Ischemia/Reperfusion of the Liver Induces Heart Injury in Rats

Vagus nerve stimulation alleviates myocardial injury following hepatic ischemia-reperfusion in rats by inhibiting ferroptosis via the activation of the SLC7A11/GPX4 axis

BACKGROUND

Vagus nerve stimulation (VNS) exhibits protective effects against remote organ injury following ischemia-reperfusion (I/R). However, its effects on acute myocardial injury induced by hepatic I/R in rats, and the underlying mechanisms, remain unclear.

METHODS

Thirty male rats were randomly assigned to five groups: Sham, I/R, VNS, VNS + Erastin, and VNS + DMSO. A hepatic I/R injury model was established by occluding the arterial and portal veins of the left and middle lobes of the liver for 1 h followed by 6 h of reperfusion. VNS was performed throughout the hepatic I/R process. Erastin was administered intraperitoneally 60 min before hepatic ischemia. Blood samples were collected from the left common carotid artery post-reperfusion to measure liver injury markers (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) and the myocardial injury marker (cardiac troponin I [cTnI]). Left ventricular myocardial tissue was also collected for ultrastructural analysis via transmission electron microscopy, reactive oxygen species (ROS) detection using dihydroethidium staining, and measurements of Fe2⁺ levels, malondialdehyde (MDA) concentration, glutathione (GSH) levels, and superoxide dismutase (SOD) activity. Western blotting assessed the expression of ferroptosis-related proteins SLC7A11 and GPX4 in the myocardial tissue.

RESULTS

VNS significantly reduced serum levels of ALT, AST, and cTnI, while also mitigating mitochondrial damage in cardiomyocytes. Additionally, VNS decreased ROS levels, alleviated iron overload, and reduced lipid peroxidation in myocardial tissue. These protective effects were associated with the activation of the SLC7A11/GPX4 axis, as evidenced by increased expression of these proteins in the VNS group. However, the cardioprotective effects of VNS were negated by the ferroptosis activator erastin, indicating that ferroptosis is involved in VNS-mediated cardioprotection.

CONCLUSION

VNS protects against myocardial injury from hepatic ischemia-reperfusion, likely by inhibiting oxidative stress and ferroptosis through activation of the SLC7A11/GPX4 axis.

Metabolic characteristics of evodiamine were associated with its hepatotoxicity via PPAR/PI3K/AKT/NF-кB/tight junction pathway-mediated apoptosis in zebrafish

Evodiae Fructus (EF), an herbal medicine, possesses remarkable anti-inflammatory and analgesic properties. It exhibits insecticidal activity as a potent insecticide candidate. However, the toxic characteristics of EF and the underlying mechanisms have not been comprehensively elucidated comprehensively. Thus, we comprehensively explored the toxic components of EF and established the relationship between the therapeutic and toxic effects of EF, encouraging its therapeutic use. We found that evodiamine (EVO), one of the main ingredients of EF, can truly reflect its analgesic properties. In phenotype observation trials, low doses of EVO (< 35 ng/mL) exhibited distinct analgesic activity without any adverse effects in zebrafish. However, EVO dose-dependently led to gross morphological abnormalities in the liver, followed by pericardial edema, and increased myocardial concentrations. Furthermore, the toxic effects of EVO decreased after processing in liver microsomes but increased after administering CYP450 inhibitors in zebrafish, highlighting the prominent effect of CYP450s in EVO-mediated hepatotoxicity. EVO significantly changed the expression of genes enriched in multiple pathways and biological processes, including lipid metabolism, inflammatory response, tight junction damage, and cell apoptosis. Importantly, the PPAR/PI3K/AKT/NF-кB/tight junction-mediated apoptosis pathway was confirmed as a critical functional signaling pathway inducing EVO-mediated hepatotoxicity. This study provided a typical example of the overall systematic evaluation of traditional Chinese medicine (TCM) and its active ingredients with significant therapeutic effects and simultaneous toxicities, especially metabolic toxicities.

Role of Peroxynitrite-Induced Activation of Poly(ADP-Ribose) Polymerase (PARP) in Circulatory Shock and Related Pathological Conditions

Peroxynitrite is a powerful oxidant, formed from the reaction of nitric oxide and superoxide. It is known to interact and modify different biological molecules such as DNA, lipids and proteins leading to alterations in their structure and functions. These events elicit various cellular responses, including cell signaling, causing oxidative damage and committing cells to apoptosis or necrosis. This review discusses nitrosative stress-induced modification in the DNA molecule that results in the formation of 8-nitroguanine and 8-oxoguanine, and its role in disease conditions. Different approaches of cell death, such as necrosis and apoptosis, are modulated by cellular high-energy species, such as ATP and NAD⁺. High concentrations of peroxynitrite are known to cause necrosis, whereas low concentrations lead to apoptosis. Any damage to DNA activates cellular DNA repair machinery, like poly(ADP-ribose) polymerase (PARP). PARP-1, an isoform of PARP, is a DNA nick-sensing enzyme that becomes activated upon sensing DNA breakage and triggers the cleavage of NAD⁺ into nicotinamide and ADP-ribose and polymerizes the latter on nuclear acceptor proteins. Peroxynitrite-induced hyperactivation of PARP causes depletion of NAD⁺ and ATP culminating cell dysfunction, necrosis or apoptosis. This mechanistic pathway is implicated in the pathogenesis of a variety of diseases, including circulatory shock (which is characterized by cellular hypoxia triggered by systemic altered perfusion and tissue oxygen utilization leading end-organ dysfunction), sepsis and inflammation, injuries of the lung and the intestine. The cytotoxic effects of peroxynitrite centering on the participation of PARP-1 and ADP-ribose in previously stated diseases have also been discussed in this review.

The protective effect of curcumin on ischemia-reperfusion-induced liver injury

OBJECTIVE

Reperfusion of the ischemic liver results in the generation of oxidative and nitrosative stresses and reaction product of peroxynitrite, which induce rapid cytotoxicity and liver injury. In this study we demonstrated that curcumin, an antioxidant, attenuated ischemia/reperfusion (I/R)-induced liver injury.

MATERIALS AND METHODS

Ischemia was induced by clamping the common hepatic artery and portal vein of rats for 30 minutes. Thereafter, flow was restored and the liver was reperfused for 80 minutes. Blood samples collected prior to ischemia and after reperfusion were analyzed for methyl guanidine (MG), nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), and adenosphate triphosphate (ATP). Blood levels of serum glutamic oxaloacetic transaminase (sGOT), serum glutamate pyruvate transaminase (sGPT), and lactic dehydrogenase (LDH), which served as indexes of liver injury, were measured.

RESULTS

The protocol resulted in elevation of blood NO (P < .001), TNF-α (P < .001), and MG (P < .001). sGOT, sGPT, and LDH were elevated significantly (P < .001), whereas ATP was significantly diminished (P < .001). Pretreatment with curcumin (25 mg/kg) significantly attenuated the reperfusion liver injury, while the ATP content reversed. In addition, MG, TNF-α, and NO release were attenuated.

CONCLUSIONS

These results indicated that curcumin exerted potent anti-inflammatory effects in I/R-induced liver injury due to its antioxidant effects.

Nitric oxide synthase in heart and thoracic aorta after liver ischemia and reperfusion injury: an experimental study in rats

OBJECTIVES

We tested the effects of liver reperfusion in the immunohistochemical expression of nitric oxide synthase on the thoracic aorta and the heart.

MATERIALS AND METHODS

We randomized 24 male Wistar rats into 3 groups: (1) control; (2) R2 group, with 60 minutes of partial (70%) liver ischemia and 2 hours of global liver reperfusion; (3) and R6 group, with 60 minutes of partial liver ischemia and 6 hours of global liver reperfusion.

RESULTS

In the heart, there was little, diffuse immunohistochemical endothelial staining; immunohistochemical inducible nitric oxide synthase staining was expressed in the adventitia layer of intramyocardial vessels in both cases, with a time-dependent but not statistically significant increase. In the thoracic aorta, a time-dependent decrease in endothelial nitric oxide synthase expression in the muscular layer after reperfusion, which was statistically significant in R6 versus the control. Positive immunostaining for inducible nitric oxide synthase was seen in the muscular and endothelial layers, and this varied from moderate in the control group, to light in the endothelium in groups R2 and R6.

CONCLUSIONS

We observed changes that may be implicated in heart injury and impairment of aortal tone after liver ischemia and reperfusion injury.

Early myocardial injury is an integral component of experimental acute liver failure - a study in two porcine models

INTRODUCTION

There is accumulating clinical evidence that acute liver failure may be regularly associated with myocardial injury. To test this hypothesis in a standardized experimental setting, we used two porcine models of ALF.

MATERIAL AND METHODS

In 14 domestic pigs ALF was induced by either a) surgical devascularization of the liver (DV group, n = 7), or b) partial (70-75%) hepatectomy and ischaemia/reperfusion of the liver remnant for 150 min (I/R group, n = 7). Four additional animals constituted the sham operation group. All animals were monitored for a 12-h period, at the end of which their hearts were harvested. Plasma troponin I (cTnI) and malondialdehyde (MDA) were measured before the operation (baseline) and at 6 h and 12 h postoperatively. The harvested hearts were histologically analysed, appointing a score from 0 (no injury) to 3 (maximum injury) to selected injury indicators.

RESULTS

In the sham group, all cTnI measurements and total myocardial injury score were zero in all animals. In both ALF groups, plasma cTnI levels increased by the 6(th) and remained elevated up to the 12(th) postoperative hour (p < 0.01 vs. sham animals). Total myocardial injury score and total histological score revealed some extent of myocardial injury. The rise of MDA levels suggests an underlying oxidative mechanism.

CONCLUSIONS

Our study provides direct evidence of early myocardial injury in the setting of acute liver failure in pigs. The mechanism of injury remains to be elucidated.

Hydrogen sulphide attenuates renal and cardiac injury after total hepatic ischemia and reperfusion

BACKGROUND

There are few studies that focus on the important organs injuries induced by total hepatic ischemia and reperfusion (THIR), which is a key to save the lives of hepatic surgery patients. We evaluated changes in the hydrogen sulphide production system and injuries to the heart and kidney. The aim of this study was to assess whether sodium hydrosulphide (NaHS) has protective effects against THIR injury.

MATERIALS AND METHODS

Under anaesthesia of the Wistar rats, the hepatic artery, the portal vein, and the inferior vena cava above and below the liver were clamped with nontraumatic arterial clamps. Hepatic reperfusion was achieved by removing the clamps.

RESULTS

Hydrogen sulphide production system was down-regulated after THIR, which caused severe damage to the heart and kidney, apart from the liver. In treated animals, CK-MB and LDH were lower by 26.9% and 14.2% (P < 0.05), respectively. The kidney showed similar change. Hematoxylin and eosin staining demonstrated fewer injuries in NaHS treated animals. The results indicated that the damage was abolished by exogenous NaHS.

CONCLUSIONS

The observed protection of exogenous NaHS is associated with reduced myocardial and renal inflammation and oxidative potential after THIR. The current results suggest that hydrogen sulphide is protective during the evolution of THIR and that either direct hydrogen sulphide administration or the modulation of endogenous production may be of clinical importance.

Water extract of Zizyphus Jujube attenuates ischemia/reperfusion-induced liver injury in rats (PP106)

AIMS

Ischemia and reperfusion (I/R) injuries in the liver remain important clinical problems. Free oxygen radicals and nitrosative stress have been shown to be involved in the pathogenesis I/R-related liver injury. The purpose of this study was to characterize the effects of an extract of Zizyphus Jujube (ZJ), which has strong antioxidant effects, on I/R-induced liver injury.

MATERIALS AND METHODS

Ischemia (I) was induced in rat livers by clamping the common hepatic artery and portal vein for 40 minutes, after which flow was restored, and the liver was reperfused for 90 minutes. Blood samples were collected prior to I and after reperfusion to assay blood levels of alanine transaminase (ALT), lactic dehydrogenase (LDH), oxygen radical (OH), and nitric oxide (NO). In the pharmacologic intervention group a water extract of the fruit of ZJ was administered orally to rats (100 mg/mL for 7 days) that were subsequently exposed to the I/R liver injury.

RESULTS

The data showed that reperfusion (R) of the liver produced increases in blood concentrations of ALT (41.9+/-8.2 vs 338.0+/-89.6; P<.01; N=7) and LDH (317+/-129 vs 4073+/-950; P<.001; N=7). Oxygen radicals (55.1+/-14.3 vs 262.4+/-60.3; P<.001; N=7) and NO (69.3+/-14.9 vs 121.6+/-27.1; P<.01; N=7) also increased significantly in this R group. In the ZJ intervention group the liver injury, oxidative stress, and nitrosative stress were all significantly attenuated.

CONCLUSION

These results suggested that I/R-induced liver injury with white blood cell activation, oxidative stress, and nitrosative stress. Pretreatment with an extract of ZJ, which shows high antioxidant effects, significantly attenuated the I/R-induced liver injury.

Poly(ADP-ribose) polymerase activity in different pathologies--the link to inflammation and infarction

DNA repair and aging are two phenomena closely connected to each other. The poly(ADP-ribosyl)ation reaction has been implicated in both of them. Poly(ADP-ribose) was originally discovered as an enzymatic reaction product after DNA damage. Soon it became evident that it is necessary for regulation of different repair pathways. Also, evidence accumulated that poly(ADP-ribose) formation capacity is at least correlated with the life span of mammalian species. As a NAD(+)-consuming process, poly(ADP-ribosyl)ation can lead to cell death by energy depletion. This finding opened the area for investigation of poly(ADP-ribose) polymerase activity and polymer formation in pathologies. This review provides an introduction into the wide and complex field of poly(ADP-ribosyl)ation in different pathologies with regards of cell death regulation, inflammation and resulting tissue damage.