| AIMsW. Beaumont had found that excessive drinking cause gastric bleeding before 170 years. The effect of alocohol and alcoholic beverage on stomach was studied only before 15 years. It was verified that the alcohol concentration above 14% in gastric lumen could injure the gastric barrier directly. The alcohol concentration and the intact period on gastric mucosa depend injury situation. The ethanol supplied into the stomach induce gastric injury by penetrating the mucosa owing high liposolubility. The pathological alterations are gastric blood flow stasis, increased penetration, albumin macromolecule leakage, extensive blood vessel damage, mucosa hyperemia, gland hyperlasia, erosion and bleeding. On the field of pathophysiology, large dose and high concentration of ethanol impairs the synthesis of mucin oligosaccharide structures which required for the retention on the mucosal surface.At present, there have been many studies of acute injury of high concentration of ethanol on gastric mucosa, most concentrated on 75% - 100% , and the intact period were centered on minutes to hours. Acute ethanol induced gastric mocosa erosion, bleeding , even ulcer. On the contrary, there has been little study on long period administration of little dose and low concentration of ethanol on gastric mocosa and the inducing gasitric mocosa atrophy.The concept of " adaptive cytoprotection" introduced by Robry at the late of 70's is the hot spot of gastric cytoprotection investigation. The adaptive cytoprotection is the protective reaction of gastric mucosa to the strong stimulation after given mild stimulation. The premier studies found that little dose and low con-centration of ethanol could induce gastric mucosa adapt to later acute and large dose of ethanol supply. It is not clear that whether long period of low dose of ethanol could injure the gastric mucosa and the alteration of mucosa, the reaction of chronic injured mucosa to the acute high concentration of ethanol is not clear.We established animal model of chronic ethanol injury on gastric mucosa in this study, and observed the alteration of gastric mucosa to chronic ethanol injury , examined gastric blood flow ( GBF) , serum or plasma level of nitric oxide (NO) ^endothelin( ET) NprostaglandinE( PGE) , and the expression of protein and mRNA of tumor necrosis factor a (TNFa) , inducible nitric oxide synthase (iNOS) , vascular endothelial growth factor(VEGF) at different stages,as well as investigated the mechanism of gastric adaptive cytoprotection to chronic ethanol injury.Methods1. Animal model establishment104 wister rats aged 8 weeks were subjected to 4 groups randomly. Among them, 24 rats were in control group A and 24 rats in control group B. 27 rats were in model group A and 29 rats in model group B. After 1 week of adaptive feeding, the model rats received alcohol at a dose of 50% , 8g kg - 1 day - 1, three times a day by intragastric perfusion for 12 weeks. The control group was treated with physiological saline in the same way as model group. At the end oï¿¡2, 4, 8, 12 weeks of perfusion, 6 rats in each control groups A and 8, 7, 6, 6 rats in model group A were kiUed respectively. According to the above period, administrated 100% ethanol lml to control group B and model group B, killed 6, 6, 6, 6 rats in control group B and 9, 7, 6, 6 rats in model group B after 1 hour respectively. Collected blood from left ventricle and fixed through heart.2. Detecting data and methodsDetected GBF with laser Doppler flowmetry, detected plasma ET level by RIA method and serum NO level by nitrate reductase method, determined the plasma PGE level by ELJSA method. Observed gastric mucosal pathological al-ternation by HE stain, observed ultra structure and apoptosis of gastric mucosa by transmission electron microscope. Detected the expression of TNFouiNOSN VEGF in gastric mucosa with inmmunohistochemistry ABC method, and determined the express of protein and mRNA of TNFouiNOS^VEGF by Western -blot and RT - PCR.Result1. The general condition of rats in model group was bad comparing to rats in control group. They were irritability and light weight ( P <0.01). The fur of rats in model group was shineless, There were significant difference between control groups and model groups (P<0.01), as well as compared to premier stage (P<0.01).2. Pathologic changes gastric mucosa in control group A showed normal, at the end of 2 weeks, the rats gastric mucosa of model group A displayed dot e-rosion, hyperemia and edema, neutrophil infiltration. At the end of 4 weeks, gastric mucosa showed local dot erosion, damage length < 4 mm, epithelium was damaged and exfoliation, also showed hyperemia and edema, neutrophil infiltration. Midst and underlayer glands were normal. At the end of 8 weeks, there were multi - erosion, chief cell and parietal cell swelling and decreased in quantity, various kinds of inflammatory cell infiltrated. At the end of 12 weeks, small ulcer can be seen, gland was atrophy and the number of chief cell and parietal cell decreased further, lymphocyte and plasma cell infiltrated. There were significant difference of lesion index and histological index between control group A and model group A ( P < 0.01).gastric mucosa in control group B manifested as extensive erosion and bleeding, normal structure disappeared under microscopy, cell in surface and deep sites necrosis, large amount of neutrophil infiltrated. Comparing to control group B, the alternation of model group B were relative mild ( P < 0. 01). But in the rats at the end of 12 weeks, the gastric injury was as serious as control group B.3. Changes under transmission electron scope Apoptosis can be seenmostly in model group. Chief cell nucleus shrinkaged with heterochromatin mar-ginating as demilune. Rough endoplasmic reticulum distended to cistema and breakaged, dibosome decreased, mitochondria showed vacuolar degeneration with ridge breakaged and dissolved. Vesicle can be seen around the parietal nucleus, Apoptotic body was observable.4. Along with the prolong of ethanol stimulation, comparing to control group A, GBF decreased gradually, ET and NO level increased gradually in model group A ( p < 0.01)5. Immuhistochemistry The expession of iNOS^TNFa of model group A in gastric mucosa significantly increased comparing to control group A ( p <0.01). In congtrol group A, iNOS ? TNFa expressed little amount. At the end of 2weeks, 4weeks and 8 weeks, they expessed increased comparing to congtro group A (p < 0. 01 ) , and there was significant difference of iNOS expression compared to premier stage (p <0.05) , but TNFa decreased observably at the end of 12 weeks comparing to 8 weeks.6. Western - blot iNOS N TNFa protein expressed little in control group A, iNOS protein increased gradually along with the stimulation, TNFa protein incereaed at the end of 2weeks, 4weeks, 8 weeks, but decreased observably at the end of 12 weeks comparing to 8 weeks.7. RT - PCR Chronic ethanol stimulation significantly increased the expression of iNOSmRNA^TNF - mRNA in model group A ( p < 0. 01) , iN-OSmRNA increased gradually along with the stimulation, TNF - mRNA incereaed at the end of 2weeks, 4weeks, 8 weeks, but decreased observably at the end of 12 weeks comparing to 8 weeks. In the controlled experiment of acute and chronic ethanol injury, the plasma PGE and expression of VEGF protein and mRNA in gastric mucosa of chronic group significantly increased ( p < 0. 01) , there was significant difference comparing to premier stage, too (p <0.01).Conclusions1. Along with the long term of chronic ethanol stimulation, the gastric injury became more and more serious, which manifested as chronic atrophy and in-creased apoptosis.2. Along with the prolong of ethanol stimulation, GBF decreased gradually , ET and NO level increased gradually, The expression of protein and mRNA of iNOS and TNFa in gastric mucosa increased. ET, NO, iNOS and TNFa decreased GBF and participated in the chronic ethanol injury to gastric mucosa.3. Along with the prolong of ethanol stimulation, plasma PGE and the expression of VEGF in gastric mucosa increased. PGE and VEGF participated in gastric adaptive cytoprotection.4. When the gastric mucosa showed atrophy, GBF decreased, the protection of PGE and VEGF attenuated.
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