Re-evaluation of tacrine hepatotoxicity using gel entrapped hepatocytes

• Published in: Toxicology letters Vol. 168; no. 2; pp. 140 - 147
• Main Authors: Meng, Qin, Ru, Jianghua, Zhang, Guoliang, Shen, Chong, Schmitmeier, Stephanie, Bader, Augustinus
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 30.01.2007; Amsterdam Elsevier Science
• Subjects: Albumins - biosynthesis; Animals; Antidepressive Agents, Second-Generation - pharmacology; Biological and medical sciences; Cell Survival - drug effects; Cells, Cultured; Chemical and Drug Induced Liver Injury - pathology; Cholinesterase Inhibitors - toxicity; CYP 1A2; Cytochrome P-450 CYP1A2 - metabolism; Female; Fluvoxamine - pharmacology; Gel entrapment; Gels; Glutathione - metabolism; Glyceraldehyde-3-Phosphate Dehydrogenases - metabolism; Glycyrrhetinic Acid - pharmacology; Hepatocytes; Hepatocytes - drug effects; Hepatocytes - pathology; Hepatotoxicity; Hollow fibers; Medical sciences; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; Tacrine; Tacrine - toxicity; Tetrazolium Salts; Thiazoles; Toxicology; Hollow fibers; CYP 1A2; Hepatocytes; Hepatotoxicity; Gel entrapment; Tacrine; Evaluation; Digestive system; Enzyme; Toxicity; Enzyme inhibitor; Hepatic disease; Esterases; Antialzheimer agent; Acetylcholinesterase; Carboxylic ester hydrolases; Colloidal gel; Hepatocyte; Hollow fiber; Digestive diseases; Hydrolases; Anticholinesterase agent; Antidote
• ISSN: 0378-4274; 1879-3169
• DOI: 10.1016/j.toxlet.2006.11.009

Controversial results about the involvement of CYP 1A2 and oxidative stress in tacrine-induced hepatotoxicity have been described by the different research groups. We suggested that different expression levels of CYP 1A2 in cell lines and primary hepatocytes in vitro may be the cause of the controversial results above. Therefore, this paper re-evaluated the toxicity of tacrine by using gel entrapment culture of rat hepatocytes. The toxic effect of tacrine on hepatocytes was assayed by the reduction of methyl thiazolyl tetrazolium (MTT) and intracellular glutathione (GSH), as well as by albumin synthesis. It was found that the detectable hepatotoxic dose of tacrine is much lower in hepatocytes entrapped in gel than in those in monolayer cultures. The fact that fluvoxamine, a potent cytochrome P450 (CYP) 1A2 inhibitor, reduced tacrine toxicity and the expression of the CYP 1A2 gene was maintained in gel entrapped hepatocytes, but not in hepatocyte monolayers, could illustrate a close association between CYP 1A2 expression levels and tacrine toxicity. Glycyrrhetinic acid (GA), a free radical scavenger, protected gel entrapped hepatocytes from tacrine toxicity, but was ineffective in hepatocyte monolayers. Hence, gel entrapped hepatocytes could reflect higher tacrine hepatotoxicity in vivo than hepatocyte monolayers.