Protective effects of carnitine in an experimental ischemia-reperfusion injury

Effects of comprehensive nutrition support on immune function, wound healing, hospital stay, and mental health in gastrointestinal surgery

BACKGROUND

Postoperative patients undergoing gastrointestinal surgery often encounter challenges such as low immune function, delayed wound healing owing to surgical trauma, and increased nutritional demands during recovery.

AIM

To assess the effect of comprehensive nutritional support program on immune function and wound healing in patients undergoing gastrointestinal surgery.

METHODS

This retrospective comparative study included 60 patients who underwent gastrointestinal surgery, randomly assigned to either the experimental group (n = 30) or the control group (n = 30). The experimental group received comprehensive nutritional support, including a combination of enteral and parenteral nutrition, whereas the control group received only conventional comprehensive nutritional support. Evaluation indicators included immune function markers (e.g., white blood cell count, lymphocyte subsets), wound healing (wound infection rate, healing time), pain score [visual analog scale (VAS) score], and psychological status (anxiety score, depression score) 7 days post-surgery) and duration of stay.

RESULTS

The immune function of patients in the experimental group was significantly better than that in the control group. The white blood cell count was 8.52 ± 1.19 × 109/L in the experimental group vs 6.74 ± 1.31 × 109/L (P < 0.05). The proportion of CD4+ T cells was higher in the experimental group (40.09% ± 4.91%) than that in the control group (33.01% ± 5.08%) (P < 0.05); the proportion of CD8+ T cells was lower (21.79% ± 3.38% vs 26.29% ± 3.09%; P < 0.05). The CD4+/CD8+ ratio was 1.91 ± 0.32 in the experimental group whereas 1.13 ± 0.23 in the control group (P < 0.05). The wound infection rate of the experimental group was significantly lower than that of the control group (10% vs 30%, P < 0.05), and the wound healing time was shorter (10.35 ± 2.42 days vs 14.42 ± 3.15 days, P < 0.05). The VAS score of the experimental group was 3.05 ± 1.04, and that of the control group was 5.11 ± 1.09 (P < 0.05); the anxiety score (Hamilton Anxiety Rating Scale) was 8.88 ± 1.87, and that of the control group was 12.1 ± 3.27 (P < 0.05); the depression score (Hamilton Depression Rating Scale) was 7.37 ± 1.41, and that of the control group was 11.79 ± 2.77 (P < 0.05). In addition, the hospitalization time of the experimental group was significantly shorter than that of the control group (16.16 ± 3.12 days vs 20.93 ± 4.84 days, P < 0.05).

CONCLUSION

A comprehensive nutritional support program significantly enhances immune function, promote wound healing, reduces pain, improves psychological status, and shortens hospitalization stays in patients recovering from gastrointestinal surgery.

Normalization of lipid oxidation defects arising from hypoxia early posthepatectomy prevents liver failure in mouse

Surgical liver failure (SLF) develops when a marginal amount of hepatic mass is left after surgery, such as following excessive resection. SLF is the commonest cause of death due to liver surgery; however, its etiology remains obscure. Using mouse models of standard hepatectomy (sHx) (68%, resulting in full regeneration) or extended hepatectomy (eHx) (86%/91%, causing SLF), we explored the causes of early SLF related to portal hyperafflux. Assessing the levels of HIF2A with or without oxygenating agent inositol trispyrophosphate (ITPP) indicated hypoxia early after eHx. Subsequently, lipid oxidation (PPARA/PGC1α) was downregulated and associated with persisting steatosis. Mild oxidation with low-dose ITPP reduced the levels of HIF2A, restored downstream PPARA/PGC1α expression along with lipid oxidation activities (LOAs), and normalized steatosis and other metabolic or regenerative SLF deficiencies. Promotion of LOA with L-carnitine likewise normalized the SLF phenotype, and both ITPP and L-carnitine markedly raised survival in lethal SLF. In patients who underwent hepatectomy, pronounced increases in serum carnitine levels (reflecting LOA) were associated with better recovery. Lipid oxidation thus provides a link between the hyperafflux of O₂-poor portal blood, the metabolic/regenerative deficits, and the increased mortality typifying SLF. Stimulation of lipid oxidation-the prime regenerative energy source-particularly through L-carnitine may offer a safe and feasible way to reduce SLF risks in the clinic.

The Ameliorative Effects of Pycnogenol® on Liver Ischemia-Reperfusion Injury in Rats

Objectives

Pycnogenol^® (PYC^®), a standardized extract from the bark of Pinus maritima, consists of different phenolic compounds. PYC^® has shown to have protective effects on chronic diseases such as diabetes, asthma, cancer, and immune disorders. The aim of this study was to determine the effects of PYC^® against the DNA damage and biochemical changes in blood, liver, and lung tissues of ischemia-reperfusion (IR)-induced Wistar albino rats.

Materials and Methods

A sham group, IR injury-induced group, and IR+PYC^® group were formed. Ischemia was induced and sustained for 45 min, then the ischemic liver was reperfused, which was sustained for a further 120 min at the end of this period. After anesthesia and before the IR inducement, 100 mg/kg PYC^® was given to the IR+PYC^® group through intraperitoneal injections. The total oxidant (TOS) and total antioxidant status (TAS), total thiol levels (TTL), advanced oxidation protein products (AOPP), and biochemical parameters [myeloperoxidase (MPO), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH)] in the rats were analyzed using spectrophotometric methods and DNA damage was assessed using single-cell gel electrophoresis.

Results

The levels of TOS, TTL, MPO, AOPP, ALT, AST, and LDH were significantly decreased in the IR+PYC^® group compared with the IR group (p<0.05). The levels of TAS were significantly increased in the IR+PYC^® group compared with the IR group (p<0.05). PYC^® reduced the DNA damage when compared with the IR group (p<0.05).

Conclusion

The present results suggest that PYC^® treatment might have a role in the prevention of IR-induced oxidative damage by decreasing DNA damage and increasing antioxidant status.

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.

Effects of L-carnitine on follicular survival and graft function following autotransplantation of cryopreserved-thawed ovarian tissues

The aim of this study was to investigate the effects of L-carnitine (LC) on follicular survival and ovarian function following cryopreservation-thawing and autotransplantation of ovarian tissues. ICR mice were divided into three groups: control; saline group (cryopreservation+autograft+saline); and LC group (cryopreservation+autograft+L-carnitine). The ovarian tissues from control group, saline group, and LC group were histological assessed. There were no significant differences in the percentage of morphologically normal primordial follicles between the LC group and the saline group. After 28 days of autotransplantation, apoptosis rates, plasma malondialdehyde (MDA), progesterone (P4) and estradiol (E2) concentrations, and follicular densities of grafts were evaluated. Apoptosis rate and the concentration of MDA in the LC group were significantly lower than those in the saline group. The concentration of E2 and follicular densities of grafts in LC group were significantly higher than that in saline group. LC inhibits follicle apoptosis and increases follicular survival and function of ovarian graft.

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.

Strategies to rescue steatotic livers before transplantation in clinical and experimental studies

The shortage of donor livers has led to an increased use of organs from expanded criteria donors. Included are livers with steatosis, a metabolic abnormality that increases the likelihood of graft complications post-transplantation. After a brief introduction on the etiology, pathophysiology, categories and experimental models of hepatic steatosis, we herein review the methods to rescue steatotic donor livers before transplantation applied in clinical and experimental studies. The methods span the spectrum of encouraging donor weight loss, employing drug therapy, heat shock preconditioning, ischemia preconditioning and selective anesthesia on donors, and the treatment on isolated grafts during preservation. These methods work at different stages of transplantation process, although share similar molecular mechanisms including lipid metabolism stimulation through enzymes or nuclear receptor e.g., peroxisomal proliferator-activated receptor, or anti-inflammation through suppressing cytokines e.g., tumor necrosis factor-α, or antioxidant therapies to alleviate oxidative stress. This similarity of molecular mechanisms implies possible future attempts to reinforce each approach by repeating the same treatment approach at several stages of procurement and preservation, as well as utilizing these alternative approaches in tandem.

Tissue damage and oxidant/antioxidant balance

The oxidant/antioxidant balance in healthy tissues is maintained with a predominance of antioxidants. Various factors that can lead to tissue damage disrupt the oxidant/antioxidant balance in favor of oxidants. In this study, disruptions of the oxidant/antioxidant balance in favor of oxidants were found to be a consequence of the over-consumption of antioxidants. For this reason, antioxidants are considered to be of importance in the prevention and treatment of various types of tissue damage that are aggravated by stress.

Effects of L-carnitine against oxidative stress in human hepatocytes: involvement of peroxisome proliferator-activated receptor alpha

BACKGROUND

Excessive oxidative stress and lipid peroxidation have been demonstrated to play important roles in the production of liver damage. L-carnitine is a natural substance and acts as a carrier for fatty acids across the inner mitochondrial membrane for subsequent beta-oxidation. It is also an antioxidant that reduces metabolic stress in the cells. Recent years L-carnitine has been proposed for treatment of various kinds of disease, including liver injury. This study was conducted to evaluate the protective effect of L-carnitine against hydrogen peroxide (H2O2)-induced cytotoxicity in a normal human hepatocyte cell line, HL7702.

METHODS

We analyzed cytotoxicity using MTT assay and lactate dehydrogenase (LDH) release. Antioxidant activity and lipid peroxidation were estimated by reactive oxygen species (ROS) levels, activities and protein expressions of superoxide dismutase (SOD) and catalase (CAT), and malondialdehyde (MDA) formation. Expressions of peroxisome proliferator-activated receptor (PPAR)-alpha and its target genes were evaluated by RT-PCR or western blotting. The role of PPAR-alpha in L-carnitine-enhanced expression of SOD and CAT was also explored. Statistical analysis was performed by a one-way analysis of variance, and its significance was assessed by Dennett's post-hoc test.

RESULTS

The results showed that L-carnitine protected HL7702 cells against cytotoxity induced by H2O2. This protection was related to the scavenging of ROS, the promotion of SOD and CAT activity and expression, and the prevention of lipid peroxidation in cultured HL7702 cells. The decreased expressions of PPAR-alpha, carnitine palmitoyl transferase 1 (CPT1) and acyl-CoA oxidase (ACOX) induced by H2O2 can be attenuated by L-carnitine. Besides, we also found that the promotion of SOD and CAT protein expression induced by L-carnitine was blocked by PPAR-alpha inhibitor MK886.

CONCLUSIONS

Taken together, our findings suggest that L-carnitine could protect HL7702 cells against oxidative stress through the antioxidative effect and the regulation of PPAR-alpha also play an important part in the protective effect.

Protective effect of L-carnitine on testicular ischaemia-reperfusion injury in rats

Testicular torsion is a urological emergency referred to as 'acute scrotum', because inappropriate treatment can lead to male subfertility and infertility. A possible cause of testicular damage is the ischaemia-reperfusion (I/R) injury attributed to oxygen free radicals. L-carnitine, a vitamin-like antioxidant, plays a pivotal role in the maturation of spermatozoa within the reproductive tract. The aim of the present paper was to determine the protective effect of L-carnitine on testicular I/R-induced injury. Thirty-two male rats were divided into 4 groups (n = 8). Testicular torsion was created by rotating the right testis 720 degrees in a clockwise direction. Group 1: sham-operated control; group 2: ischaemia; group 3: I/R; group 4: ischaemia-L-carnitine treatment-reperfusion group. L-carnitine (500 mg kg(-1), intraperitoneally) was administered before 30 min of detorsion in Group 4. After torsion (5 h) and detorsion (5 h), bilateral orchidectomy was performed. The malondialdehyde (MDA) level was evaluated in testes. Histopathologically, Johnsen's spermatogenesis criteria and mean seminiferous tubule diameter (MSTD) measurements were used. Testicular MDA levels were higher in the torsion group compared to the sham-control group (p < 0.05). Detorsion (reperfusion) caused a further increase in MDA levels (p < 0.05). Pretreatment with L-carnitine prevented a further increase in MDA levels (p < 0.05). Histologically, torsion caused some separation among germinal cells in the seminiferous tubules, which became much more prominent in the I/R group but was attenuated with L-carnitine pretreatment. In conclusion, L-carnitine pretreatment may have a protective effect in experimental testicular torsion-detorsion model in rats by its well-known antioxidant potential.

L-carnitine could not improve hepatic warm ischemia-reperfusion injury despite ameliorated blood flow

BACKGROUND

Carnitine is applied to ameliorate ischemia-reperfusion (I/R) injury of several organs. However, application to hepatic I/R injury is not frequently reported. The aim of this study was to elucidate the effect of exogenous carnitine administration to ameliorate the warm hepatic I/R injury.

MATERIALS AND METHODS

Male Wistar rats were divided into two groups, a carnitine group (Car);100 mg/kg of l-carnitine administration and a control group (C); vehicle administration. Thirty minutes after administration, the left hepatic lobes were given 60-min ischemia and then reperfused. Plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH), tumor necrosis factor (TNF)-alpha, and lipoperoxides (LPO) were measured. Hepatic adenosine triphosphate (ATP) concentration was also measured. The hepatic blood flow was estimated using a Laser Doppler. The presence of apoptosis in the livers was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining.

RESULTS

In group Car, the blood flow of the left hepatic lobes was better recovered during the reperfusion period than in group C (P < 0.0001). Plasma levels of ALT, AST, GLDH, and TNF-alpha at 1 h after reperfusion were not significantly different between the groups. Although there were no statistical significances, ALT, AST, and TNF-alpha levels in group Car at 24 h after reperfusion tended to be higher than in group C. Plasma LPO levels were not different between the two groups. Also hepatic ATP concentration was not different between the two groups. TUNEL positive liver cells were visible only in group Car at 24 h after reperfusion, but not in the controls.

CONCLUSIONS

Although carnitine administration improved the hepatic blood flow during the reperfusion period, we could not demonstrate a protective effect to the hepatic warm I/R injury.

Mild hypothermia protects liver against ischemia and reperfusion injury

AIM: To determine whether mild hypothermia could protect liver against ischemia and reperfusion injury in pigs.

METHODS: Twenty-four healthy pigs were randomly divided into normothermia, mild hypothermia and normal control groups. The experimental procedure consisted of temporary interruption of blood flow to total hepatic lobe for different lengths of time and subsequent reperfusion. Hepatic tissue oxygen pressure (P_tiO₂) and aspartate aminotransferase (AST) values were evaluated, and ultrastructural analysis was carried out for all samples.

RESULTS: Serum AST was significantly lower, and hepatic P_tiO₂ values were significantly higher in the mild hypothermia group than in the normothermia group during liver ischemia-reperfusion periods (P = 0.032, P = 0.028). Meanwhile, the histopathologic injury of liver induced by ischemia-reperfusion was significantly improved in the mild hypothermia group, compared with that in the normothermia group.

CONCLUSION: Mild hypothermia can protect the liver from ischemia-reperfusion injury in pigs.

L-carnitine ameliorates abnormal vulnerability of steatotic rat livers to cold ischemic preservation

BACKGROUND

Up to 30% of all livers retrieved for organ transplantation exhibit steatotic transformations. Chronic organ-donor shortage has led to the acceptance of these organs for transplantation, although a higher risk of graft nonfunction is associated with the preservation of steatotic livers.

METHODS

A dietary steatosis was induced in Wistar rats by fasting them for 2 days and feeding them with a fat-free diet. Fatty livers (n=14) were retrieved and flushed with 60 mL of histidine, tryptophane, alpha-ketoglutarate (HTK) solution. In half of the experiments, L-carnitine (5 mM) was added to the HTK. Functional integrity of the livers was evaluated by isolated reperfusion with KHB in a recirculating system at 37 degrees C for 45 minutes.

RESULTS

Addition of L-carnitine to the HTK promoted a significant reduction of the enzyme leakage from the livers upon reperfusion. Release of alanine-aminotransferase was reduced to one third (127+/-22 vs. 423+/-61 U/L), and the loss of glutamate dehydrogenase in the perfusate could be reduced significantly (42+/-7 vs. 542+/-134 U/L) when compared with livers stored without additional medication. Morphologic corroboration of these data was obtained by electron microscopy. Although normal appearance of liver mitochondria was preserved at the end of the cold ischemic storage, reperfusion of cold-stored fatty livers entailed massive alterations and frequent destruction of hepatic mitochondria. However, these morphologic impairments were remarkably mitigated in the carnitine-treated group.

CONCLUSIONS

L-carnitine represents a feasible metabolic adjunct for a safe and more successful preservation of ischemia-reperfusion-sensitive steatotic livers.