Anti-ulcer agents exert various functional effects on gastric epithelial cells.
The effects of a novel gastro-cytoprotective agent (rebamipide) on epithelial restoration following bile acid damage ...were assessed using primary cultured rabbit gastric epithelial cells.
Rebamipide was added to complete confluent cell sheets with deoxycholic acid just after creating a cell-free wound (2 mm2). The restoration was monitored and analysed by phase contrast microscopy and an image analyser for 48 h. The migration speed was measured during the initial 3 h after wounding. Cell proliferation was detected by staining for bromodeoxyuridine (BrdU) at 12-h intervals. The labelling index was calculated per unit area. The major cytoskeletal protein actin was detected by immunohistochemical staining.
In the controls, restoration was completed 48 h following wounding. Deoxycholic acid retarded this process. The addition of rebamipide to deoxycholic acid abolished the bile acid-induced retardation. The migration speed was 26 microns/h in the controls. 15 microns/h in the deoxycholic acid group and 27 microns/h in the deoxycholic acid plus rebamipide group. In the controls, BrdU-positive cells, which were rarely detected in the initial 24 h, were maximal at 36 h (labelling index 1.7%). In the deoxycholic acid group, proliferation was inhibited (peak labeling index; 0.5% at 48 h). Actin-containing stress fibres were detected throughout the cells and the periphery of the lamellipodia in the controls, and were disrupted in the deoxycholic acid-treated group. Rebamipide prevented these effects.
Deoxycholic acid significantly retarded restoration by the inhibition of both cell migration and proliferation, potentially through an effect on the cytoskeleton. Rebamipide protected the mucosal cells from bile acid mediated injury.
The hepatotoxic effects of alcohol have been described in detail, but factors responsible for its hepatotoxicity have only partially been characterized. For example, it is known that chronic ethanol ...ingestion increases hepatotoxicity and produces fatty liver, hepatitis and cirrhosis. However, acute ethanol consumption reduces endotoxin hepatotoxicity. It now appears that Kupffer cells participate in several aspects of these phenomena. Previously, most studies on the effects of alcohol on liver function have focused chiefly on the hepatocyte. Recently, attention has been directed towards the effect of ethanol ingestion on Kupffer cell function, which is stimulated by gut-derived endotoxins (lipopolysaccharides) via mechanisms dependent on increased gut permeability and the possible relationship between Kupffer cells and alcohol-induced liver injury. Here we will review new evidence for the proposal that Kupffer cells and endotoxins play a pivotal role in hepatotoxicity following alcohol exposure, based on studies using the continuous intragastric enteral feeding model developed by Tsukamoto and French and an acute model developed by us.
This study investigates the possible role of Kupffer cells in storage and metabolism of benzo(a)pyrene in the liver. In perfused liver, benzo(a)pyrene (4-120 microM) in 0.3% albumin increased ...fluorescence (366-->405 mm) on the liver surface in a dose-dependent manner, suggesting that it accumulated in liver tissue. The maximal increase of benzo(a)pyrene fluorescence was diminished by 60% when Kupffer cells were destroyed by gadolinium chloride treatment (10 mg/kg iv). Gadolinium chloride also decreased the yield of isolated nonparenchymal cells by 65%. In frozen sections of livers perfused with 4 microM benzo(a)pyrene for 1 hr, fluorescence was approximately 5 times greater in cells lining the sinusoids than in parenchymal cells. Moreover, yellow-green fluorescent particles were detected in cultured Kupffer cells, but were barely visible in parenchymal and Ito cells, indicating that Kupffer cells actively accumulated benzo(a)pyrene. In contrast to the cell specificity for benzo(a)pyrene accumulation, rates of monooxygenation of benzo(a)pyrene were up to 20-fold higher in isolated parenchymal than in Kupffer cells. In nonparenchymal cells, basal rates of production of benzo(a)pyrene phenols were approximately 50 pmol/10(6) cells/hr. In contrast, rates were approximately 335 pmol/10(6) cells/hr in parenchymal cells. Further, total 3Hbenzo(a)pyrene metabolism was approximately 8-fold higher in parenchymal than in nonparenchymal cells. Albumin increased production of benzo(a)pyrene phenols by 3-fold in parenchymal cells, but was without effect in nonparenchymal cells. Pretreatment of rats with gadolinium chloride increased the production of benzo(a)pyrene phenols in perfused liver by > 50%.
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