Intraperitoneal injection of D-galactosamine provides a potent cell proliferation stimulus for the detection of initiation activities of chemicals in rat liver.
In an in vivo 5-week initiation assay model, chemical hepatectomy by hepato-toxicant administration was utilized as a cell proliferation stimulus as an alternative to the two-thirds partial hepatectomy. The study investigated the effect of an intraperitoneal (i.p.) injection of D-galactosamine (D-gal) for this purpose in a medium-term liver bioassay, with a further focus on cell proliferation kinetics and cytochrome P450 (CYP) expression. In experiment I, cell proliferation in rat liver after a single administration of D-gal (700 mg kg(-1), i.p.) was analysed by the bromodeoxyuridine (BrdU) labeling method, and CYP isozymes were quantified by immunoblotting. In experiment II, the induction of glutathione S-transferase placental form (GST-P) positive foci by 1,2-dimethylhydrazine (DMH) was evaluated in a modified in vivo 5-week initiation assay model. At 84 hours after single administration of d-gal (i.p.) the BrdU index was markedly elevated (27.5% +/- 9.5%). Although CYP 2E1 and 1A2 apoprotein contents decreased transiently to less than 20% of the control level, subsequently they recovered to 60% and 40% of the control level, respectively, at 84 hours. Induction of GST-P positive foci in the group given DMH at 84 hours after a single administration of d-gal was significantly greater than in the control group, correlating with the kinetics of cell proliferation. In conclusion, the sensitivity of the present initiation assay using D-gal i.p. is high, so that D-gal i.p. can be considered an effective cell proliferation stimulus.
Asaoka
Yoshiji
Y
Department of Veterinary Pathology, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan.
Sakai
Hiroki
H
Takahashi
Naofumi
N
Hirata
Akihiro
A
Tsukamoto
Tetsuya
T
Yamamoto
Masami
M
Yanai
Tokuma
T
Masegi
Toshiaki
T
Tatematsu
Masae
M
D019813:1,2-Dimethylhydrazine / Q000008:administration & dosage / Q000633:toxicity*; D000818:Animals; D015197:Carcinogenicity Tests; D049109:Cell Proliferation / Q000187:drug effects; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003580:Cytochromes; D004357:Drug Synergism; D004790:Enzyme Induction; D005688:Galactosamine / Q000008:administration & dosage / Q000633:toxicity*; D005982:Glutathione Transferase / Q000096:biosynthesis*; D007150:Immunohistochemistry; D007274:Injections, Intraperitoneal; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D008297:Male; D011230:Precancerous Conditions / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344
D003580:Cytochromes; D005688:Galactosamine; D003577:Cytochrome P-450 Enzyme System; D019392:Cytochrome P-450 CYP2E1; C017170:Cyp1a2 protein, rat; D019388:Cytochrome P-450 CYP1A2; D005982:Glutathione Transferase; D019813:1,2-Dimethylhydrazine