Kwiecień S, Brzozowski T, Konturek P C, Pawlik M W, Pawlik W W, Kwiecień N, Konturek S J
Department of Physiology Jagiellonian University School of Medicine, Cracow, Poland.
J Physiol Pharmacol. 2004 Jun;55(2):337-55.
Impairment of blood perfusion in gastric mucosa results in the formation of erosions and ulcers. Nitric oxide (NO), produced via activity of NO-synthase (NOS), appears to be a one of major factors, involved in the regulation of the gastric blood flow (GBF). Inhibition of this enzyme by N-nitro-L-arginine (L-NNA) results in local decrease of NO production, reduces GBF and impairs gastric mucosal integrity, the effects that can be reversed by the pretreatment with L-arginine, the NOS substrate. However, little information is available regarding the contribution of reactive oxygen species (ROS)-induced lipid peroxidation and NO to the mechanism of gastric mucosal integrity. Therefore, the aim of our present study was to determine the action of pentoxyfilline (PTX), an inhibitor of tumor necrosis factor alpha (TNFalpha) with or without NOS inhibition by L-NNA administration in rats with water immersion and restraint stress (WRS)-induced gastric lesions. Experiments were carried out on 100 male Wistar rats. The gastric blood flow (GBF) was measured using laser Doppler flowmeter. The area of gastric lesions was determined by planimetry and the levels of proinflammatory cytokines (IL-1beta and TNFalpha) were measured by ELISA. Colorimetric assays were employed to determine gastric mucosal levels of lipid peroxidation products, such as malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) and antioxidant enzymes including superoxide dismutase (SOD) activity, as well as tissue concentration of reduced glutathione (GSH). Administration of PTX significantly attenuated the gastric lesions, induced by 3.5 h of WRS and this was accompanied by the rise in the GBF and a significant decrease in plasma proinflammatory cytokines (IL-1beta and TNFalpha) levels, as well as the reduction of lipid peroxidation. Exposure of rats to WRS suppressed the SOD and GSH activities and these effects were reversed by PTX. The protective and hyperemic effects of PTX, as well as an increase in mucosal SOD activity and GSH concentration were counteracted by pretreatment with L-NNA, but restored by the pretreatment with L-arginine, a NOS substrate. We conclude that PTX exerts beneficial, gastroprotective effect against WRS-induced gastric lesions due to enhancement in gastric microcirculation, possibly mediated by the enhanced NOS activity as well as local action of NO and by the attenuation of oxidative metabolism and generation proinflammatory cytokines.
胃黏膜血液灌注受损会导致糜烂和溃疡的形成。通过一氧化氮合酶（NOS）活性产生的一氧化氮（NO）似乎是参与调节胃血流量（GBF）的主要因素之一。N-硝基-L-精氨酸（L-NNA）对该酶的抑制作用会导致局部NO生成减少，降低GBF并损害胃黏膜完整性，而用NOS底物L-精氨酸预处理可逆转这些效应。然而，关于活性氧（ROS）诱导的脂质过氧化和NO对胃黏膜完整性机制的贡献，目前所知甚少。因此，我们本研究的目的是确定己酮可可碱（PTX）的作用，己酮可可碱是一种肿瘤坏死因子α（TNFα）抑制剂，在水浸束缚应激（WRS）诱导的胃损伤大鼠中，给予或不给予L-NNA抑制NOS的情况下，观察其作用。实验在100只雄性Wistar大鼠身上进行。使用激光多普勒血流仪测量胃血流量（GBF）。通过面积测量法确定胃损伤面积，并通过酶联免疫吸附测定（ELISA）测量促炎细胞因子（IL-1β和TNFα）水平。采用比色法测定胃黏膜脂质过氧化产物水平，如丙二醛（MDA）和4-羟基壬烯醛（4-HNE），以及抗氧化酶，包括超氧化物歧化酶（SOD）活性，还有还原型谷胱甘肽（GSH）的组织浓度。给予PTX可显著减轻WRS 3.5小时诱导的胃损伤，同时伴有GBF升高以及血浆促炎细胞因子（IL-1β和TNFα）水平显著降低，脂质过氧化也减少。将大鼠暴露于WRS会抑制SOD和GSH活性，而PTX可逆转这些效应。PTX的保护和充血作用，以及黏膜SOD活性和GSH浓度的增加，会被L-NNA预处理抵消，但可被NOS底物L-精氨酸预处理恢复。我们得出结论，PTX对WRS诱导的胃损伤具有有益的胃保护作用，这是由于胃微循环增强，可能是由增强的NOS活性以及NO的局部作用介导的，同时还通过减弱氧化代谢和促炎细胞因子的产生。
