16α-OHE1, a novel oestrogen metabolite, attenuates dysfunction of left ventricle contractility via regulation of autophagy after myocardial ischemia and reperfusion.

BACKGROUND: Myocardial ischemia-reperfusion (MI/R) can exacerbate the initial cardiac damage in the myocardial functional changes, including dysfunction of left ventricular contractility. Oestrogen has been proven to protect the cardiovascular system. However, whether the oestrogen or its metabolites play the main role in attenuating dysfunction of left ventricular contractility is unknown. METHODS AND RESULTS: This study used the LC-MS/MS to detect oestrogen and its metabolites in clinical serum samples (n = 62) with heart diseases. After correlation analysis with markers of myocardial injury including cTnI (P < 0.01), CK-MB (P < 0.05), and D-Dimer (P < 0.001), 16α-OHE1 was identified. The result from LC-MS/MS in female and ovariectomised (OVX) rat serum samples (n = 5) matched the findings in patients. In MI/R model of animal, the recovery of left ventricular developed pressure (LVDP), rate pressure product (RPP), dp/dtmax and dp/dtmin after MI/R in OVX or male group were worsened than those in female group. Also, the infarction area of OVX or male group was larger than that in females (n = 5, p < 0.01). Furthermore, LC3 II in the left ventricle of OVX and male group was lower than that in females (n = 5, p < 0.01) by immunofluorescence. In H9C2 cells, after the application of 16α-OHE1, the number of autophagosomes was further increased and other organelles improved in MI/R. Simultaneously, LC3 II, Beclin1, ATG5, and p-AMPK/AMPK were increased, and p-mTOR/mTOR was decreased (n = 3, p < 0.01) by Simple Western. CONCLUSION: 16α-OHE1 could attenuate left ventricle contractility dysfunction via autophagy regulation after MI/R, which also offered fresh perspectives on therapeutical treatment for attenuating MI/R injury.

Adverse skin reactions induced by sintilimab in advanced lung squamous carcinoma: a case report and review of the literature.

Background: Sintilimab is an immune checkpoint inhibitor (ICI). It can induce immune-related Adverse Events (irAEs). Severe adverse skin reactions are rare, but the mortality rate is high. We report the first case of successful treatment of adverse skin reactions using traditional Chinese medicine (TCM). Case Description: Here we present the case of a 67-year-old male with advanced lung squamous carcinoma. After 8 cycles of chemotherapy, the patient's disease progressed and the treatment regimen was adjusted to sintilimab combined with albumin paclitaxel and cisplatin. Thirty-two days after this cycle, the patient reported a sporadic rash with pruritus on the face, front chest, and both upper limbs. The area of rash was 40%, and the adverse reaction was grade 3. The level of interleukin-related indicators was above normal. The patient's skin symptoms disappeared after treatment with hormones, TCM, and other drugs. The patient's adverse skin reaction was due to an immune-related toxicity caused by sintilimab, so treatment with sintilimab was suspended. The albumin-paclitaxel plus cisplatin regimen was continued to treat lung cancer. Conclusions: Although rare, case of fatal adverse reaction caused by sintilimab have been reported. We recommend early monitoring and recognition of symptoms. During management, high-dose hormones combined TCM may be helpful.

Discovery of cyclooxygenase-2 inhibitors from Kadsura coccinea by affinity ultrafiltration mass spectrometry and the anti-inflammatory activity.

The medicinal plant Kadsura coccinea distributing in South China, was widely used for reducing inflammation and relieving pain. Previous study in our laboratory had proved the significant therapeutic effects of K. coccinea extract on adjuvant arthritis rats. To explore the responsible components and possible mechanisms, an AUF-HPLC-Q-TOF/ MS method was employed for screening and characterizing COX-2 ligands from K. coccinea stems for the first time. Meanwhile, the molecular docking was performed to simulate the binding modes for ligands and COX-2, the cell-free enzyme activity assay was applied to verify the direct COX-2 inhibition of potential inhibitors, and the cell-based study on COX-2 expression was to evaluate the anti-inflammatory effect of (+)-Anwulignan. As a result, the potential COX-2 inhibitor (+)-Anwulignan significantly suppressing COX-2 expressions in LPS signaling pathways might be a good candidate for anti-inflammation and analgesia. In conclusion, AUF mass spectrometry combining the molecular docking and bioassays in vitro was an efficient approach for discovering enzyme inhibitors from traditional herbs.

[Optimization of medical educational objectives by improving summative assessment system].

Summative assessment plays a decisive role in the educational assessment system, which is a yardstick to measure the cultivating goal of higher education. The rapid progress of modern society has put forward higher standard for higher medical education. Traditional summative assessment system with single dimension that focuses on evaluating the student's learning outcome via a standardized examination cannot meet the higher requirements for undergraduate medical education. We have improved the summative assessment system by optimizing the assessment content, criteria and method, as well as teachers' assessment skills and students' evaluation. The reform greatly increases the teaching quality and learning effect in our university.

[Danshensu delays the senescence of rat aortic endothelial cells via activation of SIRT1-SOD pathway].

The present study was aimed to investigate the effect of pretreatment with Danshensu (DSS) on rat aortic endothelial cells (RAECs) senescence and the underlying mechanisms. Cultured RAECs at fourth and twelfth passages were taken as young and old groups, respectively. DSS and DSS+nicotinamide (DSS+N) groups were incubated with DSS and DSS in combination with nicotinamide, an inhibitor of silent information regulator 1 (SIRT1), from the fourth to twelfth passage, respectively. The cell status of senescence was determined by the senescence-associated ß-galactosidase (SA ß-gal) staining, and 4,6-diamino-2-phenyl indole (DAPI) fluorescent dye was used to detect senescence associated heterochromatin foci (SAHF) formation; Thiobarbituric acid (TBA) and colorimetric methods were used to evaluate malondialdehyde (MDA) and H2O2contents; Western blot was employed to analysis the expressions of xanthine oxidase (XOD), SIRT1 and superoxide dismutase 2 (SOD2) in the RAECs. The results showed that, in comparison with young group, the old group exhibited higher SA ß-gal positive and SAHF formation rates, as well as higher MDA and H2O2levels (P < 0.05 or P < 0.01), whereas DSS pretreatment reduced SA ß-gal positive and SAHF formation rates, decreased MDA and H2O2 contents (P < 0.05 or P < 0.01). The protection of DSS was reversed by nicotinamide. Compared with the young group, the old group showed higher expression levels of XOD, but lower SIRT1 and SOD2expression levels (P < 0.05 or P < 0.01). With the pretreatment of DSS, the expression of XOD was declined, and the expression levels of SIRT1 and SOD2were elevated, while nicotinamide reversed the effects of DSS. These results suggest that DSS delays senescence of RAECs via up-regulation of SIRT1.

[Exogenous hydrogen sulfide reduces vascular aging in D-galactose-induced subacute aging rats].

The present study was aimed to observe the protective effect of exogenous hydrogen sulfide (H2S) on vascular structural and functional changes of aorta in D-galactose-induced subacute aging rats. Adult male SD rats were randomly divided to five groups: the vehicle group, the D-galactose (D-gal) group, and the three NaHS groups treated with low (1 µmol·kg⁻¹·d⁻¹), middle (10 µmol·kg⁻¹·d⁻¹) or high (100 µmol·kg⁻¹·d⁻¹) dose of NaHS respectively. The D-gal group rats were given subcutaneously injection of 125 mg/kg D-gal per day for eight weeks to induce subacute aging model. In the NaHS group, D-gal was administered as above but with NaHS intraperitoneally injected at a dosage of 1, 10, 100 µmol·kg⁻¹·d⁻¹ respectively. Equivalent volumes of saline were administered per day for eight weeks in vehicle group. Morphological changes of aorta were observed by HE and Masson staining. The level of H2S in serum, the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA), as well as anti-superoxide anions in vascular tissue were determined by spectrophotometry. Angiotensin II (AngII) levels in plasma were measured using competitive enzyme immunoassay. The expression of angiotensin II type 1 receptor (AT1R) in aorta was determined by Western blot. The results showed that the aging aortic morphologic changes in model rats were ameliorated in NaHS groups. Decreased vascular endothelial exfoliative cells and vascular smooth muscle cell (SMC) proliferation were shown in NaHS groups by HE staining. Masson staining analysis showed reduced relative contents of collagen fibers (P < 0.05) and SMC (P < 0.05) in NaHS groups. Compared to vehicle group, serum concentration of H2S in D-gal group was decreased, while it was increased in NaHS groups after treatment with NaHS (P < 0.05). In the D-gal group, the concentration of AngII in plasma was significantly increased compared with that in vehicle group, while it was decreased in NaHS groups (P < 0.05). Moreover, levels of vascular tissue anti-superoxide anion and the activity of SOD were obviously higher, MDA was significantly lower in all NaHS treated groups than those in the D-gal group respectively (P < 0.05). Western blot analysis showed that the expression of AT1R was increased in D-gal group compared with that in vehicle group, while it was decreased after treatment with NaHS compared with that in D-gal group (P < 0.05). These results suggest that exogenous H2S can ameliorate the age-related changes of aortic morphology, decrease the concentration of AngII in plasma, down-regulate the expression of AT1R in vascular tissue, and mitigate the level of oxidative stress. These changes delay the vascular aging in aging rats ultimately.

Oxidative stress induces gastric submucosal arteriolar dysfunction in the elderly.

AIM: To evaluate human gastric submucosal vascular dysfunction and its mechanism during the aging process. METHODS: Twenty male patients undergoing subtotal gastrectomy were enrolled in this study. Young and elderly patient groups aged 25-40 years and 60-85 years, respectively, were included. Inclusion criteria were: no clinical evidence of cardiovascular, renal or diabetic diseases. Conventional clinical examinations were carried out. After surgery, gastric submucosal arteries were immediately dissected free of fat and connective tissue. Vascular responses to acetylcholine (ACh) and sodium nitroprusside (SNP) were measured by isolated vascular perfusion. Morphological changes in the gastric mucosal vessels were observed by hematoxylin and eosin (HE) staining and Verhoeff van Gieson (EVG) staining. The expression of xanthine oxidase (XO) and manganese-superoxide dismutase (Mn-SOD) was assessed by Western blotting analysis. The malondialdehyde (MDA) and hydrogen peroxide (H2O2) content and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were determined according to commercial kits. RESULTS: The overall structure of vessel walls was shown by HE and EVG staining, respectively. Disruption of the internal elastic lamina or neointimal layers was not observed in vessels from young or elderly patients; however, cell layer number in the vessel wall increased significantly in the elderly group. Compared with submucosal arteries in young patients, the amount of vascular collagen fibers, lumen diameter and media cross-sectional area were significantly increased in elderly patients. Ach- and SNP-induced vasodilatation in elderly arterioles was significantly decreased compared with that of gastric submucosal arterioles from young patients. Compared with the young group, the expression of XO and the contents of MDA and H2O2 in gastric submucosal arterioles were increased in the elderly group. In addition, the expression of Mn-SOD and the activities of SOD and GSH-Px in the elderly group decreased significantly compared with those in the young group. CONCLUSION: Gastric vascular dysfunction and senescence may be associated with increased oxidative stress and decreased antioxidative defense in the aging process.

[Exogenous hydrogen sulfide attenuates gastric ischemia-reperfusion injury via activation of K(ATP) channel].

The present study aimed to investigate the protective effect and mechanism of hydrogen sulfide donor NaHS administration against gastric mucosal injury induced by gastric ischemia-reperfusion (GI-R) in rats. GI-R injury was induced by clamping the celiac artery of adult male SD rats for 30 min and followed by reperfusion for 1 h. The rats were randomly divided into sham group, GI-R group, NaHS group, glibenclamide group and pinacidil group. Gastric mucosal damage was analyzed with macroscopic injured area, deep damage was assessed with histopathology scores, and the hydrogen sulfide concentration in plasma was determined by colorimetric method. The results showed that pretreatment of NaHS significantly reduced the injured area and deep damage of the gastric mucosa induced by GI-R. However, NaHS did not significantly alter the levels of hydrogen sulfide in plasma 14 d after NaHS administration. The gastric protective effect of NaHS during reperfusion could be attenuated by glibenclamide, an ATP-sensitive potassium channel (K(ATP)) blocker. However, K(ATP) opener pinacidil inhibited the GI-R-induced injury. These results suggest that exogenous hydrogen sulfide plays a protective role against GI-R injury in rats possibly through modulation of K(ATP) channel opening.

Differential expression of Bcl-2 and Bax during gastric ischemia-reperfusion of rats.

AIM: To investigate expression of Bcl-2 and Bax in gastric ischemia-reperfusion (GI-R) and involvement of extracellular signal-regulated kinase (ERK) 1/2 activation. METHODS: The GI-R model was established by ligature of the celiac artery for 30 min and reperfusion in Sprague-Dawley rats. Rats were assigned to groups in accordance with their evaluation period: control, 0, 0.5, 1, 3, 6, 24, 48, and 72 h. Expression and distribution of Bcl-2 and Bax proteins were analyzed by immunohistochemistry and western blotting in gastric tissue samples after sacrifice. RESULTS: Compared with controls, the percentage of positive cells and protein levels of Bcl-2 decreased in the early phases of reperfusion, reached its minimum at 1 h (P < 0.05); it then increased, reaching its peak at 24 h of reperfusion (P < 0.05). The pattern of Bax expression was opposite to that of Bcl-2. Bax expression increased after reperfusion, with its peak at 1 h of reperfusion (P < 0.05), and then it decreased gradually to a minimum at 24 h after reperfusion (P < 0.05). On the other hand, inhibition of activation of ERK1/2 induced by PD98059, a specific upstream MEK inhibitor, had significant effects on Bcl-2 and Bax in GI-R. Compared with GI-R treatment only at 3 h of reperfusion, PD98059 reduced the number of Bcl-2 positive cells (0.58% of R3h group, P < 0.05) and Bcl-2 protein level (74% of R3h group, P < 0.05) but increased the number of Bax-positive cells (1.33-fold vs R3h group, P < 0.05) and Bax protein level (1.35-fold of R3h group, P < 0.05). CONCLUSION: These results indicated that the Bcl-2 and Bax played a pivotal role in the gastric mucosal I-R injury and repair by activation of ERK1/2.

The protective effect of 17beta-estradiol postconditioning against hypoxia/reoxygenation injury in human gastric epithelial cells.

The purpose of this study was to investigate the effects and mechanisms of 17beta-estradiol pharmacological postconditioning on gastric epithelial cells hypoxia/reoxygenation injury by using an in vitro model of human gastric epithelial cells. The model of hypoxia/reoxygenation was established with human gastric epithelial cell line. The gastric epithelial cell viability was detected by 3-(4, 5-dimethylthazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assays. Gastric epithelial cellular apoptosis was determined by Hoechst 33258 fluorochrome staining and flow cytometric analysis. Contents of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) were measured by Colorimetry analysis. The protein expression of Bcl-2 and Bax in different groups was determined by Western blot analyses and immunocytochemistry assay. 17beta-estradiol (10(-8), 10(-7) and 10(-6)mol/l) inhibited hypoxia/reoxygenation injury and 17beta-estradiol (10(-6)mol/l) obviously attenuated hypoxia/reoxygenation injury 3h hypoxia followed by 4h reoxygenation. 17beta-estradiol promoted gastric epithelial cell viability and inhibited the gastric epithelial cell apoptosis, and meanwhile, decreased the MDA content and increased SOD activity. The level of Bcl-2 protein was restored to the normal level by 17beta-estradiol pharmacological postconditioning. In contrast, the Bax protein level was markedly reduced by 17beta-estradiol pharmacological postconditioning. These effects of 17beta-estradiol were inhibited by pretreatment with fulvestrant. These data suggested that 17beta-estradiol seems involved in regulation of gastric hypoxia/reoxygenation injury and gastroprotection, and its protective effects were strongly related to estrogen receptor.

The protective effect of capsaicin receptor-mediated genistein postconditioning on gastric ischemia-reperfusion injury in rats.

BACKGROUND: No published study has addressed the effect of genistein postconditioning on gastric ischemia-reperfusion (GI-R) injury in rats. AIM: To examine whether capsaicin receptor-mediated genistein postconditioning protects against gastric ischemia-reperfusion injury via the PI3K/Akt signal pathway. METHODS AND RESULTS: Chloraldurat-anesthetized rats underwent occlusion of the celiac artery for 30 min, followed by 60 min of reperfusion. Based on this animal model of gastric ischemia-reperfusion injury, genistein at doses of 100, 500 or 1,000 µg/kg was administered via peripheral vein 5 min before reperfusion. The dose of 500 µg/kg was optimal for postconditioning, at which the severity of I-R-induced gastric injury significantly decreased. Immunohistochemistry also showed that gastric mucosal cell apoptosis decreased. Capsazepine (CPZ), a specific antagonist for the capsaicin receptor, was administered (1,000 µg/kg, i.v.) just before ischemia. Capsaicin (50 mg/kg, s.c.) once a day for 4 days reversed the protective effects of genistein. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting showed increased calcitonin gene-related peptide (CGRP) expression in genistein group but not in capsazepine or capsaicin group. CGRP inhibitor CGRP8-37 also prevented the effects of genistein in decreasing gastric mucosal injury index. In addition, PI3K inhibitor LY294002 (1.5 mg/kg) reversed the protective effect of genistein. Compared with genistein group, Western blots also demonstrated decreased Akt phosphorylation in LY294002 group. CONCLUSION: Our data suggest that capsaicin receptors mediated the protective effects of genistein postconditioning. CGRP secreted by activated capsaicin-sensitive neurons played an important role in the protective effects of genistein. PI3K/Akt pathway was also involved in the protective effects of genistein.

The role of nuclear factor-kappaB in the effect of angiotensin II in the paraventricular nucleus in protecting the gastric mucosa from ischemia-reperfusion injury in rats.

BACKGROUND: The purpose of this study was to elucidate the role of nuclear factor kappaB (NF-kappaB) in the development of gastric ischemia-reperfusion (GI-R) injury and in mediating the effects of angiotensin II (Ang II) in the paraventricular nucleus (PVN) on GI-R injury. METHODS: GI-R injury was induced in rats by clamping the celiac artery for 30 min and then reperfusing for 1 h. A cannula was inserted into the unilateral PVN for microinjection of Ang II. The expressions and levels of NF-kappaB (p65), IkappaB-alpha, and phosphorylated IkappaB-alpha in rat gastric mucosa were examined by Western blotting and immunohistochemistry. A laser Doppler flowmeter was used to assess gastric blood flow (GBF). Malondialdehyde (MDA) was determined using the thiobarbituric acid (TBA) method, and superoxide dismutase (SOD) activity was determined by the xanthine/xanthine oxidase method. RESULTS: Microinjection of Ang II (3, 30, and 300 ng) into the PVN dose-dependently inhibited GI-R injury. The levels and expressions of NF-kappaB (p65) and phosphospecific IkappaB-alpha protein increased 1 h after GI-R and were markedly reduced by microinjection of Ang II into the PVN. In contrast, the level and expression of IkappaB-alpha protein decreased 1 h after ischemia-reperfusion and recovered to the normal level by microinjection of Ang II into the PVN. The effects of Ang II were prevented by pretreatment with the Ang II AT1 receptor antagonist losartan (5 microg) microinjected into the lateral cerebral ventricle. Inhibition of NF-kappaB activity by pyrrolidine dithiocarbamate (PDTC, 200 mg/kg) produced similar effects in rats subjected to ischemia-reperfusion with or without microinjection of Ang II into the PVN. Administration of PDTC attenuated gastric mucosal injury and suppressed the activation of NF-kappaB (p65). Ang II microinjection into the PVN increased GBF and decreased the MDA content but did not alter SOD activity in the gastric mucosa following ischemia-reperfusion. CONCLUSIONS: NF-kappaB plays a role in PVN Ang II-mediated protection against GI-R injury. These central effects of Ang II are mediated by AT1 receptors.

Role of mitogen-activated protein kinases in the regulation of paraventricular nucleus to gastric ischemia-reperfusion injuries.

BACKGROUND: We investigated the role in electrical stimulations of paraventricular nucleus (PVN) on gastric mucosal cells and the activity of mitogen-activated protein kinases (MAPKs) family members induced by gastric ischemia-reperfusion (GI-R). And we elucidated the molecular mechanisms of the protection of PVN from GI-R injuries. METHODS: Sprague-Dawley rats were divided randomly into 4 groups: Group I, the sham-operated GI-R control group; Group II, the sham-operated electrical stimulations to PVN + sham-operated GI-R control group; Group III, the GI-R group; and Group IV, the electrical stimulations to PVN + GI-R group. In all of the experiments, the PVN was stimulated prior to the induction of GI-R. The GI-R model was established by clamping the celiac artery for 30 minutes to induce ischemia and then was released to allow reperfusion for 30 minutes, 1 hour, 3 hours and 6 hours, respectively. The gastric mucosal cellular apoptosis, proliferation, and the expression and activity of MAPKs protein were observed by immunohistochemistry and Western blotting, respectively. RESULTS: Compared with the GI-R group, the application of electrical stimulations in the PVN significantly depressed gastric mucosal cellular apoptosis and enhanced gastric mucosal cellular proliferation following the 30-minute, 1-hour and 3-hour intervals of reperfusion; it also promoted the activation of p-ERK during the early phase of reperfusion but inhibited the activation of p-JNK1/2 and p-p38 following the 30-minute, 1-hour and 3-hour intervals of reperfusion. CONCLUSIONS: The protection of PVN against GI-R injuries may attribute to the inhibition of apoptosis and the promotion of the proliferation of gastric mucosal cells during GI-R. This protective effect is mediated by activating the ERK pathway and depressing the JNK, p38 MAPK pathways of the gastric mucosal cells.

Extracellular signal-regulated kinase pathways may mediate the protective effect of electrical stimulation of the paraventricular nucleus against ischaemia-reperfusion injury of the gastric mucosa.

1. The aim of the present study was to elucidate the role of the extracellular signal-regulated kinase (ERK) pathway in mediating the effects of electrical stimulation of the paraventricular nucleus (PVN) on apoptosis and proliferation induced by gastric ischaemia-reperfusion injury (GI/RI). 2. To investigate the effects of electrical stimulation of the hypothalamic PVN on gastric mucosal apoptosis and proliferation in response to ischaemia-reperfusion (I/R), we used a GI/RI model by clamping the coeliac artery for 30 min and then reperfusing the artery for 30 min or 1, 3 or 6 h. We used immunohistochemistry and western blotting to investigate the expression, activation and distribution of ERKs and the dynamic changes in their downstream cellular factors Bcl-2 and Bax at different times subsequent to electrical stimulation of the PVN in the I/R-injured gastric mucosa. 3. Electrical stimulation of the PVN markedly attenuated GI/RI at 30 min and 1 and 3 h after reperfusion. Electrical stimulation decreased gastric mucosal apoptosis, increased gastric mucosal proliferation and promoted the expression and activation of phosphorylated (p)-ERK1/2 30 min after reperfusion. Electrical stimulation increased the expression of Bcl-2 and decreased the expression of Bax at 30 min and 1 and 3 h after reperfusion. In contrast, inhibition of ERK1/2 activity by the specific upstream mitogen-activated protein kinase kinase inhibitor PD98059 produced similar effects at 1 h after reperfusion in rats subjected to I/R with or without electrical stimulation of the PVN. Administration of PD98059 aggravated gastric mucosal injury, increased apoptosis, decreased proliferation in gastric mucosal cells, decreased the expression and activity of p-ERK1/2 and Bcl-2 expression and increased Bax expression. 4. These results indicate that the PVN protects against GI/RI and that this protection is associated with the inhibition of cellular apoptosis and the promotion of proliferation in the gastric mucosa, probably by activating the ERK pathway.

Effects of hypothalamic paraventricular nuclei on apoptosis and proliferation of gastric mucosal cells induced by ischemia/reperfusion in rats.

AIM: To investigate the effects of electrical stimulation of hypothalamic paraventricular nuclei (PVN) on gastric mucosal cellular apoptosis and proliferation induced by gastric ischemia/reperfusion (I/R) injury. METHODS: For different experimental purposes, stimulating electrode plantation or electrolytic destruction of the PVN was applied, then the animals' GI/R injury model was established by clamping the celiac artery for 30 min and allowing reperfusing the artery for 30 min, 1 h, 3 h or 6 h respectively. Then histological, immunohistochemistry methods were used to assess the gastric mucosal damage index, the gastric mucosal cellular apoptosis and proliferation at different times. RESULTS: The electrical stimulation of PVN significantly attenuated the GI/R injury at 30 min, 1 h and 3 h after reperfusion. The electrical stimulation of PVN decreased gastric mucosal apoptosis and increased gastric mucosal proliferation. The electrolytic destruction of the PVN could eliminate the protective effects of electrical stimulation of PVN on GI/R injury. These results indicated that the PVN participated in the regulation of GI/R injury as a specific area in the brain, exerting protective effects against the GI/R injury, and the protection was associated with the inhibition of cellular apoptosis and the promotion of gastric mucosal proliferation. CONCLUSION: Stimulating PVN significantly inhibits the gastric mucosal cellular apoptosis and promots gastric mucosal cellular proliferation. This may explain the protective mechanisms of electrical stimulation of PVN against GI/R injury.

Effects of gastric ischemia-reperfusion on gastric mucosal cellular apoptosis and proliferation in rats.

The effect of gastric ischemia-reperfusion (GI-R) on gastric mucosal cellular apoptosis and proliferation was investigated using histological, immunohistochemical methods in Sprague-Dawley rats. The GI-R model was established by clamping the celiac artery for 30 min and reperfusing for 0, 0.5, 1, 3, 6, 24, 48, 72 h, respectively. Mild gastric mucosal injury was induced by ischemia alone. However, the injury worsened and reached the maximum at 1 h after reperfusion, almost simultaneously with the gastric mucosal cellular apoptosis increase and cellular proliferation decrease in gastric mucosa. Then, gastric mucosal cells began to repair by increasing gastric cellular proliferation, which achieved the maximum at 24 h after reperfusion. The mucosal lesions were almost completely repaired at about 72 h after reperfusion. These results indicate that the gastric mucosal injury after GI-R is mainly induced by reperfusion. The damaged gastric mucosa could initiate its repairing mechanism immediately through inhibiting cellular apoptosis and increasing the number of proliferative cells, which substitute the damaged cells gradually. The plerosis almost completes in three days after reperfusion showing a strong self-repair ability of gastric mucosa.

Extracellular signal-regulated kinase 1- and 2-mediated gastric mucosal injury and repair in gastric ischemia-reperfusion of rats.

BACKGROUND: The current study was undertaken to investigate the time course of gastric ischemia-reperfusion (GI-R)-induced gastric mucosal injury and repair and whether extracellular signal-regulated kinase 1/2 (ERK1/2) were involved in GI-R-induced gastric mucosal injury and repair. METHODS: Immunohistochemistry and Western blot analyses were used. RESULTS: Gastric mucosal injury induced by ischemia alone was mild. However, the injury worsened after reperfusion, reaching a maximum at 1 h, and was accompanied by increased apoptotic cells and decreased proliferative cells. Then, the gastric mucosal cells began to repair the injury by enhanced proliferation, which peaked at 24 h after reperfusion, and by 72 h the damaged gastric mucosa was mostly repaired. The ERK1/2 (nonactivated ERK1/2) protein expression level and distribution profile showed no significant changes during the entire reperfusion phase, but the p-ERK1/2 (activated ERK1/2) level changed dramatically. The p-ERK1/2 protein level was decreased at 0.5 h after reperfusion began, and then gradually increased, peaking after 3 h of reperfusion; these changes in p-ERK1/2 occurred simultaneously in the cytoplasm and nucleus. On the other hand, inhibition of the activation of ERK1/2, induced by PD98059, a specific ERK1/2 upstream inhibitor, aggravated the gastric mucosal injury, and apoptosis was increased and proliferation was reduced in the gastric mucosal cells after the same duration of reperfusion. CONCLUSIONS: Serious gastric mucosal damage involving apoptotic cells occurred rapidly at an early stage of reperfusion and was closely related to the suppression of ERK1/2 activation. The activated ERK1/2 signaling transduction pathway played an important role. Activated ERK1/2 participated in the regulation of gastric mucosal injury and repair induced by GI-R, and might be mediated by the inhibition of apoptosis and the promotion of proliferation in gastric mucosal cells.