Melatonin modulates inflammatory response and suppresses burn-induced apoptotic injury

Introduction: Melatonin, the principal secretory product of the pineal gland, has antioxidant functions as a potent antioxidant and free radical scavenger. Objectives of the present study were to investigate the effect of melatonin against inflammatory response, burn-induced oxidative damage and apoptotic changes of rat liver. Methods: Melatonin (10 mg /kg, i.p.) was applied immediately after 30% of total body surface area (TBSA) burns on male Wistar rats. The level of malondialdehyde (MDA) as a marker of an oxidative stress was quantified by thiobarbituric method. Hepatic TNFα and IL-10 as inflammatory markers were assayed by ELISA. Using light immunоchistochemistry the expression Ki67 proliferative marker was investigated. Results: Hepatic MDA and TNF-α levels increased significantly following burns without any change in IL-10 level. Intracellular vacuolization, hepatic cell degeneration and apoptosis occurred in rats after burns. The number of apoptotic cells was increased whereas no significant increase in Ki67 proliferative marker. Melatonin decreased the MDA and TNF-α content and increased the IL-10 level. It also limited the degenerative changes and formation of apoptotic cells in rat liver but did not increase expression of the marker of proliferation. In conclusion, our data show that melatonin relieves burn-induced hepatic damage associated with modulation of the proinflammatory/anti-inflammatory balance, mitigation of lipid peroxidation and hepatic apoptosis

Melatonin attenuates oxidative stress and modulates inflammatory response after experimental burn trauma

Introduction. Thermal injury activates an inflammatory response. Melatonin possesses anti-oxidant and anti-inflammatory properties. The objective of the present work was to study melatonin effects on the inflammatory response under conditions of oxidative stress during the early stage of thermal injury. Materials and methods. We used 24 white male rats of Wistar breed, randomly divided into three experimental groups. Group one was the control, group two was inflicted with burn trauma, and group three was inflicted with burn trauma, with melatonin application following the thermal injury. Melatonin was applied twice in doses of 10 g/kg b.m. immediately after the burn trauma and again at 12 hours. Plasma levels of tumor necrosis-factor-α (TNF-α), a pro-inflammatory mediator, and of interleukin-10 (Il-10), an anti-inflammatory mediator, were examined and their ratio was calculated. The levels of malondialdehyde (MDA), an oxidative stress marker, were also estimated. Results. Thermal trauma significantly increased plasma TNF-α levels (ð\u3c0.01) and TNF-α /IL-10 ratio but did not change IL-10 ones. Plasma MDA concentrations were significantly elevated as well (ð\u3c0.0001). Melatonin application significantly reduced TNF-α (ð\u3c0.05), increased IL-10 (ð\u3c0.05), down-regulated TNF-α/IL-10 ratio and changed MDA concentrations (ð\u3c0.01). In conclusion, our results show that local alteration induces oxidative stress and inflammatory response with TNF-α /IL-10 disbalance. Melatonin modulates this response and attenuates oxidative stress in experimental burn injury

Apoptosis as a mechanism for burn-induced gastric mucosal injury

ABSTRACTIntroduction: Severe thermal burns disturb tissue homeostasis of many organs, but the exact mechanisms of gastric mucosa changes are not yet clear. Various cellular mechanisms, such as cell activation, mitochondrial dysfunction, free oxygen radicals and cytokine overproduction may be involved in this process.Aim: The aim of this study was to assess the levels of malondialdehyde (MDA), apoptotic proteins Bax and Bcl-2 in normal gastric mucosa and to test the hypothesis that oxidative stress activation induces apoptotic processes in the stomach after experimental thermal trauma.Materials and Methods: Under anesthesia, the shaved rats` dorsum was exposed to 90° C bath for 10 s to induce third-degree burn injury, involving 30% of the total body surface area. We determined the tissue level of MDA, a lipid peroxidation marker, by spectrophotometric method and the apoptosis of epithelial cells in gastric mucosa, which was immunohistochemically determined at the level of Bcl-2 and Bax in burn trauma.Results: The gastric MDA level was higher (p<0.01) in the burned group compared to the control group 24 hours after thermal injury. The gastric mucosa in the treated group showed congestion, degenerative changes in the surface epithelium, focal destruction of glandular epithelium with formation of acute erosions. Bax expressed moderately in epithelial cells, predominantly in the basal parts of the gastric glands, while in the control group protein content was localized in the same region, but it was weak. Bcl-2 protein in the control group revealed nuclear expression in surface epithelium, while in the basal layer of gastric mucosa the expression was moderate and mainly cytoplasmic. In the burned group, Bcl-2 expression was more diffuse, nuclear and cytoplasmic, but cytoplasmic expression was weak.Conclusion: Thermal skin trauma induces gastric mucosal injury through the activation of lipid peroxidation, increase of pro-apoptotic Bax protein expression and decrease of anti-apoptotic Bcl-2 protein expression in epithelial cells. We suggest that apoptosis is a possible mechanism for structural changes in the gastric mucosa

Metabolic changes in experimental model of metabolic syndrome - induced by high-fructose diet in rats

The global epidemic of metabolic syndrome (MS) correlates with changes in the environment, feeding, behavior and lifestyle, leading to obesity, glucose intolerans, dyslipidemia and elevated cardiovascular risk. AIM: The aim of our study was to develop an experimental model of the MS in rat that imitate the investigated metabolic disorders using high-fructose diet. METHODS: We used two groups: control group (C)- rats, maintained on plain water (n=6); fructose group (FRU)- rats received 12.5% high-fructose corn syrup in drinking water for 12 weeks (n=6). The main markers of metabolic abnormalities (glucose, total cholesterol, triglycerides, uric acid, body and organs weight), the markers of oxidative stress (malondialdehyde (MDA), total thiols) and C-reactive protein (CRP) - inflammatory marker were measured. RESULTS: Our data showed hypercholesterolemia, hyperglycemia, hyperuricemia and significant elevated levels of CRP, MDA, body and organs weight, and inhibited antioxidant defense in fructose- drinking rats. CONCLUSION: The experimental model will support our studies associated with pathophysiology and pharmacology of MS

Study On Some Possible Liver Damage Mechanisms Related To Oxidative Stress In Experimental Thermal Trauma Conditions And Melatonin Hepatoprotection Role// Проучване на някои възможни механизми за увреждане на черния дроб, свързани с оксидативния стрес в условията на експериментална термична травма и ролята на мелатонина в хепатопротекцията

[EN] This is the first of its kind comprehensive study focused on the potential pathophysiological mechanisms of liver damage after thermal injury associated with the development of oxidative stress. Test results are convincing evidence of melatonin effect as a potent endogenous protector against thermal injury-induced liver damage. Unlike other known antioxidants which neutralize ROS and have damaging effect on antioxidant enzymes, when applied melatonin stimulates the synthesis of antioxidant enzymes and increases antioxidant protection. Practical benefits of the research: *Research on the effects of melatonin on antioxidant protection, oxidative stress, inflammation and microcirculatory dysfunction, apoptosis and regeneration is an important aspect in studying its role in the liver protection mechanisms and its future use as a therapeutic agent for improving hepatic dysfunction associated with thermal trauma. *Research of the Nrf2 and NF-kB transcription factors delivers a more reliable and global picture of the pathophysiological mechanisms of tissue damage, as compared to testing only single markers of oxidative stress, inflammation, and apoptosis. *This study points the way for future therapeutic approaches addressing the impact of transcription factors Nrf2 and NF-kB mainly, which regulate the expression of many genes of damaging and protective factors. *The complex of methods demonstrated in the study can be effectively administered as an innovative in the clinical practice for diagnosing tissue injury in a variety of diseases.Това е първото по рода си целенасочено комплексно проучване върху възможните патофизиологичните механизми на увреждане на черния дроб при термична травма, свързани с развитието на оксидативния стрес. Резултатите от проведените изследвания представляват убедителни доказателства за ролята на мелатонина като мощен ендогененен протектоp срещу индуцираното от термичната травма увреждане на черния дроб. За разлика от другите известни антиоксиданти, които неутрализират ROS и увреждащото им действие върху антиоксидантните ензими, приложеният мелатонин стимулира синтеза на антиоксидантни ензими и повишава антиоксидантната защита. Практическите ползи от проучването са свързани със следното: 1. Изследванията на ефектите на мелатонина върху антиоксидантната защита, оксидативния стрес, възпалението и микроциркулаторната дисфункция, апоптозата и регенерацията е важен аспект при изучаване ролята му в механизмите, протектиращи черния дроб и бъдещо използване като терапевтично средство за подобряване на чернодробната дисфункция при TT. 2. Изследването на транскрипционните фактори Nrf2 и NF-kB дава по-достоверна и глобална представа за патофизиологичните механизми на тъканно увреждане, в сравнение с изследване само на отделни маркери на оксидативен стрес, възпаление и апоптоза. 3. Настоящото проучване посочва пътя на бъдещите терапевтични подходи, насочени към въздействие, основно върху транскрипционните фактори Nrf2 и NF-kB, които регулират експресията на много гените на увреждащи и защитни фактори. 4. Комплексът от представените в проучването методи може да бъде ефективно приложен като иновативен в клиничната практика при диагностициране на тъканното увреждане при различни заболявания

Markers of endothelial dysfunction in the methabolic syndrom

The metabolic syndrome (MS) has been represented as a `clustering` of strongly interrelated risk factors for cardiovascular disease (CVD). These include dyslipidemia, hypertension, obesity and insulin resistance. The components of metabolic syndrome can act directly and indirectly on endothelial function. A common mechanism underlying endothelial dysfunction is related with increase of oxidative stress. Free radicals cause the initial disturbances of endothelial function, enhance the release of Endothelin-1 (ET-1), the main endothelial constrictor peptide, im pair of NO metabolism and decrease of endothelium-dependent vasodilatation, stimulate release of proinflamatory mediators- adhesion molecule 1 (ICAM-1) and vascular adhesion molecule-1(VCAM-1), enhance the release of plasmingen activator inhibitor-1 (PAI-1) and von Willebrand factor (vWF), modulate the PI2/TxA2 ration, leading to a prothrombogenic state, formatting represent a key early step in atherogenesis. Plasma ET-1, adhesion molecules VCAM-1 and ICAM-1, PAI-1 and vWF may serve as biomarkers pointing to endothelial disfunction (ED) and increased cardiovascular risk. Significant in creased plasma levels of these biomarkers along other biochemical parameters can be seen in condition like obesity, diabetes of type 2 and others component of metabolic syndrome. Thus measurement of endothelial function might indetify atherogenic risk individuals at the early stage long before clinical diagnosis of CVD.This may prove to be a useful means of assessing response to treatment aimed at reducing long-term morbility and mortality from CVD. Scripta Scientifica Medica 2007;39(2):133-13

Effects Of Melatonin Suplementation On Body Mass Index In A Diet-Induced Obesity Rat Model

Introduction: Оbesity has been labelled as a “non-infectious pandemic of our time”. It increases the risk of several debilitating diseases, including cardiovascular disorders, diabetes mellitus, tumors, and other pathologies. Up to date both therapeutic and preventive approaches have been largely unsuccessful. At the present time body mass index (BMI) is considered the most common anthropometric method to diagnose obesity. According to a variety of in vivo and in vitro studies, exogenous melatonin has a pronounced effect on carbohydrate and lipid metabolism. Furthermore, supplementation with melatonin improves oxidative stress and insulin resistance preventing hypertrophy of the adipose tissue and body weight gain.Aim: We evaluated the effect of melatonin supplementation on BMI and retroperitoneal fat mass in diet-induced obesity rat model.Materials and Methods: Male Wistar rats (n = 32), provided with standard rat chow and tap water freely available, were randomly divided into four groups as follows: control group – rats received standard rodent diet and tap water; melatonin group – rats received standard rodent diet and tap water, and melatonin administered per os (4 mg/kg/24h); fructose group – rats received standard rodent diet and tap water supplemented with 20% fructose; and fructose plus melatonin group – rats received standard rodent diet and tap water supplemented with 20% fructose, and melatonin administered per os (4 mg/kg/24 h). At the end of the experimental period, the animals were sacrificed, zoometric measurements were taken and BMI was calculated.Results: Statistically significant differences were observed between the anthropometric parameters of the experimental groups. When compared with the control group, fructose-supplemented rats showed a remarkable increase in retroperitoneal fat mass and BMI. In contrast, groups supplemented with melatonin showed significant reductions in these parameters.Conclusion: Melatonin supplementation reduces fructose-induced obesity. In particular, body weight, retroperitoneal fat mass and BMI were remarkably decreased in melatonin-treated groups

HEME OXYGENASE-1 UPREGULATED BY MELATONIN: POTENTIAL PROTECTION AGAINST BURN-INDUCED OXIDATIVE GASTRIC MUCOSAL INJURY.

Melatonin is indoleamine hormone derived from L-tryptophan. Due to its lipophilic nature, it is accessible to every cell. Melatonin has immunomodulatory and antioxidant activities thus protecting tissue injury. Heat shock proteins such as HSP32 known as heme oxygenase-1 (HO-1) possesses antioxidant, anti-inflammatory, and vasodilatory properties and plays an important role in the protecting of tissues from several stresses. The aim of study is to investigate the expression of HO-1 in gastric mucosa and its connection with oxidative stress and melatonin mediated protection after thermal injury. On rats back, under anesthesia, third degree burn was applied involving 30% of total body surface area (TBSA). Melatonin (10 mg per kg body mass) was injected i.p. immediately and 12 hours after thermal skin injury. We used tissue malondialdehyde (MDA), lipid peroxidation product, as a marker of oxidative stress. Gastric mucosa histopathology were observed on light microscopy and light immunohistochemistry investigating the HO-1 too. Results: The levels of MDA in gastric mucosa were elevated (p< 0.05). The HO-1 expression was significantly increased in rats with trauma. Melatonin inhibited elevation in lipid peroxidation product and augmented the increase in expression of HO-1 in the gastric mucosa. In conclusion, our data suggest that HO-1 induction following burn injury is an adaptive response protecting gastric mucosal against further oxidative damage. Melatonin increased the antioxidant capacity and restricted burn-induced oxidative damage in gastric mucosa and thus could be used therapeutically in organ protection

Melatonin attenuates oxidative stress and modulates inflammatory response after experimental burn trauma

Introduction. Thermal injury activates an inflammatory response. Melatonin possesses anti-oxidant and anti-inflammatory properties. The objective of the present work was to study melatonin effects on the inflammatory response under conditions of oxidative stress during the early stage of thermal injury. Materials and methods. We used 24 white male rats of Wistar breed, randomly divided into three experimental groups. Group one was the control, group two was inflicted with burn trauma, and group three was inflicted with burn trauma, with melatonin application following the thermal injury. Melatonin was applied twice in doses of 10 g/kg b.m. immediately after the burn trauma and again at 12 hours. Plasma levels of tumor necrosis-factor-α (TNF-α), a pro-inflammatory mediator, and of interleukin-10 (Il-10), an anti-inflammatory mediator, were examined and their ratio was calculated. The levels of malondialdehyde (MDA), an oxidative stress marker, were also estimated. Results. Thermal trauma significantly increased plasma TNF-α levels (ð<0.01) and TNF-α /IL10 ratio but did not change IL-10 ones. Plasma MDA concentrations were significantly elevated as well (ð<0.0001). Melatonin application significantly reduced TNF-α (ð<0.05), increased IL-10 (ð<0.05), down-regulated TNF-α/IL-10 ratio and changed MDA concentrations (ð<0.01). In conclusion, our results show that local alteration induces oxidative stress and inflammatory response with TNF-α /IL-10 disbalance. Melatonin modulates this response and attenuates oxidative stress in experimental burn injury