Transit Time Changes with Age in the Gastrointestinal Tract of the Rat

Varga, F

doi:10.1159/000197947

Cited by 77 publications

(39 citation statements)

References 3 publications

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“…For example, decreased esophageal (Butt et al, 1993) and colonic (Madsen, 1992) motility, delayed gastric emptying (Van Leire and Northup, 1941;Moore et al, 1983;Horowitz et al, 1984;Wegener et al, 1988;Clarkston et al, 1996;Brogna et al, 1999), and increased intestinal transit times (Brocklehurst and Khan, 1969;Anuras and Leoning-Baucke, 1984) occur with aging. Similar age-related changes in GI function have been reported for the rat (delayed gastric emptying: Smits and Lefebvre, 1996; increased intestinal transit times: Varga, 1976;McDougal et al, 1984; decreased fecal output: Smits and Lefebvre, 1996). GI diseases also occur more frequently in elderly than in younger populations (Shamburek and Farrar, 1990).…”

Section: Indexing Terms: Autonomic Nervous System; Vagus; Myenteric; supporting

confidence: 64%

“…The present study and others suggest that neuronal loss in the gut is a progressive degenerative process of aging, and not a result of the natural developmental elimination of redundant neurons. Relevant observations include: (1) loss of redundant connections usually occurs soon after the successful completion of neuronal wiring, not over the adult lifespan of the animal Purves and Lichtman, 1980); (2) evidence for our "neuroprotective hypothesis" predicting that the deterioration of the extrinsic sympathetic motor innervation of the gut is responsible for the concurrent loss of myenteric cells ; (3) GI function gradually declines in aging rats (e.g., Varga, 1976;McDougal et al, 1984;Smits and Lefebvre, 1996), counter to the developmental axiom of enhanced or optimal function being produced by the pruning of ineffective neurons and circuits; and (4) differential loss of myenteric neurons in the various regions of the GI tract (i.e., no cell loss in the stomach until almost the maximum lifespan has been reached, whereas, cell loss in the intestines occurs across the adult lifespan of the rat) is inconsistent with a global developmental scheme. For these reasons, deterioration of the myenteric innervation of the gut does not appear to be a reflection of the normal development of the enteric nervous system (i.e., those changes in the nervous system that result in functionally appropriate cell numbers or axonal wiring and connections); rather, it appears to be a process of gradual deterioration that eventually results in a decline in function.…”

Section: Myenteric Cell Loss: Developmental Ormentioning

confidence: 99%

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As the gut ages: Timetables for aging of innervation vary by organ in the Fischer 344 rat

Phillips

Powley

2001

J of Comparative Neurology

105

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To explore the effects of aging on the vagal innervation of the gastrointestinal (GI) tract, male Fischer 344 rats at 3 and 24 months of age were injected in the left nodose ganglion with 3 microl of either 4% wheat germ agglutinin-horseradish peroxidase (to label sensory endings) or 1% cholera toxin subunit B-horseradish peroxidase (to label motor endings). The stomach and duodenum were prepared as wholemounts and processed with tetramethyl benzidine. In addition, to study age-related changes in the myenteric plexus, the stomachs, small intestines, and large intestines from 3-, 12-, 21-, 24- and 27-month-old rats were prepared as wholemounts and processed with Cuprolinic Blue (to stain the neurons). Vagal afferent endings, motor terminal profiles, and myenteric neurons were counted and mapped with a sampling grid. In the stomach, both the vagal and myenteric innervation were stable between the ages of 3 and 24 months; however, a decrease in the number of myenteric neurons in the forestomach was noted at 27 months. In the small and large intestines, myenteric cell loss occurred by 12 months of age, progressed with age, and appeared to be governed by several general principles: (1) the rate of cell loss was organ-specific, with a gradient of increasing severity from proximal to distal in the gut; (2) within organs of the GI tract, the rate of cell loss differed between regions; and (3) for given regions, cell losses progressed linearly with increasing age. The findings suggest that a positive relationship exists between the density of vagal extrinsic innervation and myenteric neuron survival; however, whether this results from the vagal innervation and/or other factor(s) protecting or rescuing myenteric neurons from age-related attrition remains to be determined.

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Section: Indexing Terms: Autonomic Nervous System; Vagus; Myenteric; supporting

confidence: 64%

Section: Myenteric Cell Loss: Developmental Ormentioning

confidence: 99%

As the gut ages: Timetables for aging of innervation vary by organ in the Fischer 344 rat

Phillips

Powley

2001

J of Comparative Neurology

105

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“…However, there is no evidence of altered bowel habits towards constipation with advancing age per se [4], While in rats a marked prolongation of large intestine transit has been observed with in creasing age [26] we could not demonstrate any difference in whole-gut transit -mainly reflecting large-intestine transit -of a mixed solid-liquid meal including an unresorbable carbohydrate (lactulose) between young and old subjects with normal bowel habits. This observation corresponds to the findings of Melkerson et al [17], who did not find any age-related changes of intestinal transit of a radioisotope capsule in young and aged sub jects unaffected by constipation.…”

Section: Discussioncontrasting

confidence: 65%

Effect of Ageing on the Gastro-Intestinal Transit of a Lactulose-Supplemented Mixed Solid-Liquid Meal in Humans

Wegener¹,

Börsch²,

Schaffstein³

et al. 1988

Digestion

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Gastro-intestinal transit of a mixed solid-liquid meal containing wheat bread, scrambled eggs, coffee labelled with ^99mTc, orange juice with lactulose and indigocarmine was evaluated in 21 young control (mean age 33.5 years) and 25 elderly subjects (mean age 81.7 years) without gastro-intestinal complaints or severe medical illness. The rate of gastric emptying was determined by an anterior gamma camera technique, mouth-to-caecum transit by the hydrogen breath test and whole-gut transit by the first stool passage of indigocarmine. Gastric emptying was significantly prolonged in older subjects: t_½ = 136 ± (SEM) 13 versus 81 ± 4 min; p < 0.001. Concerning mouth-to-caecum or whole-gut transit time, significant differences between the two study groups were not detected.

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“…Alternatively, proteases may be progressively activated as they pass dis tally in the digesta, and mucosal enzymes acquired by exfoliation could contribute to this activity. Motility could also affect the concentrations of luminal proteases, since transit through the proximal small intestine is more rapid than that through the distal small intestine [23].…”

Section: Discussionmentioning

confidence: 99%

Development of Luminal Protein Digestion in Suckling and Weanling Rats

Britton

Koldovský²

1988

Neonatology

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Because previous measurements of early postnatal, small intestinal fluid, proteolytic activity in man and animals have been contradictory, we characterized the development of luminal protein digestion using a sensitive assay in which iodinated bovine casein was incubated in vitro at 37°C with luminal fluid flushed from the stomach and small intestine of 12-day-old suckling and 31-day-old weanling rats, followed by measurement of radioactivity in trichloroacetic acid-soluble material. Gastric proteolysis at pH 3.2 in the weanling rat was approximately 50-fold greater than that in the suckling rat. Analysis of stomach fluid acid-soluble casein degradation products of weanling rats by chromatography on G-50 Sephadex in the presence of sodium dodecyl sulfate revealed three peaks of radioactivity comprising 65, 18 and 12% of the total product in order of elution. In the jejunum at neutral pH, the proteolytic capacity of the weanling rat was approximately five times that of the suckling rat; such differences were more pronounced in the ileum, however, in which protein hydrolysis of weanling rats was 30-fold higher than that in the suckling rat. In the suckling rat, small intestine proteolytic activity was greater in the jejunum than in the ileum, but in the weanling rat greater protein hydrolysis was present in the ileum. Gel filtration analysis of reaction products in both intestinal segments and at both ages demonstrated two peaks, which constituted 60–70 and 15–23% of the acid-soluble material in order of elution. These studies demonstrate that luminal proteolysis increases in stomach and small intestine during postnatal development in the rat; moreover, segmental differences in proteolytic activity exist. Presumably, these findings reflect the balance between proteases and protease inhibitors from pancreatic secretions, desquamated intestinal epithelial cells, and diet.

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Transit Time Changes with Age in the Gastrointestinal Tract of the Rat

Cited by 77 publications

References 3 publications

As the gut ages: Timetables for aging of innervation vary by organ in the Fischer 344 rat

As the gut ages: Timetables for aging of innervation vary by organ in the Fischer 344 rat

Effect of Ageing on the Gastro-Intestinal Transit of a Lactulose-Supplemented Mixed Solid-Liquid Meal in Humans

Development of Luminal Protein Digestion in Suckling and Weanling Rats

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