Effect of melatonin on burn-induced gastric mucosal injury in rats. Burns. 2009;35:863-868. [PMID: 19477599 DOI: 10.1016/j.burns.2008.09.009]

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.

Changes in serum melatonin and estrogen levels in women with functional dyspepsia

AIM: To detect the levels of serum melatonin and estrogen in women with functional dyspepsia (FD), and to evaluate the possible mechanism of FD.

METHODS: Sixty women diagnosed with FD according to Roman Ⅲ criteria were included into an experimental group, which was further divided into two subgroups: patients with epigastric pain syndrome (EPS) (n = 35) and those with postprandial distress syndrome (PDS) (n = 25). Thirty healthy person were chose as normal controls. Serum melatonin and estrogen levels were measured and analyzed in these subjects.

RESULTS: In the FD group and PDS subgroup, the levels of serum melatonin were significantly higher than that in normal controls (P < 0.05). In the PDS subgroup, the concentration of serum melatonin was significantly higher than that in the EPS subgroup (P < 0.05). There was no significant difference in the concentration of serum melatonin between the EPS subgroup and the normal control group (P > 0.05). PDS patients with severe symptoms displayed a higher melatonin concentration as compared with patients with moderate symptoms (P < 0.05). EPS patients with severe symptoms displayed a lower melatonin concentration as compared with patients with moderate symptoms (P < 0.05). In the FD subgroup (menopausal transition), the concentration of serum estrogen was significantly lower than that in normal controls (P < 0.05). FD patients (menopausal transition) with severe symptoms displayed a lower estrogen concentration as compared with patients with moderate symptoms (P < 0.05). In FD patients (menopausal transition), there was no significant correlation between the levels of serum melatonin and estrogen (r = -0.03, P > 0.05).

CONCLUSION: The alteration of serum melatonin may play a role in the pathogenesis of FD, especially PDS, but has no obvious relation with EPS. Serum melatonin level maybe have certain significance for the diagnosis of various clinical forms of FD. The alteration of serum estrogen may play a role in the development of FD. Supplementing exogenous estrogen may improve symptoms of FD patients with perimenopausal symptoms.

Melatonin protection against burn-induced liver injury. A review

Severe thermal injury may be complicated by dysfunction of organs distant from the original burn wound, including the liver, and represents a serious clinical problem. Although pathophysiology of burn-induced liver injury remains unclear, increasing evidence implicate activation of inflammatory response, oxidative stress, endothelial dysfunction and microcirculatory disorders as the main mechanisms of hepatic injury. Several studies suggest melatonin as a multifunctional indolamine that counteracts some of the pathophysiologic steps and displays significant beneficial effects against burn-induced cellular injury. This review summarizes the role of melatonin in restricting the burn-induced hepatic injury and focuses on its effects on oxidative stress, inflammatory response, endothelial dysfunction and microcirculatory disorders as well as on signaling pathways such as regulation of nuclear erythroid 2-related factor 2 (Nrf2) and nuclear factor-kappaB (NF-kB). Further studies are necessary to elucidate the modulating effect of melatonin on the transcription factor responsible for the regulation of the pro-inflammatory and antioxidant genes involved in burn injuries.

Melatonin Protection against Burn-Induced Hepatic Injury by Down-Regulation and Nuclear Factor Kappa B Activation

Melatonin exhibits a wide variety of biological activity including antioxidant and anti-inflammatory effects. We have previously reported its protective effect on hepatic oxidative hepatic injury in burns. In this study, we investigated the role of nuclear factor kappa B (NF-kB) in melatonin-mediated protection against liver injury by using the burned-rat model. Melatonin (N-acetyl-5-methoxytriptamin, 10mg/kg (-1), i.p.) was administered immediately and 12 hours after thermal skin injury. Hepatic NF-kB expression was determined by Western blotting. TNF-α level in liver homogenate was quantified using enzyme-linked immunosorbent assay (ELISA) kit. Plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were determined to assess liver injury at the 24th hour after burns. Thermal skin injury caused significant elevation of hepatic NF-kB expression by 48%, TNF-α level by 55% and plasma AST and ALT activities by 2- and 3-fold, respectively, in comparison with normal control rats. Treatment with melatonin decreased significantly elevated hepatic NF-kB activity and TNF-α, maintaining the levels close to the control values Melatonin suppressed the elevation of plasma AST and ALT activities (p<0.001), which remained significantly increased compared to controls. In conclusion, thermal skin injury causes hepatic NF-kB activation that may mediate the release of hepatic TNF-α and contribute to liver damage. Melatonin protects against burn-induced hepatic injury as to a certain extent this effect may result from the suppression of NF-kB-mediated inflammatory response.

Propagation of cutaneous thermal injury: a mathematical model

Cutaneous burn wounds represent a significant public health problem with 500,000 patients per year in the USA seeking medical attention. Immediately after skin burn injury, the volume of the wound burn expands due to a cascade of chemical reactions, including lipid peroxidation chain reactions. Such expansion threatens life and is therefore highly clinically significant. Based on these chemical reactions, the present paper develops for the first time a three-dimensional mathematical model to quantify the propagation of tissue damage within 12 hours post initial burn. We use the model to investigate the effect of supplemental antioxidant vitamin E for intercepting propagation. We show, for example, that if tissue levels of vitamin E tocotrienol are increased, postburn, by five times then this would slow down the lipid peroxide propagation by at least 50%. We chose the alpha-tocotrienol form of vitamin E as it is a potent inhibitor of 12-lipoxygenase, which is known to propagate oxidative lipid damage. Our model is formulated in terms of differential equations, and sensitivity analysis is performed on the parameters to ensure the robustness of the results.