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  • 1995-1999  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Increased intestinal glucose absorption and postprandial hyperglycaemia at the early step of glucose intolerance in Otsuka Long-Evans Tokushima Fatty Rats (1998)
    Springer
    Diabetologia 41 (1998), S. 1459-1466 
    Details
    ISSN: 1432-0428
    Keywords: Keywords OLETF ; xylose ; SGLT1 ; intestinal hypertrophy ; glucose absorption ; postprandial hyperglycaemia.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Otsuka Long-Evans Tokushima Fatty (OLETF) rats are reported to be obese Type II (non-insulin-dependent) diabetic rats with insulin resistance and impaired insulin secretion. To investigate the contribution of intestinal glucose absorption to postprandial hyperglycaemia, we determined the plasma xylose concentrations after an 0.8 g/kg oral xylose load which was used as a test of small intestinal glucose absorption in 6-week-old OLETF rats and weight-matched Long-Evans Tokushima Otsuka (LETO) rats. An oral glucose tolerance test showed that OLETF rats developed hyperglycaemia at 60 and 90 min after the glucose load, though the fasting plasma glucose concentration, insulin concentration and insulin-induced in vivo glucose utilization rate were similar. Consistently, in an oral D-xylose loading test, the peak concentration of plasma xylose in OLETF rats was increased by 58.7 % compared with that of LETO rats (p 〈 0.005). The disappearance rate of plasma xylose concentrations after intravenous xylose loading did not differ between the two strains. Co-treatment with 0.4 g/kg phlorizin, a specific inhibitor of sodium-dependent glucose transporter 1 (SGLT1), abolished both plasma glucose and xylose concentrations after the loads. Morphological studies showed that both the small intestinal wet weight and surface area were 30 % larger in the OLETF rats than in the LETO rats. Furthermore, the SGLT1 mRNA content of OLETF rats also increased compared with LETO rats. These results suggest that an increased SGLT1 expression concomitant with intestinal hypertrophy in OLETF rats is partly associated with postprandial hyperglycaemia before the onset of insulin resistance and hyperinsulinaemia. [Diabetologia (1998) 41: 1459–1466]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250051092
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Distribution of serotonin-immunoreactive nerve cells and fibers in the rat gastrointestinal tract (1997)
    Springer
    Histochemistry and cell biology 107 (1997), S. 105-114 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The distribution of serotonin-immunoreactive (5HT-IR) nerve cells and fibers was thoroughly investigated immunohistochemically in the rat stomach, duodenum, jejunum, ileum, and colon. The immunoreactivity of the 5HT neurons was compared between non-treated controls and animals treated with colchicine, colchicine plus 5-hydroxytryptophan (5HTP), colchicine plus pargyline, and reserpine. The intensity of immunoreactivity in nerve fibers as well as nerve cell bodies was enhanced mostly in colchicine plus pargyline treated animals, therefore these animals were used for an observation of precise localization of 5HT in the rat gastrointestinal (GI) tract. Immunoreactivity in the nerve cell bodies and fibers was completely abolished in the GI tract of reserpine treated animals. The pattern of localization and projection of 5HT-IR neurons was similar in all segments of the rat GI tract. 5HT-IR nerve cell bodies were located in the myenteric plexus and showed the distinctive features of Dogiel type I neurons. Prominent bundles of varicose fibers traversed the myenteric ganglia and some of them surrounded the cell bodies of immunopositive and immunonegative neurons. 5HT-IR nerve fibers were located in the submucous plexus, densely entwined about the submucosal blood vessels. Most characteristically, 5HT-IR nerve fibers invaded the lamina propria of mucosa where they underlay the crypt epithelium. In conclusion, the present study showed that 5HT-IR neurons located in the myenteric plexus projected fibers widely in the rat GI tract. The localization of fibers in the lamina propria of mucosa implies that this neuron may exert an important role in the epithelial function of the GI tract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050094
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Immunoelectron microscopic study of the luminal release of chromogranin A from rat enterochromaffin cells (1999)
    Springer
    Histochemistry and cell biology 111 (1999), S. 253-257 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Recently we found that raising the intraluminal pressure caused an increase in the luminal release of serotonin from enterochromaffin (EC) cells and serotonin immunoreactivity normally restricted within the secretory granules was diffusely scattered over the extragranular matrix. In the present study we investigated the intracellular localization of chromogranin A, a protein co-stored with serotonin in the EC cells, after stimulating the luminal release of serotonin. In situ vascularly and luminally perfused rat duodenum was exposed to intraluminal pressure and fixed for immunoelectron microscopic study. For immunoelectron microscopy, the pre-embedding DAB reaction for serotonin combined with the postembedding immunogold reaction for chromogranin A was used. Results showed that a number of secretory granules labeled with immunogold chromogranin A immunoreactivity located close to the apical plasma membrane. Some EC cells showed that one part of the apical cytoplasm was protruded into the lumen and a number of secretory granules with immunogold labeling were included in the protruded cytoplasm. These results suggest that EC cells may release chromogranin A into the intestinal lumen together with serotonin, by means of a different manner of secretion from that in serotonin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050355
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Immunoelectron microscopic study of the luminal release of serotonin from rat enterochromaffin cells induced by high intraluminal pressure (1997)
    Springer
    Histochemistry and cell biology 108 (1997), S. 105-113 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Since definitive morphological studies showing the luminal release of serotonin have not been reported, we used a perfused system which allows physiological monitoring and biochemical as well as morphological evidence indicating release of serotonin from enterochromaffin cells. Isolated vascularly and luminally perfused rat duodenums exposed to 5–35 cmH2O of luminal pressure were measured for release of serotonin into the blood vessels and intestinal lumen. Immediately after raising the luminal pressure, the duodenum was fixed for immunoelectron microscopic localization of serotonin. Peristaltic contraction and serotonin content of the perfusates were continuously measured. The luminal release of serotonin increased with elevated intraluminal pressure, but the vascular release of serotonin was not altered. Tetrodotoxin had no effect on the pressure-stimulated luminal serotonin release. Enterochromaffin cells in control animals without increased luminal pressure contained immunogold-labeled secretory granules in the apical and basal cytoplasm. After intraluminal pressure increased, many apical secretory granules were no longer dense and immunogold particles were localized over the cytoplasmic matrix and microvilli. These findings indicate that luminal serotonin release is increased after raising the intraluminal pressure and serotonin, normally stored in the secretory granules of enterochromaffin cells, appears to be released into the cytoplasmic matrix and then diffuses or is transported into the intestinal lumen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050151
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    Paper (German National Licenses)
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