| 1. |
- Ekblad, Eva, et al.
(författare)
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Innervation of the small intestine.
- 2002
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Ingår i: Biology of the Intestine in Growing Animals. - 9780444509284 - 0444509283 ; , s. 235-235
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Intestinal activities are controlled and co-ordinated by way of neuronal reflexes involving both extrinsic and intramural neurones, the enteric nervous system (ENS). This review focuses on the organisation, development and functional properties of the intestinal innervation and of the neurotransmitters utilised.
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| 4. |
- Li, Zhao-Qi
(författare)
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Mechanisms of secretagogue action in isolated parietal cells
- 1995
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The mechanisms of secretagogue action and various intracellular events in isolated pig and rat gastric parietal cells were investigated. The response to gastrin in aminopyrine accumulation, an index of the acid produced and n·apped by the cells, was ilifferent in pig and rat parietal cells. In pig, gastrin alone stimulated (unaffected by H2 antagonist ranitidine) and potentiated the action of histamine, IBMX, DBcAMP and Sp-cAMP[S]. In rat cells, gastrin alone was ineffective but potentiated the actions of histamine, DBcAMP and Sp-cAMP[S]. The stimulation of aminopyline accumulation by the acetylcholine analogue carbachol, or by gastrin (in pig), was dosedependently inhibited by the protein kinase A inhibitor Rp-cAMP[S]. In rat cells, histamineandDBcAMP-stimulated aminopyrine accumulations were dose-dependently inhibited by the intracellular Ca2+ chelator BAPT A. The basal intracellular cAMP content in pig palietal cells was 3.5-fold higher than that in rat parietal cells. Although IBMX slightly increased cAMP content, it was not enough to increase aminopyrine accumulation in rat. Histamine combined with IBMX increased the cAMP content by 8- to 38-fold. The aminopyrine accumulation, however, was not stimulated further than that observed with histamine-stimulation alone. Gasn·in increased cytosolic free Ca2+ in both pig and rat palietal cell. Basal Ca2+ was reduced by the intracellular Ca2+ chelator BAPTA, and both gasn·in- and carbachol-induced increases in cytosolic free Ca2+ were abolished by the inclusion of BAPT A. Gastrin was as efficient as histamine in inducing the formation of vacuolar/canalicular spaces in the parietal cells, i.e., inducing a secretion-associated morphology. Ranitidine abolished histamine- but not gasn·in-induced morphological n·ansformation. In the presence of BAPTA, the morphological transformations induced by either gastrin, the cAMP analogues DBcAMP or Sp-cAMP[S] were completely abolished. It is concluded that: I) gastrin has a direct action on the parietal cells; 2) species difference of gastrin action seems to be related to different basal cAMP contents; 3) Ca2+. dependent morphological transformation is essential for aminopyrine accumulation; and 4) a threshold level of either Ca2+ or cAMP seems to be required for the stimulation by the other second messenger.
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| 5. |
- Ludvigsen, Eva, 1974-
(författare)
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Somatostatin Receptor Expression and Biological Functions in Endocrine Pancreatic Cells
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 diabetes is resulting from the selective destruction of insulin-producing beta-cells within the pancreatic islets. Somatostatin acts as an inhibitor of hormone secretion through specific receptors (sst1-5).All ssts were expressed in normal rat and mouse pancreatic islets, although the expression intensity and the co-expression pattern varied between ssts as well as between species. This may reflect a difference in response to somatostatin in islet cells of the two species.The Non-Obese Diabetic (NOD) mouse model is an experimental model of type 1 diabetes, with insulitis accompanied by spontaneous hyperglycaemia. Pancreatic specimens from NOD mice at different age and stage of disease were stained for ssts. The islet cells of diabetic NOD mice showed increased islet expression of sst2-5 compared to normoglycemic NOD mice. The increase in sst2-5 expression in the islets cells may suggest either a contributing factor in the process leading to diabetes, or a defense response against ongoing beta-cell destruction.Somatostatin analogues were tested on a human endocrine pancreatic tumour cell line and cultured pancreatic islets. Somatostatin analogues had an effect on cAMP accumulation, chromogranin A secretion and MAP kinase activity in the cell line. Treatment of rat pancreatic islets with somatostatin analogues with selective receptor affinity was not sufficient to induce an inhibition of insulin and glucagon secretion. However, a combination of selective analogues or non-selective analogues via co-stimulation of receptors can cause inhibition of hormone production. For insulin and glucagon, combinations of sst2 + sst5 and sst1 + sst2, respectively, showed a biological effect.In summary, knowledge of islet cell ssts expression and the effect of somatostatin analogues with high affinity to ssts may be valuable in the future attempts to influence beta-cell function in type 1 diabetes mellitus, since down-regulation of beta-cell function may promote survival of these cells during the autoimmune attack.
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| 7. |
- Sundler, Frank, et al.
(författare)
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GI Tract, General Anatomy (Cells)
- 2004
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Ingår i: Encyclopedia of Endocrine Diseases. - 0124755704 - 9780124755703 ; , s. 208-215
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Tømmerås, Karin, et al.
(författare)
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Effects of Extracellular Matrix Proteins on Development of Fetal Rat Gastric Epithelial Cells in Culture
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Undifferentiated fetal gastric epithelial cells and stem cells of adult gastric glands give rise to surface mucous, parietal, mucous neck, zymogenic, caveolated, and endocrine cells by yet-unknown mechanisms. Our aim was to establish an in vitro model for investigating the effects of extracellular matrix proteins on development of gastric epithelial cells, and to determine whether collagen type I affects growth and maturation of undifferentiated epithelial cells. Fetal rat gastric cells were isolated and then cultured for 15 days on uncoated glass coverslips or on collagen types I or IV, fibronectin, or laminin. The appearance of epithelial cells was investigated by means of Alcian blue-periodic acid Schiff (AB-PAS) staining, inununostaining for cytokeratin, H,K-ATPase and chromogranin A, acridine orange accumulation, and by transmission and scamting electron microscopy. AB-PAS-positive cells containing mucous-type granules were detected. These mucoid cells were abundant on uncoated coverslips and collagen, but scarce on fibronectin and laminin. No cytokeratin, H,K-ATPase or chromogranin A, or increased acridine orange accumulation in response to secretagogues were observed. Rarely, endocrine cells were observed by electron microscopy. In conclusion, undifferentiated epithelial cells did proliferate and differentiate, and mucoid and endocrine cells matured in the established in vitro system. Moreover, development of mucoid cells from undifferentiated gastric epithelial cells was stimulated by collagen matrices but inhibited by fibronectin and laminin.
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