title: Ochratoxin A impairs activity of the membrane bound enzymes in rat pancreas.
abstract: Ochratoxin A is a mycotoxin produced by Aspergillus ochraceus and is a natural contaminant of moldly food. Ochratoxin A has a number of toxic effects, some of which may be related to the changes in the cell membrane. We measured the activities of 5 pancreatic, membrane bound enzymes in female Fisher rats that were given low oral doses of ochratoxin A (120 micrograms/kg body weight per day) during 20-35 days. The amount of toxin corresponds to 1.5 mg/kg in the feed, daily. These doses are in the range of natural contamination found in feed. The enzymes studied were alanine aminopeptidase, alkaline phosphatase, ecto-Ca2+/Mg(2+)-ATPase, gamma-glutamyl transferase and ecto-5'-nucleotidase. Treatment lasting 20 days caused a strong decrease in the activity of alanine aminopeptidase, Ca2+/Mg(2+)-ATPase and alkaline phosphatase to 0.76 +/- 0.04, 0.53 +/- 0.03 and 0.30 +/- 0.02 of the control values, respectively (p < 0.05). No significant changes in the activity of gamma-glutamyl transferase and 5'-nucleotidase were observed. However, activity of alanine aminopeptidase returned to normal values after 35 days of treatment, suggesting an adaptation of the organism, or a substitution of a released enzyme. Activities of alkaline phosphatase and Ca2+/Mg(2+)-ATPase remained significantly reduced to 0.42 +/- 0.03 and 0.52 +/- 0.04, respectively (p < 0.01). We conclude that treatment of rats with low doses of ochratoxin A resulted in reduction of the activities of the membrane bound enzymes, most probably by inducing their release, as a result of the impairment of the functional integrity of cell membranes.
authors.affiliation: Department of Medical Biochemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb, Croatia.
authors.forename: T
authors.initials: T
authors.lastname: Zanić-Grubisić
authors.forename: R
authors.initials: R
authors.lastname: Zrinski
authors.forename: I
authors.initials: I
authors.lastname: Cepelak
authors.forename: J
authors.initials: J
authors.lastname: Petrik
authors.forename: S
authors.initials: S
authors.lastname: Pepeljnjak
mesh_terms: D015720:5'-Nucleotidase / Q000187:drug effects / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D018826:CD13 Antigens / Q000187:drug effects / Q000378:metabolism; D017301:Ca(2+) Mg(2+)-ATPase / Q000187:drug effects / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D005260:Female; D008051:Lipid Bilayers / Q000378:metabolism; D009183:Mycotoxins / Q000633:toxicity*; D009793:Ochratoxins / Q000633:toxicity*; D010179:Pancreas / Q000187:drug effects* / Q000201:enzymology*; D051381:Rats; D011916:Rats, Inbred F344; D005723:gamma-Glutamyltransferase / Q000187:drug effects / Q000378:metabolism
chemical_list: D008051:Lipid Bilayers; D009183:Mycotoxins; D009793:Ochratoxins; C025589:ochratoxin A; D005723:gamma-Glutamyltransferase; D000469:Alkaline Phosphatase; D015720:5'-Nucleotidase; D018826:CD13 Antigens; D017301:Ca(2+) Mg(2+)-ATPase