Biochemical and histochemical properties of hepatic tumors of rainbow trout, Oncorhynchus mykiss.
Biochemical and histochemical studies were conducted in aflatoxin B1-induced liver tumors in adult rainbow trout. Specific activities of the phase I enzymes, ethoxyresorufin-O-deethylase (EROD), microsomal and cytosolic epoxide hydrolase (mEH and cEH), aldehyde dehydrogenase (ALDH) and DT-diaphorase, and the phase II enzymes, gamma-glutamyltransferase (gamma-GT), glutathione transferase (GST) and uridine diphosphoglucuronyl transferase (UDPGT) were measured. Cryostat sections of tumor and surrounding liver from the same cohorts were analyzed immunohistochemically for cytochrome P450IA1 and histochemically for ALDH (benzaldehyde and hexanal), DT-diaphorase, gamma-GT and uridine diphosphoglucuronyl dehydrogenase (UDPGdH). In tumor tissues, the largest biochemical changes were found with benzaldehyde dehydrogenase, where activity increased from undetectable levels to 7.4 nmol/min/mg protein, and gamma-GT, where activity increased 12-fold over controls. Increases in other enzymes ranged from 1.26 to 2.84 times that of control liver, except EROD, which decreased, and cEH and mEH, which were unchanged. Histochemical analyses showed the induction of ALDH, gamma-GT, DT-diaphorase and UDPGdH, and the depression of cytochrome P450IA1 in hepatic neoplasms. In addition, marker enzyme histochemistry of neoplasms revealed heterogeneous populations of hepatocytes and absence of necrotic areas.
Parker
L M
LM
Department of Medicine, School of Veterinary Medicine, University of California, Davis 95616.
Laurén
D J
DJ
Hammock
B D
BD
Winder
B
B
Hinton
D E
DE
D016604:Aflatoxin B1; D000444:Aldehyde Dehydrogenase / Q000378:metabolism; D000818:Animals; D019363:Cytochrome P-450 CYP1A1; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004195:Disease Models, Animal; D014453:Glucuronosyltransferase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D007150:Immunohistochemistry; D008099:Liver / Q000166:cytology / Q000201:enzymology; D008113:Liver Neoplasms / Q000139:chemically induced / Q000201:enzymology* / Q000473:pathology; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D014337:Trout / Q000378:metabolism*; D014533:Uridine Diphosphate Glucose Dehydrogenase / Q000378:metabolism; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D003577:Cytochrome P-450 Enzyme System; D016604:Aflatoxin B1; D010088:Oxidoreductases; D014533:Uridine Diphosphate Glucose Dehydrogenase; D019363:Cytochrome P-450 CYP1A1; D000444:Aldehyde Dehydrogenase; D016660:NAD(P)H Dehydrogenase (Quinone); D005723:gamma-Glutamyltransferase; D014453:Glucuronosyltransferase; D005982:Glutathione Transferase