engleski

Ochratoxin A Impairs Activity of the Membrane Bound Enzymes in Rat Pancreas

Ochratoxin A is a mycotoxin produced by Aspergillus ochraceus and is a natural contaminant of moldy 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 pancreatic, membrane bound enzymes in female Fisher rats that were given low oral doses of ochratoxin A (120 &#61549 ; g/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 aminopepetidase, alkaline phosphatase, ecto-Ca2+/Mg2+-ATPase, &#61543 ; -glutamyl transferase and ecto-5-nucleotidase. Treatment lasting 20 days caused a strong decrease in the activity of alanine aminopeptidase, Ca2+/mg2+-ATPase and alkaline phosphatase to 0.76+0.04, 0.53+0.03 and 0.30+0.02 of teh control values, respectively (p<0.05). No significant changes in the activity of &#61543 ; -glutamyl transferase and 5-nucleotidase were observed. How ever, 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 alkalne phosphatase and Ca2+/Mg2+ATP-ase 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.

Ochratoxin A; membrane bound enzymes; rat pancreas

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