The protective effects of carnosine and melatonin in ischemia-reperfusion injury in the rat liver

Immunomodulation of Oxidative Stress during Organ Donation Process: Preliminary Results

The objective was to quantify oxidative stress resulting from ischemia during the donation process, using malondialdehyde (MDA) measurement, and its modulation by the administration of melatonin. We designed a triple-blind clinical trial with donors randomized to melatonin or placebo. We collected donors by donation after brain death (DBD) and controlled donation after circulatory death (DCD), the latter maintained by normothermic regional perfusion (NRP). Melatonin or placebo was administered prior to donation or following limitation of therapeutic effort (LTE). Demographic variables and medical history were collected. We also collected serial measurements of MDA, at 60 and 90 min after melatonin or placebo administration. A total of 53 donors were included (32 from DBD and 21 from DCD). In the DBD group, 17 donors received melatonin, and 15 placebo. Eight DCD donors were randomized to melatonin and 13 to placebo. Medical history and cause for LTE were similar between groups. Although MDA values did not differ in the DBD group, statistical differences were observed in DCD donors during the 0–60 min interval: −4.296 (−6.752; −2.336) in the melatonin group and −1.612 (−2.886; −0.7445) in controls. Given the antioxidant effect of melatonin, its use could reduce the production of oxidative stress in controlled DCD.

Trade-off expression of melatonin receptor subtypes (Mel1a and Mel1b) and androgen receptor in lung of a tropical bird, Perdicula asiatica

The role of circulatory steroid hormone along with melatonin in lung of any seasonally breeding bird has never been explored so far. This could be interesting because steroid hormones are immunosuppressive while melatonin is immunostimulatory in nature. In our present study, we report the effect of exogenous melatonin and testosterone on expression of melatonin receptor subtypes (Mel_1a and Mel_1b ) and androgen receptor in lung of a tropical bird Perdicula asiatica. Birds were collected from vicinity of Varanasi and acclimatized in laboratory with sufficient food and water. The birds were treated with melatonin and testosterone at dose of 25 µg/100 g B.wt./day and 1 mg/100 g B.wt./day, respectively, for 28 days. At the end of the experiment, the birds were sacrificed and lung tissue and blood sample were collected for immunohistochemistry, Western blot analysis and hormonal assay. Testosterone treatment increased circulatory testosterone and upregulated expression of androgen receptors whereas downregulated expression of melatonin receptor subtypes Mel_1a and Mel_1b . Melatonin administration increased peripheral melatonin and upregulated expression of melatonin receptor subtypes Mel_1a and Mel_1b while downregulated androgen receptor. Thus, our results suggest that a trade-off relationship between melatonin and testosterone exists in regulation of their receptors in lung of Perdicula asiatica.

Histopathological changes in androgenized ovaries are recovered by melatonin treatment

Nandrolone decanoate (ND) is a synthetic steroid, which promotes adverse effects on the ovarian tissue, and melatonin (MLT) exhibits a number of beneficial properties in the reproductive system. This study evaluated the general features of the ovarian tissue and the immunoexpression of sex steroid receptors in ND-treated rats that were submitted to short-term melatonin treatment. Adult rats received mineral oil (control group) and ND at doses of 7.5 mg/kg for 15 days (ND-treated group). The treatment with MLT (10mg/kg for 7 days) was given alone, before or in combination with ND. All ND-treated animals showed persistent dioestrus. In the androgenized groups that received MLT, ovarian morphology and size, and the number/area of corpora lutea were recovered. The number of healthy and atretic follicles was recovered when MLT was administered prior to ND; this was similar to the ovaries of control and MLT groups. There was a decrease in estrogen receptors immunostaining in the follicles of androgenized rats that were treated with MLT, and pretreatment with MLT reduced the expression of androgen receptor in atretic follicles and corpora lutea, when compared with ND-treated group. We conclude that MLT treatment recovered the histopathological aspects of the androgenized ovaries, and MLT pretreatment was the most effective.

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.

Therapeutic effect of carnosine in rat model of experimental liver carcinogenesis

The possible anticancer effect of carnosine versus doxorubicin was investigated against hepatocellular carcinoma (HCC) induced by trichloroacetic acid (TCA) (500mg/kg/day, p.o., for 5days) in rats. Following induction of HCC, rats treated with either carnosine (10mg/kg/day, i.p.), or doxorubicin (2.5mg/kg, i.p., once weekly), for 2 weeks. Carnosine significantly decreased serum alanine aminotransferase, and hepatic lipid peroxidation, nitric oxide, tumor necrosis factor-α, and nuclear factor-κB p65 unit, and significantly increased liver total antioxidant status in TCA-challenged rats. The effects of doxorubicin on oxidative, nitrative, and inflammatory biomarkers were less significant than carnosine. However, both carnosine and doxorubicin significantly induced liver tissue apoptotic biomarkers, Bax, cytosolic cytochrome C, and caspase-3, in a comparable manner. Additionally, carnosine and doxorubicin reduced the histopathological dysplastic changes, and alpha-fetoprotein expression in liver of rats with HCC. It was concluded that carnosine significantly protected against TCA-induced liver carcinogenesis in rats, through its antioxidant, antinitrative, and anti-inflammatory effects, and induction of apoptosis.

Protective effect of propofol preconditioning on ischemia-reperfusion injury in human hepatocyte

BACKGROUND

Blood reperfusion after ischemia is the main measure to restore cell function. This study was aimed to explore the effect of propofol on rat and cell models of liver ischemia-reperfusion (I/R) injury, and to investigate its possible mechanism.

METHODS

Wistar rats were divided into four groups: control group, sham group, I/R group, and propofol group. Human hepatocyte HL7702 was divided into six groups: control group, I/R group and propofol (5, 10, 20 and 40 µmol/L) groups. After the animal and cell models were established, the alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA) and adenosine triphosphate (ATP) levels in liver tissues and hepatocytes were measured. Cell viability and apoptosis of hepatocytes were respectively determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry. Furthermore, the expressions of apoptosis-related proteins in hepatocytes were determined by Western blot analysis.

RESULTS

ALT, AST and MDA levels were all decreased significantly, and the ATP level was increased significantly in propofol group compared with that in I/R group in both liver tissues and hepatocytes. Additionally, cell viability of hepatocytes in propofol group was higher than that in I/R group, while the percentage of apoptotic cells in propofol group was less than that in I/R group. Moreover, the expression of caspase-3 decreased and the expression of Bcl-2 increased significantly after propofol preconditioning.

CONCLUSIONS

Our findings suggested that propofol preconditioning might be an effective strategy for protecting the liver from I/R injury, which might provide a scientific basis for clinical application.

Protective effects of carnosine alone and together with alpha-tocopherol on lipopolysaccharide (LPS) plus ethanol-induced liver injury

The aim of this study was to investigate the effect of carnosine (CAR) alone and together with vitamin E (Vit E) on alcoholic steatohepatitis (ASH) in rats. ASH was induced by ethanol (3 times; 5 g/kg; 12 h intervals, via gavage), followed by a single dose of lipopolysaccharide (LPS; 10 mg/kg; i.p.). CAR (250 mg/kg; i.p.) and Vit E (200 mg D-α-tocopherol/kg; via gavage) were administered 30 min before and 90 min after the LPS injection. CAR treatment lowered high serum transaminase activities together with hepatic histopathologic improvements in rats with ASH. Reactive oxygen species formation, malondialdehyde levels, myeloperoxidase activities and transforming growth factor β1 (TGF-β1) and collagen 1α1 (COL1A1) expressions were observed to decrease. These improvements were more remarkable in CAR plus Vit E-treated rats. Our results indicate that CAR may be effective in suppressing proinflammatory, prooxidant, and profibrotic factors in the liver of rats with ASH.

Beneficial effects of carnosine and carnosine plus vitamin E treatments on doxorubicin-induced oxidative stress and cardiac, hepatic, and renal toxicity in rats

OBJECTIVE

Oxidative stress plays an important role in doxorubicin (DOX)-induced toxicity. Carnosine (CAR) is a dipeptide with antioxidant properties. The aim of this study was to evaluate the decreasing or preventive effect of CAR alone or combination with vitamin E (CAR + Vit E) on DOX-induced toxicity in heart, liver, and brain of rats.

METHODS

Rats were treated with CAR (250 mg kg(-1) day(-1); intraperitoneally (i.p.)) or CAR + Vit E (equals 200 mg kg(-1) α-tocopherol; once every 3 days; intramuscularly) for 12 consecutive days. On the 8th day of treatment, rats were injected with a single dose of DOX (30 mg kg(-1), i.p.). Serum cardiac troponin I (cTnI), urea, and creatinine levels; alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities; and oxidative stress parameters in tissues were measured. We also determined thiobarbituric acid reactive substances, diene conjugate, protein carbonyl (PC), and glutathione levels and antioxidant enzyme activities.

RESULTS

DOX resulted in increased serum cTnI, ALT, AST, urea, and creatinine levels and increased lipid peroxide and PC levels in tissues. CAR or CAR + Vit E treatments led to decreases in serum cTnI levels and ALT and AST activities. These treatments reduced prooxidant status and ameloriated histopathologic findings in the examined tissues.

CONCLUSION

Our results may indicate that CAR alone, especially in combination with Vit E, protect against DOX-induced toxicity in heart, liver, and kidney tissues of rats. This was evidenced by improved cardiac, hepatic, and renal markers and restoration of the prooxidant state and amelioration of histopathologic changes.

Amelioration of titanium dioxide nanoparticles-induced liver injury in mice: possible role of some antioxidants

This study investigates the efficacy of idebenone, carnosine and vitamin E in ameliorating some of the biochemical indices induced in the liver of titanium dioxide nanoparticles (TiO2 NPs) intoxicated mice. Nano-anatase TiO2 (21 nm) was administered (150 mg/kg/day) for 2 weeks followed by the aforementioned antioxidants either alone or in combination for 1 month. TiO2 NPs significantly increased serum liver function enzyme activities, liver coefficient and malondialdehyde levels in hepatic tissue. They also suppressed hepatic glutathione level and triggered an inflammatory response via the activation of macrophages and the enhancement of tumor necrosis factor-α and interleukin-6 levels. Moreover, the mRNA expression of nuclear factor-erythroid-2-related factor 2, nuclear factor kappa B and Bax was up-regulated whereas that of Bcl-2 was down-regulated following TiO2 NPs. Additionally, these NPs effectively activated caspase-3 and caused liver DNA damage. Oral administration of idebenone (200mg/kg), carnosine (200mg/kg) and vitamin E (100mg/kg) alleviated the hazards of TiO2 NPs with the combination regimen showing a relatively higher effect. The histopathological examination reinforced these findings. In conclusion, oxidative stress could be regarded as a key player in TiO2 NPs-induced liver injury. The study also highlights the anti-inflammatory and the anti-apoptotic potentials of these antioxidants against the detrimental effects of TiO2 NPs.

Melatonin: buffering the immune system

Melatonin modulates a wide range of physiological functions with pleiotropic effects on the immune system. Despite the large number of reports implicating melatonin as an immunomodulatory compound, it still remains unclear how melatonin regulates immunity. While some authors argue that melatonin is an immunostimulant, many studies have also described anti-inflammatory properties. The data reviewed in this paper support the idea of melatonin as an immune buffer, acting as a stimulant under basal or immunosuppressive conditions or as an anti-inflammatory compound in the presence of exacerbated immune responses, such as acute inflammation. The clinical relevance of the multiple functions of melatonin under different immune conditions, such as infection, autoimmunity, vaccination and immunosenescence, is also reviewed.

The effects of carnosine in an experimental rat model of septic shock

BACKGROUND

To examine the effect of carnosine on liver function and histological findings in experimental septic shock model, 24 Sprague-Dawley rats were used.

MATERIAL/METHODS

Rats were divided into control, septic shock, and carnosine-treated septic shock groups. Femoral vein and artery catheterization were performed on all rats. Rats in the control group underwent laparotomy and catheterization; in the test groups, cecal ligation-perforation and bladder cannulation were added. Rats in the treatment group received a single intraperitoneal (IP) injection of 250 mg/kg carnosine 60 minutes after cecal ligation-perforation. Rats were monitored for blood pressure, heart rate, and body temperature to assess the postoperative septic response, and body fluids were replaced as necessary. At the end of 24 hours, rats were sacrificed and liver samples were collected.

RESULTS

Statistically significant improvements were observed in liver function, tissue and serum MDA levels, and histological findings in rats treated with carnosine, compared to rats with untreated sepsis. HB and HCT values did not change significantly during the course of the experiment. Rats exposed to septic shock and treated with carnosine exhibited decreased sinusoidal dilatation and cellular inflammation into the portal region, compared to the sepsis group; the livers of rats in this group had near-normal histological structure.

CONCLUSIONS

We conclude that carnosine may be an effective treatment for oxidative damage due to liver tissue perfusion defects in cases of septic shock.

Melatonin treatment protects liver of Zucker rats after ischemia/reperfusion by diminishing oxidative stress and apoptosis

Fatty livers occur in up to 20% of potential liver donors and increase cellular injury during the ischemia/reperfusion phase, so any intervention that could enable a better outcome of grafts for liver transplantation would be very useful. The effect of melatonin on liver ischemia/reperfusion injury in a rat model of obesity and hepatic steatosis has been investigated. Forty fa/fa Zucker rats were divided in 4 groups. 3 groups were subjected to 35 min of warm hepatic ischemia and 36 h of reperfusion. One experimental group remained untreated and 2 were given 10mg/kg melatonin intraperitoneally or orally. Another group was sham-operated. Plasma ALT, AST and hepatic content of ATP, MDA, hydroxyalkenals, NOx metabolites, antioxidant enzyme activity, caspase-9 and DNA fragmentation were determined in the liver. The expression of iNOS, eNOS, Bcl2, Bax, Bad and AIF were determined by RT-PCR Melatonin was effective at decreasing liver injury by both ways as assessed by liver transaminases, markers of apoptosis, of oxidative stress and improved liver ATP content. Melatonin administration decreased the activities or levels of most of the parameters measured in a beneficial way, and our study identified also some of the mechanisms of protection. We conclude that administration of melatonin improved liver function, as well as markers of pro/antioxidant status and apoptosis following ischemia/reperfusion in obese rats with fatty liver. These data suggest that this substance could improve outcome in patients undergoing liver transplantation who receive a fatty liver implant and suggest the need of clinical trials with it in liver transplantation.

Dietary supplementation of some antioxidants against hypoxia

The present study aims to clarify the protective effect of supplementation with some antioxidants, such as idebenone (200 mg/kg, ip), melatonin (10 mg/kg, ip) and arginine (200 mg/kg, ip) and their combination, on liver function (T. protein, albumin, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase), energetic parameters (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, inorganic phosphate, total adenylate, adenylate energy charge and potential phosphate). The effect on glycolytic and glycogenolytic enzymes (glucose, glycogen, glycogen phosphorylase, pyruvate kinase and phosphofructokinase against hypoxia) was also studied. The drugs were administered 24 and 1 h prior sodium nitrite intoxication. All biochemical parameters were estimated 1 h after sodium nitrite injection. Injection of sodium nitrite (75 mg/kg, sc) produced a significant disturbance in all biochemical parameters of liver function, energetic parameters and glycolytic and glycogenolytic enzymes. Hepatic damage was confirmed by histopathological examination of the liver as compared to controls. The marked changes in hepatic cells induced by sodium nitrite were completely abolished by pretreatment with the drug combination, suggesting potential protection against sodium nitrite-induced hypoxia. It could be concluded that a combination of both idebenone and melatonin or idebenone and arginine provides potential protection against sodium nitrite-induced hypoxia by improving biochemical parameters and preserving liver histology.

The protective effects of carnosine in alcohol-induced hepatic injury in rats

Consumption of alcohol leads to oxidative stress in liver by inducing lipid peroxidation. The aim of this study was to investigate the effects of carnosine (CAR) in alcohol-induced liver injury by biochemical and histomorphological evaluations. The rats were divided into four groups, namely, control group, alcohol (AL) group, CAR group and AL + CAR group. Three doses of ethanol (5 g/kg, 25% (v/v) in distilled water) were given by nasogastric catheter for twice-a-day. CAR (100 mg/kg) was given 1 h before the administration of ethanol using the same method. Levels of alanine aminotransferase, aspartate aminotransferase, myeloperoxidase and malondialdehyde were significantly increased in the AL group compared with control, CAR and AL + CAR groups. Glutathione level was significantly decreased in the AL group, while it was increased in the AL + CAR group. Immunoreactivity of caspase-3 and bax increased in the hepatocytes of AL group when compared with control and AL + CAR groups. Expression of bcl-2 was decreased in AL group than AL + CAR group. Under electron microscopy, dense mitochondria, accumulation of lipid, sinusoidal dilatation, vacuolization and decrease in the number of microvilli were observed in AL group, while these findings were markedly less in the AL + CAR group. In conclusion, pretreatment of CAR is effective for recovering biochemical alterations and morphologic damage in the liver of rats treated with ethanol.

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.

Intratracheal instillation of cerium oxide nanoparticles induces hepatic toxicity in male Sprague-Dawley rats

BACKGROUND

Cerium oxide (CeO(2)) nanoparticles have been posited to have both beneficial and toxic effects on biological systems. Herein, we examine if a single intratracheal instillation of CeO(2) nanoparticles is associated with systemic toxicity in male Sprague-Dawley rats.

METHODS AND RESULTS

Compared with control animals, CeO(2) nanoparticle exposure was associated with increased liver ceria levels, elevations in serum alanine transaminase levels, reduced albumin levels, a diminished sodium-potassium ratio, and decreased serum triglyceride levels (P < 0.05). Consistent with these data, rats exposed to CeO(2) nanoparticles also exhibited reductions in liver weight (P < 0.05) and dose-dependent hydropic degeneration, hepatocyte enlargement, sinusoidal dilatation, and accumulation of granular material. No histopathological alterations were observed in the kidney, spleen, and heart. Analysis of serum biomarkers suggested an elevation of acute phase reactants and markers of hepatocyte injury in the rats exposed to CeO(2) nanoparticles.

CONCLUSION

Taken together, these data suggest that intratracheal instillation of CeO(2) nanoparticles can result in liver damage.

Protection against adriamycin-induced cardiomyopathy by carnosine in rats: role of endogenous antioxidants

The aim of this study was to investigate the effects of carnosine, a biological antioxidant, on the acute cardiac damage induced by a single dose of adriamycin in rats. The experimental design consisted of four groups: Control (saline, i.p.); carnosine (CAR; 10 mg/kg/day, i.p.); adriamycin (ADR; 16 mg/kg on the 14th day, i.p.); carnosine with adriamycin. Carnosine was given 2 weeks before and following adriamycin treatment. Blood samples were collected for analysis of plasma creatine kinase (CK) and plasma antioxidant enzymes, glutathione peroxidase (GSH-Px), Cu, Zn-superoxide dismutase (SOD), and catalase (CAT). The rats were then sacrificed, and the hearts were autopsied for hemodynamic study, ECG, and histopathological examination. Results showed that adriamycin produced evident cardiac damage revealed by hemodynamic change, histological alterations, decreased plasma antioxidant enzymes activities, and increased lipid peroxidation to the control value. Carnosine treatment led to significant attenuation of adriamycin-induced cardiomyopathy revealed by normalization of the LVDP, ST interval, CK, SOD, GSH-Px, CAT, and lipid peroxidation. An increase in oxidative stress and inactivation of SOD, GSH-Px, CAT by a single dose of adriamycin were prevented when carnosine was given 2 weeks before and on the same day adriamycin treatment was administered.

Carnosine prevents apoptosis of glomerular cells and podocyte loss in STZ diabetic rats

BACKGROUND/AIMS

We identified carnosinase-1 (CN-1) as risk-factor for diabetic nephropathy (DN). Carnosine, the substrate for CN-1, supposedly is a protective factor regarding diabetic complications. In this study, we hypothesized that carnosine administration to diabetic rats might protect the kidneys from glomerular apoptosis and podocyte loss.

METHODS

We examined the effect of oral L-carnosine administration (1g/kg BW per day) on apoptosis, podocyte loss, oxidative stress, AGEs and hexosamine pathway in kidneys of streptozotocin-induced diabetic Wistar rats after 3 months of diabetes and treatment.

RESULTS

Hyperglycemia significantly reduced endogenous kidney carnosine levels. In parallel, podocyte numbers significantly decreased (-21% compared to non-diabetics, p<0.05), apoptotic glomerular cells numbers increased (32%, compared to non-diabetic, p<0.05) and protein levels of bax and cytochrome c increased (175% and 117%). Carnosine treatment restored carnosine kidney levels, prevented podocytes loss (+23% compared to diabetic, p<0.05), restrained glomerular apoptosis (-34% compared to diabetic; p<0.05) and reduced expression of bax and cytochrome c (-63% and -54% compared to diabetics, both p<0.05). In kidneys of all diabetic animals, levels of ROS, AGEs and GlcNAc-modified proteins were increased.

CONCLUSION

By inhibition of pro-apoptotic signaling and independent of biochemical abnormalities, carnosine protects diabetic rat kidneys from apoptosis and podocyte loss.

Effect of preischemic treatment with fenofibrate, a peroxisome proliferator-activated receptor-α ligand, on hepatic ischemia-reperfusion injury in rats

Liver ischemia/reperfusion (I/R) injury is a serious clinical problem. The reactive oxygen species (ROS) and tumor necrosis factor alpha (TNF-α) are important mediators in liver I/R injury. This study was designed to investigate the effect of preischemic treatment with fenofibrate (Peroxisome proliferator-activated receptor- α agonist) on the oxidative stress and inflammatory response to hepatic I/R injury in rats. Hepatic I/R was induced by clamping the blood supply of the left lateral and median lobes of the liver for 60 min, followed by reperfusion for 4 h. Each animal group was pretreated with a single dose of fenofibrate (50 mg/kg body weight) intraperitoneally 1 h before ischemia. At the end of reperfusion, blood samples and liver tissues were obtained to assess serum alanine aminotransferase (ALT), TNF-α, hepatic malondialdehyde (MDA) and superoxide dismutase activity (SOD). Liver specimens were obtained and processed for light and electron microscopic study. Hepatic I/R induced a significant elevation of serum ALT and TNF-α with significant elevation of hepatic MDA and reduction of SOD activity. Histopathological examination revealed hepatic inflammation, necrosis and apoptosis. Preischemic treatment with fenofibrate at a dose of 50 mg/kg significantly attenuated the biochemical and structural alterations of I/R-induced liver injury.

Hepatoprotective actions of melatonin: Possible mediation by melatonin receptors

Melatonin, the hormone of darkness and messenger of the photoperiod, is also well known to exhibit strong direct and indirect antioxidant properties. Melatonin has previously been demonstrated to be a powerful organ protective substance in numerous models of injury; these beneficial effects have been attributed to the hormone’s intense radical scavenging capacity. The present report reviews the hepatoprotective potential of the pineal hormone in various models of oxidative stress in vivo, and summarizes the extensive literature showing that melatonin may be a suitable experimental substance to reduce liver damage after sepsis, hemorrhagic shock, ischemia/reperfusion, and in numerous models of toxic liver injury. Melatonin’s influence on hepatic antioxidant enzymes and other potentially relevant pathways, such as nitric oxide signaling, hepatic cytokine and heat shock protein expression, are evaluated. Based on recent literature demonstrating the functional relevance of melatonin receptor activation for hepatic organ protection, this article finally suggests that melatonin receptors could mediate the hepatoprotective actions of melatonin therapy.

In vivo DTI assessment of hepatic ischemia reperfusion injury in an experimental rat model

PURPOSE

To investigate hepatic ischemia reperfusion injury (IRI) using diffusion tensor imaging (DTI).

MATERIALS AND METHODS

Ten Sprague-Dawley rats were scanned at 7 Tesla (T) with DTI using b-value of 1000 s/mm(2) and 6 gradient directions before, 2 h, and 1 day after 30-min total hepatic IRI. Apparent diffusion coefficient or mean diffusivity (MD), directional diffusivities and fractional anisotropy (FA) were measured. Seven of the animals were also examined with spin-echo echo-planar diffusion-weighted imaging (DWI) with seven b-values up to 2000 s/mm(2) to estimate the true diffusion coefficient (D), blood pseudodiffusion coefficient (D), and perfusion fraction (f) using a bi-compartmental model.

RESULTS

MD 2 h after IRI (0.77 +/- 0.07 x 10(-3) mm(2)/s) was significantly lower (P < 0.01) than that before (1.03 +/- 0.07 x 10(-3) mm(2)/s) and 1 day after IRI (1.01 +/- 0.05 x 10(-3) mm(2)/s). Meanwhile, FA 2 h after IRI (0.33 +/- 0.03) was significantly higher (P < 0.01) than that before (0.21 +/- 0.02) and 1 day after IRI (0.20 +/- 0.02). The bi-compartmental model analysis revealed the transient decrease in D, D and f 2 h after IRI. Liver histology showed the multifocal cell swelling 3 h after IRI and widespread cell necrosis/apoptosis 1 day after IRI. Sinusoidal narrowing and congestion of erythrocytes were also observed 3 h and 1 day after IRI.

CONCLUSION

DTI can characterize hepatic IRI by detecting the transient change in both MD and FA.

Melatonin--a pleiotropic molecule involved in pathophysiological processes following organ transplantation

Mammals adjust their physiology in response to seasonal changes to environment (i.e. photoperiod, temperature, food availability). These changes are thought to predominantly occur for the conservation of energy during winter, by pervasive changes such as the inhibition of reproduction. Previous reports have suggested that circannual changes also occur to the immune system. In mammals, this chronological effect may be dependent on photoperiod, and evidence exists to suggest that there is a great deal of immune variation in response to light, or circadian rhythm. This is a clinically relevant, yet under-reported area of human transplantation. The aim of this review is to discuss immune variation, with specific emphasis on melatonin secretion, in the context of organ rejection, infection, neoplasia formation, and immunosuppression.

NAD+ availability and proteotoxicity

It has been shown that NAD(+) availability is important for neuronal survival following ischemia (Liu et al., Neuromolecular Med 11:28-42, 2009). It is proposed here that NAD(+) may also control proteotoxicity by influencing both formation and catabolism of altered proteins. It is suggested that low NAD(+) availability promotes synthesis of methylglyoxal (MG) which can induce formation of glycated proteins, ROS, and dysfunctional mitochondria. That glyoxalase overexpression and carnosine are both protective against MG and ischemic injury support this proposal. Recognition and elimination of altered proteins is enhanced by NAD(+) through effects on stress protein expression and autophagy.