Therapeutic potential of cannabidiol against ischemia/reperfusion liver injury in rats

Abstract

The therapeutic potential of cannabidiol, the major non-psychotropic Cannabis constituent, was investigated in rats exposed to ischemia/reperfusion liver injury. Ischemia was induced by clamping the pedicle of the left hepatic lobe for 30 min, and cannabidiol (5 mg/kg, i.v.) was given 1 h following the procedure and every 24 h thereafter for 2 days. Ischemia/reperfusion caused significant elevations of serum alanine aminotransferase and hepatic malondialdehyde, tumor necrosis factor-α and nitric oxide levels, associated with significant decrease in hepatic reduced glutathione. Cannabidiol significantly attenuated the deterioration in the measured biochemical parameters mediated by ischemia/reperfusion. Histopathological examination showed that cannabidiol ameliorated ischemia/reperfusion-induced liver damage. Immunohistochemical analysis revealed that cannabidiol significantly reduced the expression of inducible nitric oxide synthase, cyclooxygenase-2, nuclear factor-κB, Fas ligand and caspase-3, and increased the expression of survivin protein in ischemic/reperfused liver tissue. These results emphasize that cannabidiol represents a potential therapeutic option to protect the liver against hypoxia–reoxygenation injury.

Introduction

Ischemia/reperfusion injury is a major determinant in many clinical conditions such as liver resection and liver transplantation. Hepatic pedicle clamping (Pringle's maneuver) is often used during liver surgery to reduce intraoperative bleeding. However, the resulting ischemia/reperfusion causes liver failure and contributes to high postoperative morbidity and mortality (Belghiti et al., 1999, Serracino-Inglott et al., 2001). Tissue injury occurs during the ischemic phase and much injury arises upon restoring the blood supply (reperfusion phase). Reperfusion of ischemic hepatic tissue initiates complex cellular events leading eventually to necrosis and apoptosis of liver cells (Kim et al., 2004, Nagai et al., 2007). Several lines of evidence indicate that oxidative stress with increased free radical generation and intense inflammatory reaction with increased production of proinflammatory cytokines play a crucial role in the pathogenesis of ischemia/reperfusion liver injury. Also, previous studies demonstrated that antioxidants and anti-inflammatory agents effectively protected against liver damage induced by ischemia/reperfusion (Kim et al., 2010, Subhas et al., 2010, Zhang et al., 2006).

Cannabidiol is the major non-psychoactive cannabinoid component derived from the plant Cannabis sativa. It possesses powerful antioxidant and anti-inflammatory activities. However, the exact mechanisms of action of cannabidiol remain obscure. In contrast to the other cannabinoids, cannabidiol is known to have a very low affinity for the cannabinoid CB₁ and CB₂ receptors. The antioxidant and anti-inflammatory effects of cannabidiol may be due to its direct action or mediated through a new abnormal cannabinoid, non-CB₁ and non-CB₂, receptor (Begg et al., 2005, De Petrocellis and Di Marzo, 2010). Cannabidiol may also exert its beneficial effects by inhibiting adenosine uptake and activating transient receptor potential vanilloid-1 (Bisogno et al., 2001, Carrier et al., 2006). Previous reports proved that cannabidiol may have therapeutic utility in a number of conditions involving inflammation and oxidative stress, including diabetes mellitus, rheumatoid arthritis and neurodegenerative disorders (Blake et al., 2006, Iuvone et al., 2009, Rajesh et al., 2010). The protective effect of cannabidiol was also demonstrated in animal models with cerebral and myocardial ischemia/reperfusion by attenuating the oxidative stress and inflammatory response (Alvarez et al., 2008, Durst et al., 2007, Hayakawa et al., 2009, Walsh et al., 2010). A recent study revealed that cannabidiol pretreatment significantly protected against liver ischemia for 60 min followed by reperfusion for 24 h (Mukhopadhyay et al., 2011).

Therefore, the present study was conducted to evaluate the therapeutic effect of cannabidiol given to rats 1 h after being exposed to liver ischemia, and every 24 h thereafter for 2 days. Also, the possible mechanisms underlying this therapeutic effect were investigated.