Melatonin and 1400 W Ameliorate both Intestinal and Remote Organ Injury Following Mesenteric Ischemia/Reperfusion

Protective and therapeutic potential of melatonin against intestinal diseases: updated review of current data based on molecular mechanisms

INTRODUCTION

Intestinal diseases, a leading global cause of mortality and morbidity, carry a substantial socioeconomic burden. Small and large intestines play pivotal roles in gastrointestinal physiology and food digestion. Pathological conditions, such as gut dysbiosis, inflammation, cancer, therapy-related complications, ulcers, and ischemia, necessitate the urgent exploration of safe and effective complementary therapeutic strategies for optimal intestinal health.

AREAS COVERED

This article evaluates the potential therapeutic effects of melatonin, a molecule with a wide range of physiological actions, on intestinal diseases including inflammatory bowel disease, irritable bowel syndrome, colon cancer, gastric/duodenal ulcers and other intestinal disorders.

EXPERT OPINION

Due to anti-inflammatory and antioxidant properties as well as various biological actions, melatonin could be a therapeutic option for improving digestive disorders. However, more researches are needed to fully understand the potential benefits and risks of using melatonin for digestive disorders.

The effect of ozone on the expression of metallothionein in tissues of rats chronically exposed to cadmium

Our aims were to evaluate the expression of metallothionein (MT) in an experimental rat model which experienced chronic exposure to cadmium (Cd) and to measure its expression after ozone therapy (OT) or oxygen (Ox) in the same model, as compared to the control group, which was exposed to neither cadmium nor ozone. Forty male Wistar rats were divided into 5 groups: control, Cd, Cd and Ox, Cd and Oz, and Oz. During our research, Cd concentration (ASA) and MT concentration (ELISA) were determined in supernatants of the kidneys, liver and pancreas. SDS-PAGE analyses and immunohistochemical localization were used to evaluate the level of MT expression in the tissue. In rats intoxicated with Cd, the highest concentration of both Cd and MT was observed in the kidneys and liver, with a significantly lower concentration measured in the pancreas. Ozone therapy reduces the accumulation of cadmium in the liver and kidneys, resulting in a reduced expression of metallothionein in those tissues.

Naringin protects viscera from ischemia/reperfusion injury by regulating the nitric oxide level in a rat model

We investigated the effects of naringin on small intestine, liver, kidney and lung recovery after ischemia/reperfusion (I/R) injury of the gut. Rats were divided randomly into four groups of eight. Group A was the sham control; group B was ischemic for 2 h; group C was ischemic for 2 h and re-perfused for 2 h (I/R); group D was treated with 50 mg/kg naringin after ischemia, then re-perfused for 2 h. Endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) expressions were detected by immunolabeling. We also measured arginase activity, amounts of nitric oxide (NO) and total protein. iNOS was increased significantly in the small intestine, liver and kidney in group C. iNOS was decreased significantly only in small intestine and lung in group D. eNOS was increased significantly in the small intestine, liver and lung in group C. eNOS was decreased in small intestine, liver and lung in group D; however, eNOS was decreased in the kidney in group C and increased in the kidney in group D. The amount of NO was decreased significantly in all tissues in group D, but arginase activity was decreased in the small intestine and lung, increased in the kidney and remained unchanged in the liver in group D. The total protein increased in the small intestine and liver in group D, but decreased significantly in the kidney and lung in group D. Naringin had significant, salutary effects on the biochemical parameters of I/R by decreasing the NO level, equilibrating iNOS and eNOS expressions, and decreasing arginase activity.

Medical ozone therapy reduces shock wave therapy-induced renal injury

OBJECTIVES

Extracorporeal shock wave (ESW) lithotripsy is the preferred treatment modality for uncomplicated kidney stones. More recently free oxygen radical production following ESW application has been considered to be crucial in shock wave-induced renal damage. It has been shown that ozone therapy (OT) has ameliorative and preventive effects against various pathological conditions due to increased nitro-oxidative stress. In current study, we aimed to evaluate the efficacy of OT against ESW-induced renal injury.

METHODS

Twenty-four male Sprague-Dawley rats were divided into three groups: sham-operated, ESW, and ESW + OT groups. All groups except sham-operated group were subjected to ESW procedure. ESW + OT group received 1 mg/kg/day of oxygen/ozone mixture intraperitoneally at 2 h before ESW, and OT was continued once a day for consecutive three days. The animals were killed at the 4th day, and kidney tissue and blood samples were harvested for biochemical and histopathologic analysis.

RESULTS

Serum ALT and AST levels, serum neopterin, tissue nitrite/nitrate levels, and tissue oxidative stress parameters were increased in the ESW group and almost came close to control values in the treatment group (p < 0.05, ESW vs. ESW + OT). Histopathological injury scores were significantly lower in treatment group than the ESW group (p < 0.05, ESW vs. ESW + OT). Immunohistochemical iNOS staining scores in ESW group were higher than those of sham-operated group (p < 0.05, ESW vs. sham-operated), iNOS staining scores in OT group were significantly lower than the ESW group (p < 0.05, ESW + OT vs. ESW).

CONCLUSION

OT ameliorates nitro-oxidative stress and reduces the severity of pathological changes in the experimental ESW-induced renal injury of rat model.

Naloxone pretreatment prevents kidney injury after liver ischemia reperfusion injury

PURPOSE

The aim of this study was to assess the effects of naloxone, an opioid receptor antagonist, on the renal injury as a remote organ after hepatic ischemia reperfusion (IR) in rats.

MATERIALS AND METHODS

Forty male Wistar rats were randomly allocated into four groups as follows: sham, sham + naloxone, IR and IR + naloxone. In anesthetized rats, hepatic ischemia was applied for 30 min in IR and IR + naloxone groups. Sham + naloxone and IR + naloxone groups were given naloxone (3.0 mg/kg, iv) 30 min before ischemia. After 24 h, blood and tissue samples were obtained for histopathological, tissue malondialdehyde (MDA) and biochemical analyses.

RESULTS

Histopathological study of liver in IR group showed enlarged sinusoids, sinusoidal congestion, cellular degenerative changes and necrosis. The kidney of the rats with hepatic IR showed pathological changes in tubular cell swelling, tubular dilatation, moderate to severe necrosis, glomerular fibrosis and hemorrhage. Histological examination confirmed the extent of hepatic and renal changes in IR group was higher (P < 0.05) than in other groups. Rats that underwent hepatic IR exhibited significant increase in serum concentrations of urea and creatinine levels (P < 0.05). The serum alanine aminotransferase and aminotransferase values were significantly higher in IR group compared to the other groups (P < 0.05). Liver IR produced a significant increase in hepatic and renal tissue MDA levels, while pretreatment with naloxone was associated with a significantly lower MDA levels (P < 0.05).

CONCLUSION

The results of this study showed that naloxone pretreatment protected the renal injury from hepatic IR.

The antioxidant effects of pomegranate extract on local and remote organs in a mesenteric ischemia and reperfusion model

OBJECTIVES

We investigated whether pomegranate extract plays a protective antioxidant role against mesenteric ischemia-reperfusion injury (IR), which can lead to a systemic response and damage distant organs, such as the lung, liver, and kidney.

METHODS

Forty female Wistar-Albino rats were separated into four groups: laparotomy, laparotomy + PG, mesenteric IR, and mesenteric IR and pomegranate (IR + PG). In the laparotomy + PG and IR + PG groups, pomegranate (225 mg/kg) was given by oral gavage at the beginning of the study. Ischemia was induced for 30 minutes, and reperfusion was subsequently allowed for 60 minutes in the IR and IR + PG groups. The malondialdehyde (MDA) and total antioxidant activity (AOA) levels were evaluated in blood samples. Additionally, all tissues were removed for the measurement of AOA and total oxidant status as well as for subsequent histopathological evaluation. The oxidative stress index was calculated.

RESULTS

Histopathological changes in all organs were significantly higher in the IR group and significantly lower in the IR + PG group vs. the other groups. Serum MDA levels were significantly lower in the IR + PG group than in the IR group. No significant difference was found in AOA levels of the groups.

DISCUSSION

These data may explain the positive protective effects of pomegranate based on the histopathologic findings in ischemic conditions in an intestinal IR injury model.

Effects of intralipid and caffeic acid phenyl esther (CAPE) against hepatotoxicity and nephrotoxicity caused by glyphosate isopropylamine (GI)

This study was aimed to investigate the protective effects of caffeic acid phenyl esther (CAPE) and Intralipid (IL) against hepatotoxicity and nephrotoxicity caused by acute intoxication of glyphosate (N-phosphonomethyl)glycine) (GI) in rats. Forty-nine Wistar Albino rats were randomly divided into seven groups as: I, Control; II, Intralipid (IL) (18.6 mL/kg, orally); III, CAPE (10 µmol/kg, intraperitoneally); IV, GI (4 mg/kg/day, intraperitoneally); V, GI + IL; VI, GI+CAPE; and VII, GI + IL + CAPE. Total antioxidant status (TAS) and total oxidant status (TOS) levels were measured in serum samples. Tissues were analyzed with hematoxylin and eosin (H&E) staining protocol. Bcl-2, Bax, and caspase-3 were evaluated by immunohistochemical method. The results revealed that, in hepatic tissues, the TAS levels were lower and the TOS levels were higher in the GI group compared to other groups. In renal tissues, the TAS levels were significantly lower in the GI group than in the control, IL, CAPE, and GI + IL + CAPE groups. The TOS levels were significantly higher in the GI group than in the control group. Moreover, histopathological analysis revealed severe hepatotoxicity in the GI group. In the GI + CAPE + IL group, hepatotoxicity recovered significantly. Nephrotoxicity was also observed in the GI group and moderately reduced in the GI + CAPE group. Biochemical results were confirmed by histopathologic examination. The results also revealed that CAPE and IL, due to their antioxidant effects, have a decreasing effect against both hepatotoxicity and nephrotoxicity caused by GI. Therefore, CAPE and IL may function as potential agents for supportive therapy since they decrease organ damage, or may facilitate the therapeutic effects of the routine treatment of patients with GI poisoning.

Protective effect of melatonin-supported adipose-derived mesenchymal stem cells against small bowel ischemia-reperfusion injury in rat

We tested the hypothesis that combined melatonin and autologous adipose-derived mesenchymal stem cells (ADMSC) was superior to either alone against small bowel ischemia-reperfusion (SBIR) injury induced by superior mesenteric artery clamping for 30 min followed by reperfusion for 72 hr. Male adult Sprague Dawley rats (n = 50) were equally categorized into sham-operated controls SC, SBIR, SBIR-ADMSC (1.0 × 10(6) intravenous and 1.0 × 10(6) intrajejunal injection), SBIR-melatonin (intraperitoneal 20 mg/kg at 30 min after SI ischemia and 50 mg/kg at 6 and 18 hr after SI reperfusion), and SBIR-ADMSC-melatonin groups. The results demonstrated that the circulating levels of TNF-α, MPO, LyG6+ cells, CD68+ cells, WBC count, and gut permeability were highest in SBIR and lowest in SC, significantly higher in SBIR-ADMSC group and further increased in SBIR-melatonin group than in the combined therapy group (all P < 0.001). The ischemic mucosal damage score, the protein expressions of inflammation (TNF-α, NF-κB, MMP-9, MPO, and iNOS), oxidative stress (NOX-1, NOX-2, and oxidized protein), apoptosis (APAF-1, mitochondrial Bax, cleaved caspase-3 and PARP), mitochondrial damage (cytosolic cytochrome C) and DNA damage (γ-H2AX) markers, as well as cellular expressions of proliferation (PCNA), apoptosis (caspase-3, TUNEL assay), and DNA damage (γ-H2AX) showed an identical pattern, whereas mitochondrial cytochrome C exhibited an opposite pattern compared to that of inflammation among all groups (all P < 0.001). Besides, antioxidant expressions at protein (NQO-1, GR, and GPx) and cellular (HO-1) levels progressively increased from SC to the combined treatment group (all P < 0.001). In conclusion, combined melatonin-ADMSC treatment offered additive beneficial effect against SBIR injury.

The effect of hypothermia on adnexal torsion/detorsion injury in a rat ovary model

PURPOSE

Much attention has been given to hypothermia as it is effective in inhibiting inflammatory responses and also ischemia/reperfusion injury. Therefore, the aim of this study was to evaluate the effect of hypothermia on torsion/detorsion injury in rats.

METHODS

Twenty-eight rats were randomly divided into four groups of sham-operated (SG), adnexal torsion/detorsion group (TG), adnexal torsion/detorsion+hypothermia group (THG) and hypothermia group (HG). In the SG group, right ovaries were excised after 3-h fixation to abdominal wall. In the TG, right adnexal underwent 720° torsion in a counterclockwise direction for 3h and then excised after 3-h detorsion period. In the THG, after 3-h torsion period, ovaries were immediately subjected to hypothermia (4°C) for 30-min and they were excised after 3-h detorsioned period. In the HG, the right ovaries were subjected to hypothermia for 30-min and excised after 3-h fixation period. One half of each ovary was immediately stored for antioxidant enzyme activity and tissue lipid peroxidation. The remainder was fixed for histopathological examination.

RESULTS

Adnexal torsion and detorsion significantly increased the tissue level of Malondialdehyde, Superoxide dismutase and Reduced glutathione. On the other hand, hypothermia significantly reduced these oxidative stress parameters. The histopathological changes were less in the THG group; these changes were not statistically different from the other groups.

CONCLUSION

The results of this study suggested that hypothermia inhibited the production of oxidative stress in the ovaries subjected to torsion/detorsion injury.

Melatonin attenuates intestinal ischemia--reperfusion-induced lung injury in rats by upregulating N-myc downstream-regulated gene 2

BACKGROUND

Successful drug treatment for ischemia--reperfusion-induced lung injury remains a major clinical problem. Melatonin (MT) is a hormone that is principally synthesized in the pineal gland. It has been shown to exhibit a variety of functions including anti-inflammatory and antioxidant effects. Previous reports on N-myc downstream-regulated gene (NDRG)2 have suggested that it is involved in cellular differentiation, development, antiapoptosis, anti-inflammatory cytokine, and antioxidant. The objective of this study was to test whether MT, a novel NDRG2 activator, can protect against intestinal ischemia-reperfusion-induced lung injury (IIRI).

MATERIALS AND METHODS

IIRI was induced in rats by occlusion of the superior mesenteric artery for 60 min, and the occlusion was then released for reperfusion. Rats were randomly divided into six groups as follows: control group; MT group; IIRI group; IIRI+5 mg/kg MT group; IIRI+15 mg/kg MT group; and IIRI+25 mg/kg MT group. The effects of MT on intestinal ischemia-reperfusion-induced lung pathologic changes, inflammatory cytokines release, myeloperoxidase and superoxide dismutase activities, and malondialdehyde level were examined. In addition, the NDRG2 activation in lung tissues was detected by Western blot analysis.

RESULTS

MT pretreatment attenuated edema and the pathologic changes in the lung. MT also decreased the levels of tumor necrosis factor-α, interleukin-1β, and interleukin-8 in bronchoalveolar lavage fluid. In addition, MT markedly prevented IIRI-induced elevation of malondialdehyde and myeloperoxidase levels, as well as reduction of superoxide dismutase activity. Furthermore, the expression of NDRG2 was activated by MT pretreatment in lung tissues.

CONCLUSIONS

The present study demonstrates that MT exerted protection against IIRI-induced oxidative stress. The potential mechanism of this action may attribute partly to the activation of NDRG2 expression.

Melatonin treatment further improves adipose-derived mesenchymal stem cell therapy for acute interstitial cystitis in rat

This study tests the hypothesis that combined melatonin and adipose-derived mesenchymal stem cell (ADMSC, 1.2 × 10(6) given intravenously) treatment offer superior protection against cyclophosphamide (CYP 150 mg/kg)-induced acute interstitial cystitis (AIC) in rats. Male adult Sprague-Dawley rats were treated as follows: sham controls, AIC alone, AIC + melatonin, AIC + ADMSC, and AIC + melatonin +ADMSC. When melatonin was used, it was given as follows: 20 mg/kg at 30 min after CYP and 50 mg/kg at 6 and 18 hr after CYP. Twenty-four-hour urine volume, urine albumin level, and severity of hematuria were highest in AIC rats and lowest in the controls; likewise urine volume was higher in AIC + melatonin rats than in AIC + ADMSC and AIC + melatonin + ADMSC treated rats; in all cases, P < 0.001. The numbers of CD14+, CD74+, CD68+, MIP+, Cox-2+, substance P+, cells and protein expression of IL-6, IL-12, RANTES, TNF-α, NF-κB, MMP-9, iNOS (i.e. inflammatory biomarkers), glycosaminoglycan level, expression of oxidized protein, and protein expression of reactive oxygen species (NOX-1, NOX-2, NOX-4) in the bladder tissue exhibited an identical pattern compared with that of hematuria among the five groups (all P < 0.0001). The integrity of epithelial layer and area of collagen deposition displayed an opposite pattern compared to that of hematuria among all groups (P < 0.0001). The cellular expressions of antioxidants (GR, GPx, HO-1, NQO 1) showed a significant progressive increase form controls to AIC + melatonin + ADMSC (all P < 0.0001). Combined regimen of melatonin and ADMSC was superior to either alone in protecting against CYP-induced AIC.

Additional benefit of combined therapy with melatonin and apoptotic adipose-derived mesenchymal stem cell against sepsis-induced kidney injury

This study tested whether combined therapy with melatonin and apoptotic adipose-derived mesenchymal stem cells (A-ADMSCs) offered additional benefit in ameliorating sepsis-induced acute kidney injury. Adult male Sprague-Dawley rats (n = 65) were randomized equally into five groups: Sham controls (SC), sepsis induced by cecal-ligation and puncture (CLP), CLP-melatonin, CLP-A-ADMSC, and CLP-melatonin-A-ADMSC. Circulating TNF-α level at post-CLP 6 hr was highest in CLP and lowest in SC groups, higher in CLP-melatonin than in CLP-A-ADMSC and CLP-melatonin-A-ADMSC groups (all P < 0.001). Immune reactivity as reflected in the number of splenic helper-, cytoxic-, and regulatory-T cells at post-CLP 72 hr exhibited the same pattern as that of circulating TNF-α among all groups (P < 0.001). The histological scoring of kidney injury and the number of F4/80+ and CD14+ cells in kidney were highest in CLP and lowest in SC groups, higher in CLP-melatonin than in CLP-A-ADMSC and CLP-melatonin-A-ADMSC groups, and higher in CLP-A-ADMSC than in CLP-melatonin-A-ADMSC groups (all P < 0.001). Changes in protein expressions of inflammatory (RANTES, TNF-1α, NF-κB, MMP-9, MIP-1, IL-1β), apoptotic (cleaved caspase 3 and PARP, mitochondrial Bax), fibrotic (Smad3, TGF-β) markers, reactive-oxygen-species (NOX-1, NOX-2), and oxidative stress displayed a pattern identical to that of kidney injury score among the five groups (all P < 0.001). Expressions of antioxidants (GR+, GPx+, HO-1, NQO-1+) were lowest in SC group and highest in CLP-melatonin-A-ADMSC group, lower in CLP than in CLP-melatonin and CLP-A-ADMSC groups, and lower in CLP-melatonin- than in CLP-A-ADMSC-tretaed animals (all P < 0.001). In conclusion, combined treatment with melatonin and A-ADMSC was superior to A-ADMSC alone in protecting the kidneys from sepsis-induced injury.

Melatonin reduces cardiac morbidity and markers of myocardial ischemia after elective abdominal aortic aneurism repair: a randomized, placebo-controlled, clinical trial

The aim was to examine the effect of perioperative melatonin treatment on clinical cardiac morbidity and markers of myocardial ischemia in patients undergoing elective surgery for abdominal aortic aneurism. Reperfusion injury results in increased cardiac morbidity in patients undergoing surgery for abdominal aortic aneurisms (AAA). A randomized, placebo-controlled, clinical trial including patients undergoing surgery for AAA was performed. The patients received by infusion over a 2-hr period either, 50 mg melatonin or placebo intra-operatively, and 10 mg melatonin or placebo orally, the first three nights after surgery. Postoperative cardiac morbidity was registered, and blood samples for analysis of troponin-I (TpI) were collected preoperatively, and at 5 min, 6, 24, 48, 72, and 96 hr after clamp removal/recirculation of the first leg. Continuous measurement of ST-segment depression was performed by Holter monitoring. A total of 26 patients received melatonin, while 24 received placebo. A significant reduction in cardiac morbidity was seen in the melatonin-treated patients compared with those given placebo [4% versus 29% (P = 0.02)]. Five patients (19%) who received melatonin had increased TpI levels in the postoperative period compared with 12 patients (50%) who were given placebo (P = 0.036). The median number of ST-segment deviations was less in the melatonin-treated patients compared with the placebo group [median 1 (range 0-4) versus 6 (range 0-13) (P = 0.01)], but no differences were found in the duration of ST-segment deviations. Melatonin treatment in the perioperative period decreased clinical cardiac morbidity as well as the occurrence of myocardial ischemia after abdominal aortic aneurism repair.

Evaluation of melatonin and prostaglandin E1 combination on necrotizing enterocolitis model in neonatal rats

BACKGROUND

Necrotizing enterocolitis (NEC) is one of the most common gastrointestinal emergencies in newborn infants but up to now there is no completely effective treatment for it.

OBJECTIVE

In order to show that a combination of melatonin and prostaglandins may be useful to save lives, we use newborn rat as a model of necrotizing enterocolitis to test the hypothesis of using the combination therapy might have more potential effect on mucosal cytoprotection and healing.

PATIENTS AND METHODS

A total of 60 newborn pups from 5 time-mated Sprague-Dawley pregnant rats were divided equally into 5 groups as follows: NEC (subjected to NEC), NEC+Melatonin, NEC+Prostaglandin, NEC+Prostaglandin+Melatonin and control. These animals were fed with hyperosmolar formula 3 times daily and subjected to 100% CO2 inhalation for 10 min, +4°C cold exposure for 5 min, and 97% O2 for 5 min twice daily to induce NEC. This procedure was applied to the pups for 3 days.

RESULTS

The macroscopic scoring, intestinal injury scoring and apoptosis index scoring were all found to be significantly lower in NEC+Prostaglandin+Melatonin group compared with NEC group. Anti-oxidant enzyme activities were significantly higher, whereas lipid peroxidation was significantly lower in NEC+Prostaglandin+Melatonin group compared with NEC group.

CONCLUSION

This combination therapy showed cytoprotective and healing effects on mucosa in the intestinal tissue of rat pups in necrotizing enterocolitis model. Therefore, this therapy might also show benefit in preterm infants with NEC. After confirmation of this data by other clinical and experimental studies, it may be a novel therapeutic option for the prevention of NEC in preterm infants.

Mast-cell-releasing tryptase triggers acute lung injury induced by small intestinal ischemia-reperfusion by activating PAR-2 in rats

Mast cell has been demonstrated to be involved in the small intestinal ischemia-reperfusion (IIR) injury, however, the precise role of tryptase released from mast cell on acute lung injury(ALI) induced by IIR remains to be elucidated, our study aimed to observe the roles of tryptase on ALI triggered by IIR and its underlying mechanism. Adult SD rats were randomized into sham-operated group, sole IIR group in which rats were subjected to 75 min superior mesenteric artery occlusion followed by 4 h reperfusion, or IIR being respectively treated with cromolyn sodium, protamine, and compound 48/80. The above agents were, respectively, administrated intravenously 5 min before reperfusion. At the end of experiment, lung tissue was obtained for assays for protein expressions of tryptase and mast cell protease 7 (MCP7) and protease-activated receptor 2 (PAR-2). Pulmonary mast cell number and levels of IL-8 were quantified. Lung histologic injury scores and lung water content were measured. IIR resulted in lung injury evidenced as significant increases in lung histological scores and lung water contents, accompanied with concomitant increases of expressions of tryptase and MCP7, and elevations in PAR-2 expressions and IL-8 levels in lungs. Stabilizing mast cell with cromolyn sodium and inhibiting tryptase with protamine significantly reduced IIR-mediated ALI and the above biochemical changes while activating mast cell with compound 48/80 further aggravated IIR-mediated ALI and the increases of above parameters. Tryptase released from mast cells mediates ALI induced by intestinal ischemia-reperfusion by activating PAR-2 to produce IL-8.

Pulmonary impact of N-acetylcysteine in a controlled hemorrhagic shock model in rats

BACKGROUND

Experimental hemorrhagic shock (HS) is based on controlling bleeding and the treatment of fluid resuscitation to restore tissue oxygenation and perfusion. The HS could promote ischemia/reperfusion injury, which induces a general exacerbation of the inflammatory process, initially compromising the lungs. N-acetylcysteine (NAC), an antioxidant, may attenuate ischemia/reperfusion injury. This study evaluated the effect of NAC in association with fluid resuscitation on pulmonary injury in a controlled HS model in rats.

METHODS

Male Wistar rats were submitted to controlled HS (mean arterial pressure of 35 mm Hg for 60 min). Two groups were constituted according to resuscitation solution administered: RLG (Ringer's lactate solution) and RLG+NAC (Ringer's lactate in association with 150 mg/kg NAC. A control group was submitted to catheterization only. After 120 min of resuscitation, bronchoalveolar lavage was performed to assess intra-alveolar cell infiltration and pulmonary tissue was collected for assessment of malondialdehyde, interleukin 6, and interleukin 10 and histopathology.

RESULTS

Compared with the RLG group, the RLG+NAC group showed lower bronchoalveolar lavage inflammatory cell numbers, lower interstitial inflammatory infiltration in pulmonary parenchyma, and lower malondialdehyde concentration. However, tissue cytokine (interleukin 6 and interleukin 10) expression levels were similar.

CONCLUSION

N-acetylcysteine was associated with fluid resuscitation-attenuated oxidative stress and inflammatory cell infiltration in pulmonary parenchyma. N-acetylcysteine did not modify cytokine expression.

Melatonin reduces acute lung inflammation, edema, and hemorrhage in heatstroke rats

AIM

To assess the therapeutic effect of melatonin on heat-induced acute lung inflammation and injury in rats.

METHODS

Heatstroke was induced by exposing anesthetized rats to heat stress (36 °C, 100 min). Rats were treated with vehicle or melatonin (0.2, 1, 5 mg/kg) by intravenous administration 100 min after the initiatioin of heatstroke and were allowed to recover at room temperature (26 °C). The acute lung injury was quantified by morphological examination and by determination of the volume of pleural exudates, the number of polymorphonuclear (PMN) cells, and the myeloperoxidase (MPO) activity. The concentrations of tumor necrosis factor, interleukin (IL)-1β, IL-6, and IL-10 in bronchoalveolar fluid (BALF) were measured by ELISA. Nitric oxide (NO) level was determined by Griess method. The levels of glutamate and lactate-to-pyruvate ratio were analyzed by CMA600 microdialysis analyzer. The concentrations of hydroxyl radicals were measured by a procedure based on the hydroxylation of sodium salicylates leading to the production of 2,3-dihydroxybenzoic acid (DHBA).

RESULTS

Melatonin (1 and 5 mg/kg) significantly (i) prolonged the survival time of heartstroke rats (117 and 186 min vs 59 min); (ii) attenuated heatstroke-induced hyperthermia and hypotension; (iii) attenuated acute lung injury, including edema, neutrophil infiltration, and hemorrhage scores; (iv) down-regulated exudate volume, BALF PMN cell number, and MPO activity; (v) decreased the BALF levels of lung inflammation response cytokines like TNF-alpha, interleukin (IL)-1β, and IL-6 but further increased the level of an anti-inflammatory cytokine IL-10; (vi) reduced BALF levels of glutamate, lactate-to-pyruvate ratio, NO, 2,3-DHBA, and lactate dehydrogenase.

CONCLUSION

Melatonin may improve the outcome of heatstroke in rats by attenuating acute lung inflammation and injury.

Radiation protection following nuclear power accidents: a survey of putative mechanisms involved in the radioprotective actions of taurine during and after radiation exposure

There are several animal experiments showing that high doses of ionizing radiation lead to strongly enhanced leakage of taurine from damaged cells into the extracellular fluid, followed by enhanced urinary excretion. This radiation-induced taurine depletion can itself have various harmful effects (as will also be the case when taurine depletion is due to other causes, such as alcohol abuse or cancer therapy with cytotoxic drugs), but taurine supplementation has been shown to have radioprotective effects apparently going beyond what might be expected just as a consequence of correcting the harmful consequences of taurine deficiency per se. The mechanisms accounting for the radioprotective effects of taurine are, however, very incompletely understood. In this article an attempt is made to survey various mechanisms that potentially might be involved as parts of the explanation for the overall beneficial effect of high levels of taurine that has been found in experiments with animals or isolated cells exposed to high doses of ionizing radiation. It is proposed that taurine may have radioprotective effects by a combination of several mechanisms: (1) during the exposure to ionizing radiation by functioning as an antioxidant, but perhaps more because it counteracts the prooxidant catalytic effect of iron rather than functioning as an important scavenger of harmful molecules itself, (2) after the ionizing radiation exposure by helping to reduce the intensity of the post-traumatic inflammatory response, and thus reducing the extent of tissue damage that develops because of severe inflammation rather than as a direct effect of the ionizing radiation per se, (3) by functioning as a growth factor helping to enhance the growth rate of leukocytes and leukocyte progenitor cells and perhaps also of other rapidly proliferating cell types, such as enterocyte progenitor cells, which may be important for immunological recovery and perhaps also for rapid repair of various damaged tissues, especially in the intestines, and (4) by functioning as an antifibrogenic agent. A detailed discussion is given of possible mechanisms involved both in the antioxidant effects of taurine, in its anti-inflammatory effects and in its role as a growth factor for leukocytes and nerve cells, which might be closely related to its role as an osmolyte important for cellular volume regulation because of the close connection between cell volume regulation and the regulation of protein synthesis as well as cellular protein degradation. While taurine supplementation alone would be expected to exert a therapeutic effect far better than negligible in patients that have been exposed to high doses of ionizing radiation, it may on theoretical grounds be expected that much better results may be obtained by using taurine as part of a multifactorial treatment strategy, where it may interact synergistically with several other nutrients, hormones or other drugs for optimizing antioxidant protection and minimizing harmful posttraumatic inflammatory reactions, while using other nutrients to optimize DNA and tissue repair processes, and using a combination of good diet, immunostimulatory hormones and perhaps other nontoxic immunostimulants (such as beta-glucans) for optimizing the recovery of antiviral and antibacterial immune functions. Similar multifactorial treatment strategies may presumably be helpful in several other disease situations (including severe infectious diseases and severe asthma) as well as for treatment of acute intoxications or acute injuries (both mechanical ones and severe burns) where severely enhanced oxidative and/or nitrative stress and/or too much secretion of vasodilatory neuropeptides from C-fibres are important parts of the pathogenetic mechanisms that may lead to the death of the patient. Some case histories (with discussion of some of those mechanisms that may have been responsible for the observed therapeutic outcome) are given for illustration of the likely validity of these concepts and their relevance both for treatment of severe infections and non-infectious inflammatory diseases such as asthma and rheumatoid arthritis.

Melatonin ameliorates necrotizing enterocolitis in a neonatal rat model

INTRODUCTION

We designed the present study to evaluate the efficacy of melatonin (M) on the severity of necrotizing enterocolitis (NEC) in a neonatal rat model.

MATERIALS AND METHODS

Immediately after birth, pups were weighed and randomized into 3 groups: NEC, NEC + M, and control. Necrotizing enterocolitis was induced by enteral formula feeding and exposure to hypoxia after cold stress at 4°C and oxygen. The NEC + M group received 10 mg/kg M daily for 3 days after the first day of the NEC procedure. The pups were killed on the fourth day, and their intestinal tissues were harvested for biochemical and histopathologic analysis. Blood samples were also obtained from the pups.

RESULTS

The mortality rate and weight loss were highest in the NEC group. Malondialdehyde and protein carbonyl content were significantly increased, whereas superoxide dismutase and glutathione peroxidase were decreased in the NEC-treated pups. Melatonin prevented these changes, with these values being similar to control levels in the NEC + M group. Nitrate plus nitrite levels and serum tumor necrosis factor α and interleukin-1β were increased in the NEC group, and histopathologic injury score in the NEC group was significantly higher than that in the NEC + M group.

CONCLUSION

Melatonin significantly reduced the severity of NEC in our study.

The effects of sirolimus on target organs during mesenteric ischemia and reperfusion damage in an experimental rat model

BACKGROUND

Mesenteric ischemia and reperfusion (I/R) syndrome (MIRS) has been considered a clinicopathologic entity associated with a variety of clinically severe conditions with decreased intestinal blood flow and has been known to induce I/R damage in various organs. Sirolimus (SRL), a macrolide antibiotic isolated from a strain of Streptomyces hygroscopicus, is a potent and nonnephrotoxic immunosuppressant.

OBJECTIVE

This study was designed to investigate the potential impact of sirolimus on MIRS-induced I/R damage in renal, intestinal, pulmonary, and hepatic tissues in an experimental rat model.

METHODS

Twenty-four male Sprague-Dawley rats, aged 6 to 8 weeks and weighing 280 (±20 g), were studied. Using computer-generated random numbers, rats were assigned to 1 of the following 3 groups: group 1 (I/R group, n = 8), group 2 (I/R + sirolimus group, n = 8), and group 3 (control group, n = 8). Sirolimus, in a 1 mg/mL (60 mL) solution, was administered intraperitoneally in a dose of 1.5 mg/kg/d to the rats assigned to group 2 starting from 3 days before the surgical procedure. In surgery, a laparotomy was performed to clamp the superior mesenteric artery and, thus, induce bowel ischemia in groups 1 and 2. After 60 minutes of ischemia, the microvascular clamp on the superior mesenteric artery was removed for 3 hours of reperfusion. Soon after experimental induction of MIRS, bowel, lung, kidney, and liver specimens from each animal were harvested for both biochemical and histopathologic analysis.

RESULTS

There were statistically significant differences between groups 1 and 3 with regard to degrees of intestinal (P < 0.001), hepatic (P = 0.001), renal (P < 0.001), and pulmonary (P = 0.01) I/R damage. The lung specimens from group 2 had less inflammation and perivascular edema formation compared with specimens from group 1, but no statistical significance was observed between the groups (P < 0.33). There were statistically significant differences between groups 1 and 2 with regard to degrees of intestinal, hepatic, and renal I/R damage (P = 0.001 for all).

CONCLUSION

The findings of the present study demonstrate the attenuating effects of sirolimus on I/R damage in the intestine and remote organs, including the liver and kidney in the setting of MIRS in an experimental rat model. As a therapeutic implication, the utility of sirolimus may be of clinical value in procedures associated with a high likelihood of I/R damage, including major abdominal operations and renal transplantation. However, whether these results apply to humans is unclear. Additional experimental and clinical studies are warranted to confirm the clinical utility of sirolimus in conditions potentially associated with I/R damage.

Evaluation of effects of s-methyl isothiourea and melatonin on intestinal ischemia/reperfusion injury in rats

The present study was designed to evaluate whether the administration of s-methylisothiourea and melatonin has protective potential in intestinal ischemia/reperfusion injury. Forty male Sprague-Dawley rats were divided into five groups. Ileal specimens were obtained to determine the levels of malondialdehyde, protein carbonyl content, levels of antioxidant enzymes and evaluation of histologic changes. Combination of s-methylisothiourea and melatonin, led to a statistically significant increase in activities of antioxidant enzymes with a decrease in malondialdehyde and protein carbonyl content and intestinal mucosal injury scores. It was shown; combination of SMT and melatonin may exert more promised results.