Serotonin,reserpine, and motility inMesocestoides tetrathyridia

The relationship between serotonin (5-HT) and motility in tetrathyridia ofMesocestoides vogae (syn.M. corti) was studied with the aid of reserpine. Reserpine decreases the content of 5-HT as measured spectrofluorometrically and immunocytochemically and, furthermore, inhibits the motility, thus indicating a connection between the two. The results support the hypothesis about 5-HT being an excitatory neurotransmitter of motor activity inM. vogae. New neuroanatomical details were revealed by immunocytochemical staining.     

Serotonin uptake inhibition: in vivo effect of sertraline in rats.

Sertraline, a potent and selective serotonin uptake inhibitor, was used to analyze the changes occurring in the serotonin system after uptake inhibition in vivo. Sertraline (11 mg/kg) lowered extracellular 5-hydroxyindolacetic acid (5-HIAA), measured in rat hippocampus by in vivo voltammetry, for about 3 h. The interaction between sertraline and drugs known to interfere with the release or uptake of serotonin (L-5-hydroxytryptophan (5-HTP), d-norfenfluramine and tianeptine) was then studied. The sertraline-induced decrease in extracellular 5-HIAA was related to the inhibition of uptake.     

Histopathological effect of Clostridium perfringens enterotoxin in the rabbit ileum.

Highly purified enterotoxin from Clostridium perfringens was found to have histopathological activity in the rabbit ileum. Unlike the action of cholera, Escherichia coli, and Shigella enterotoxins, epithelium was denuded from the tips of ileal villi at concentrations of the enterotoxin necessary to induce fluid accumulation in the rabbit. Whether or not this observed histopathology is essential for the diarrheal syndrome associated with Clostridium perfringens food poisoning remains unclear.     

Investigation into the effects of mosapride on motility of Guinea pig stomach,ileum, and colon

Mosapride citrate (Mosapride) is a new prokinetic agent that enhances the gastrointestinal (GI) motility by stimulation of 5-HT4 receptors. This agent stimulates acetylcholine release from enteric cholinergic neurons in the GI wall. It was reported in several studies that mosapride selectively enhanced the upper, but not lower, GI motor activity. However, in these studies other 5-HT4 receptor agonists exerted stimulating effects on the motility of the colon. Moreover, it is well known that the receptors of 5-HT4 are also located in the colon. The purpose of this study was to estimate the effect of mosapride on the motility of the stomach, ileum and colon in the guinea pig and to investigate whether or not mosapride influenced the colonic motility. Mosapride significantly increased the amplitude of the contraction waves in the guinea pig stomach by electrical stimulation. In addition, it significantly increased the number of peaks, the area under the curve and the propagation velocity of the peristaltic contraction of the guinea pig ileum in a concentration dependent fashion. Mosapride also significantly shortened the transit time of the guinea pig colon. Accordingly, we concluded that mosapride exerted prokinetic effect on the entire GI tract of the guinea pig. Based on the possibility of similar results in humans, we suggest the potential use of mosapride for lower GI motor disorders such as constipation and upper GI motor disorders such as gastroesophageal reflex disease or gastroparesis.     

The effect of helper component on the uptake and localization of potyviruses in Myzus persicae

125I-labeled virions were used to determine whether helper component (HC) affected the uptake or distribution of potyviruses in aphids. Aphids were allowed to acquire purified, 125I-labeled tobacco etch virus or potato virus Y mixed with HC or with inactivated HC. Helper component had no effect upon uptake of labeled virus, as measured by gamma counting. Autoradiography of freeze-sectioned aphids revealed, however, that in the presence of HC, label was associated with the maxillary stylets and with portions of the alimentary canal anterior to the gut, as well as with the gut region. Label accumulated only in the gut in control aphids. This selective localization of virus acquired in the presence of HC supports a binding mechanism for the mode of action of HC.     

Intestinal morphology, marker enzymes and lipid content of brush border membranes from rabbit jejunum and ileum: effect of aging

Aging is associated with changes in the intestinal uptake of nutrients. This study was undertaken to determine whether the morphology, enzyme markers and the lipid content of the intestinal brush border membrane (BBM) was influenced by aging. There was an increase in the height of the jejunal villi and number of cells/villus, resulting in an age-related increase in the jejunal villus and mucosal surface area in young as compared with weanling rabbits. In mature 1-year-old animals, there was a decline in villus height, number of cells/villus, and mucosal surface area, so that the jejunal characteristics of the mature animals resembled those of the weanling rabbits. In the ileum, aging was associated with an increase (weanling vs. young), then a decrease (young vs. mature) in the height of the villi, and the number of cells/villus. Aging had no effect on the size of the villus cells. At all ages there was a direct positive relationship between the height of the villi and the mucosal surface area, and between villus surface area and sucrase activity. An established technique was used to purify rabbit BBM and to measure the BBM content of enzyme markers and lipids in weanling, young and mature animals. Both the BBM sucrase (S) and alkaline phosphatase (AP) increased in young as compared with weanling rabbits, and the ratio of AP/S remained unchanged. The S remained high in mature rabbits, but AP declined, so that AP/S fell. There was a positive linear correlation between S and villus surface area. In weanling rabbits, the total BBM phospholipid content and the ratio of total phospholipid/total cholesterol were lower in the ileum than in the jejunum. In the jejunal BBM of young animals, there was more total free fatty acids and cholesterol ester than in the weanling jejunum. The jejunal BBM total phospholipids and total cholesterol were higher in the mature than in the weanling animal jejunum when expressed as nmoles/mg protein, but the ratio of total phospholipid/total cholesterol was unaffected by aging. The greatest percentage of jejunal BBM phospholipid was comprised of lecithin and phosphatidyl ethanolamine. The increased BBM total phospholipid content in mature animals was associated with a higher amount and lower proportion of lecithin, but a higher proportion of sphingomyelin and phosphatidyl serine.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effects of capsaicin on the circular muscle motility of the isolated guinea-pig ileum

Effects of capsaicin on the circular muscle motility of the isolated guinea-pig ileum were investigated. Capsaicin produced a contraction followed by a relaxation of the circular muscle. Both responses were easily desensitized. As the late relaxation response was not sufficiently intense to be analyzed, the inhibitory effect of capsaicin on substance P-induced contractions was explored. Capsaicin abolished the substance P-induced contractions. This inhibitory effect was not affected by tetrodotoxin, and the effect was desensitized. Therefore, all effects of capsaicin on circular muscle motility seem to be due to the release of sensory neuropeptides, similarly to those elicited in the longitudinal muscle.     

Real-time measurement of serotonin release and motility in guinea pig ileum

Enterochromaffin (EC) cells are sensors that detect chemical or mechanical stimuli and respond with release of serotonin (5-HT). 5-HT activates local motor reflexes, but whether local motor reflexes also evoke 5-HT release is unknown. The aim of the present study was to establish the relationship between the release of 5-HT and the enteric neural circuits controlling the movements of the intestine. Recordings were made from full-thickness preparations of guinea pig ileum using electrochemical techniques with carbon fibre electrodes to measure local concentrations of 5-HT. The tension in the circular muscle (CM) and longitudinal muscle (LM) was recorded with force transducers. The release of 5-HT from the EC cells was detected selectively and the timing of the events quantified. Pressure-evoked peristalsis caused detectable 5-HT release only when the recording site was invaded by a ring of CM contraction. Spontaneous and stretch-evoked reflex contraction of the CM and LM occurred simultaneously with 5-HT release. Paralysis of the smooth muscle significantly reduced the stretch-evoked release. Muscarinic agonists evoked reflexes that were associated with increases in tension in CM and LM simultaneous with 5-HT release. Tetrodotoxin abolished the coordination between the CM contraction and 5-HT release but not the direct activation of the CM and EC cells by the agonists. In conclusion, the correlation between local motor reflexes and 5-HT release observed in the present study is caused primarily by the contraction of the smooth muscle and subsequent deformation of the mucosa. The EC cell is, thus, a site of convergence for mechanical forces that contribute to the release of 5-HT during motor reflexes.     

Short-circuit current and total conductance measurements on rabbit ileum.

1. Short-curcuit current (SCC) and total conductance (Gt) measurements were made in in vitro preparations of rabbit terminal ileum. 2. Successive additions of D-glucose increased the SCC and Gt in a stepwise way and both effects were seen to correlate linearly. 3. Measurements of SCC ant Gt were also made after replacing Na in the Krebs solution by K or sucrose. The SCC decreased to nearly zero in both cases but the decrease in Gt was larger when sucrose was used. 4. SCC and Gt were monitored after the addition of ouabain. SCC decreased to nearly zero but Gt remained constant. 5. On successive additions of sucrose after the preparation was mounted in 1/4 Na Krebs without osmolal compensation, SCC decreased and Gt increased, a linear relationship being found between both changes. 6. Successive additions of 2-deoxy-td-glucose caused a stepwise decrease of SCC and an increase in Gt. These effects seemed independent of the presence of glucose. 7. A model in which a resistance in series is added to the basic model by Ussing & Windhager (1964), modified by Rose & tschultz (1971), is proposed to account for these findings.     

Salmonella 3, 10:r: toxicity in rabbit ileum and liver by light and electron microscopy

Salmonella 3, 10:r:- (a monophasic variety of otherwise diphasic serotypes such as S. weltevreden and S. simi) Cell_free filtrate, when introduded into rabbit ligated ileal loops causes fluid exsorption, as studied 18-hr after treatment. Light microscopic histology of treated ileum shows denudation of the columnar epithelium at several places, thereby allowing the passage of the toxic principle into circulation. An important target organ, liver shows extensive centrilobular necrosis, as observed by light microscopy. Transmission electron microscopy of ileum reveals opening of membrane junctions between the adjacent cells of epithelial lining of the treated ileum at places, and focal devitalization including formation of intra-cellular membranous inclusinos. Electron microscopy of liver shows extensive damage and swelling of cytoplasmic membranes. However, the areas of darkly staining lamellae of granulated endoplasmic reticulum are also seen in stacks as will as dispersed. These studies stress that Salmonella toxic substances can cause extensive damage to intestine and liver both.     

Histochemical localization of NADPH-diaphorase in neurons of the pheasant ileum

Localization patterns of NADPH-diaphorase-positive neurons in the pheasant ileum were investigated using an enzyme histochemical method. NADPH-diaphorase activity in the pheasant ileum was demonstrated in neuronal cells bodies and nerve fibres. The NADPH-diaphorase-positive nerve cells showed a polygonal shape and were present solitary or arranged in groups in the submucosal and muscular layers. Nerve fibres penetrated the wall of the ileum at its serosal surface, frequently in the vicinity of ileal arterial branches. They were abundantly present in muscular and submucosal layers of the ileum forming thicker nerves. Some nerve fibres traversed the submucosa into the lamina propria mucosae to form dense nerve plexuses. Fine nerve fibres were found to penetrate into intestinal villi encompassing the crypts underneath the epithelium. We conclude that the pheasant ileum is characterized by abundance of NADPH-diaphorase-positive nerve structures which may play a significant functional role in the small intestine of the pheasant.     

Autoradiographic localization of putrescine uptake to type II pneumocytes of rabbit lung slices

At low concentrations (0.4-5.0 microM), the polyamine, putrescine, is accumulated predominantly by a saturable process in rabbit lung slices. The question of why the lung should possess polyamine transport capabilities and the known cellular compartmentalization of various other pulmonary functions prompted us to investigate whether putrescine uptake was localized to a specific cell type(s) within rabbit lung. Localization of putrescine uptake in rabbit lung was investigated by frozen and plastic section autoradiography, combined with electron microscopy. Rabbit lung slices were incubated with [3H]putrescine at a concentration (0.4 microM) at which the saturable component of uptake predominates. Both frozen and plastic section autoradiograms revealed relatively minor amounts of radiolabel associated with either vascular or bronchiolar tissues, whereas a greater density of radiolabel was present over the alveolar epithelium. Highly localized areas of radiolabel were found at the junctions of adjacent alveoli and these labeled cells were identified by electron microscopy as type II pneumocytes. We conclude that the type II pneumocyte is a major site of putrescine uptake in rabbit lung slices. Our study also indicates that different rabbit lung cell types possess differing abilities to accumulate putrescine.     

Observations on the solitary cilium of rabbit oviductal epithelium: Its motility and ultrastructure

Solitary cilia have been observed on rabbit oviductal epithelial cells. In tissue cultures of fimbrial epithelium of 3- and 4-day-old animals observed by phase microscopy, most of these single cilia exhibited a vortical or funnel-type movement while others had the usual to-and-fro motility. Primary cilia are usually considered immotile. Transmission electron microscopy of specifically identified single cilia revealed differences between the ciliary shafts and basal bodies of the single cilia as compared to those of mature oviductal ciliated cells. The basal body of the solitary cilium often had at least two triangular, striated, basal foot processes, lacked electron-dense satellite material around its basal end, and occasionally had striated rootlets. In contrast, the cilia of mature ciliated cells had only one basal foot, exhibited much electron-dense satellite material, and lacked rootlets. Cross sections of the single cilia showed patterns of microtubules different from the usual 9 + 2 axonemal complexes of normal cilia and included 9 + 0, 10 + 2 singlets, 7 + 2 doublets, and 8 + 1 doublet and 2 singlets; one did have the usual 9 + 2 arrangement. We postulate that the presence of more than one basal foot process may be responsible for the vortical motility observed. The primary cilia are shorter than normal cilia; the longest one measured was 1.86 μm in length, 0.28 μm in width at its base, and 0.14 μm at its tip. Based on the lightmicroscopic, scanning-electron-microscopic and transmission-electron-microscopic observations, such solitary cilia were observed more frequently in the oviductal tissues of the 3- to 4-day postnatal rabbits grown in tissue culture and in ovariectomized and ovariectomized/progesterone-treated adult animals than in estrous, ovulatory, or ovariectomized/estradiol-treated rabbits.     

Migrating action-potential complexes in vitro in cholera-exposed rabbit ileum

The objective of this study was to determine whether cholera-exposed rabbit ileum exhibits altered myoelectric activity in vitro, without central nervous system connections. Whole-cell lysate of Vibrio cholerae, 100 mg in 1 ml saline, was injected into the jejunum of New Zealand White rabbits. Segments of ileum were removed at 12 and 24 h after inoculation and studied in vitro using myoelectric recording techniques. Propagating ring contractions were visualized and corresponded to intense action-potential activity that propagated over consecutive electrode sites. This altered myoelectric activity was similar to the previously described migrating action-potential complex (MAPC) in vivo after infection of rabbit ileum with live V. cholerae, its wholecell lysate, or the purified enterotoxin choleragen, with one exception. All MAPC activity propagated aborally in the in vivo-infected loops; in contrast 26% of the MAPCs propagated retrograde in the in vitro loops. Control segments were injected with saline, and no in vitro MAPCs were observed. Thus, the MAPC stimulated by cholera toxin may be maintained by the enteric nervous system of the gut wall. Although a role for extrinsic nerves is not excluded, our observations suggest that the small intestine may work autonomously, independent of the central nervous system.     

Effect of vitamin A intake on absorption and localization of zinc in the chick ileum

Laboratory of Biochemistry and Physiology of Animals, Institute of Biology, Academy of Sciences of the Latvian SSR, Salaspils. Department of Histology, Riga Medical Institute. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 7, pp. 37–40, July, 1989.