| Peptic ulcer mainly refers to chronic ulcer of stomach and duodenum, of which gastric ulcer takes up about 25%. The occurrence and healing of gastric ulcer is the result of combination of many factors, for example, the secretion of gastric acid, infection of H.pylori, the effect of gastrointestinal peptide, drug intervention, genetic factors, environmental factors and mental factors and so on. The study about Ariations of pilot show that peptic ulcer is one of chronic diseases with high rate of incidence and recurrence in pilot. It has something not only with the special working environment of high acceleration, high and low temperature and low oxygen which pilot exposed to, but also with intensive work load and stress of the psychology of pilot. When Pilots fly in high air, they will be suffer from the effect of acceleration. Under the condition of acceleration, ulcer easily happened bleeding and perforation, which threats to safety of flight. Exposed to the positive acceleration(+ Gz), the pilot are subjected to inertial centrifugal force with the direction from head to foot which lead to the deformation and displacement of organs, transfer and redistribution of blood inertia and also stimulate the adrenal system to affect the secretion of gastrointestinal hormones and the release of inflammatory mediators. Our preliminary experiments show that under the condition of + Gz, content of secrete hormone, somatostatin, epidermal growth factor in gastric mucosa of rats and prostaglandins, calcitonin gene related peptide, nitric oxide in the blood changes so as to aggravate injury of gastric mucosa and affect the healing of ulcer. It laid the foundation for this study about effects of positive acceleration on ulcer healing in rats with experimental gastric ulcer and relating gastric mucosal blood flow and molecular mechanism.In this experiment, we build the gastric ulcer model in rats by acetic acid burning and then simulated + Gz exposure with animal centrifuge. The aim is to explore the effects of different + Gz on ulcer healing in rats with experimental gastric ulcer and relating gastric mucosal blood flow and possible molecular mechanism by studing the macroscopic characteristics of gastric specimens, histopathologic features of surrounding tissue of ulcer, area size of gastric ulcer and testing gastric mucosal blood flow and the content of calcitonin gene related peptide mRNA in gastric mucosa and nitric oxide and endothelin in serum of rat with experimental gastric ulcer after different + Gz exposure, Which may provide scientific theory for the prevention and treatment of peptic ulcer disease of pilot. The 40 male SD rats were randomly and equally divided into 5 groups which were marked with A, B, C, D, E. The rats of A is belong to the normal control group. Group B is the sham operation group(only openning abdominal cavity without inducing ulcer formation). The gastric ulcer is induced with acetic acid in rats of the group C, D, E. After 3 d, The rats of group C were bound on the ground for 5 mins(exposure of constant +1 Gz). Accordingly, the rats of group D and E were respectively exposed to +5 Gz and +10 Gz for 5 mins(each other day for 1 time, 4 times in all). After 1 week, sample of rats were collected to test. the results show that: 1 the macroscopic characteristics and histopathologic features of gastric specimens of rats with experimental gastric ulcer after exposure to differen + GzGastric mucosa tissue of rats in A, B group were smooth and complete. Different size ulcer lesions were in gastric antrum lesser curvature of rats of C, D, E groups. Ulcer surface of rats in D, E group were covered with white moss, even with gastric mucosa erosion of rats in group E. Then pathological sections of gastric tissue of rats with were made according to the conventional method. Pathological features of gastric tissue were observed by light microscopy. In addition to group A and B, gastric tissue of rats in the rest group were with a large number of inflammatory cells infiltration, thinning of the gastric mucosa and fewer glands. After exposure to + Gz, the glands in gastric tissue of rats in group D were irregular line and obvious expansion. The degree of performance in group E was more serious than in group D. The result show that exposure to + Gz can aggravate inflammation reaction in gastric mucosa and mucosal injury of rats and with the increasing of + Gz value, the injury is much more significant. 2 The size of gastric ulcer area of rats with experimental gastric ulcer after exposure to differen + GzArea size of ulcer is measured with vernier calipers. Gastric of rats in A, B group were without ulceration. Compared with group C, ulcer area of rats in D and E group was significantly bigger(P < 0.01). The ulcer area of rats of E group was bigger than of D groups, the difference was statistically significant(P < 0.05). The results show that the higher + Gz value, the bigger the ulcer area, which is consistent with the results of macroscopic characteristics histopathologic features. The three results consistently suggested that exposure to + Gz can aggravate the damage of gastric mucosa and affect ulcer healing and the degree of damage is related to value of + Gz. 3 GMBF in rats with experimental gastric ulcer after exposure to differen + Gz and the relevance to the ulcer areaGMBF was masured with MoorVMS- LDF2 laser doppler blood flow meter. there was no obvious difference between group A and group B. Compared with B group, GMBF of rats with gastric ulcer in group C was significantly lower(P < 0.01). After exposure to the + Gz, GMBF of rats in group D and E were significantly lower than of rats in group C(P < 0.01). GMBF of rats of E group was lower than D group. The difference was statistically significant(P < 0.05). The correlation the size of gastric ulcer area and GMBF of rat was analyzed statistically. the result showed the obvious negative correlation(r = 0.928, P < 0.05). In all, it suggested that exposure to + Gz can lead to decreases of GMBF which is closely related to ulcer healing of rat. 4 Expression of CGRP- mRNA in gastric mucosa of rats with experimental gastric ulcer after exposure to differen + GzCGRP-mRNA in gastric mucosa were determinated quantitatively by fluorogenic RT-PCR. The result according to relative quantity 2- Δ Δ CT was calculated. there was no obvious difference between group A and group B. Compared with group B, the content of CGRP-mRNA of rats with gastric ulcer in group C was higher significantly(P < 0.01). After exposure to the +Gz, the content of CGRP-mRNA of rats in group D and E were significantly lower than it in group C(P < 0.01), and the content of CGRP-mRNA of rats in E group decreased more significantly(P < 0.01).The result appeared exposure to + Gz can reduce of content of CGRP-mRNA in gastric mucosa, which may be one of the reasons for decrease of GMBF and weakening of protection to gastric mucosal under the condition of + Gz so as to affect the healing of ulcer. 5 NO,ET in serum of rats with experimental gastric ulcer after exposure to differen + GzSerum were collected to determinate the content of NO by nitrate reductive enzymatic the content of ET by radioimmunoassay. There was not significant difference between NO, ET in Serum of rats in group A and it in group B. Compared with group B, the content of NO in group C is lower and the content of ET is higher(P<0.01). After exposure to the + Gz, compared with group C, the content of NO in group D is higher significantly(P < 0.01) and the content of ET is lower(P < 0.05). However, the content of NO in group E was lower than it in group D and the content of ET compared with group D and group E cut down the content of NO was opposite,The difference was statistically significant(P < 0.01). The results show that after exposure to + Gz, the content of NO,ET in serum changed regularly, but both of the effect on the body are consistent relatively with the above change of content of CGRPmRNA. CGRP, NO and ET is strong vascular active substances. After exposure to + Gz, obvious reduce of GMBF may is closely related to the change of three levels and interaction.Above all, exposure to + Gz can lead to ulcer healing delay and affect the quality of ulcer healing. + Gz of low value make less effect on the body while + Gz of high value has a greater effect on ulcer healing. and its mechanism may be associated with reduction of GMBF, decreasing CGRP-mRNA in mucosal and changes of the content of NO, ET in serum under the condition of + Gz. The conlusion provide theoretical basis for the treatment of peptic ulcer of pilots in the aspects of blood supply. It enlighten clinical staff that the drugs increasing GMBF should be considered to use for canker pilot at the same time of conventional drugs, which will be helpful for the healing of ulcer and reduce the possibility of recurrence in the short term. |
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