Comparison of the efficacy of melatonin and 1400W on renal ischemia/reperfusion injury: a role for inhibiting iNOS

The protective effect of 1400W against ischaemia and reperfusion injury is countered by transient medullary kidney endothelial dysregulation

Renal ischaemia and reperfusion (I/R) is caused by a sudden temporary impairment of the blood flow. I/R is a prevalent cause of acute kidney injury. As nitric oxide generated by inducible nitric oxide synthase (iNOS) has detrimental effects during I/R, the pharmacological blockade of iNOS has been proposed as a potential strategy to prevent I/R injury. The aim of this study was to improve the understanding of 1400W (an iNOS inhibitor) on renal I/R as a pharmacological strategy against kidney disease. BALB/c mice received 30 min of bilateral ischaemia, followed by 48 h or 28 days of reperfusion. Vehicle or 1400W (10 mg/kg) was administered 30 min before inducing ischaemia. We found that after 48 h of reperfusion 1400W decreased the serum creatinine, blood urea nitrogen, neutrophil gelatinase-associated lipocalin and proliferating cell nuclear antigen 3 in the I/R animals. Unexpectedly, we observed mRNA upregulation of genes involved in kidney injury, cell-cycle arrest, inflammation, mesenchymal transition and endothelial activation in the renal medulla of sham animals treated with 1400W. We also explored if 1400W promoted chronic kidney dysfunction 28 days after I/R and did not find significant alterations in renal function, fibrosis, blood pressure or mortality. The results provide evidence that 1400W may have adverse effects in the renal medulla. Importantly, our data point to 1400W-induced endothelial dysfunction, establishing therapeutic limitations for its use. KEY POINTS: Acute kidney injury is a global health problem associated with high morbidity and mortality. The pharmacological blockade of inducible nitric oxide synthase (iNOS) has been proposed as a potential strategy to prevent AKI induced by ischaemia and reperfusion (I/R). Our main finding is that 1400W, a selective and irreversible iNOS inhibitor with low toxicity that is proposed as a therapeutic strategy to prevent kidney I/R injury, produces aberrant gene expression in the medulla associated to tissue injury, cell cycle arrest, inflammation, mesenchymal transition and endothelial activation. The negative effect of 1400W observed in the renal medulla at 48 h from drug administration, is transient as it did not translate into a chronic kidney disease condition.

Protective Effect of Melatonin for Renal Ischemia-Reperfusion Injury: A Systematic Review and Meta-Analysis

Background: Renal ischemia-reperfusion (I/R) injury is one of the major causes related to acute kidney damage. Melatonin has been shown as a powerful antioxidant, with many animal experiments have been designed to evaluate the therapeutic effect of it to renal I/R injury.

Objectives: This systematic review aimed to assess the therapeutic effect of melatonin for renal I/R injury in animal models.

Methods and Results: The PubMed, Web of Science, Embase, and Science Direct were searched for animal experiments applying melatonin to treat renal I/R injury to February 2021. Thirty-one studies were included. The pooled analysis showed a greater reduction of blood urea nitrogen (BUN) (21 studies, weighted mean difference (WMD) = −30.00 [−42.09 to −17.91], p < 0.00001), and serum creatinine (SCr) (20 studies, WMD = −0.91 [−1.17 to −0.66], p < 0.00001) treated with melatonin. Subgroup analysis suggested that multiple administration could reduce the BUN compared with control. Malondialdehyde and myeloperoxidase were significantly reduced, meanwhile, melatonin significantly improved the activity of glutathione, as well as superoxide dismutase. The possible mechanism for melatonin to treat renal I/R injury is inhibiting endoplasmic reticulum stress, apoptosis, inflammation, autophagy, and fibrillation in AKI to chronic kidney disease.

Conclusions: From the available data of small animal studies, this systematic review demonstrated that melatonin could improve renal function and antioxidative effects to cure renal I/R injury through, then multiple administration of melatonin might be more appropriate. Nonetheless, extensive basic experiments are need to study the mechanism of melatonin, then well-designed randomized controlled trials to explore the protective effect of melatonin.

The effect of hypothermia in a rat testicular torsion/detorsion model

BACKGROUND

Testicular torsion is an emergent condition. The protective effect of medical hypothermia in ischemia/reperfusion injury is well defined.

OBJECTIVES

To evaluate the late results of hypothermia through a rat testicular torsion/detorsion model compatible with human testicular torsion.

STUDY DESIGN

Rats were divided into 5 groups (n = 7): (1)Sham (S) group, (2)T/D group: right testis was torted for 1-h, (3)T/D + H30 group: hypothermia at 4 °C was applied for 30 min before detorsion, (4)T/D + H90 group: hypothermia at 4 °C was applied for a total of 90 min (30 min before and 1-h after detorsion), (5)H group: hypothermia at 4 °C was applied to right testis for 90 min. Testicular diameters at preoperative period and 8th postoperative week were measured. Biochemically, MPO, NO, 3-NT and 4-HNE in testicular tissue and serum levels of NO, PGF 2α, 3-NT, 8-OHdG and 4-HNE were studied. Histopathologic examination and TUNEL assay were also performed.

RESULTS

Biochemical and macroscopical parameters of both T/D + H30 and T/D + H90 groups were statistically different from group T/D with respect to protective effects of hypothermia. Johnsen's score was also statistically different in group T/D + H90.

DISCUSSION

Hypothermia can easily be applied with ice bags both in perioperative period. This is the first study evaluating the effect of hypothermia applied postoperatively. Tissue level of protein oxidation marker (3-NT) and serum levels of DNA damage (8-OHdG), lipid peroxidation (4-HNE), protein oxidation (3-NT) and oxidative stress (PGF-2α) markers were measured for the first time.

CONCLUSIONS

Hypothermia has been shown to be macroscopically, biochemically and histopathologically beneficial in the long-term experimental testicular torsion model.

Melatonin protects against tenofovir-induced nephrotoxicity in rats by targeting multiple cellular pathways

Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection and chronic hepatitis B infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to its better tolerance, and a more effective treatment can be achieved. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats and to determine its cellular targets. Rats were divided into groups and treated as follows. Group I (control): Rats in this group (n = 6) received sterile water only by gavage for 35 days. Group II: Rats (n = 6) in this group received 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group III: Rats (n = 6) in this group received once daily 20 mg/kg bodyweight melatonin i.p. 2 h before the administration of 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group IV: Rats were pretreated daily with 20 mg/kg body weight melatonin i.p. 2 h before the administration of sterile water by gavage. All the rats were sacrificed on the 36th day, after overnight fast. Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced, oxidative stress, nitrosative stress, mitochondrial pathway of apoptosis, PARP overactivation and preserved proximal tubular function (p < 0.01). This suggests that melatonin may be useful in ameliorating TDF nephrotoxicity.

The long-term protective effect of hypothermia and gradual detorsion on ovarian tissue in adnexal torsion/detorsion model in rats

INTRODUCTION

Ischemia in ovarian torsion and subsequent reperfusion has significant effects on fertility in the long term. The most important reason for these changes is thought to be a reperfusion injury rather than ischemia. We aimed to evaluate whether the reperfusion injury following ovarian detorsion could be reduced by hypothermia and intermittent reperfusion.

MATERIALS AND METHODS

Forty adult female rats were divided into five groups as follows: Sham (Sh) (n = 8), torsion detorsion (control TD) (n = 8), progressive reperfusion "gradual detorsion" (GD) (n = 8), hypothermia (H) (n = 8) and the progressive reperfusion + hypothermia (GD + H) (n = 8). In all rats, except for the Sh group, the left ovary was rotated counter clockwise 1080° and fixed to the abdominal wall by three 5-0 non-absorbable sutures followed by the closure of the laparotomy. After 30 h, reperfusion was achieved following the detorsion of the ovaries. In both the control TD and H groups, the torsed ovaries were detorsed. H group, however, was subjected to hypothermia with ice packs 30 min before and during the detorsion. Tissue temperature was kept constant at 4 °C, controlled by a digital thermometer. In the GD group, the torsed ovary and pedicle were detorsed by 360°, followed by a 5 min pause. This procedure was repeated twice until a complete detorsion was achieved. GD + H group underwent hypothermia with ice packs 30 min before the procedure and the torsed ovary and pedicle were detorsed by 360°. After a 5 min pause, we repeated this process twice to provide full detorsion. The tissue temperature was constantly held at 4 °C. In the hypothermia groups, we applied hypothermia for an additional 30 min after detorsion and then left the rats at normal body temperature during reperfusion. We followed the rats in all groups for 60 days. Then we excised the left ovaries of all rats through laparotomy and spared some of the ovaries for biochemical and pathological examination. Intracardiac blood was taken at the end of the procedure and it was sent to the biochemical laboratory to assess oxidative stress markers. Finally, all the animals were sacrificed with high-dose of anesthesia.

RESULTS

Evaluation of the results revealed that oxidative stress markers were significantly lower, and antioxidant parameters were higher in the experimental groups compared with the control TD group (p < 0.05). Histopathologically, we found that tissues were preserved in GD, H, GD + H groups (p < 0.05). When we compared the groups among each other, both biochemical and histopathological values in GD + H group showed that the tissue was preserved from oxidative damage, albeit the difference did not reach a level of significance.

DISCUSSION

Several studies have shown that both hypothermia and intermittent reperfusion protect tissue from IR damage in the early period. However, as far as we know there is no study on long-term outcomes of both practices. Our study showed that both hypothermia and intermittent reperfusion alone protect tissue from IR damage in the long term. However, it did not show the superiority of the combination of both methods compared to that of individual application. The advantages of these methods lie in their easy application and cost-effectiveness. We believe that our study will serve as a base for future studies on the subject.

Inducible nitric oxide synthase inhibitor 1400W increases Na+ ,K+ -ATPase levels and activity and ameliorates mitochondrial dysfunction in Ctns null kidney proximal tubular epithelial cells

Nitric oxide (NO) has been shown to play an important role in renal physiology and pathophysiology partly through its influence on various transport systems in the kidney proximal tubule. The role of NO in kidney dysfunction associated with lysosomal storage disorder, cystinosis, is largely unknown. In the present study, the effects of inducible nitric oxide synthase (iNOS)-specific inhibitor, 1400W, on Na⁺ ,K⁺ -ATPase activity and expression, mitochondrial integrity and function, nutrient metabolism, and apoptosis were investigated in Ctns null proximal tubular epithelial cells (PTECs). Ctns null PTECs exhibited an increase in iNOS expression, augmented NO and nitrite/nitrate production, and reduced Na⁺ ,K⁺ -ATPase expression and activity. In addition, these cells displayed depolarized mitochondria, reduced adenosine triphosphate content, altered nutrient metabolism, and elevated apoptosis. Treatment of Ctns null PTECs with 1400W abolished these effects which culminated in the mitigation of apoptosis in these cells. These findings indicate that uncontrolled NO production may constitute the upstream event that leads to the molecular and biochemical alterations observed in Ctns null PTECs and may explain, at least in part, the generalized proximal tubular dysfunction associated with cystinosis. Further studies are needed to realize the potential benefits of anti-nitrosative therapies in improving renal function and/or attenuating renal injury in cystinosis.

Histomorphological changes in the pancreas and kidney and histopathological changes in the liver in male Wistar rats on antiretroviral therapy and melatonin treatment

Combination antiretroviral therapy (cART) has shown to cause inflammation, cellular injury and oxidative stress, whereas melatonin has been successful in reducing these effects. The aim of the study was to determine potential morphometric changes caused by cART in combination with melatonin supplementation in human immunodeficiency virus (HIV)-free rats. Tissue samples (N = 40) of the pancreas, liver and kidney from a control (C/ART-/M-), cART group (C/ART + ), melatonin (C/M + ) and experimental group (ART+/M + ) were collected and stained with haematoxylin and eosin (H&E) and evaluated for histopathology. The pancreata were labelled with anti-insulin and anti-glucagon to determine α- and β-cell regions. Kidneys were stained with periodic acid Schiff (PAS) to measure the area, perimeter, diameter and radius of renal corpuscles, glomeruli and proximal convoluted tubules (PCTs). Blood tests were conducted to determine hepatotoxicity. No significant changes in histopathology were seen. Melatonin stimulated pancreatic islet abundance, as the number of islets per mm² was significantly higher in the C/M+ than in the C/ART-/M- and ART+/M+. Parameters of the renal corpuscle, glomeruli, renal space and PCTs were significantly lower in the C/ART+ compared to the other groups, thus cART may have caused tubular dysfunction or cellular damage. A significant increase in serum haemoglobin was observed in the C/ART+ compared to the C/ART-, which showed cART increases serum haemoglobin in the absence of immune deficiency. Serum lipids were significantly decreased in the C/M+ compared to the C/ART-, possibly due to the effect of melatonin on the decrease of lipolysis, decreasing effect on cholesterol absorption and stimulation of lipoprotein lipase (LPL) activity. In conclusion, we have demonstrated that melatonin stimulated α-cell production, increased the number of pancreatic islets and caused a decrease in total lipids, whereas cART increased serum haemoglobin and decreased various parameters of the nephron in an HIV-free rat model, suggestive of tubular dysfunction.

Magnesium isoglycyrrhizinate protects against renal‑ischemia‑reperfusion injury in a rat model via anti‑inflammation, anti‑oxidation and anti‑apoptosis

The present study aimed to investigate whether magnesium isoglycyrrhizinate protects against renal ischemia‑reperfusion injury (RIRI), and to verify the underlying mechanisms. An RIRI rat model was induced by removing the right kidney, and exposing and clamping the left kidney. RIRI model rats were administered 30 mg/kg magnesium isoglycyrrhizinate for 3 days. Blood urea nitrogen (BUN) and serum creatinine levels in the blood of RIRI model rat were examined, compared with sham‑operated controls. Magnesium isoglycyrrhizinate suppressed the activities of tumor necrosis factor‑α, interleukin (IL)‑1β, IL‑6, superoxide dismutase, glutathione peroxidase, inducible nitric oxide synthase (iNOS) and caspase‑3 in RIRI model rats. Renal iNOS, matrix metalloproteinase (MMP)‑2, phosphorylated‑signal transducers and activators of transcription 3 (STAT3) and intercellular adhesion molecule‑1 (ICAM‑1) protein expression levels were suppressed by magnesium isoglycyrrhizinate treatment in RIRI model rats. These findings suggested that magnesium isoglycyrrhizinate protects RIRI via anti‑inflammatory, ‑oxidative and ‑apoptotic mechanisms in an RIRI rat model. These results implicate magnesium isoglycyrrhizinate pretreatment as a potential approach to protect against RIRI via suppression of the iNOS, ICAM‑1, MMP‑2 and STAT3 signaling pathways.

Melatonin Scavenger Properties against Oxidative and Nitrosative Stress: Impact on Gamete Handling and In Vitro Embryo Production in Humans and Other Mammals

Oxidative and nitrosative stress are common problems when handling gametes in vitro. In vitro development in mammalian embryos is highly affected by culture conditions, especially by reactive oxygen species (ROS) and reactive nitrogen species (RNS), because their absence or overproduction causes embryo arrest and changes in gene expression. Melatonin in gamete co-incubation during in vitro fertilization (IVF) has deleterious or positive effects, depending on the concentration used in the culture medium, demonstrating the delicate balance between antioxidant and pro-oxidant activity. Further research is needed to better understand the possible impact of melatonin on the different IVP steps in humans and other mammals, especially in seasonal breeds where this neuro-hormone system highly regulates its reproduction physiology.

Comparison of intraperitoneal and intratesticular ozone therapy for the treatment of testicular ischemia-reperfusion injury in rats

We compare the efficacy of intratesticular ozone therapy with intraperitoneal ozone therapy in an experimental rat model. For this purpose, 24 rats were divided into four groups including sham-operated, torsion/detorsion, torsion/detorsion plus intraperitoneal ozone (O-IP), and torsion/detorsion plus intratesticular ozone (O-IT). The O-IP ozone group received a 4 mg kg-1 intraperitoneal injection of ozone, and the O-IT group received the same injection epididymally. At 4 h after detorsion, the rats were sacrificed and orchiectomy materials were assessed histopathologically. Spermatogenesis in the seminiferous tubules and damage to the Sertoli cells were histopathologically evaluated in the testes using the Johnsen scoring system. i-NOS and e-NOS activities in the testis tissue were also evaluated. Torsion-detorsion caused a decreased Johnsen score and increased apoptosis of spermatogonial and Sertoli cells. Ozone injection prevented increases in Johnsen score and i-NOS level. e-NOS level of the O-IP group was significantly lower than that of the O-IP group, and i-NOS level of the O-IT group was significantly lower than that of the O-IP group. Local ozone therapy is more effective than systemic ozone therapy at improving IRI-related testicular torsion. Our study is the first to show that the efficacy of intratesticular implementation of ozone therapy is higher than that of intraperitoneal ozone therapy.

A nested case-control study of the association between melatonin secretion and incident myocardial infarction

OBJECTIVES

Low nocturnal melatonin secretion is associated with cardiovascular risk factors, diabetes and hypertension, while individuals with prevalent cardiovascular disease have lower nocturnal melatonin levels. However, the prospective association of melatonin secretion with myocardial infarction (MI) has not been studied. We aimed to study the association between melatonin secretion and the risk of developing MI.

METHODS

We performed a prospective nested case-control study of participants from the Nurses' Health Study cohorts I and II. A total of 209 incident cases of fatal and non-fatal MI were identified among women who provided first morning voided urine specimens at baseline and were matched to 209 controls. Nocturnal melatonin secretion was assessed using 6-sulfatoxymelatonin concentrations in morning urines normalised to the urines' creatinine concentration. Multivariable conditional logistic regression was used to analyse associations independent of important risk factors.

RESULTS

Lower melatonin secretion was significantly associated with a higher risk of MI. After conditioning on matching variables, the OR for every one unit lower log-transformed sulfatoxymelatonin/creatinine ratio was 1.51 (95% CI 1.16 to 1.96). In multivariable models controlling for factors included in the American Heart Association Cardiovascular Risk Score plus circadian factors, every one unit lower in the ratio was associated with a significantly increased risk of MI (OR, 1.40; 95% CI 1.02 to 1.93). Women in the highest category had an estimated absolute risk of MI of 84 cases per 100 000 person-years compared with 197 cases per 100 000 person-years in the lowest category. The association was strongly modified by body mass index (BMI) (p value for interaction=0.02).

CONCLUSIONS

Lower melatonin secretion was significantly associated with a greater risk of incident MI in women with increased BMI. Melatonin may be a novel and modifiable risk factor for MI among such women.

Melatonin prevents secondary intra-abdominal hypertension in rats possibly through inhibition of the p38 MAPK pathway

Exogenous administration of melatonin has been demonstrated to down-regulate inflammatory responses and attenuate organ damage in various models. However, the salutary effect of melatonin against secondary intra-abdominal hypertension (IAH) remains unclear. This study sought to test the influence of melatonin on secondary IAH in a pathophysiological rat model and the underlying mechanisms involved. Before resuscitation, male rats underwent a combination of induced portal hypertension, applying an abdominal restraint device, and hemorrhaging to mean arterial pressure (MAP) of 40mmHg for 2h. After blood reinfusion, the rats were treated with lactated Ringer solution (LR) (30mL/h), melatonin (50mg/kg) +LR, and SB-203580 (10μmol/kg)+LR. LR was continuously infused for 6h. MAP, the inferior vena cava pressure and urine output were monitored. Histopathological examination, immunofluorescence of tight junction proteins, and transmission electron microscopy were administered. Intestinal permeability, myeloperoxidase activity, malondialdehyde, glutathione peroxidase, and levels of TNF-a, IL-2, and IL-6, were assessed. The expression of extracellular signal-regulated kinase, p38, c-Jun NH2-terminal kinase, translocation of nuclear factor kappa B subunit, signal transducers and activators of transcription and tight junction proteins were detected by Western blot. We found that melatonin inhibited the inflammatory responses, decreased expression of p38 MAPK, attenuated intestinal injury, and prevented secondary IAH. Moreover, administration of SB203580 abolished the increase in p38 MAPK and also attenuated intestinal injury. These data indicate that melatonin exerts a protective effect in intestine in secondary IAH primarily by attenuating the inflammatory responses which are in part attributable to p38 MAPK inhibition.

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 modulates endoplasmic reticulum stress and Akt/GSK3-beta signaling pathway in a rat model of renal warm ischemia reperfusion

Melatonin (Mel) is widely used to attenuate ischemia/reperfusion (I/R) injury in several organs. Nevertheless, the underlying mechanisms remain unclear. This study was conducted to explore the effect of Mel on endoplasmic reticulum (ER) stress, Akt and MAPK cascades after renal warm I/R. Eighteen Wistar rats were randomized into three groups: Sham, I/R, and Mel + I/R. The ischemia period was 60 min followed by 120 min of reperfusion. Mel (10 mg/kg) was administrated 30 min prior to ischemia. The creatinine clearance, MDA, LDH levels, and histopathological changes were evaluated. In addition, Western blot was performed to study ER stress and its downstream apoptosis as well as phosphorylation of Akt, GSK-3β, VDAC, ERK, and P38. Mel decreased cytolysis and lipid peroxidation and improved renal function and morphology compared to I/R group. Parallely, it significantly reduced the ER stress parameters including GRP 78, p-PERK, XBP 1, ATF 6, CHOP, and JNK. Simultaneously, p-Akt level was significantly enhanced and its target molecules GSK-3β and VDAC were inhibited. Furthermore, the ERK and P38 phosphorylation were evidently augmented after Mel administration in comparison to I/R group. In conclusion, Mel improves the recovery of renal function by decreasing ER stress and stimulating Akt pathway after renal I/R injury.

Increased exhaled nitric oxide precedes lung fibrosis in two murine models of systemic sclerosis

Exhaled nitric oxide (NO) is increased as a result of lung inflammation, which in turn causes subsequent interstitial lung disease in patients with systemic sclerosis (SSc). However, the exact time course of inflammatory and fibrotic changes in the SSc lung has not yet been described. Our objective was to assess the chronological evolution of lung inflammatory and fibrotic processes in mice pre-treated with hypochlorous acid (HOCl) or bleomycin. C57BL/6 mice were randomized into three groups receiving subcutaneous injections of HOCl, bleomycin, or PBS for 2, 4 or 6 weeks. Exhaled NO (eNO) was measured at the end of each injection period and after 2 resting weeks without injection (8 week group). Mice were then sacrificed to obtain skin and lung tissues to measure fibrotic changes and NO synthases (NOS) expression. Increased eNO, inducible NOS and nitrotyrosine expression in bronchial epithelium, lung neutrophils and macrophages were observed at early phases in both HOCl- and bleomycin-treated mice. Conversely, lung vascular endothelial NOS expression decreased significantly at 6th and 8th weeks. Skin fibrosis was significantly increased from the 4th week and lung fibrosis from 6th week. We conclude that lung inflammation occurs early after injury as reflected by increased exhaled NO and inducible NOS expression, and precedes fibrotic changes in skin and lungs of mice pre-treated with bleomycin and HOCl. Early detection and treatment of pulmonary inflammation might be useful in preventing subsequent occurrence of lung fibrosis in SSc patients.

Metabolic and Histopathological Effects of Fructose Intake During Pregestation, Gestation and Lactation in Rats and their Offspring

OBJECTIVE

Studies have demonstrated a significant relationship between maternal fructose intake and metabolic outcome in their offspring. However, there is a paucity of data about the long-term effects of fructose intake on the offspring of fructose-fed dams. Therefore, we planned a study to evaluate the long-term effects of fructose intake on the offspring of dam rats fed a high-fructose diet.

METHODS

Sixteen virgin female Sprague-Dawley rats were divided into two groups. Group 1 received a regular diet and Group 2 a high-fructose diet. Both groups received their experimental diets for 8 weeks before conception. They were mated and continued to feed with their experimental diet during mating and during their pregnancy and lactation periods. After weaning, the offspring from each group were divided into two groups. Group 1A received a regular diet, Group 1B - a fructose diet, Group 2A - a regular diet and Group 2B received a fructose diet. After weaning, the offspring were anesthetized and blood samples were collected for biochemical analysis. Liver, kidney and retroperitoneal adipose tissue were harvested for histopathological examination. Primary antibodies against inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were determined as early inflammation markers.

RESULTS

After weaning, while daily water consumption was found to be significantly higher in Groups 2B and 1B (p<0.01), daily laboratory chow consumption was significantly lower in Groups 1A and 2A (p<0.01). Body weight was significantly higher in Groups 1B and 2B (p<0.01). Serum glucose, triglyceride, low-density lipoprotein cholesterol and very low-density lipoprotein cholesterol levels were found to be increased and high-density lipoprotein cholesterol levels decreased in Group 2B (p<0.05). The intensities of iNOS staining in the retroperitoneal adipose tissue, COX-2 staining in the liver and both iNOS and COX-2 staining in the kidney were higher in Group 2B (p<0.05).

CONCLUSION

Based on our findings, we believe that the offspring of dams which received a high fructose intake during their pregestation, gestation and lactation periods are at risk of developing metabolic syndrome in their later life only if they continue to receive a high intake of fructose. We therefore propose that the risk of developing metabolic syndrome can probably be reduced by modifying the diet of the offspring after weaning.

Inhibition of inducible nitric oxide synthase ameliorates myocardial ischemia/reperfusion injury - induced acute renal injury

OBJECTIVES

Acute kidney injury occurs frequently in patients subsequent to coronary artery revascularization or myocardial ischemia and reperfusion (MIR). Hypotension and excessive nitric oxide (NO) production through inducible nitric oxide synthase (iNOS) were implicated in renal injury. On the other hand, NO may have a protective role during early reperfusion. In this study, we aim to compare protective effectiveness of 1,400W, a highly selective iNOS inhibitor, and L-NG-nitroarginine methyl ester (L-NAME), a non-specific nitric oxide synthase (NOS) inhibitor, against MIR-induced hemodynamic stabilization and kidney injury.

METHODS

Male Sprague-Dawley rats were evenly divided in four groups including sham-operated, MIR, and groups pretreated with 1,400W (20 mg/kg, intraperitoneally, [ip]) or L-NAME (30 mg/kg, ip) 15 minutes before MIR. Ischemia was conducted by occluding the left coronary artery for 30 minutes, followed by 120 minutes of reperfusion. We determined the measured aortic pressure (MAP) and assessed kidney injury through serum levels of blood urea nitrogen (BUN), methylguanidine (MG), malondialdehyde (MDA) and NO at different phases during the study.

RESULTS

MAP, decreased during myocardial ischemia, increased during early reperfusion; however, that was abolished with L-NAME pretreatment, and the increase was moderate with 1,400W pretreatment. Serum MDA, MG and BUN levels, although relatively unaltered during ischemia, significantly increased after 120 minutes of reperfusion. Treatment with 1,400W reduced post-reperfusion MDA and MG levels (P < .05), but the improvement was not significant with L-NAME.

CONCLUSIONS

1,400W was effective in reducing MIR-induced hemodynamic instability and kidney injury, in contrast to no apparent protection with L-NAME administration.

1400W reduces ischemia reperfusion injury in an ex-vivo porcine model of the donation after circulatory death kidney donor

AIM: To investigate the effects of 1400W-a selective inducible nitric oxide synthase (iNOS) inhibitor in a model of donation after circulatory death (DCD) kidneys.

METHODS: Porcine kidneys were retrieved after 25 min warm ischemia. They were then stored on ice for 18 h before being reperfused ex vivo with oxygenated autologous blood on an isolated organ perfusion system. The selective iNOS inhibitor 1400W (10 mg/kg) was administered before reperfusion (n = 6) vs control group (n = 7). Creatinine (1000 μmol/L) was added to the system, renal and tubular cell function and the level of ischemia reperfusion injury were assessed over 3 h of reperfusion using plasma, urine and tissue samples.

RESULTS: Kidneys treated with 1400W had a higher level of creatinine clearance (CrCl) [area under the curve (AUC) CrCl: 2.37 ± 0.97 mL/min per 100 g vs 0.96 ± 0.32 mL/min per 100 g, P = 0.004] and urine output [Total: 320 ± 96 mL vs 156 ± 82 mL, P = 0.008]. There was no significant difference in levels of fractional excretion of sodium (AUC, Fr ex Na+: Control, 186.3% ± 81.7%.h vs 1400W, 153.4% ± 12.1%.h, P = 0.429). Levels of total protein creatinine ratio were significantly lower in the 1400W group after 1 h of reperfusion (1h Pr/Cr: 1400W 9068 ± 6910 mg/L/mmol/L vs Control 21586 ± 5464 mg/L/mmol/L, P = 0.026). Levels of 8-isoprostane were significantly lower in the 1400W group [8-iso/creatinine ratio: Control 239 ± 136 pg/L/mmol/L vs 1400W 139 ± 47 pg/L/mmol/L, P = 0.041].

CONCLUSION: This study demonstrated that 1400W reduced ischaemia reperfusion injury in this porcine kidney model of DCD donor. Kidneys had improved renal function and reduced oxidative stress.

Role of progesterone in melatonin-mediated protection against acute kidney injury

BACKGROUND

Melatonin is released by pineal gland and maintains circadian rhythm in the body. It has been reported as renoprotective agent because of its antioxidant property. Recently, a cross talk between progesterone and melatonin has been observed in various preclinical studies. The present study investigated the involvement of progesterone receptors in melatonin-mediated protection against ischemia reperfusion induced acute kidney injury (AKI) in rats.

MATERIALS AND METHODS

The rats were subjected to bilateral renal ischemia for 40 min followed by reperfusion for 24 h to induce AKI. The AKI was assessed by measuring creatinine clearance, serum urea, uric acid level, potassium level, fractional excretion of sodium, lactate dehydrogenase activity, and microproteinuria. The oxidative stress in renal tissues was assessed by quantification of myeloperoxidase activity, thiobarbituric acid reactive substances, superoxide anion generation, reduced glutathione level, and catalase activity. The hematoxylin-eosin staining was carried out to observe histopathologic changes in renal tissues. The melatonin (4 and 10 mg/kg, intraperitoneally) and progesterone receptor antagonist mifepristone (5 mg/kg, intraperitoneally) were used in the present study.

RESULTS

The renal ischemia reperfusion induced AKI as indicated by significant change in serum, urinary, and tissue parameters that was ameliorated by prior treatment with melatonin. No significant difference in serum progesterone level was observed between various groups used in the present study. The prior administration of mifepristone abolished melatonin-mediated protection against AKI.

CONCLUSIONS

It is concluded that melatonin treatment affords protection against ischemia reperfusion induced AKI. Moreover, progesterone receptors are essentially involved in mediating protective role of melatonin against AKI in rats.

Melatonin attenuates the effects of sub-acute administration of lead on kidneys in rats without altering the lead-induced reduction in nitric oxide

Exposure to lead induces oxidative stress and renal damage. Although most forms of oxidative stress are characterized by simultaneous elevation of nitrogen and oxidative species, lead-induced oxidative stress is unusual in that it is associated with a reduction in nitric oxide (NO) levels in the kidney. The role of NO in kidney injury is controversial; some studies suggest that it is associated with renal injury, whereas others show that it exerts protective effects. Concentration-dependent effects have also been proposed, linking low levels with vasodilatation and high levels with toxicity. The aim of this study was to evaluate the effects of melatonin co-exposure on the lead-induced reduction in renal NO levels. We found that sub-acute intraperitoneal administration of 10 mg/kg/day of lead for 15 days induced toxic levels of lead in the blood and caused renal toxicity (pathological and functional). Under our experimental conditions, lead induced an increase in lipid peroxidation and a decrease in NO. Melatonin co-treatment decreased lead-induced oxidative stress (peroxidation level) and toxic effects on kidneys without altering the lead-induced reduction in renal NO. These results suggest that, in our experimental model, the reduction in renal NO levels by lead exposure is not the only responsible factor for lead-induced kidney damage.

A preclinical study on the protective effect of melatonin against methotrexate-induced small intestinal damage: effect mediated by attenuation of nitrosative stress, protein tyrosine nitration, and PARP activation

PURPOSE

One of the major toxic side effects of methotrexate (MTX) is enterocolitis. To date, there is no efficient standard treatment for this side effect. Nitrosative stress is reported to play a critical role in MTX-induced mucositis. The purpose of this study is to investigate whether pretreatment with melatonin, an inhibitor of nitro-oxidative stress, prevents MTX-induced mucositis in rats.

METHODS

Rats were pretreated with melatonin (20 and 40 mg/kg body weight) i.p. daily 1 h before MTX (7 mg/kg body weight) administration for three consecutive days. After the final dose of MTX, the rats were killed and the small intestines were used for analysis.

RESULTS

The small intestines of MTX-treated rats showed moderate to severe injury. The villi were distorted, blunted, and atrophied and focally absent in various segments of the small intestines. Crypt abscesses were also found, suggesting an inflammatory response. Pretreatment with melatonin had a dose-dependent protective effect on MTX-induced mucositis. Morphology was saved to a moderate extent with 20 mg melatonin pretreatment, and near-normal morphology was achieved with 40 mg melatonin pretreatment. Damage to the villi and crypt abscess was reduced. The villi/crypt ratio was almost restored. Melatonin pretreatment protected the small intestines from MTX-induced damage by attenuating nitrosative stress, protein tyrosine nitration and PARP expression.

CONCLUSION

Because of its versatility in protecting against nitro-oxidative stress and reducing inflammation, we suggest that melatonin could be beneficial in ameliorating MTX-induced enteritis in humans.

A review of the molecular aspects of melatonin's anti-inflammatory actions: recent insights and new perspectives

Melatonin is a highly evolutionary conserved endogenous molecule that is mainly produced by the pineal gland, but also by other nonendocrine organs, of most mammals including man. In the recent years, a variety of anti-inflammatory and antioxidant effects have been observed when melatonin is applied exogenously under both in vivo and in vitro conditions. A number of studies suggest that this indole may exert its anti-inflammatory effects through the regulation of different molecular pathways. It has been documented that melatonin inhibits the expression of the isoforms of inducible nitric oxide synthase and cyclooxygenase and limits the production of excessive amounts of nitric oxide, prostanoids, and leukotrienes, as well as other mediators of the inflammatory process such as cytokines, chemokines, and adhesion molecules. Melatonin's anti-inflammatory effects are related to the modulation of a number of transcription factors such as nuclear factor kappa B, hypoxia-inducible factor, nuclear factor erythroid 2-related factor 2, and others. Melatonin's effects on the DNA-binding capacity of transcription factors may be regulated through the inhibition of protein kinases involved in signal transduction, such as mitogen-activated protein kinases. This review summarizes recent research data focusing on the modulation of the expression of different inflammatory mediators by melatonin and the effects on cell signaling pathways responsible for the indole's anti-inflammatory activity. Although there are a numerous published reports that have analyzed melatonin's anti-inflammatory properties, further studies are necessary to elucidate its complex regulatory mechanisms in different cellular types and tissues.

Preservation strategies to reduce ischemic injury in kidney transplantation: pharmacological and genetic approaches

PURPOSE OF REVIEW

In the current graft shortage, it is paramount to improve the quality of transplanted organs. Organ preservation represents an underused therapeutic window with great potential to reduce ischaemia-reperfusion injury (IRI) and improve graft quality. Herein, we review strategies using this window as well as other promising work targeting IRI pathways using pharmacological treatments and gene therapy.

RECENT FINDINGS

We highlight studies using molecules administered during kidney preservation to target key components of IRI such as inflammation, oxidative stress, mitochondrial activity and the coagulation pathway. We further expose recent studies of gene therapy directed against inflammation or apoptosis during cold storage. Other pathways with potential therapeutic molecules are cited.

SUMMARY

The use of cold preservation as a therapeutic window to deliver pharmacological or gene therapy treatments can significantly improve both short-term and long-term graft outcomes. Even if human gene therapy remains hampered by the quantity of agent needed and the potential harmfulness of the vector, it clearly offers a wide array of possibilities for the future. Although gene therapy is still too immature, we expose pharmacological strategies which can readily be applied to the clinic and improve both transplantation success rates and the patients' quality of life.

Beneficial effects of N-acetylcysteine and ebselen on renal ischemia/reperfusion injury

INTRODUCTION

It has been demonstrated that peroxynitrite accompanies acute renal ischemia and contributes to the pathophysiology of renal damage. Therefore, we aimed to investigate the roles of N-acetylcysteine (NAC), a well-known powerful antioxidant, and ebselen (E), a scavenger of peroxynitrite, on renal injury induced by renal ischemia/reperfusion injury (IRI) of rat kidney.

MATERIALS AND METHODS

Forty male Sprague-Dawley rats were divided into five groups: sham, renal IRI, renal IRI+NAC, renal IRI+E, and renal IRI+NAC+E. IR injury was induced by 60 min of bilateral renal ischemia followed by 6 h of reperfusion. After reperfusion, kidneys and blood samples were obtained for histopathological and biochemical evaluations.

RESULTS

Renal IR resulted in increased malondialdehyde and nitrite/nitrate levels suggesting increased lipid peroxidation and peroxynitrite production and decreased superoxide dismutase and glutathione peroxidase activities. Both NAC and E alone significantly decreased malondialdehyde and nitrite/nitrate levels and increased superoxide dismutase and glutathione peroxidase activities. Additionally in the renal IRI+NAC+E group, all biochemical results were quite close to those of sham group. Histopathologically, the kidney injury in rats treated with combination of NAC and E was found significantly less than the other groups.

CONCLUSIONS

Both NAC and E are able to ameliorate IRI of the kidney by decreasing oxidative and nitrosative stresses and increasing free radical scavenger properties. Additionally, combination of NAC and E prevents kidney damage more than when each drug is used alone, suggesting that scavenging peroxynitrite nearby antioxidant activity is important in preventing renal IRI.