The importance of "zinc" in the healing mechanism of gastric ulcer
- Categories:Stomach healthy
- Time of issue:2020-12-02
The importance of "zinc" in the healing mechanism of gastric ulcer
- Categories:Stomach healthy
- Time of issue:2020-12-02
Zinc is a trace element that plays an important role in cell growth and development and other biochemical reactions and physiological processes. It can stimulate gene transcription and cell proliferation, and activate DNA and RNA polymerases. These two enzymes are cell antioxidants. An important part of enzyme activity. The mechanism of zinc-induced antioxidant function is not clear, but zinc slows down the oxidation process, which may be the reason for its potential antioxidant activity. Zinc is an indispensable element for the best function of the human immune system. At the same time, zinc can accelerate the wound healing process of various tissues including gastric ulcers. Polaprezin is a chelate composed of zinc ions and L-carnosine, and is widely used clinically to treat gastric ulcers. Carnosine can promote the formation of granulation tissue and accelerate the healing of gastric ulcers. Studies have shown that Polyprezinc has a protective effect on gastric damage caused by various harmful substances, and it can accelerate the healing of gastric ulcers. This gastric protection and anti-ulcer effect is mainly attributed to its endogenous prostaglandins (PGs) production, membrane stabilization and antioxidant properties.
This study aims to determine the role of zinc in the healing process of gastric ulcers by monitoring the changes in the size of the gastric ulcer during the healing process and the changes in the gastric blood flow (GBF) of the ulcer edge, ulcer bed and non-ulcer gastric mucosa. In addition, the quality of healing of acetic ulcers was evaluated histologically, and gastric acid secretion and plasma gastrin were measured to evaluate the effect of zinc aspartic acid on ulcer healing.
1 Materials and methods 1.1 Animals
Male Wistar rats, weighing 200-250g.
1.2 Induction of gastric ulcer
Rats were anesthetized with sodium pentobarbital, the abdomen was cut open, and the stomach was exposed. Pour 75μL of acetic acid into the serosal surface of the anterior gastric wall close to the antral glands for 25s, resulting in necrosis of the entire mucosa and submucosa (not serous), about 28mm². Remove excess acetic acid and wash the serous membrane with saline. After acetic acid pretreatment, they only drink water on the same day (day 0). They are divided into groups and eat and drink freely for 3, 7 and 14 days.
1.3 The effect of zinc aspartic acid on gastric acid secretion, ulcer healing rate and gastric blood flow
Experiment A: To determine the effect of intragastric administration (normal saline) or different doses of HZnAsp (16.25-130mg/kg) on gastric acid secretion, ulcer healing rate and gastric blood flow. The chemical structure of HZnAsp is shown in Figure 1. Experiment B: Determine the effect of HZnAsp (65mg/kg) on gastric acid secretion in 12 rats with gastric fistula (GF). Experiment C: HZnAsp (65 mg/kg day) was administered in divided doses or twice a day for 3, 7 and 14 days.
In order to evaluate the effect of exogenous administration of HZnAsp on gastric blood flow (GBF), rats were anesthetized with ether, the abdomen was cut, the stomach was exposed, and the gastric ulcer edge, ulcer opening and contralateral side were measured by H2 gas scavenging technique or laser flow method GBF with intact mucosa. The gastric blood perfusion was measured by laser Doppler technology, with the unit of mL/min/100g gastric tissue. GBF was detected at the bottom of the ulcer, the edge of the ulcer, and the area not affected by the ulcer. Under blind conditions, the area of gastric ulcer was measured by two investigators by plane method. Tissues were taken, fixed in 10% formalin, embedded in paraffin, stained with hematoxylin and eosin, and Alcian Blue/Periodic Acid Schiff (AB-PAS) histological evaluation of ulcer healing quality. Under blind conditions, mucosal coding specimens stained with hematoxylin and eosin were evaluated at 260x magnification.
1.4 Determination of plasma gastrin level
After the exogenous delivery vehicle or HZnAsp is over, a blood sample (about 3 mL) is taken from the vena cava. For comparison, rats were fasted overnight, only drank saline, anesthetized with ether, and collected blood samples to determine the control value of gastrin in plasma. The recognition rate of gastrin-17 and gastrin-34 by anti-gastrin antibody is quite high. The gastrin radioimmunoassay system is sensitive enough to detect about 2.5μm/L of plasma, which is equivalent to human gastrin-17.
1.5 Determination of gastric acid secretion and gastric mucosal Zn2+ concentration in rats
Thirty starving rats were used as the experimental group, and the rats were treated with normal saline or HZnAsp to observe the changes in gastric acid secretion during the healing process of ulcers and perform chronic gastric fistula surgery. Apply 70μl of normal saline to the surface of the gastric serous membrane for 20s, and pretreat rats with vehicle or HZnAsp (65 mg/kg) at a dose of 65 mg/kg per day. After recovery from anesthesia (day 0) or 1 to 3 days, and 7 and 14 days after ulcer induction, GF rats with and without gastric ulcer were placed in separate cages to prevent co-feeding. Then open each GF and gently rinse the stomach with 5-8 mL of distilled water at 37°C. The basal gastric secretions were collected for 120 minutes, during which time, rats were injected subcutaneously with 4 mL/h normal saline. Collect gastric juice every 30 minutes, measure the volume, and then determine the acid concentration and output, expressed as output every 30 minutes. On the second day after the start of ulcer induction, the control rats without ulcer and the rats with gastric ulcer were placed in a special cage, and the gastric fistula was opened to collect gastric juice. Within a period of 6 to 30 minutes, the gastric juice is collected in a calibrated test tube. Every 30 minutes, the volume of gastric juice of vehicle control and HZnAsp pretreated rats was recorded, and the H+ concentration in each sample was measured by titrating the gastric juice with 0.1 N NaOH to calculate the gastric acid output. In addition, the F-AAS method was used to measure Zn2+ ions. Under standard conditions (wavelength 213.9nm; slit 0.7mm), the U.S. 3110 Perkin-Elmer spectrometer was used to measure the concentration of Zn2+ in an air-acetylene flame.
1.6 Differential pulse anodic stripping voltammetry (DP-ASV) to determine the concentration of Zn2+
Three-electrode quartz battery, with a volume of 10mL. The M164 controlled growth mercury drop electrode (CGMDE) is used as the working electrode, and the suspended mercury drop electrode (HMDE) mode is used. The platinum wire is the auxiliary electrode and Ag/AgCl/3M-KCl is the reference. electrode. Measure the pH value with a pH meter. All solutions used for analysis were purged with argon. The experiment was carried out at room temperature. All solutions and sample preparations use quadruple distilled water. The samples and supporting electrolyte were prepared with 65% nitric acid, 30% hydrogen peroxide and potassium nitrate. At the same time use zinc (II) standard stock solution. Weigh about 50 mg of dry gastric mucosa sample and transfer it to a high-pressure PTFE container, pre-treat it with 4mL HNO3 and 2mL H2O2 (30%). Then put the container in the microwave. The sample digestion was carried out according to the following procedure: microwave irradiation for 20 minutes, cooling for 45 minutes, and waiting for 5 minutes. Place the digested sample on the heating plate to evaporate the excess reagent. After the sample solution is cooled to room temperature, it is quantitatively transferred to a volumetric flask (5 mL), and filled to the mark with four times distilled water. The glassware was first immersed in 6M nitric acid, and then washed repeatedly with distilled water. Peel in differential pulse (DP) mode. The analysis is performed in 5 mL aliquots containing 0.01 M KNO3 and 20-200 µL of sample solution. 1.7 Statistical analysis results are expressed as mean±SEM. The comparison between the two groups was performed by Student’s test for unequal variance test. The comparison between the two groups was performed by analysis of variance. If the result is statistically significant, the post-hoc Dunnett’s test was used. If the distribution of the data is significantly different from the normal distribution, use the nonparametric Kruscal Wallis test instead of the analysis of variance. A computer program (SPSS for Windows) was used for statistical analysis. All statistical analyses were performed using SAS JMP 7.02 software package.
2 Results and analysis
2.1 The effect of HZnAsp on gastric ulcer healing and GBF at the edge of ulcer
2.1.1 The gross morphology of acetic acid-induced gastric ulcer in rats. The macroscopic picture of the acetic acid gastric ulcer on the 7th day after the rats in the solvent (normal saline) group induced the ulcer. The deep ulcer pit is visible, the ulcer edge is clear, and the ulcer bed is clearly visible.
2.1.2 Zinc reduces the area of ulcers and increases peripheral blood flow
Within 7 days, the ulcer area of rats in the vehicle control group decreased from 28mm² to 18.6±2.1mm², but the administration of HZnAsp (16.25 mg/kg) did not significantly affect the gastric ulcer area. As the dose of HZnAsp was increased to 32.5, 65 mg/kg, and 130 mg/kg, the area of gastric ulcers was significantly reduced to approximately 14%, 34%, 59%, and 82%, respectively. The GBF of the non-ulcer mucosa of rats in the vehicle group averaged 46±6ml/min-100g (100%). 16.25 mg/kg HZnAsp failed to affect GBF at the edge of the ulcer, but the GBF from the gastric mucosa to the edge of the ulcer increased significantly in rats (Figure 3). After the administration of 130 mg/kg HZnAsp, GBF was significantly increased. Compared with the administration of 65 mg/kg HZnAsp, the increase was not significantly different. The use of vehicle (Veh) and HZnAsp 16.25-130 mg/kg (6-8 mice) Rats) mean±scanning electron microscopy to observe the gastric ulcer area and gastric blood flow (GBF) at the edge of the ulcer in rats on day 7. * Indicates a significant change from the value obtained in the vehicle-treated gastric mucosa on the 7th day after ulcer induction.
2.1.3 Zinc reduces ulcer area and is dose-dependent
The time course of gastric ulcer healing in rats administered with vehicle or standard dose of HZnAsp (65 mg/kg i.g.) from day 0 to day 3, day 7 and day 14. Acetic acid gastric ulcer of rats in the vehicle control group gradually healed. The area of the ulcer was significantly reduced within 14 days after ulcer induction, but about 65% of the rat ulcers did not heal. On the 7th and 14th days after ulcer induction, the area of gastric ulcer in the vehicle control group gradually decreased, which was about 58% and 80%, respectively. In contrast, the ulcer area of rats in the HZnAsp group was smaller than that of rats in the vehicle control group
The average area of gastric ulcers in rats treated with vehicle (Veh, saline) and HZnAsp (65 mg/kg i.g.) was measured on 0, 3, 7 and 14 days after ulcer induction. Mean ± SEM of 6-8 rats. *Indicates a significant change from the values obtained on day 0 and day 3. Crossing means a significant decrease, which is lower than the value of vehicle control rats.
2.1.4 Administration for 7 days significantly reduces the area of gastric ulcer
As shown in Figure 5, compared with the vehicle control group rats, the HZnAsp group rats had a significantly reduced gastric ulcer area on the 7th day of ulcer induction. The change of gastric ulcer area on the 7th day after treatment with vehicle (normal saline) and HZnAsp (65mg/kg i.g.) in rats. Mean ± SEM of 8-10 rats. * Indicates a significant change compared with the value of the gastric mucosa of the vehicle control group.
2.1.5 Histological manifestations of zinc on gastric ulcer healing
Through histological examination, the unulcerated gastric mucosa showed normal glandular structure and complete continuity of surface epithelium. The histological appearance of this gastric mucosa was similar to that of rats in the HZnAsp group without ulcer induction (Fig. 6A and 6B) . On day 7, only 15% of rats in the control group had gastric ulcers healed almost completely, but in rats where the ulcers were generally healed, the ulcer scars under the microscope showed obvious gland expansion and incomplete reconstruction of the mucosal cells at the ulcer edge ( Figure 6C). In contrast, in most rats in the HZnAsp group, no gastric ulcers were observed macroscopically or microscopically. The healing area at the edge of the ulcer showed a good recovery of surface epithelium, but the "healed" gastric mucosa showed abnormal glandular appearance. Histological manifestations of intact gastric mucosa without gastric ulcer
2.1.6 After 7 days of administration, the marginal blood flow was significantly increased
Compared with the intact non-ulcer gastric mucosa, the GBF at the edge of the ulcer in the vehicle control group was significantly reduced. Compared with the GBF value of the ulcer edge recorded in the vehicle control group, the HZnAsp group significantly increased the GBF of the ulcer edge
"After 7 days of treatment with vehicle (normal saline) or HZnAsp (65mg/kg i.g.), the gastric blood flow (GBF) of the gastric mucosa in normal rats and rats with acetic gastric ulcer. Mean ± SEM of 6-8 rats. *Indicates a significant change compared to the value obtained on a complete animal. * And + indicate significant changes compared with control rats.
Figure 8 shows the GBF value in the intact gastric mucosa. HZnAsp has no obvious effect on GBF of non-ulcer gastric mucosa. In contrast, the GBF value at the ulcer edge and the ulcer bed was significantly lower than the non-ulcer gastric mucosa, but the GBF at the ulcer edge was significantly higher than the ulcer bed. Compared with the GBF values at the ulcer edge and the ulcer bed recorded in the vehicle control group, the GBF at the ulcer edge and the ulcer bed in the HZnAsp group increased significantly after 7 days of treatment with vehicle (normal saline) or HZnAsp (65 mg/kg ig) , The changes of non-ulcer gastric mucosa, ulcer edge and gastric blood flow (GBF) at the ulcer bed in rats. Mean ± SEM of 6-8 rats. * Indicates a significant change compared to the value obtained for animals treated with drugs.
2.2 Zinc reduces gastric acid secretion and increases plasma gastrin
Table 1 and Figure 9 show the results of gastric acid secretion studies in conscious rats with gastric fistula induced with or without gastric ulcer. In the control group without gastric ulcer, the average basal acid output was 137±12μmol/30min, and the plasma gastrin level reached 38±3pm/L. After induction of gastric ulcer, compared with the control group without induced ulcer, gastric acid output was significantly reduced by about 55%, and plasma gastrin level was significantly increased by about 15%. Compared with the vehicle (normal saline) control group, HZnAsp (65 mg/kg i.g.) significantly reduced gastric acid secretion and significantly increased plasma gastrin (Table 1). On day 3, compared with rats without gastric ulcer, the gastric juice secretion of the vehicle control rats tended to increase, but the gastric acid output was still significantly suppressed. Compared with the vehicle group, HZnAsp significantly reduced gastric acid output and significantly increased plasma gastrin concentration. After 7 days, the gastric acid output of rats in the vehicle control group was still significantly lower than that of rats without ulcers (Figure 9). In the HZnAsp group of rats, compared with the vehicle control group, the gastric acid output on day 7 was still significantly decreased (Table 1, Figure 9). On the 14th day, the gastric acid output of rats in the vehicle control group reached a value similar to that of the rats without induced ulcers, but on the contrary, the gastric acid output of rats in the HZnAsp group was still decreased.
"Using vehicle (normal saline) and HZnAsp (65mg/kg, 7 consecutive days) to treat the gastric acid output of rats without gastric ulcer or gastrostomy. Mean ± SEM of 6-8 rats. * Indicates a significant change from the value obtained in rats treated with drugs. Compared with rats without gastric ulcer, Cross showed a significant change. * And + indicate a significant change compared with the value of gastric ulcer rats without HZnAsp treatment.
2.3 The effect of zinc on the concentration of Zn2+ in the gastric juice and gastric mucosa of rats without gastric ulcerSV method was used to determine the change of Zn2+ concentration in gastric juice of rats with gastric ulcer. Mean ± SEM of 8-10 rats. * Indicates a significant change compared with uninjured rats and rats treated with vehicle for gastric ulcer. * And + indicate a significant change compared with the value recorded on the 3rd day of HZnAsp-treated gastric ulcer rats. Figure 11 shows the effect of vehicle and HZnAsp on the concentration of Zn2+ in the gastric mucosa at the edge of the ulcer after 7 days of administration. In the intact non-ulcer gastric mucosa, the gastric ulcer vehicle control group and HZnAsp-treated rats had similar gastric Zn2+ content on day 1 and day 3, but in contrast, on day 7, compared with the vehicle Compared with the respective measured values of the rats in the control group, the content of Zn2+ in the gastric cavity increased significantly. In rats with gastric ulcer, compared with the control group without gastric ulcer, the Zn2+ ion concentration in the lumen of gastric ulcer rats was significantly reduced on day 7 (Figure 10). In contrast, HZnAsp treatment significantly increased the Zn2+ content in the lumen and mucosa on the 7th day of ulcer induction.
The DP-ASV method was used to measure the change of Zn2+ concentration in gastric mucosa of normal rats and gastric ulcer rats. Mean ± SEM of 8-10 rats. *Indicates a significant change compared to the value of intact rats. Compared with the values recorded by rats without gastric ulcer, the crossover showed a significant change.
"Zinc" decreases the area of ulcers in a dose-dependent manner and increases the marginal blood flow. At the same time, "zinc" can also reduce gastric acid secretion and increase plasma gastrin, but gastric ulcers will cause a decrease in the concentration of "zinc" in the gastric mucosa. This study provides preliminary evidence that zinc aspartic acid promotes ulcer healing. The mechanism involves enhancing gastric microcirculation, inhibiting gastric acid secretion, and increasing plasma gastrin levels. The healing effect of zinc aspartic acid is accompanied by an increase in the content of Zn2+ in the mucosa and lumen, and an increase in the gastric microcirculation around the ulcer (including the ulcer edge and the ulcer bed). The trace element zinc has a gastroprotective effect on various experimental lesions because it participates in the integrity of the gastric mucosa. Zinc-containing compounds, such as Relaisen (Polyprezinc Granules), are used as anti-ulcer drugs for the treatment of human peptic ulcers. "Zinc" has anti-oxidant and anti-secretory effects, helps ulcer healing and improves microcirculation.
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