Toxicological Sciences, Vol 51, 36-43, Copyright © 1999 by Society of Toxicology
F Waechter, P Beilstein, AG Burger, M O'Connell, C Fabreguettes, R Forster and H Weideli
To evaluate the toxicological profile of the phenolic antioxidant
ethylene-bis-(oxyethylene)-bis-(3-tert-butyl-4-hydroxy-5-methyl-
hydrocinnamate) (EOC) in a non-human primate, male cynomolgus monkeys
(Macaca fascicularis) were treated for 4 weeks by oral administration of 0,
200, or 1000 mg/kg body weight/day. Special attention was directed to
parameters of the pituitary-thyroid-liver axis. Moderately increased liver
weights and minimal to moderate hepatocellular hypertrophy were observed in
treated animals. Otherwise, no treatment- related changes were detected in
hematological, clinical chemistry, or urinalysis parameters or upon
histopathological examination. Except for a slight induction of microsomal
testosterone 16beta-hydroxylation, liver xenobiotic-metabolising enzyme
activities and peroxisomal fatty acid beta-oxidation remained unchanged.
Likewise, serum levels of thyroid stimulating hormone, thyroxine,
3,3',5-triiodothyronine and 3,3',5'-triiodothyronine as well as
5'-monodeiodinase type 1 mRNA levels in the liver, heart, cerebral cortex,
and thyroid were found unchanged. The results demonstrate that, in the
Cynomolgus monkey, EOC is only a very weak inducer of liver
xenobiotic-metabolizing enzymes and has no effect on thyroid function. In
contrast, upon feeding rats at dose levels up to 1000 ppm (equivalent to
between 50 and 100 mg/kg body weight/day), EOC has been identified as a
strong phenobarbital- and peroxisome proliferator-type inducer of hepatic
xenobiotic- metabolizing enzymes, interfering with thyroid hormone
homeostasis, causing thyroid follicular hypertrophy, and, upon chronic
treatment, inducing thyroid gland follicular cell tumors (Thomas et al.,
1995. In Toxicology of Industrial Compounds, pp. 319-339. Taylor and
Francis). Thus, the results of this study with EOC in the cynomolgus monkey
show that effects of xenobiotics on the pituitary-thyroid-liver axis as
frequently observed in rodents can not necessarily be extrapolated to
primates including man.
ARTICLES
Subchronic toxicity study with ethylene-bis-(oxyethylene)-bis-(3-tert- butyl-4-hydroxy-5-methylhydro cin namate) in the cynomolgus monkey: lack of stimulation of the pituitary-thyroid-liver axis
Novartis Crop Protection AG, Toxicology, Basel, Switzerland. felix.waechter@cp.novartis.com
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