Effects of melatonin administration to rats with glycerol-induced acute renal failure

Melatonin: Potential avenue for treating iron overload disorders

Iron overload as a highly risk factor, can be found in almost all human chronic and common diseases. Iron chelators are often used to treat iron overload; however, patient adherence to these chelators is poor due to obvious side effects and other disadvantages. Numerous studies have shown that melatonin has a high iron chelation ability and direct free radical scavenging activity, and can inhibit the lipid peroxidation process caused by iron overload. Therefore, melatonin may become potential complementary therapy for iron overload-related disorders due to its iron chelating and antioxidant activities. Here, the research progress of iron overload is reviewed and the therapeutic potential of melatonin in the treatment of iron overload is analyzed. In addition, studies related to the protective effects of melatonin on oxidative damage induced by iron overload are discussed. This review provides a foundation for preventing and treating iron homeostasis disorders with melatonin.

Protective Effects of Melatonin Against Aristolochic Acid-Induced Nephropathy in Mice

Melatonin, a pineal hormone, is well known to regulate the sleep–wake cycle. Besides, the hormone has been shown to display pleiotropic effects arising from its powerful anti-oxidant and anti-inflammatory activities. Recent studies have reported that melatonin exerts protective effects in animal models of kidney disease. However, the potential effects of melatonin on aristolochic acid (AA)-induced nephropathy (AAN) have not yet been investigated. Here, we found that the administration of melatonin ameliorated AA-induced renal dysfunction, as evidenced by decreased plasma levels of blood urea nitrogen and creatinine and histopathological abnormalities such as tubular dilatation and cast formation. The upregulation of tubular injury markers after AA injection was reversed by melatonin. Melatonin also suppressed AA-induced oxidative stress, as evidenced by the downregulation of 4-hydroxynonenal and reduced level of malondialdehyde, and modulated expression of pro-oxidant and antioxidant enzymes. In addition, p53-dependent apoptosis of tubular epithelial cells, infiltration of macrophages and CD4⁺ T cells into damaged kidneys, and renal expression of cytokines and chemokines were inhibited by melatonin. Moreover, melatonin attenuated AA-induced tubulointerstitial fibrosis through suppression of the tumor growth factor-β/Smad signaling pathway. These results suggest that melatonin might be a potential therapeutic agent for AAN.

The Protective Effect of Melatonin against Fumonisin-Induced Renal Damage in Rats

The present study was designed to investigate the potential protective effect of melatonin against the renal toxicity of fumonisin in female rats. Six groups of animals were used in this study. The first group served as control. The second group was given melatonin only at a dose level of 10 mg/kg. The third group was fed ration contaminated with fumonisin (100 mg/kg diet). The fourth group was fed ration contaminated with fumonisin (200 mg/kg diet). The fifth group was given daily interperitoneal injection (IP) 10 mg/kg melatonin and fed ration contaminated with fumonisin (100 mg/kg diet). The sixth group was given daily interperitoneal injection of 10 mg/kg melatonin and fed ration contaminated with fumonisin (200 mg/kg diet). The rats were treated for 1 month. Histopathological and histochemical changes in the kidney were investigated. In addition, DNA ploidy was measured in the kidney. Fumonisin administration (100 or 200 mg/Kg diet) to unpretreated control rats caused extensive renal damage as evaluated by histopathology, histochemistry, and/or DNA ploidy measurement. No apparent changes following administration of melatonin. Melatonin coadministration to the fumonisin-administered rats reduced kidney damage and the tissues appeared more or less like the normal. The present study indicates that melatonin has a protective effect in fumonisin-induced renal damage.

A study on the effect of cimetidine and L-carnitine on myoglobinuric acute kidney injury in male rats

Myoglobinuric acute renal failure is the most important life threatening complication of rhabdomyolysis. Iron, free radicals, nitric oxide and cytochrome p450 are involved in the pathogenesis of mARF. The aim of this study is to compare the effect of cimetidine, l-carnitine and both agents together on mARF in rats. Forty rats were divided into 5 groups; group I: control rats, group II: myoglobinuric ARF rats, group III: mARF rats received l-carnitine (200mg/kg, i.p.), group IV: mARF rats received cimetidine (150mg/kg i.p.) and group V: mARF rats received both agents together. 48h after glycerol injection, systolic blood pressure was measured. Urine and blood samples were collected to evaluate urine volume, GFR, BUN, creatinine, K, Na, serum creatine kinase, NO and glutathione levels. Kidney specimens were taken to investigate renal cytochrome p450 and for histological examinations. Cimetidine treatment significantly decreased creatinine, BUN, K, Na, SBP and creatine kinase and increased GFR and urine volume compared to group II. l-carnitine exerted similar changes except for the effect on K and GFR. NO was significantly decreased, while renal glutathione and cytochrome p450 were significantly increased in groups treated with l-carnitine or cimetidine as compared to group II. Combined treatment further improved renal functions, creatine kinase, oxidative stress parameters and SBP as compared to each therapy alone. The histological changes confirmed the biochemical findings. Cimetidine and l-carnitine have protective effects - almost equally - against mARF. Using both agents together, minimises the renal injury.

The hormone melatonin stimulates renoprotective effects of "early outgrowth" endothelial progenitor cells in acute ischemic kidney injury

Endothelial progenitor cells (EPCs) protect the kidney from acute ischemic injury. The aim of this study was to analyze whether pretreatment of murine "early outgrowth" EPCs (eEPCs) with the hormone melatonin increases the cells' renoprotective effects in the setting of murine acute ischemic renal failure. Male (8-12 wk old) C57Bl/6N mice were subjected to unilateral ischemia-reperfusion injury postuninephrectomy (40 min). Postischemic animals were injected with either 0.5×10(6) untreated syngeneic murine eEPCs or with cells, pretreated with melatonin for 1 h. Injections were performed shortly after reperfusion of the kidney. While animals injected with untreated cells developed acute renal failure, eEPC pretreatment with melatonin dramatically improved renoprotective actions of the cells. These effects were completely reversed after cell pretreatment with melatonin and the MT-1/-2 antagonist luzindole. In vitro analysis revealed that melatonin reduced the amount of tumor growth factor-β-induced eEPC apoptosis/necrosis. Secretion of vascular endothelial growth factor by the cells was markedly stimulated by the hormone. In addition, migratory activity of eEPCs was enhanced by melatonin and supernatant from melatonin-treated eEPCs stimulated migration of cultured mature endothelial cells. In summary, melatonin was identified as a new agonist of eEPCs in acute ischemic kidney injury.

Melatonin Reduces Nitric Oxide via Increasing Arginase in Rhabdomyolysis-Induced Acute Renal Failure in Rats

Melatonin, the chief secretory product of the pineal gland, is a direct free radical scavenger. In addition to a direct scavenging effect on nitric oxide (NO), its inhibitory effect on nitric oxide synthase (NOS) activity has been also reported. L-arginine is the substrate for both NOS and arginase. It has been suggested that there is a competition between arginase and NOS and that they control each other's level. NO plays a crucial role in the pathogenesis of myoglobinuric acute renal failure (ARF). In this study, the authors aimed to investigate the effect of melatonin on arginase activity, ornithine, and NO levels on the myoglobinuric ARF formed by intramuscular (i.m.) injection of hypertonic glycerol. Forty rats were randomly divided into four groups. Rats in SHAM were given saline, and those in groups ARF, ARF-M5, and ARF-M10 were injected with glycerol (10 mL/kg) i.m. Concomitant and 24 hours after glycerol injection for the ARF-M5 and ARF-M10 groups, melatonin--5 mg/kg and 10 mg/kg, respectively--was administrated intraperitoneally. Forty-eight hours after the glycerol injection, kidneys of the rats were taken under anesthesia. Arginase activity, ornithine, and NO levels in the kidney tissue were determined. Melatonin had an increasing effect on kidney tissue arginase activities and ornithine levels while decreasing NO concentration. It is possible that besides the direct scavenging effect, the stimulatory effect of melatonin on arginase activity may result in an inhibition of NOS activity and, finally, a decrease in the kidney NO level.

Effects of Exogenous Melatonin on Myoglobinuric Acute Renal Failure in the Rats

Free oxygen radicals and nitric oxide (NO) play a crucial role in the pathogenesis of myoglobinuric acute renal failure (ARF). In this study, we aimed to investigate the effect of melatonin, a potent free radical scavenger, on the myoglobinuric ARF formed by injecting hypertonic glycerol intramuscularly (i.m.). The rats were randomly divided into 4 Groups. Rats in Group 1 were given saline and those in Groups 2, 3, and 4 were injected with glycerol (10 mL/kg) i.m. Concomitant and 24 hours after glycerol injection Group 3 (5 mg/kg) and Group 4 (10 mg/kg) were administrated melatonin intraperitoneally. Forty-eight hours after the glycerol injection, the blood and kidneys of the rats were taken under anesthesia. Kidney morphology and the levels of urea, creatinine and nitric oxide metabolites (NOx) in the plasma and the enzyme activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) and the level of malondialdehyde (MDA) in the kidney were determined. In both groups of melatonin administration, there was no protective effect of melatonin. Moreover, melatonin significantly decreased the level of NO. As a result, we suggest that the decreasing effect of melatonin on NO, which is a strong vasodilatator, may further increase the renal ischemia in this model. Thus, melatonin may have worsening rather than beneficial effects on myoglobinuric ARF.

Hyperbaric oxygen treatment improves GFR in rats with ischaemia/reperfusion renal injury: a possible role for the antioxidant/oxidant balance in the ischaemic kidney

BACKGROUND

Ischaemic kidney injury continues to play a dominant role in the pathogenesis of acute renal failure (ARF) in many surgical and medical settings. A major event in the induction of renal injury is related to the generation of oxygen-free radicals. Hyperbaric oxygen therapy (HBO) is indicated for treatment of many ischaemic events but not for ARF. Therefore, the present study examined the effects of HBO on kidney function and renal haemodynamics in rats with ischaemic ARF.

METHODS

Renal ischaemia was induced by unilateral renal artery clamping (45 min) in rats. Within 24 h following ischaemia, rats were treated twice with HBO of 100% O(2) at 2.5 absolute atmospheres for 90 min each (+HBO). Untreated rats (-HBO) served as a control. Forty-eight hours later, GFR, RBF and endothelial-dependent vasorelaxation were measured. In addition, the immunoreactive staining of 4-hydroxy-2-noneal (4-HNE), a major product of endogenous lipid peroxidation, and superoxide dismutase (SOD) were assessed.

RESULTS

In the -HBO group, GFR was reduced by 94% compared with the untouched normal kidney (ischaemic: 0.06 +/- 0.03 ml/min, normal: 1.02 +/- 0.13 ml). In contrast, in the +HBO group, GFR of the ischaemic kidney (0.36 +/- 0.07 ml/min) was reduced only by 68% compared with the contralateral normal kidney (1.12 +/- 0.12 ml/min). In line with these findings, HBO improved the vasodilatory response to ACh as expressed in enhancement of both total and regional renal blood flow. In addition, HBO reduced the formation of 4-HNE by 33% and 76% and increased SOD by 30% and 70% in the cortex and outer stripe region of the medulla of the ischaemic kidney, respectively.

CONCLUSION

HBO attenuates the decline in GFR following renal ischaemia, and improves endothelial-dependent vasorelaxation, suggesting that treatment with HBO may be beneficial in the setting of ischaemic ARF.

The Effect of Hyperbaric Oxygen Treatment on the Renal Functions in Septic Rats: Relation to Oxidative Damage

PURPOSE

To investigate the effects of hyperbaric oxygen (HBO) treatment on renal functions and damage in septic rats.

METHODS

The animals were divided into four groups, each containing ten animals: control, hyperbaric oxygen, sepsis, and sepsis/hyperbaric oxygen. One milliliter of saline containing live Escherichia coli cells (2.1 x 10(9)) was injected intraperitoneally to induce sepsis. The groups treated with HBO were given five sessions of 2 atmospheres absolute of 100% oxygen at intervals of 6 h. Blood, urine, and tissue samples were then collected, and the functional renal parameters, malondialdehyde (MDA) levels, and superoxide dismutase (SOD) and catalase activities were examined.

RESULTS

The reduced glomerular filtration rate and urine flow returned to normal levels after HBO treatment; however, the increase in fractionated sodium excretion continued. The increased MDA levels in the renal cortex and medulla also decreased to the level of the control group. In the sepsis group, both the SOD and catalase activities decreased in the renal cortex, while a reduction was observed only in the catalase activity in the medulla. The reduced enzyme activities significantly increased in the sepsis/hyperbaric oxygen group.

CONCLUSION

HBO treatment has a beneficial effect on renal dysfunction in sepsis. The probable reason for this effect is the reduction in oxidative damage because of the increase in antioxidative capacity.

Molsidomine, a nitric oxide donor and l-arginine protects against rhabdomyolysis-induced myoglobinuric acute renal failure

Rhabdomyolysis-induced myoglobinuric acute renal failure accounts for about 10-40% of all cases of acute renal failure (ARF). Nitric oxide and reactive oxygen intermediates play a crucial role in the pathogenesis of myoglobinuric acute renal failure (ARF). This study was designed to investigate the effect of molsidomine and L-arginine in glycerol induced ARF in rats. Six groups of rats were employed in this study, group I served as control, group II was given 50% glycerol (8 ml/kg, intramuscularly), groups III and IV were given glycerol plus molsidomine (5 mg/kg, and 10 mg/kg p.o. route respectively) 60 min prior to the glycerol injection, group V animals were given glycerol plus L-arginine (125 mg/kg, p.o.) 60 min prior to the glycerol injection, and group VI received L-NAME (10 mg/kg, i.p.) along with glycerol 30 min prior to glycerol administration. Renal injury was assessed by measuring plasma creatinine, blood urea nitrogen, creatinine and urea clearance. The oxidative stress was measured by renal malondialdehyde levels, reduced glutathione levels and by enzymatic activity of catalase, reduced glutathione and superoxide dismutase. Tissue and urine nitrite levels were measured as an index of total nitric oxide levels. Glycerol treatment resulted in a marked decrease in tissue and urine nitric oxide levels, renal oxidative stress and significantly deranged the renal functions along with deterioration of renal morphology. Pre-treatment of animals with molsidomine (10 mg/kg) and L-arginine 60 min prior to glycerol injection markedly attenuated fall in nitric oxide levels, renal dysfunction, morphological alterations, reduced elevated TBARS and restored the depleted renal antioxidant enzymes. The animals treated with L-NAME along with glycerol further worsened the renal damage observed with glycerol. As a result, our results indicate that molsidomine and L-arginine may have beneficial effects in myoglobinuric ARF.

Antioxidants: a possible role in kidney protection

Oxidative stress contributes to the pathophysiology of kidney injury. Beneficial renal effects of some medications, such as angiotensin-converting enzyme inhibitors, angiotensin II type 1 receptor antagonists, calcium channel blockers, beta-blockers and lipid lowering agents depend at least partially on the ability to alleviate oxidative stress. The administration of various natural or synthetic antioxidants has been shown to be of benefit in prevention and attenuation of renal scaring in numerous animal models of kidney diseases. These include vitamins, N-acetylcysteine, alpha-lipoic acid, melatonin, dietary flavonoids and phytoestrogens, and many others. Human studies are limited in this regard. Under certain conditions, surprisingly, the antioxidant supplements may exhibit pro-oxidant properties and even worsen renal damage. To date, the evidence is insufficient to recommend antioxidant supplements in patients with kidney disease. Prospective, controlled clinical trials on safety and effectiveness of different therapeutic antioxidant strategies are indispensable.