状上皮,胃和小肠的是单层柱状上皮.黄喉拟水龟的舌桔红色,不能伸缩;食管中无食管腺,扩张性强;胃呈囊状,有大量胃腺,腔面皱襞较多;小肠较长,是消化的主要场所,表面有大量的绒毛,在绒毛中可见肠腺;大肠无绒毛,也存在皱襞.     

The development of arylsulphatase in the small intestine of the rat

1. Arylsulphatase activity was measured in stomach, proximal and distal third of small intestine, colon, liver and kidney of foetal and neonatal Sprague-Dawley rats and Swiss mice, with nitrocatechol sulphate as substrate. 2. The specific activity in the distal small intestine, but not in the stomach, proximal small intestine or colon, increased about fourfold between 5 and 16 days after birth in both conventional and germ-free rats. 3. No comparable increase occurred in the distal small intestine of the mouse. 4. The specific activity of acid phosphatase in the distal small intestine of the rat rose only slightly when the arylsulphatase activity increased. 5. The pH optimum and Michaelis constant of arylsulphatase activity of the distal small intestine were similar for 1-day-old, 9-day-old and adult rats. 6. When extracts of distal small intestine of 1-day-old and 9-day-old rats were incubated together, the arylsulphatase activities were additive.     

Cross-fostering in Macropus eugenii leads to increased weight but not accelerated gastrointestinal maturation

Stomach and small intestine development was characterized in tammar wallaby (Macropus eugenii) pouch young (PY) using both morphological and immunohistological criteria. At birth, the stomach is undeveloped in comparison to the well-developed intestinal mucosa. The stomach maintains a uniform morphology in both the forestomach and hindstomach regions until the specialization of cardiac and gastric glands are seen at PY170. Parietal cells, found throughout the mucosa are downregulated in the forestomach as cardiac glandular stomach is developing prior to the transition of the offspring to a diet that includes herbage. In the small intestine, mature-type villi are present at birth but the muscularis externa is immature and undergoes significant development around PY120 onwards. We investigated the effects of changes in maternal milk on gut development in the tammar wallaby using a cross fostering approach that provided younger pouch young with older stage milk. Younger PY (average age 67 days postpartum, n = 5) were transferred onto teats vacated by older stage PY (average age 100 days postpartum, n = 6) for 34 days before gut development was assessed. In addition milk analysis was performed before and after fostering events. Cross-fostered PY animals receiving older stage milk were found to be 31% heavier than controls. There was no difference between carbohydrate and protein concentrations however, fostered PY milk had a higher concentration of lipid than that of controls that may have contributed to heavier fostered PY. No difference was found in stomach or small intestine development between these groups using the criteria employed in this study.     

Studies on new intracellular proteases in various organs of rat. 3. Control of group-specific protease under physiological conditions.

1. To study the role of group-specific protease in enzyme degradation, alternation of its activity under various physiological conditions was examined. 2. Studies on the distribution of group-specific protease in various organs of rats showed high activity in skeletal muscle and the muscle layer of small intestine, and rather low activity in liver. The activity varied in different muscles, but red muscle tended to have higher activity than white muscle. Activity was much lower in the muscles of the stomach and colon than in those of the small intestine. 3. Group-specific protease in skeletal muscle increased under various dietary conditions (starvation, protein-free diet or high protein diet), but the activities in the muscle layer of the small intestine and liver were not greatly influenced by dietary conditions. None of the hormones tested (i.e. hydrocortisone, glucagon, insulin, growth hormone and estrogen) influenced the activity of group-specific protease in liver. 4. The level of group-specific protease in skeletal muscle was increased markedly fifteen days after denervation, with a reciprocal decrease in the level of muscle phosphorylase, which is a good substrate of the protease. 5. Liver protease activity appeared in the late suckling period. The activity in skeletal muscle was high at the time of birth and attained the adult level 3 weeks after birth. The activity in the muscle layer of the small intestine did not change after birth. Thus the mechanism for evoking these three specific proteases during development are apparently different. The activity of liver protease began to decrease approximately 12 h after partial hepatectomy and reached a minimum after about 72 h. Recovery of the protease activity was very slow and activity had not returned to the normal value 7 days after the operation. This observation seems to be consistent with the fact that there is little or no protease activity in liver in the neonatal period.     

Distribution, quantitation, and origin of immunoreactive neuropeptide Y in the human gastrointestinal tract

A radioimmunoassay for measurement of immunoreactive neuropeptide Y has been developed using antiserum from a rabbit (221) immunized with porcine neuropeptide Y. Antibody 221 has been characterized for both sensitivity and specificity. To determine the distribution of neuropeptide Y in the human gastrointestinal tract, fresh tissue specimens were separated by microdissection into the muscularis externa and the mucosa-submucosa. To examine the origin of neuropeptide Y in human colon, specimens of aganglionic and ganglionic colon were obtained from patients with Hirschsprung's disease. Immunoreactive neuropeptide Y in human gut was present in highest concentrations in the muscularis externa of the stomach and in lowest concentrations in the muscularis externa of the ileum and descending colon. Neuropeptide Y in the stomach was present in higher concentrations in the muscularis externa than in the mucosa-submucosa, but in the descending colon there were lower concentrations of neuropeptide Y in the muscularis externa than in the mucosa-submucosa. In Hirschsprung's disease, concentrations of neuropeptide Y were increased in aganglionic colon in both the muscularis externa and the mucosa-submucosa, compared to corresponding layers from proximal ganglionic colon. Extracts of the gastric muscularis externa and the colonic mucosa-submucosa were separated by C18 reverse-phase high-performance liquid chromatography. One major immunoreactive species was identified by radioimmunoassay which eluted in a position similar to synthetic human neuropeptide Y. These results demonstrated both regional and layer differences in concentrations of neuropeptide Y in human gut. Increased concentrations of neuropeptide Y in aganglionic colon from Hirschsprung's disease most likely result from enlargement of neuropeptide Y-containing extrinsic nerve fibers in both the mucosa-submucosa and the muscularis externa.     

Innervation of the gastrointestinal canal of the toad Bufo marinus by neurons containing 5-hydroxytryptamine-like immunoreactivity

Summary The gut of the toad, Bufo marinus, was examined for evidence of enteric neurons containing 5-hydroxytryptamine-like immunoreactivity. Such neurons were absent from the stomach. They were present in the small intestine, with processes confined to the myenteric plexus. Immunoreactive nerve cell bodies lay on branches of the pelvic nerves supplying the large intestine; fibres were found in the submucosa of the posterior large intestine and in the muscularis externa of the anterior large intestine. It is concluded, on morphological grounds, that the neurons in the small intestine are interneurons, whereas those in the large intestine are postganglionic parasympathetic motoneurons.     

A quantitative study of the morphological development and bacterial colonisation of the gut of the tammar wallaby Macropus eugenii eugenii and brushtail possum Trichosurus vulpecula during in-pouch development

We compared the rates of change of various morphological parameters of the stomach, small intestine, caecum and colon of tammar wallabies and brushtail possums with body mass during in-pouch development. These were correlated with changes in the numbers of bacterial species in the various gut segments. In the pouch-young of both species, the wet tissue masses of all gut segments increased with body mass in a positively allometric manner (i.e. with a body mass exponent > 1), suggesting that the mass of each component was disproportionately low at birth, but increased disproportionately rapidly postnatally. However, the lengths of the wallaby stomach and small intestine scaled isometrically with respect to body mass (i.e. with a body mass exponent around 0.33), which may indicate that the shape of these components changes to the adult form during early neonatal development. Conversely, the length of the caecum and colon of both wallabies and possums scaled in a positively allometric manner with respect to body mass, showing area to volume compensation. This may indicate a more general pattern of disproportionately rapid postnatal enlargement in areas that are distal to the principal sites of neonatal digestion (i.e. the stomach). The numbers of bacterial species present in the various gastrointestinal segments of both species were low in animals aged 100 days or less but there was a significant increase in microbial diversity in the caecum of brushtail possums aged over 100 days. The possum caecum also showed the greatest rate of increase in wet tissue mass relative to body mass. It is postulated that caecal development may act as a nidus for establishment of communities of commensal microflora in the developing marsupial.     

Immunohistochemical analysis of connexin26 and 43 expression in the mouse alimentary tract

The spatial pattern of connexins26 (Cx26) and 43 (Cx43) expressions were investigated in the mouse digestive tract by immunocytochemistry. High levels of connexin43 in the epithelium of the oesophagus, non-glandular part of the stomach, and the circular layer of duodenal and ilea muscularis externa were detected. Cx26 was expressed in stratum granulosum of oesophagal folds and in the non-glandular part of the stomach. A low level of immunoreactivity of Cx43 was observed in the circular, and very low in the longitudinal layer of the muscularis externa in the stomach and colon. No immunoreactivity for Cx26 and Cx43 was found in the entire muscularis externa of the oesophagus or in the longitudinal muscle layers of the duodenum and ileum.     

Seasonal changes in morphology and function of the gastrointestinal tract of free-living alpine marmots (Marmota marmota)

The gastrointestinal tracts of 76 free-living alpine marmots ( Marmota marmota) shot during a population control program in Switzerland were collected and analysed for patterns of change in morphology and function over the period from emergence from hibernation in April to just before re-entry into hibernation in September. Between first emergence and mid-summer (July) the fresh tissue mass of the stomach increased by 105%, the small intestine by 259% (among the largest recorded for a mammal), caecum by 185%, proximal colon by 138%, and distal colon by 144%. Mitotic activity was greatest in the small intestine; the mitotic index was high (40%) compared with indexes in the stomach and hindgut (approximately 4%) even at emergence, and increased to approximately 60% by mid-summer. Microbial activity in the caecum was also significant at emergence. The stomach (length) and caecum (length and fresh mass) increased in response to ingested food earlier than did the small intestine. Between mid-summer and September there were decreases in small intestinal tissue mass and mitotic activity. It is concluded that the gastrointestinal tract of alpine marmots probably continues to function throughout hibernation at a low level, with a mid-winter trough as part of an endogenous circannual rhythm. However, after emergence in spring, increases in size and activity of the tract appear to be a response to ingested food rather than to an endogenous signal. The early signs of down-regulation of the small intestine before re-entry into hibernation, together with its delayed up-regulation in response to food in spring, are consistent with the high costs of maintaining this section of the digestive system.     

Absorption of alpha-ketoglutarate by the gastrointestinal tract of pigs

Only a small percentage of alpha-ketoglutarate (AKG) administered lumenally to pigs appears in the portal circulation. This has been attributed to mucosal metabolism, and possibly by limited absorption. Although transporters for di- and tricarboxylic acids, which includes the sodium-dependent transporter NaDC-1, have been detected in the small intestine, correlations with functional assays are lacking. Therefore, intact tissues from three regions of the small intestine, stomach, and colon of weaned pigs were used to measure rates of AKG absorption. Western analysis was used to detect NaDC-1 in the three regions of small intestine. Rates of AKG absorption were highest in the small intestine, lowest in the colon, and intermediate in the stomach. Immunoreactive NaDC-1 was detected in the small intestine and this coincided with a component of AKG absorption that was inhibited by AKG and succinate. In contrast, absorption of AKG was inhibitable by unlabeled AKG, but not succinate, in the stomach, and by neither in the colon. Feeding studies indicated that the amounts of AKG that might be included in practical diets for pigs would not (1) upregulate rates of AKG absorption or (2) exceed estimated capacities of the small intestine to absorb AKG. The present findings indicate that the efficacy of AKG as an alternative metabolic fuel for enterocytes to spare dietary amino acids is not limited by absorption.     

Binding of a pure 125I-monoiodoleptin analog to mouse tissues: a developmental study

The preparation of a pure 125I-labeled monoiododerivative of mouse leptin is described. This radiolabeled analog has been used to characterize and localize central and peripheral leptin binding sites (Ob-R) of the mouse at different stages of its development. The affinity values found in membrane homogenates of various mouse tissues are similar and range between 0.1 and 0.3 nM, indicating that all the Ob-R isoforms have a similar affinity. Leptin binding sites are highly expressed at the membrane level in lung, intestine, kidney, liver, and skin and to a lesser degree in stomach, heart, and spleen. Brain, thymus, and pancreas homogenates are devoid of any specific binding. The distribution of mouse Ob-R has also been explored by autoradiography and dipping techniques on whole mouse sections. In lung, leptin binding sites are located at the pulmonary parenchyma and at the bronchiolar epithelial level. Binding sites are expressed all along the digestive tract from the tongue to the rectum (esophagus, stomach, intestine, colon, and rectum). In muscular visceral structures (stomach, intestine, and bladder) the binding is mainly present in the lamina propria. During development, leptin receptors are early expressed in the liver, kidney, and bone. In the lung, the Ob-R level increased gradually from birth to adulthood where the expression is maximal. By contrast, leptin receptors located in the medulla of the kidney remain remarkably constant all along the development. A broad signal is present in cartilage and bone particularly in vertebrae, limb, and ribs. Interestingly, leptin receptors are barely detectable in the mouse brain except in the choroid plexus and leptomeninges, whereas in the rat brain leptin binding sites are located in the thalamus, the piriform cortex, the cerebellum (at the granular and molecular cell layer), and the pineal gland.     

Interindividual variation and organ-specific patterns of glutathione S-transferase alpha,mu, and pi expression in gastrointestinal tract mucosa of normal individuals

Glutathione S-transferase (GST) protein in gastrointestinal (GI) tracts of 16 organ donors, from whom all or substantial portions of the GI tract (stomach-colon) were available, was quantitated by HPLC and examined for interindividual variability/consistency of organ-specific patterns of expression. GSTP1, GSTA1, and GSTA2 were major components, and GSTM1 and GSTM3 were minor components. Consistent patterns of organ-specific expression were evident despite a high degree of interindividual variation of expression. GSTP1 was expressed throughout the GI tract and showed a decrease of expression from stomach to colon. GSTA1 and GSTA2 were expressed at high levels in duodenum and small intestine and expression decreased from proximal to distal small intestine. In contrast, GSTA1 and GSTA2 expression in colon and stomach of all subjects was low, particularly for colon where GSTA1 expression was 20- to 800-fold lower than that in corresponding small intestine. These consistent patterns of expression would suggest that compared to duodenum and small intestine, colon and to a lesser extent stomach always have low potential for GST-dependent detoxification of chemical carcinogens and are therefore at greater risk of genotoxic effects, particularly via substrates that are specific for GSTA1. This may be a factor in the greater susceptibility of stomach and colon to cancers compared to duodenum/small intestine.     

c-kit immunoreactive interstitial cells of Cajal in the human small and large intestine

 c-kit immunohistochemistry was performed on unfixed frozen sections of human small (duodenum, jejunum, and ileum) and large intestine (ascending, transverse, descending, and sigmoid colon). The c-kit immunoreactive cells in the muscularis externa of the intestinal wall were identified as interstitial cells of Cajal (ICC) and mast cells. ICC were identified by their morphology, localization, and organization based on previous light and electron microscopic studies. In the small intestine, ICC were located primarily in relation to the myenteric plexus of Auerbach, but also in septa between circular muscle lamellae. In the large intestine, ICC were seen in relation to Auerbach’s plexus, but also and in great numbers in the circular muscle layer and in teniae of the longitudinal muscle layer. The morphology of the ICC was similar in the small and large intestine, but the pattern of distribution was obviously different. c-kit immunoreactive mast cells were found predominantly in the inner part of the circular muscle layer. The anti-c-kit method is found to be an easy and reliable method to study at least most of the interstitial cells of Cajal and thereby contribute to further normal and pathological studies. Accepted: 31 July 1997     

Degradation of phytate in the gut of pigs ‐ pathway of gastrointestinal inositol phosphate hydrolysis and enzymes involved

The present study gives an overview on the whole mechanism of phytate degradation in the gut and the enzymes involved. Based on the similarity of the human and pigs gut, the study was carried out in pigs as model for humans. To differentiate between intrinsic feed phytases and endogenous phytases hydrolysing phytate in the gut, two diets, one high (control diet) and the other one very low in intrinsic feed phytases (phytase inactivated diet) were applied. In the chyme of stomach, small intestine and colon inositol phosphate isomers and activities of phytases and alkaline phosphatases were determined. In parallel total tract phytate degradation and apparent phosphorus digestibility were assessed. In the stomach chyme of pigs fed the control diet, comparable high phytase activity and strong phytate degradation were observed. The predominant phytate hydrolysis products were inositol phosphates, typically formed by plant phytases. For the phytase inactivated diet, comparable very low phytase activity and almost no phytate degradation in the stomach were determined. In the small intestine and colon, high activity of alkaline phosphatases and low activity of phytases were observed, irrespective of the diet fed. In the colon, stronger phytate degradation for the phytase inactivated diet than for the control diet was detected. Phytate degradation throughout the whole gut was nearly complete and very similar for both diets while the apparent availability of total phosphorus was significantly higher for the pigs fed the control diet than the phytase inactivated diet. The pathway of inositol phosphate hydrolysis in the gut has been elucidated.     

Cytochemical and biochemical studies on the differentiation of microperoxisomes in the small intestine of the fetal mouse

The localization of catalase activity during the morphogenesis of duodenum and ileum has been studied in Swiss ICR mouse embryos from the 16th day of fetal life until birth. Catalase activity was also measured by a spectrophotometric method. Few diaminobenzidine-positive microperoxisomes are present at 15 days of gestation in undifferentiated cells of the stratified epithelium lining the lumen of duodenum and ileum. The number of microperoxisomes increases considerably in the duodenal enterocytes at 17 days; the highest concentration of microperoxisomes is attained at 18 days, after which time their number becomes stable until 4 weeks after birth. Biochemically, catalase activity is barely detected at 15 days in the first half of the small intestine, but afterwards it increases steadily up to 1 day after birth. In the ileum, the increase in microperoxisome number is far less important than in the duodenal enterocytes and reaches a maximum at 19 days of gestation, that is, immediately at birth. The level of catalase activity in the second half of the small intestine is also much lower than that measured in the first half. These results are discussed in relation to the biogenesis of microperoxisimes in the small intestine before birth.     

Expression and localization of Muc4/sialomucin complex (SMC) in the adult and developing rat intestine: implications for Muc4/SMC function

Muc4/sialomucin complex (SMC) is a high molecular mass heterodimeric membrane mucin, encoded by a single gene, and originally discovered in a highly metastatic ascites rat mammary adenocarcinoma. Subsequent studies have shown that it is a prominent component of many accessible and vulnerable epithelia, including the gastrointestinal tract. Immunoblot and immunofluorescence analyses demonstrated that Muc4/SMC expression in the rat small intestine increases from proximal to distal regions and is located predominantly in cells at the base of the crypts. These cells were postulated to be Paneth cells, based on their location, morphology, and secretory granule content. Immunohistochemistry indicated the presence of Muc4/SMC in these granules. Muc4/SMC expression was higher in the rat colon than small intestine and was abundantly present in colonic goblet cells, but not in goblet cells in the small intestine. Immunohistochemistry also suggested the presence of MUC4 in human colonic goblet cells. Biochemical analyses indicated that rat colonic Muc4/SMC is primarily the soluble form of the membrane mucin. Analyses of Muc4/SMC during development of the rat gastrointestinal tract showed its appearance at embryonic day 14 of the esophagus and at day 15 at the surface of the undifferentiated stratified epithelium at the gastroduodenal junction, then later at cell surfaces in the more distal regions of the differentiated epithelium of the small intestine, culminating in expression as an intracellular form in the crypts of the small intestine at about day 21. Limited expression in the colon was observed during development before birth at cell surfaces, with expression as an intracellular form in the goblet cells arising during the second week after birth. These results suggest that membrane mucin Muc4/SMC serves different functions during development of the intestine in the rat, but is primarily a secreted product in the adult animal.     

Prenatal and postnatal development of the small intestine in the insectivore Suncus murinus

The development of the small intestine in the insectivore Suncus murinus was noted during the period from 21 days' gestation to 20 days after birth. At 21 days of gestation, the proximal small intestine exhibited the beginning of villus formation, whereas the distal small intestine preserved the stratified epithelium. Stratified epithelium in the distal small intestine changed into a single layer by 24 days' gestation. At 26 days' gestation, each epithelial cell was immature; but by 28 days mature-looking epithelial cells were found. The shape of the villi changed from cuboid to columnar during the same period. The connective-tissue cores of the villi began to develop at 7 days after birth in the proximal small intestine and at 15 days after birth in the distal small intestine. Crypts appeared at 15 days after birth. Endocytosis of epithelial cells took place at 28 days of gestation. In the proximal small intestine, supranuclear vesicle clusters were observed first at birth; they began to decrease both in number and size at 10 days' gestation and then disappeared completely by 20 days after birth. In the distal small intestine, large supranuclear vacuoles were observed first at 28 days of gestation. Although these vacuoles invariably were found up to 15 days after birth, they also disappeared completely by 20 days. Epithelial cells showed a structure similar to those of the adult after weaning.     

Stimulatory effects of epidermal growth factor on deoxyribonucleic acid synthesis in the gastrointestinal tract of the suckling mouse

The effects of epidermal growth factor (EGF), cortisone and thyroxine on deoxyribonucleic acid (DNA) synthesis in the esophagus, stomach, small intestine and colon have been studied in suckling mouse. Daily administration of EGF [4 micrograms/g body weight (bw)/day] during 3 days to 8-day-old mice induced a significant increase of the incorporation of [3H]thymidine into DNA in the stomach, the small intestine, and the two halves of the colon. The DNA synthesis in the esophagus remained unaffected by the EGF treatment. The maximal increase of [3H]thymidine incorporation into DNA was observed in the colon, and represented 112%. Daily administration of cortisone acetate (25 micrograms/g bw/day) or thyroxine (1 microgram/g bw/day) during 3 days to 8-day-old mice had no significant influence of the DNA synthesis of any part of the gastrointestinal tract. These results show that EGF is able to affect the DNA synthesis in the stomach, small intestine and colon of suckling mice.     

Partial characterization of the gastrointestinal weight changes produced in the female rat by 16,16-dimethylprostaglandin E2

Oral and subcutaneous administration of 16,16-dimethylprostaglandin E₂ (16,16-dimethyl PGE₂) resulted in an increase in the dry weight of the stomach and small intestine of the female rat. This weight response was rapid, controlled rather than continuously progressing, dose dependent and reversible. The dry weight of the colon also increased but this was not studied in detail.Two-day treatment with 16,16-dimethyl PGE₂ caused an increase in the incorporation of ³H-thymidine into the duodenum, jejunum and colon suggesting an increase in cell number. Incorporation into the stomach and ileum was not changed.The number of goblet cells per crypt was increased by prostaglandin treatment in all parts of the small intestine. Since these are mucus producing cells, the small intestine may have increased in cell number and mucus production.Both anti-secretory and cytoprotective doses of 16,16-dimethyl PGE₂ caused weight increases in the stomach and small intestine. However, the weight gain by itself was not sufficient to protect the stomach or small intestine from necrotic agents after the prostaglandin was discontinued.