Immunohistochemical analysis of expressions of hepatic cytochrome P450 in F344 rats following oral treatment with kava extract

• Published in: Experimental and toxicologic pathology : official journal of the Gesellschaft für Toxikologische Pathologie Vol. 58; no. 4; pp. 223 - 236
• Main Authors: Clayton, Natasha P., Yoshizawa, Katsuhiko, Kissling, Grace E., Burka, Leo T., Chan, Po-Chuen, Nyska, Abraham
• Format: Journal Article
• Language: English
• Published: Jena Elsevier GmbH 01.01.2007; Elsevier
• Subjects: Administration, Oral; Animals; Biological and medical sciences; Blood Glucose - drug effects; Cholesterol - blood; Cytochrome P-450 Enzyme System - drug effects; Cytochrome P-450 Enzyme System - metabolism; Cytochrome P450; Dietary Supplements - toxicity; Dose-Response Relationship, Drug; F344 rat; Female; gamma-Glutamyltransferase - blood; gamma-Glutamyltransferase - drug effects; Hepatocellular hypertrophy; Herb; Hypertrophy - chemically induced; Immunohistochemistry; Investigative techniques, diagnostic techniques (general aspects); Kava; Kava - toxicity; Liver - drug effects; Liver - enzymology; Liver - pathology; Liver Function Tests; Male; Medical sciences; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Piper methysticum; Rats; Rats, Inbred F344; Kava; Piper methysticum; F344 rat; Cytochrome P450; Hepatocellular hypertrophy; Herb; Immunohistochemistry; Rat; Digestive system; Liver; Rodentia; Oral administration; Piperaceae; Extract; Vertebrata; Anatomic pathology; Mammalia; Dicotyledones; Animal; Angiospermae; Spermatophyta; Hypertrophy
• ISSN: 0940-2993; 1618-1433
• DOI: 10.1016/j.etp.2006.08.002

Kava ( Piper methysticum), used for relaxation and pain relief, has been one of the leading dietary supplements and several reports linking hepatic functional disturbances and liver failure to kava have resulted in a ban on sales in Europe and Canada and the issuance of warnings by the US FDA. The National Toxicology Program conducted 14-week rat studies to characterize the toxicology of kava exposure in Fischer 344 rats [National Toxicity Program. 90 day gavage toxicity studies of KAVA KAVA EXTRACT in Fischer rats and B6C3F1 mice. Research Triangle Park, NC; 2005a; National Toxicity Program. Testing status of agents at NTP (KAVA KAVA EXTRACT M990058). Research Triangle Park, NC; 2005b. ( http://ntp.niehs.nih.gov/index.cfm?objectid=071516E-C6E1-7AAA-C90C751E23D14C1B)]. Groups of 10 male and 10 female rats were administered kava extract by gavage at 0, 0.125, 0.25, 0.5, 1.0, and 2.0 g/kg/day. Increased γ-glutamyl-transpeptidase (GGT) activities were observed in the 2.0 g/kg males and 1.0 and 2.0 g/kg females, as well as increased serum cholesterol levels in males and females at 0.5 g/kg and higher. Increases in incidence and severity of hepatocellular hypertrophy (HP) were noted in males at 1.0 g/kg and females at 0.5 g/kg and higher, as well as increased liver weights. Immunohistochemical analyses of the expression of cytochrome-P450 (CYP) enzymes in liver of the control and 1.0- and 2.0-g/kg-treated groups indicated decreased expression of CYP2D1 (human CYP2D6 homolog) in 2.0 g/kg females and increased expression of CYP1A2, 2B1, and 3A1 in 1.0 and 2.0 g/kg groups of both sexes. The no observed adverse effect levels were decided as 0.25 g/kg in both genders, based on neurotoxic effects, increases in GGT, cholesterol, liver weight, and HP and decreases in body weight. Kava-induced hepatic functional changes in the F344 rat might be relevant to human clinical cases of hepatotoxicity following exposure.