Linked Life Data

10959800

Source:http://linkedlifedata.com/resource/pubmed/id/10959800

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4-5
pubmed:dateCreated
2000-12-1
pubmed:abstractText
The hepatoproliferative and cytochrome P450 enzyme inducing effects of two antiestrogens, tamoxifen and toremifene, were compared in female Sprague-Dawley rats using immunohistochemical staining methods. Equimolar doses of the antiestrogens (tamoxifen 45 mg/kg and toremifene 48 mg/kg) were given by oral administration to 6-week-old rats for 12 months including a 3-month recovery period. Controls received the vehicle carboxymethylcellulose. Altogether 90 rats were used in the study. Five rats per dose group were killed after 14 days, 5 weeks, 3, 6 and 12 months of treatment as well as after the 3-month recovery period. Hepatocellular carcinoma was found in four out of five rats after 12 months of tamoxifen treatment. After the 3-month recovery period all tamoxifen-treated rats had large liver tumors (diameter up to 3 cm). No tumors were observed in toremifene-treated rats. Liver cell proliferation was measured by the index of proliferating cell nuclear antigen (PCNA) expression. Immunohistochemical staining with the placental form of glutathione S-transferase (GST-P) was used as a marker for preneoplastic foci. Cytochrome P450 induction was measured using specific antibodies to isoenzymes. Tamoxifen increased the incidence of GST-P-positive foci significantly by 3 months of treatment but toremifene did not as compared with the controls. Liver cell proliferation increased significantly only in the liver tumors of tamoxifen-treated rats after 12 months of treatment and during the recovery period. Both antiestrogens induced the isoenzymes CYP2B1/2 and CYP3A1 within 14 days although tamoxifen was a more powerful inducer. Immunohistochemistry of rat liver sections showed a centrilobular localization of these induced enzyme proteins. The expression of CYP2B1/2 and 3A1 could also be observed in foci after 3 and 6 months of administration and in liver adenomas and in some carcinomas after 12 months of administration with tamoxifen. The results show that tamoxifen, but not toremifene, has the potential to induce and promote the development of rat hepatocarcinogenesis in this experimental model.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0340-5761
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
249-56
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed-meshheading:10959800-Animals, pubmed-meshheading:10959800-Aryl Hydrocarbon Hydroxylases, pubmed-meshheading:10959800-Body Weight, pubmed-meshheading:10959800-Cell Division, pubmed-meshheading:10959800-Cytochrome P-450 CYP3A, pubmed-meshheading:10959800-Cytochrome P-450 Enzyme System, pubmed-meshheading:10959800-Enzyme Induction, pubmed-meshheading:10959800-Estrogen Receptor Modulators, pubmed-meshheading:10959800-Female, pubmed-meshheading:10959800-Glutathione Transferase, pubmed-meshheading:10959800-Immunohistochemistry, pubmed-meshheading:10959800-Isoenzymes, pubmed-meshheading:10959800-Liver Neoplasms, Experimental, pubmed-meshheading:10959800-Precancerous Conditions, pubmed-meshheading:10959800-Proliferating Cell Nuclear Antigen, pubmed-meshheading:10959800-Rats, pubmed-meshheading:10959800-Rats, Sprague-Dawley, pubmed-meshheading:10959800-Tamoxifen, pubmed-meshheading:10959800-Toremifene
pubmed:year
2000
pubmed:articleTitle
Comparison of the effects of tamoxifen and toremifene on rat hepatocarcinogenesis.
pubmed:affiliation
Department of Pathology, University of Turku, BioCity, Finland.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't