Cannabidiol Attenuates Palmitic Acid-Induced Injury in Cultured Hepatocytes Through Promoting Autophagic Flux

Objective: This work was designed to investigate the protection of cannabidiol (CBD) against palmitic acid (PA)-induced injury in cultured hepatocytes and the underlying mechanism associated with autophagic flux. Methods: Experiment 1: Primary cultured hepatocytes were stimulated with PA (800 μmol/L) and treated with CBD (5 μmol/L) and chloroquine (CQ, 50 nmol/L) or not for 24 hours (1: control group; 2: PA-stimulated group; 3: PA-stimulated group treated with CBD; 4: PA-stimulated group treated with CBD and CQ). Autophagic flux was evaluated by Western blot analysis. Apoptosis was measured by flow cytometry. The mRNA expression of genes involved in endoplasmic reticulum stress was determined by reverse transcription PCR. The mitochondrial function was determined by using fluorescent probe including Rh123 and lucigenin. Experiment 2: Primary cultured hepatocytes were treated with CBD alone for 24 h (1: control group; 2: lower-dose CBD-treated group; 3: higher-dose CBD-treated group). Then, the autophagic flux was evaluated by Western blot analysis. Results: When compared to control group, exposure to PA significantly led to impaired autopagic flux (evidenced by increased ratio of LC3-II/LC3-I and protein expression of p62), increased apoptosis, endoplasmic reticulum stress (evidenced by increased mRNA expression of C/EBP homologous protein, glucose-regulated protein 78, and X-box protein 1), and mitochondrial dysfunction (evidenced by reduced mitochondrial membrane potential and enhanced formation of mitochondrial reactive oxygen species). When compared to PA-stimulated group, CBD treatment significantly attenuated PA-induced impaired autophagic flux, apoptosis, endoplasmic reticulum stress, and mitochondrial dysfunction in cultured hepatocytes. The protection of CBD against PA was abolished by co-incubation with CQ. In addition, treatment with CBD alone had no significant effect on autophagic flux in cultured hepatocytes Conclusion: Cannabidiol attenuates palmitic acid-induced impaired autophagic flux, apoptosis, endoplasmic reticulum stress, and mitochondrial dysfunction in cultured hepatocytes through promoting autophagic flux.