title: Comparison of the effects of Wyeth-14,643 in Crl:CD BR and Fisher-344 rats.
abstract: Wyeth-14,643 (WY) belongs to a diverse class of compounds which have been shown to produce hepatic peroxisome proliferation and hepatocellular carcinoma in rodents. Based on a review of bioassay data, a relationship appears to exist between peroxisome proliferating compounds and Leydig cell adenoma formation. Most rat bioassays with peroxisome proliferators have been conducted in the Fisher-344 (F344) rat, which has a high spontaneous incidence of Leydig cell adenomas. Thus, it was necessary to use an alternative animal model to investigate this relationship further. Therefore the Crl:CD BR (CD) rat, which has a low spontaneous Leydig cell adenoma incidence, was chosen for a 2-year feeding study with WY. Before initiating this 2-year feeding study, it was necessary to investigate whether any strain differences existed between CD and F344 rats with respect to WY-induced peroxisome and cell proliferation. In this study, male CD and F344 rats were fed diets containing 0, 50, or 1000 ppm WY for 21 days. Peroxisome proliferation in the liver and testis was determined biochemically by measuring beta-oxidation activity and was confirmed ultrastructurally. Serum hormone levels and cell proliferation rates in the liver and testis were also measured. In addition, basal beta-oxidation activity and cell proliferation rates were compared between the CD and F344 rats. A significant decrease in final body weight was observed in the 1000 ppm WY groups for both CD and F344 rats.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Haskell Laboratory for Toxicology and Industrial Medicine, E. I. du Pont de Nemours & Company, Newark, Delaware 19714.
authors.forename: L B
authors.initials: LB
authors.lastname: Biegel
authors.forename: M E
authors.initials: ME
authors.lastname: Hurtt
authors.forename: S R
authors.initials: SR
authors.lastname: Frame
authors.forename: M
authors.initials: M
authors.lastname: Applegate
authors.forename: J C
authors.initials: JC
authors.lastname: O'Connor
authors.forename: J C
authors.initials: JC
authors.lastname: Cook
mesh_terms: D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D001835:Body Weight / Q000187:drug effects; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008830:Microbodies / Q000187:drug effects; D009929:Organ Size / Q000187:drug effects; D010084:Oxidation-Reduction; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D011919:Rats, Inbred Strains; D013045:Species Specificity
chemical_list: D000924:Anticholesteremic Agents; D011743:Pyrimidines; C006253:pirinixic acid