Molecular Mechanisms of Melatonin Protection from Gastric Mucosal Apoptotic Injury in Experimental Burns

Bletilla striata Polysaccharide Nanoparticles Improved the Therapeutic Efficacy of Omeprazole on the Rat Gastric Ulcer Induced by Ethanol

Gastric ulcers are a common clinical presentation affecting anyone, regardless of their age or gender. Nanoparticles (NPs) containing Bletilla striata polysaccharide (BSP) and omeprazole (OME) were investigated in the study for their therapeutic effect on gastric ulcers. Ethanol-induced gastric ulcers in rats (240 ± 30 g) were established. Our OME-BSP NPs were more stable than free OME in the acidic environment and can increase the absorption of OME in rat stomach, which was confirmed by in situ gastric absorption and distribution experiments. The extended blood circulation of OME-BSP NPs was also observed in rats with gastric ulcer. More importantly, OME-BSP NPs not only decreased the area of gastric ulcer and inhibited gastric acid secretion but also reversed gastric tissue damage and cell apoptosis, as revealed by HE and TUNEL staining. Subsequent SOD, MDA, PGE₂, IL-6, and TNF-α tests further verified the superiority of OME-BSP NPs against rat gastric ulcer, which properly originated from superior antioxidant and anti-inflammatory effects. As a result, our OME-BSP NPs' drug delivery system improved the stability and absorption of OME in the rat stomach and achieved targeted treatment of gastric ulcers.

Protective Effects of Melatonin against Severe Burn-Induced Distant Organ Injury: A Systematic Review and Meta-Analysis of Experimental Studies

Extensive burns result in a local wound response and distant-organ injury (DOI) caused by oxidative-stress and inflammation. Melatonin (MT) shows promise in alleviating oxidative-stress and inflammation, but its role in thermal injury is largely unexplored. The present systematic review and meta-analysis were designed to assess the effects of MT on oxidative-stress and inflammatory markers against severe burn-induced DOI. Mean difference (MD)/standard mean difference (SMD) with 95% confidence interval (CI) were estimated using fixed-effect/random-effects models. Eighteen experimental studies met the inclusion criteria. Compared with the control group, MT significantly decreased the levels of malondialdehyde (SMD, −1.03; 95% CI, −1.30, −0.76, p < 0.00001) and 4-hydroxynonenal (MD, −1.06; 95% CI, −1.57, −0.56, p < 0.0001). Additionally, MT increased the levels of glutathione (SMD, 1.94; 95% CI, 1.27, 2.61, p < 0.00001) and superoxide-dismutase (SMD, 0.76; 95% CI, 0.08, 1.45, p = 0.03). Finally, MT significantly decreased the levels of tumor necrosis factor-α (SMD, −1.34; 95% CI, −1.92 to −0.77; p < 0.00001) and C-reactive protein (MD, −12.67; 95% CI, −16.72 to −8.62; p < 0.00001). Meta-analysis indicates that severe burn followed by immediate MT (10 mg/kg) intervention shows significant beneficial effects after 24-h against DOI by regulating oxidative-stress and the inflammatory response.

Effect of water immersion restraint stress on gastric mucosa in rats with removed salivary glands

OBJECTIVE

To explore the effect of salivary gland removal on water immersion restraint stress (WIRS)-induced gastric mucosal injury (GMI) in rats.

METHODS

Eighty male WISTAR rats were allocated into sham operation (sham) group, sham + WIRS group, salivary gland removal group, and salivary gland removal + WIRS group, with 20 rats in each group. In the sham group, skin and subcutaneous tissues were cut to expose glands. The rats in other three groups were subjected to a total salivary gland resection, and all their submandibular glands and sublingual glands and part of the parotid glands were removed, and the parotid duct was ligated. Afterwards, rats were exposed to WIRS for one and a half months and sacrificed. The severity of GMI was scored, and any histologic and ultrastructural changes were monitored.

RESULTS

There were differences in the Guth index (GMI evaluation) scores among the four groups (P=0.000), which were higher in salivary gland removal + WIRS group than those in the other three groups (all P<0.001), and were higher in the sham + WIRS group and salivary gland removal group than those in the sham group (all P=0.000). Compared with other groups, the gastric mucosa was severely injured in the salivary gland removal + WIRS group, with obvious congestion, edema, inflammatory cell infiltrate, mucosal shedding, bleeding ulcers, enlarged intercellular spaces, and damaged organelles.

CONCLUSION

Salivary gland removal aggravates WIRS-induced GMI to a certain extent.

Edaravone reduces oxidative stress and intestinal cell apoptosis after burn through up-regulating miR-320 expression

BACKGROUND

Intestinal mucosa barrier dysfunction after burn injury is an important factor for causing mortality of burn patients. The current study established a burn model in rats and used a free radical scavenger edaravone (ED) to treat the rats, so as to investigate the effect of edaravone on intestinal mucosa barrier after burn injury.

METHODS

Anesthetized rats were subjected to 40% total body surface area water burn immediately, followed by treatment with ED, scrambled antagomir, or antagomiR-320. Intestinal mucosa damage was observed by hematoxylin-eosin staining and graded by colon mucosal damage index (CMDI) score. The contents of total sulfhydryl (TSH), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) were determined by spectrophotometry. Cell apoptosis, protein relative expression,and the in situ expressions of p-Akt and p-Bad were detected by flow cytometry, Western blotting and immunohistochemistry, respectively. The miR-320 expression was determined by quantitative real-time polymerase chain reaction.

RESULTS

ED alleviated intestinal mucosal damage caused by burn injury, down-regulated the levels of MDA, cytochrome C, cleaved caspase-9 and cleaved caspase-3, but up-regulated the levels of TSH, SOD, CAT and Bcl-2. We also found that ED could reduce oxidative stress, inhibit cell apoptosis, increase the expressions of p-Akt, p-Bad and miR-320, and decrease PTEN expression. PTEN was predicted to be the target gene for miR-320, and cell apoptosis could be promoted by inhibiting miR-320 expression.

CONCLUSION

ED regulates Akt/Bad/Caspase signaling cascade to reduce apoptosis and oxidative stress through up-regulating miR-320 expression and down-regulating PTEN expression, thus protecting the intestinal mucosal barrier of rats from burn injury.

Melatonin for prevention of placental malperfusion and fetal compromise associated with intrauterine inflammation-induced oxidative stress in a mouse model

Melatonin has been shown to reduce oxidative stress and mitigate hypercoagulability. We hypothesized that maternally administered melatonin may reduce placental oxidative stress and hypercoagulability associated with exposure to intrauterine inflammation (IUI) and consequently improve fetoplacental blood flow and fetal sequelae. Mice were randomized to the following groups: control (C), melatonin (M), lipopolysaccharide (LPS; a model of IUI) (L), and LPS with melatonin (ML). The expression of antioxidant mediators in the placenta was significantly decreased, while that of pro-inflammatory mediators was significantly increased in L compared to C and ML. The systolic/diastolic ratio, resistance index, and pulsatility index in uterine artery (UtA) and umbilical artery (UA) were significantly increased in L compared with other groups when analyzed by Doppler ultrasonography. The expression of antioxidant mediators in the placenta was significantly decreased, while that of pro-inflammatory mediators was significantly increased in L compared to C and ML. Vascular endothelial damage and thrombi formation, as evidenced by fibrin deposits, were similarly increased in L compared to other groups. Maternal pretreatment with melatonin appears to modulate maternal placental malperfusion, fetal cardiovascular compromise, and fetal neuroinflammation induced by IUI through its antioxidant properties.

The implication of the crosstalk of Nrf2 with NOXs, and HMGB1 in ethanol-induced gastric ulcer: Potential protective effect is afforded by Raspberry Ketone

Ethanol consumption is one of the common causative agents implicated in gastric ulcer development. Oxidative stress plays a major role in the induction and development of gastric ulceration. NADPH oxidases (NOXs) and Nuclear factor erythroid 2-related factor 2 (Nrf2) are key players in ethanol-induced ulcers. High-mobility group box 1 (HMGB1), a ubiquitous nuclear protein, mediates various inflammation functions. However, the role of HMGB1 in ethanol-induced gastric ulcer is not yet elucidated. Raspberry Ketone (RK) is a natural phenolic compound with antioxidant and anti-inflammatory properties. In the present study, absolute ethanol (7.5 ml/kg) was used to induce gastric ulceration in rats. Raspberry Ketone (RK) (50 mg/kg) was given orally one hour before the administration of absolute ethanol. Interestingly, ethanol-induced gastric ulcer was associated with Nrf2 downregulation, which was correlated with NOX-1, 2 NOX-4, and HMGB1 upregulation, and was significantly reversed by RK pre-treatment. RK pre-treatment provided 80% gastroprotection. Gastroprotective properties of RK were mediated via antioxidant, anti-inflammatory (suppression of NF-kB and tumor necrosis factor-α), and antiapoptotic activities (reduction of Bax/Bcl2 ratio). Gastroprotective properties of RK were confirmed by histopathological examination. In conclusion, this study is the first to provide evidence to the role of HMGB1 in ethanol-induced gastric ulcer, and the crosstalk of Nrf2, NOXs and HMGB1. It also demonstrates that RK represents a promising gastroprotective activity comparable to omeprazole.