Protective effect of L-carnitine on renal ischaemia-reperfusion injury in the rat

The Effect of L-Carnitine on Critical Illnesses Such as Traumatic Brain Injury (TBI), Acute Kidney Injury (AKI), and Hyperammonemia (HA)

L-carnitine (LC) through diet is highly beneficial for critical patients. Studies have found that acetyl-L-carnitine (ALC) can reduce cerebral edema and neurological complications in TBI patients. It significantly improves their neurobehavioral and neurocognitive functions. ALC has also been shown to have a neuroprotective effect in cases of global and focal cerebral ischemia. Moreover, it is an effective agent in reducing nephrotoxicity by suppressing downstream mitochondrial fragmentation. LC can reduce the severity of renal ischemia-reperfusion injury, renal cast formation, tubular necrosis, iron accumulation in the tubular epithelium, CK activity, urea levels, Cr levels, and MDA levels and restore the function of enzymes such as SOD, catalase, and GPx. LC can also be administered to patients with hyperammonemia (HA), as it can suppress ammonia levels. It is important to note, however, that LC levels are dysregulated in various conditions such as aging, cirrhosis, cardiomyopathy, malnutrition, sepsis, endocrine disorders, diabetes, trauma, starvation, obesity, and medication interactions. There is limited research on the effects of LC supplementation in critical illnesses such as TBI, AKI, and HA. This scarcity of studies highlights the need for further research in this area.

Propionyl-l-carnitine mitigates ischemia-reperfusion injury in rat epigastric island flaps

Background

Ischemia-reperfusion injury presents a substantial concern in various medical scenarios, notably in reconstructive surgery involving tissue flaps. Despite reports on the protective benefits of Propionyl-l-carnitine against ischemia-reperfusion injury, a thorough assessment of its efficacy in epigastric island flap models is currently lacking.

Methods

Sixteen male Sprague-Dawley rats underwent epigastric island flap surgery and were divided into two groups: a Propionyl-l-carnitine group that received intraperitoneal Propionyl-l-carnitine prior to ischemia induction and a sham group that received saline treatment. A comprehensive evaluation was performed including macroscopic, biochemical and histological assessments encompassing measurements of flap survival areas, lipid peroxidation (malondialdehyde), glutathione, myeloperoxidase, nitric oxide and peripheral neutrophil counts.

Results

The Propionyl-l-carnitine group demonstrated significantly increased flap survival areas when compared to the sham group. Administration of Propionyl-l-carnitine led to reduced malondialdehyde levels and elevated glutathione levels indicating a reduction in oxidative stress. Furthermore, the Propionyl-l-carnitine group exhibited lower myeloperoxidase levels, higher nitric oxide levels and reduced peripheral neutrophil counts, suggesting a decrease in the inflammatory response. Histopathological analysis revealed decreased levels of inflammation, necrosis, polymorphonuclear leukocyte infiltration and edema in the Propionyl-l-carnitine group. Additionally, vascularity was enhanced in the Propionyl-l-carnitine group.

Conclusion

This study provides compelling evidence that Propionyl-l-carnitine administration effectively mitigates the deleterious effects of ischemia-reperfusion injury in epigastric island flaps. This is substantiated by the improved flap survival, diminished oxidative stress and inflammation, as well as the enhanced vascularity observed. Propionyl-l-carnitine emerges as a promising therapeutic intervention to enhance tissue flap survival in reconstructive surgery, warranting further exploration through larger-scale investigations.

L-Carnitine Prevents Behavioural Alterations in Ketamine-Induced Schizophrenia in Mice: Possible Involvement of Oxidative Stress and Inflammation Pathways

Schizophrenia is a chronic mental complaint known as cognitive impairment. There has been evidence that inflammation and oxidative stress play a main role in schizophrenia pathophysiology. This study aimed to investigate the effects of l-carnitine, as a potent antioxidant, on the treatment of behavioural and biochemical disturbances in mice with ketamine-induced schizophrenia. In this study, schizophrenia was induced in mice by ketamine (25 mg/kg/day, i.p). Before induction of schizophrenia, mice were treated with l-carnitine (100, 200, and 400 mg/kg/day, i.p). Then, behavioural impairments were evaluated by open field (OF) assessment and social interaction test (SIT). After brain tissue isolation, reactive oxygen species (ROS), glutathione concentration (GSH), lipid peroxidation (LPO), protein carbonyl oxidation, superoxide dismutase activity (SOD), and glutathione peroxidase activity (GPx) were assessed as oxidative stress markers. Furthermore, inflammatory biomarkers such as tumour necrosis factor alpha (TNF-α) and nitric oxide (NO) were evaluated in brain tissue. Our results showed ketamine increased inflammation and oxidative damage in brain tissue that was similar to behaviour disorders in mice. Interestingly, l-carnitine significantly decreased oxidative stress and inflammatory markers compared with ketamine-treated mice. In addition, l-carnitine prevented and reversed ketamine-induced alterations in the activities of SOD and GPx enzymes in mice's brains. Also, improved performance in OFT (locomotor activity test) and SIT was observed in l-carnitine-treated mice. These data provided evidence that, due to the antioxidant and anti-inflammatory effects of l-carnitine, it has a neuroprotective effect on mice model of schizophrenia.

Targeting Inflammation and Oxidative Stress as a Therapy for Ischemic Kidney Injury

Inflammation and oxidative stress are the main pathological processes that accompany ischemic injury of kidneys and other organs. Based on this, these factors are often chosen as a target for treatment of acute kidney injury (AKI) in a variety of experimental and clinical studies. Note, that since these two components are closely interrelated during AKI development, substances that treat one of the processes often affect the other. The review considers several groups of promising nephroprotectors that have both anti-inflammatory and antioxidant effects. For example, many antioxidants, such as vitamins, polyphenolic compounds, and mitochondria-targeted antioxidants, not only reduce production of the reactive oxygen species in the cell but also modulate activity of the immune cells. On the other hand, immunosuppressors and non-steroidal anti-inflammatory drugs that primarily affect inflammation also reduce oxidative stress under some conditions. Another group of therapeutics is represented by hormones, such as estrogens and melatonin, which significantly reduce severity of the kidney damage through modulation of both these processes. We conclude that drugs with combined anti-inflammatory and antioxidant capacities are the most promising agents for the treatment of acute ischemic kidney injury.

Effect of L-carnitine and atorvastatin on a rat model of ischemia-reperfusion injury of spinal cord

Pro-inflammatory cytokines and reactive oxygen species (ROS) are produced in acute spinal cord injury, leading to myelin breakdown, inflammation, mitochondrial dysfunction, and apoptosis of neurons and glial cells. The aim of the present study was to investigate possible protective effects of L-carnitine (carn) or atorvastatin (ator) on spinal cord ischemia-reperfusion injury (IRI). Rats were randomized into nine equal groups (n = 8): control and control taking carn (100 mg/kg BW), ator (2.5 mg/kg BW) or both, as well as sham-operation, IRI and IRI taking same doses of carn, ator or both. Neurological assessments were done 48 hours after IRI, and serum nitrite/nitrate was measured. Finally, lumbar segments of spinal cord were excised, and part was homogenized and prepared for measuring tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), malondialdehyde (MDA), advanced oxidation protein products (AOPP), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase. The other part was sectioned for evaluation of histopathological changes and for immunostaining by glial fibrillary acidic protein (GFAP), Bax and Bcl-2. The IRI increased ROS (nitrite/nitrate, MDA, AOPP) and pro-inflammatory cytokines (TNF-α, IL-1β), and decreased antioxidants (GSH, GPx, SOD, catalase) with impaired sensory and motor functions. Astrogliosis was detected by GFAP, and increased apoptosis was demonstrated by increasing Bax and decreasing Bcl-2. Treatment with carn or ator alone decreased TNF-α, IL-1β, nitrite/nitrate, MDA and AOPP, and increased GSH, GPx, SOD, and catalase with improvement of neurological functions and histological studies. Combination of carn and ator improved most of measured IRI-affected parameters better than isolated carn or ator administration.

The footprints of mitochondrial impairment and cellular energy crisis in the pathogenesis of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and Fanconi's syndrome: A comprehensive review

Fanconi's Syndrome (FS) is a disorder characterized by impaired renal proximal tubule function. FS is associated with a vast defect in the renal reabsorption of several chemicals. Inherited and/or acquired conditions seem to be connected with FS. Several xenobiotics including many pharmaceuticals are capable of inducing FS and nephrotoxicity. Although the pathological state of FS is well described, the exact underlying etiology and cellular mechanism(s) of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and FS are not elucidated. Constant and high dependence of the renal reabsorption process to energy (ATP) makes mitochondrial dysfunction as a pivotal mechanism which could be involved in the pathogenesis of FS. The current review focuses on the footprints of mitochondrial impairment in the etiology of xenobiotics-induced FS. Moreover, the importance of mitochondria protecting agents and their preventive/therapeutic capability against FS is highlighted. The information collected in this review may provide significant clues to new therapeutic interventions aimed at minimizing xenobiotics-induced renal injury, serum electrolytes imbalance, and FS.

What we need to know about lipid-associated injury in case of renal ischemia-reperfusion

Renal segmental metabolism is reflected by the complex distribution of the main energy pathways along the nephron, with fatty acid oxidation preferentially used in the cortex area. Ischemia/reperfusion injury (IRI) is due to the restriction of renal blood flow, rapidly leading to a metabolic switch toward anaerobic conditions. Subsequent unbalance between energy demand and oxygen/nutrient delivery compromises kidney cell functions, resulting in a complex inflammatory cascade including the production of reactive oxygen species (ROS). Renal IRI especially involves lipid accumulation. Lipid peroxidation is one of the major events of ROS-associated tissue injury. Here, we briefly review the current knowledge of renal cell lipid metabolism in normal and ischemic conditions. Next, we focus on renal lipid-associated injury, with emphasis on its mechanisms and consequences during the course of IRI. Finally, we discuss preclinical observations aiming at preventing and/or attenuating lipid-associated IRI.

Mechanism of valproic acid-induced Fanconi syndrome involves mitochondrial dysfunction and oxidative stress in rat kidney

AIM

Drug-induced kidney proximal tubular injury and renal failure (Fanconi syndrome; FS) is a clinical complication. Valproic acid (VPA) is among the FS-inducing drugs. The current investigation was designed to evaluate the role of mitochondrial dysfunction and oxidative stress in VPA-induced renal injury.

METHODS

Animals received VPA (250 and 500 mg/kg, i.p., 15 consecutive days). Serum biomarkers of kidney injury and markers of oxidative stress were assessed. Moreover, kidney mitochondria were isolated and mitochondrial indices, including succinate dehydrogenase activity (SDA), mitochondrial depolarization, mitochondrial permeability transition pore (MPP), reactive oxygen species (ROS), lipid peroxidation (LPO), mitochondrial glutathione, and ATP were determined.

RESULTS

Valproic acid-treated animals developed biochemical evidence of FS as judged by elevated serum gamma-glutamyl transferase (γ-GT), alkaline phosphatase (ALP), creatinine (Cr), and blood urea nitrogen (BUN) along with hypokalaemia, hypophosphataemia, and a decrease in serum uric acid. VPA caused an increase in kidney ROS and LPO. Renal GSH reservoirs were depleted and tissue antioxidant capacity decreased in VPA-treated animals. Renal tubular interstitial nephritis, tissue necrosis, and atrophy were also evident in VPA-treated rats. Mitochondrial parameters including SDA, MMP, GSH, ATP and MPP were decreased and mitochondrial ROS and LPO were increased with VPA treatment. It was found that carnitine (100 mg/kg, i.p.) mitigated VPA adverse effects towards the kidney.

CONCLUSIONS

These data suggest that mitochondrial dysfunction and oxidative stress contributed to the VPA-induced FS. On the other hand, carnitine could be considered a potentially safe and effective therapeutic option in attenuating VPA-induced renal injury.

L-Carnitine and Potential Protective Effects Against Ischemia-Reperfusion Injury in Noncardiac Organs: From Experimental Data to Potential Clinical Applications

The mechanism of ischemia-reperfusion (I/R) injury is complex and multifactorial. In this condition, systemic event results in morbidity and mortality in several pathologies, including myocardial infarction, ischemic stroke, acute kidney injury, trauma, and circulatory arrest. Hypoxia over ischemia phase leads to energy imbalance and changes of cellular homeostasis and functional or structural alterations. In addition, during the reperfusion period, some events, including calcium influx, release of intracellular enzymes, and cell membrane integrity breakdown, cause cell death. L-carnitine (LC) and its derivatives have been suggested to improve tolerance against I/R injury in various tissues. The favorable effects of LC are possibly mediated by its antioxidant and anti-inflammatory effects or by other capability due to increase in the intracellular carnitine content. In this article, anti-ischemic properties of LC and its derivative in noncardiac organs are reviewed using relative animal and human research. Although most of the studies on noncardiac internal organs have shown protective effects of LC administration against I/R injury, more clinical trials are needed to clarify the clinical importance of LC as a treatment option for I/R-induced injury.

Protective Effects of L-Carnitine Against Delayed Graft Function in Kidney Transplant Recipients: A Pilot, Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

OBJECTIVE

Delayed graft function (DGF) is an early complication after deceased donor kidney transplantation with significant adverse effects on graft outcomes. Ischemia-reperfusion injury during transplantation is a major cause of DGF. Tissue concentrations of carnitine, an antioxidant and regulator of cellular energy supply, decrease in the kidney following ischemia-reperfusion insult. Based on promising animal data, this study evaluated the possible protective effect of L-carnitine against DGF.

DESIGN

This study is a pilot, randomized, double-blind, placebo-controlled clinical trial that was conducted on kidney transplantation patients in kidney transplant ward of Imam Khomeini hospital complex affiliated to Tehran University of Medical Sciences, Tehran, Iran.

SUBJECTS

Patients older than 14 years old undergoing their first kidney transplantation from a deceased donor were evaluated for eligibility to take part in this study. Fifty-six patients were randomly assigned to L-carnitine or placebo groups.

INTERVENTION

During this trial, 3 g of oral L-carnitine or placebo was administered in 3 divided doses each day for 4 consecutive days starting the day before kidney transplantation (i.e., days -1, 0, 1, and 2).

MAIN OUTCOME MEASURE

The need for dialysis within the first week after transplantation, serum creatinine and urine output were assessed daily. After hospital discharge, patients were followed for 3 months regarding organ function.

RESULTS

DGF incidence did not differ between the L-carnitine and placebo groups (18.51% vs. 23.8%, respectively; P = .68). Total allograft failure within 3 months after kidney transplantation happened in 6 patients in the placebo and 1 patient in the L-carnitine group (P = .05).

CONCLUSION

This study showed no protective effects of oral L-carnitine supplementation against DGF occurrence recipients; however, 3-month graft loss was lower in the L-carnitine supplemented group.

Dietary l-carnitine prevents histopathological changes in tilapia (Oreochromis Niloticus) exposed to cylindrospermopsin

Cylindrospermopsin (CYN) is a cytotoxin highly water-soluble, which is easily taken up by several aquatic organisms. CYN acts as a potent protein and glutathione synthesis inhibitor, as well as inducing genotoxicity, oxidative stress, and histopathological alterations. This is the first study reporting the protective effect of a l-carnitine (LC) pretreatment (400 or 880 mg LC/kg bw fish/day, for 21 days) on the histopathological alterations induced by pure CYN or Aphanizomenon ovalisporum lyophilized cells (400 µg CYN/kg bw fish) in liver, kidney, heart, intestines, and gills of tilapia (Oreochromis niloticus) acutely exposed to the toxin by oral route. The main histopathological changes induced by CYN were disorganized parenchyma with presence of glycogen and lipids in the cytoplasm (liver), glomerulonephritis, glomerular atrophy, and dilatation of Bowman's capsule (kidney), myofibrolysis, loss of myofibrils, with edema and hemorrhage (heart), intestinal villi with necrotic enterocytes and partial loss of microvilli (gastrointestinal tract), and hyperemia and hemorrhage (gills). LC pretreatment was able to totally prevent those CYN-induced alterations from 400 mg LC/kg bw fish/day in almost all organs, except in the heart, where 880 mg LC/kg bw fish/day were needed. In addition, the morphometric study indicated that LC managed to recover totally the affectation in the cross sections of the proximal and distal convoluted tubules in CYN-exposed fish. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 241-254, 2017.

Metabolic Response of Pediatric Traumatic Brain Injury

Traumatic brain injury (TBI) in the pediatric brain presents unique challenges as the complex cascades of metabolic and biochemical responses to TBI are further complicated ongoing maturational changes of the developing brain. TBIs of all severities have been shown to significantly alter metabolism and hormones which impair the ability of the brain to process glucose for cellular energy. Under these conditions, the brain's primary fuel (glucose) becomes a less favorable fuel and the ability of the younger brain to revert to ketone metabolism can an advantage. This review addresses the potential of alternative substrate metabolic intervention as a logical pediatric TBI neuroprotective strategy.

Biochemical and biomechanical assessment of effects of L-carnitine on oral mucosal wounds

OBJECTIVES

The present study aimed to investigate the oral mucosal wound healing potential of L-carnitine in a rat model.

MATERIALS AND METHODS

Twenty-four Wistar-albino rats were divided into 4 groups: control group (group I), L-carnitine groups (100 and 200 mg/kg/day, intraperitoneally) (groups II and III), and vitamin E group (100 mg/kg/day, intraperitoneally) (group IV). A 1.5-cm linear incision was created on the buccal mucosa of each rat and was left to heal by secondary intention. On the tenth day, rats were anesthetized and sacrificed. The tensile strength of wound was measured with a tensiometer. Hydroxyproline (HYP) and malondialdehyde (MDA) levels in wound were assayed by spectrophotometry. Results were statistically analyzed using a one-way ANOVA analysis (p ≤ 0.001).

RESULTS

In the analysis of tissue samples, there was a statistically significant decrease in MDA levels in group II (p < 0.01) and group IV (p < 0.001). Wound tension strength that was seen in groups II (57.88 %) and IV (48.71 %) was better than group III (33.39 %). Hydroxyproline levels in group II (46.98 ± 1.37) was higher than groups III (29.40 ± 1.64) and IV (38.83 ± 1.41).

CONCLUSION

Although there was a tendency toward faster healing in the groups receiving L-carnitine, it may have a dose-related positive effect for wound healing.

CLINICAL RELEVANCE

With the advantages of having positive effects on wound healing, being a natural substance in the body, being easy to procure, and having a practical usage, L-carnitine may be clinically feasible for human oral mucosal wounds.

The effects of exogenous l-carnitine on lipid peroxidation and tissue damage in an experimental warm hepatic ischemia-reperfusion injury model

BACKGROUND

l-Carnitine is the essential endogenous factor for the transport of long-chain fatty acids from the cytoplasm to within the mitochondrion where the β-oxidation process takes place. l-Carnitine is a superoxide scavenger and an antioxidant that possesses an anti-ischemic action and a stabilizing effect on cell membranes. It may be of help in liver ischemia reperfusion injury. RESULTS regarding the effects of l-carnitine on liver ischemia and reperfusion injury are few and conflicting.

OBJECTIVE

The aim of this study was to investigate the efficacy of exogenous l-carnitine on lipid peroxidation and protecting liver at different stages of experimental total warm hepatic ischemia-reperfusion (TWHIR) procedure in rats.

METHODS

This experimental study in healthy, weanling, male Wistar rats (weighing 180-200 g) was conducted at the Experimental Animal Research Laboratory of the Faculty of Medicine of Mersin University, Mersin, Turkey. Rats were randomly divided into 5 groups: (A) Control group; (B) TWHIR procedure only; (C) l-carnitine administered 2 hours before the TWHIR procedure; (D) l-carnitine administered just before the TWHIR procedure; and (E) l-carnitine administered after total warm hepatic ischemia but just before the reperfusion procedure. Total warm hepatic ischemia (via the Pringle maneuver) and reperfusion were performed for 45 and 30 minutes, respectively. l-Carnitine (200 mg/kg) was administered intravenously. At the end of each procedure a blood sample was drawn and total hepatectomy was performed following reperfusion. Malondialdehyde (MDA) and myeloperoxidase (MPO) levels of both plasma and liver tissue, total antioxidant capacity (TAOC), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in plasma, and histopathologic examination were analyzed to assess lipid peroxidation and damage in liver tissue.

RESULTS

Thirty-four rats (mean [SD]age, 59.26 [1.2]days; mean [SD] weight, 194.1 [5.1] g) were used in the study. There was a significant difference observed between groups A (n = 5) and B (n = 5) for all evaluation parameters. The TWHIR procedure performed in group B was associated with significant increases versus baseline in ALT, AST, MDA, and MPO in plasma, and MDA and MPO in liver tissue, but a significant decrease of TAOC in plasma. ALT, AST, serum and liver MDA, and MPO levels of group B were significantly higher than all groups administered l-carnitine. l-Carnitine administration between total warm hepatic ischemia and reperfusion was associated with a significant attenuation in all parameters. The liver MDA levels of groups C (n = 8) and D (n = 8) were significantly lower than that of group E (n = 8) (mean [SD]: C, 16.53 [3.32] and D, 18.28 [1.67] vs E, 23.05 [3.52]; P = 0.001 and P = 0.016, respectively). The mean (SD) liver MPO level of group C (1.09 [0.16]) was significantly lower than that of groups D (2.12 [0.25]) and E (2.11 [0.28]) (both, P = 0.001). The TAOC of group B (0.77 [0.12]) was significantly lower than that of groups C (1.34 [0.19]) and D (1.08 [0.20]) (P = 0.001 and P = 0.015, respectively). The TAOC of group C was significantly higher than that of the other l-carnitine groups (E, 0.94 [0.13]) (P = 0.023 vs group D; and P = 0.001 vs group E). Histopathologic scores of groups A, C, and E were significantly lower than that of group B, but the difference between groups B and D was not statistically significant.

CONCLUSIONS

In this experimental study, administration of exogenous l-carnitine was associated with significantly decreased lipid peroxidation in plasma and liver tissue when administered prior to a TWHIR procedure. In addition, l-carnitine seemed to be more effective with regard to decreasing lipid peroxidation in liver tissue when administered before warm hepatic ischemia. l-Carnitine was associated with significantly decreased leukocyte sequestration in plasma and liver tissue. A significant increase in TAOC was associated with l-carnitine administered prior to ischemia. These observations suggest that l-carnitine might have a protective effect against ischemia-reperfusion injury in rat liver tissue.

The effect of L-carnitine on oxidative stress responses of experimental contrast-induced nephropathy in rats

This study was conducted to investigate the prophylactic effects of carnitine against contrast-induced nephropathy (CIN) and its relation to oxidant/antioxidant status in kidney, liver, heart, spleen and lung tissues in a CIN rat model. Twenty-eight adult male Wistar rats were divided into 4 groups, the control, contrast media (CM), carnitine and contrast media+carnitine (CM+carnitine) groups. Animals were placed in individual metabolism cages, and on the 2nd day, rats were deprived of water for 24 hr. On the 3rd day, contrast media were administered to groups CM and CM+carnitine. L-carnitine was administered on days 2, 3 and 4. Histopathological changes were evaluated in the right kidney after euthanization. Superoxide dismutase (SOD) and catalase (CAT) activities and glutathione (GSH) and malondialdehyde (MDA) levels were measured in renal, liver, heart, spleen and lung tissues. The SOD activities in the renal (P<0.05), liver (P<0.001) and spleen (P<0.05) tissues were increased in the carnitine group. The CAT activities in the spleen tissue were decreased (P<0.01) only in the CM group. Renal (P<0.05), liver (P<0.001), spleen (P<0.001) and lung tissue (P<0.01) GSH levels were found to be higher in the carnitine group. In renal, liver and lung tissues, the MDA levels increased in the CM group (P<0.001). The histopathological findings showed that L-carnitine may have a preventative effect in alleviating the negative effects of CIN. Similar to this, L-carnitine may play a major role in the stability of the antioxidant status in the kidney, liver, spleen and lung of the CIN rat model.

Post-treatment with the combination of 5-aminoimidazole-4-carboxyamide ribonucleoside and carnitine improves renal function after ischemia/reperfusion injury

Renal ischemia/reperfusion (I/R) injury is a major clinical problem where main metabolic pathways are compromised and cellular homeostasis crashes after ATP depletion. Fatty acids are major energy source in the kidneys. Carnitine palmitoyltransferase I (CPT1), a mitochondrial membrane enzyme, utilizes carnitine to transport fatty acids to mitochondria for the process of β-oxidation and ATP generation. In addition, CPT1 activity is indirectly regulated by adenosine monophosphate-activated protein kinase, which can be activated by 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR). We hypothesized that administration of carnitine and AICAR could reestablish the energetic balance after reperfusion and ameliorate renal I/R injury. Male adult rats were subjected to renal I/R by bilateral renal pedicle clamping for 60 min, followed by administration of saline (vehicle), carnitine (250 mg/kg BW), AICAR (30 mg/kg BW), or combination of both drugs. Blood and renal tissues were collected 24 h after reperfusion for various measurements. Renal carnitine levels decreased 53% after I/R. The combined treatment significantly increased CPT1 activity and ATP levels and lowered renal malondialdehyde and serum TNF-α levels against the vehicle group. It led to improvement in renal morphology and histological damage score associated with diminution in serum creatinine, blood urea nitrogen, and aspartate aminotransferase levels. Moreover, the combined treatment significantly improved the survival rate in comparison to the vehicle group. In contrast, administration of either drug alone did not show a significant improvement in most of the measurements. In conclusion, enhancing energy metabolism by combination of carnitine and AICAR provides a novel modality to treat renal I/R injury.

Preliminary study comparing the effects of locally and systemically applied L-carnitine on the healing of full-thickness skin defects

BACKGROUND AND AIMS

L-carnitine as an endogenous cofactor has a role in the regulation of energy flow between different oxidative sources. The purpose of this study is to investigate that the clinical and histopathologic effects of L-carnitine locally and systemically on secondary healing in wounds of full thickness defects. We also measured the effects of L-carnitine on wound tensile strength as mechanical.

MATERIAL AND METHODS

sixty adult male Sprague-Dawley rats were divided into three groups randomly; group 1 (control group, n = 20), group 2 (local experimental group, n = 20), group 3 (systemic experimental group, n = 20). Group 1 was not given any pharmacologic agents. L-carnitine was administered locally in the group 2, and systemically in group 3 for a total of 14 days. The healing days of all groups were recorded. On the 7th, 10th,14th and 21st postoperative days, biopsy specimens, including tissue samples both from healing wound sites and sur-rounding healthy skin were evaluated for neovascularization, inflammation, the amount of collagen deposit, fibroblast migration and re-epithelization. Tensile strength was measured in the samples which completed healing on the 30th day. The results were evaluated by nonparametric Kruskall-Wallis test followed by Mann Whitney-U test.

RESULTS

the mean clinical healing days were 18.25 days, 16.5 days, 15 days for the control group, local experimental and systemic group, respectively. The differences between groups were statistically significant (p < 0.005). Mean tensile strength values were 762.10 centinewton (cN), 801.69 cN and 786.13 cN for the control group, local experimental group and systemic experimental group, respectively. There were no statistically significant differences between groups (p > 0.05). There was no statistically significant difference in the histopathologic ex-amination on the 7th, 10th, 14th and 21st days in the neovascularization, inflammation and fibroblast migration. Collagen deposit was most prevalent in the systemic experimental group and was least in the control group. Complete wound closure rate was observed on the 7th day in the systemic administration group, on the 10th day in local administration group and on the 14th day in the control group. Re-epithelization thickness in the systemic carnitine group was more than the other groups.

CONCLUSIONS

L-carnitine administered locally or systemically has positive effects on wound healing rate and tensile strength in rats.

L-Carnitine ameliorates glycerol-induced myoglobinuric acute renal failure in rats

There is increasing evidence indicating that oxidative stress plays an important role in the pathogenesis of rhabdomyolysis-induced myoglobinuric acute renal failure (ARF). During times of war and natural disasters, myoglobinuric ARF can assume epidemic proportions. Thus, early and effective renoprotective treatments are of utmost importance. It has been shown that L-carnitine, used as a safe and effective nutritional supplement for more than three decades, is effective in preventing renal injury in many renal injury models involving oxidative stress. The present study was performed to investigate the effects of L-carnitine in an experimental model of myoglobinuric ARF. Four groups of rats were employed in this study: group 1 served as a control; group 2 was given glycerol (10 mL/kg, i.m.); group 3 was given glycerol plus L-carnitine (100 mg/kg, i.p.), starting at the same time as the glycerol injection; group 4 was given glycerol plus L-carnitine (100 mg/kg, i.p.), starting 48h before the glycerol injection. After glycerol injections, the i.p. injections of L-carnitine were repeated every 24h for four days. Ninety-six hours after glycerol injections, blood samples and kidney tissues were taken from the anesthetized rats. Urea and creatinine levels in plasma, N-acetyl-beta-D-glucosaminidase activity in urine, and malondialdehyde levels and catalase enzyme activity in kidney tissue were determined. Histopathological changes and iron accumulation in the kidney tissue were evaluated. In this study, glycerol administration led to marked renal oxidative stress, as well as severe functional and morphological renal deterioration. L-carnitine, possibly via its antioxidant properties, ameliorates glycerol-induced myoglobinuric kidney injury.

Protective effects of DIDS against ethanol-induced gastric mucosal injury in rats

The compound 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) is an efficient anion exchanger inhibitor that can block the activities of anion exchanger 2 (AE2), which plays an indispensable role in gastric acid secretion. DIDS also has potent anti-oxidative and antiapoptosis activities. This study aimed to investigate the effect of DIDS on ethanol-induced mucosal damage in rats and to evaluate the underlying mechanisms that mediate the action of the compound. The rats received 1 ml of absolute ethanol or saline orally. DIDS [50 mg/kg intravenous (i.v.)] was given 5 min before ethanol administration. Gastric lesions were evaluated macroscopically, microscopically, and electron microscopically at 60 min after ethanol challenge. Gastric myeloperoxidase (MPO) activity, malonyldialdehyde (MDA) level, prostaglandin E2 (PGE2) synthesis, and cyclooxygenase-2 (COX-2) expression were assessed. For the evaluation of the effect of DIDS on gastric acid secretion, histamine-stimulatory gastric acid secretion was examined with or without pretreatment of DIDS (50 mg/kg; i.v.). Ethanol-induced gastric lesions were characterized by increasing gastric MDA level, MPO activity, and COX-2 expression, and decreasing PGE2 synthesis. It was found that DIDS significantly reduced the extent of gastric mucosal damage and reversed tissue MDA level and MPO activity. DIDS further enhanced the expression of COX-2 and reversed the decrease of PGE2. Our results suggested that DIDS is beneficial in rat model of gastric injury through mechanisms that involve inhibiting inflammatory cell infiltration and lipid peroxidation and up-regulating the COX-2/PGE2 pathway.

Novel pharmacological approaches to the treatment of renal ischemia-reperfusion injury: a comprehensive review

Renal ischemia-reperfusion (I-R) contributes to the development of ischemic acute renal failure (ARF). Multi-factorial processes are involved in the development and progression of renal I-R injury with the generation of reactive oxygen species, nitric oxide and peroxynitrite, and the decline of antioxidant protection playing major roles, leading to dysfunction, injury, and death of the cells of the kidney. Renal inflammation, involving cytokine/adhesion molecule cascades with recruitment, activation, and diapedesis of circulating leukocytes is also implicated. Clinically, renal I-R occurs in a variety of medical and surgical settings and is responsible for the development of acute tubular necrosis (a characteristic feature of ischemic ARF), e.g., in renal transplantation where I-R of the kidney directly influences graft and patient survival. The cellular mechanisms involved in the development of renal I-R injury have been targeted by several pharmacological interventions. However, although showing promise in experimental models of renal I-R injury and ischemic ARF, they have not proved successful in the clinical setting (e.g., atrial natriuretic peptide, low-dose dopamine). This review highlights recent pharmacological developments, which have shown particular promise against experimental renal I-R injury and ischemic ARF, including novel antioxidants and antioxidant enzyme mimetics, nitric oxide and nitric oxide synthase inhibitors, erythropoietin, peroxisome-proliferator-activated receptor agonists, inhibitors of poly(ADP-ribose) polymerase, carbon monoxide-releasing molecules, statins, and adenosine. Novel approaches such as recent research involving combination therapies and the potential of non-pharmacological strategies are also considered.

Hyperbaric oxygenation attenuates renal ischemia-reperfusion injury in rats

BACKGROUND

Oxygen-derived free radicals play an important role in ischemia-reperfusion injury (IR). Hyperbaric oxygenation (HO) decreases free radical production. The aim of this study was to determine the effect of HO treatment on renal ischemia-reperfusion injury in rats.

METHODS

Rats were divided into four groups. All groups underwent right nephrectomy. Group I served as the control group; group II had left renal ischemia-reperfusion; group III was pretreated with HO; and group IV, ischemia-reperfusion and HO pretreatment. Tissue malondialdehyde (MDA) and glutathione (GSH) levels were measured, and histopathologic damage scored.

RESULTS

HO pretreatment significantly decreased tissue MDA levels and histopathologic scores among rats with IR. There was an increased GSH in HO-pretreated rats with IR; however, the difference was not significant.

CONCLUSION

HO prior to ischemia displayed a beneficial effect on renal IR by reducing oxygen radical peroxidation of lipid membranes.

Mitochondrial membrane permeabilization in cell death

Irrespective of the morphological features of end-stage cell death (that may be apoptotic, necrotic, autophagic, or mitotic), mitochondrial membrane permeabilization (MMP) is frequently the decisive event that delimits the frontier between survival and death. Thus mitochondrial membranes constitute the battleground on which opposing signals combat to seal the cell's fate. Local players that determine the propensity to MMP include the pro- and antiapoptotic members of the Bcl-2 family, proteins from the mitochondrialpermeability transition pore complex, as well as a plethora of interacting partners including mitochondrial lipids. Intermediate metabolites, redox processes, sphingolipids, ion gradients, transcription factors, as well as kinases and phosphatases link lethal and vital signals emanating from distinct subcellular compartments to mitochondria. Thus mitochondria integrate a variety of proapoptotic signals. Once MMP has been induced, it causes the release of catabolic hydrolases and activators of such enzymes (including those of caspases) from mitochondria. These catabolic enzymes as well as the cessation of the bioenergetic and redox functions of mitochondria finally lead to cell death, meaning that mitochondria coordinate the late stage of cellular demise. Pathological cell death induced by ischemia/reperfusion, intoxication with xenobiotics, neurodegenerative diseases, or viral infection also relies on MMP as a critical event. The inhibition of MMP constitutes an important strategy for the pharmaceutical prevention of unwarranted cell death. Conversely, induction of MMP in tumor cells constitutes the goal of anticancer chemotherapy.

Effects of L-carnitine on oxidant/antioxidant status in acetic acid-induced colitis

Recently, the role of oxidative stress in the pathogenesis of ulcerative colitis has been investigated. This study was designed to evaluate the possible beneficial effects of L-carnitine on tissue injury and oxidative stress in acetic acid-induced colitis in rats. Acetic acid administration induced severe damage macroscopically and histopathologically in colon and significantly increased the levels of malondialdehyde and myeloperoxidase in colonic tissue. Supplementation of L-carnitine to acetic acid-treated rats did not prove to induce any improvements in macroscopic scores, while L-carnitine administration improved histopathologic scores and significantly decreased malondialdehyde and myeloperoxidase levels in treatment groups. Acetic acid administration significantly decreased reduced glutathione, superoxide dismutase, and catalase levels in colonic homogenate. Supplementation of L-carnitine prevented the depletion of reduced glutathione levels but significantly increased superoxide dismutase levels. On the other hand, no significant change in catalase activity was observed. In conclusion, these results may reflect that L-carnitine could be beneficial as a complementary agent in treatment of ulcerative colitis.