Konturek P C, Brzozowski T, Duda A, Kwiecien S, Löber S, Dembinski A, Hahn E G, Konturek S J
First Department of Medicine I, University Erlangen-Nuremberg, Krankenhasustrasse 12, D-91054 Erlangen, Germany.
J Physiol Paris. 2001 Jan-Dec;95(1-6):361-7. doi: 10.1016/s0928-4257(01)00049-3.
The repair of damaged gastric mucosa is a complex process involving prostaglandins (PG) and mucosal growth factors such as epidermal growth factor (EGF). Recently, we postulated that the increased occurrence of apoptosis in the gastric epithelium might be of pathophysiological importance in the development of stress lesions. The aim of the present study was to assess the effect of the pretreatment of rats, exposed to 3.5 h of water immersion and restraint stress (WRS), with EGF and PG (16,16 dmPGE(2)) on the number of stress lesions, recovery of gastric mucosa from stress and the expression of apoptosis related genes such as caspase-3 and antiapoptotic bcl-2. Rats were divided in following groups: (1) vehicle; (2) EGF 100 microg/kg i.p.; (3) 16,16 dm-PGE(2) (5 microg/kg i.g.) and caspase-1 inhibitor (ICE-I; 100 microg/kg i.p.). One hour later, the rats were exposed to 3.5 h of WRS and then sacrificed immediately (0 h) or at 6, 12, or 24 h after WRS. The number of acute gastric lesions was determined. Gastric epithelial apoptosis was assessed by TUNEL staining. In addition, mRNA expression of caspase-3, Bcl-2 and proinflammatory cytokines (IL-1 beta, TNFalpha) was assessed by RT-PCR. PGE(2) generation in gastric mucosa and luminal EGF were determined by RIA. Exposure to WRS resulted in the development of multiple acute stress erosions ( approximately 18) which almost completely healed during 24 h. The gastric blood flow was significantly reduced (approximately 70% of intact mucosa) immediately after WRS. The expression of mRNA for IL-1 beta and TNF alpha reached their peak at 12 h after stress exposure. The apoptosis rate was highest at 6 h after WRS and was accompanied by the highest caspase-3 expression. In rats pretreated with EGF or 16,16 dm-PGE(2), a significant decrease in caspase-3 mRNA and upregulation of bcl-2 mRNA as observed as compared to vehicle controls. Caspase-1 inhibitor significantly reduced the number of stress lesions. We conclude that EGF and PGE(2) accelerate healing of stress-induced lesions due to the attenuation of apoptosis via upregulation of bcl-2 in gastric mucosa. Inhibitors of apoptosis accelerate healing of stress lesions and may be potentially effective agents in the healing of damaged gastric mucosa.
受损胃黏膜的修复是一个复杂的过程，涉及前列腺素（PG）和黏膜生长因子，如表皮生长因子（EGF）。最近，我们推测胃上皮细胞凋亡发生率的增加在应激性损伤的发生发展中可能具有病理生理学意义。本研究的目的是评估用EGF和PG（16,16 -二甲基前列腺素E₂）预处理暴露于3.5小时水浸束缚应激（WRS）的大鼠，对应激性损伤数量、胃黏膜从应激中恢复以及凋亡相关基因如半胱天冬酶 - 3和抗凋亡基因bcl - 2表达的影响。大鼠分为以下几组：（1）赋形剂组；（2）EGF 100μg/kg腹腔注射组；（3）16,16 -二甲基前列腺素E₂（5μg/kg灌胃）和半胱天冬酶 - 1抑制剂（ICE - I；100μg/kg腹腔注射）组。1小时后，将大鼠暴露于3.5小时的WRS，然后立即（0小时）或在WRS后6、12或24小时处死。测定急性胃损伤的数量。通过TUNEL染色评估胃上皮细胞凋亡。此外，通过逆转录聚合酶链反应（RT - PCR）评估半胱天冬酶 - 3、Bcl - 2和促炎细胞因子（IL - 1β、TNFα）的mRNA表达。通过放射免疫分析法（RIA）测定胃黏膜中PGE₂的生成和腔内EGF。暴露于WRS导致多发性急性应激性糜烂（约18处）的发生，这些糜烂在24小时内几乎完全愈合。WRS后立即，胃血流量显著降低（约为完整黏膜的70%）。应激暴露后12小时，IL - 1β和TNFα的mRNA表达达到峰值。凋亡率在WRS后6小时最高，且伴有最高的半胱天冬酶 - 3表达。与赋形剂对照组相比，用EGF或16,16 -二甲基前列腺素E₂预处理的大鼠，半胱天冬酶 - 3 mRNA显著降低，bcl - 2 mRNA上调。半胱天冬酶 - 1抑制剂显著减少了应激性损伤的数量。我们得出结论，EGF和PGE₂通过上调胃黏膜中bcl - 2来减轻凋亡，从而加速应激诱导损伤的愈合。凋亡抑制剂可加速应激性损伤的愈合，可能是受损胃黏膜愈合的潜在有效药物。
