No abstract

SummaryThe effects of chronic treatment with oxprenolol (CAS 6452-72-7) (OXP, 15 mg/ kg/day), or glibenclamide (CAS 10238-21-8) (GL, 2.5 mg/kg/day), or their combination administered for 6 and 12 weeks, on the butyrylcholinesterase (BuChE) activity in plasma and liver and on the plasma levels of triglycerides, total cholesterol and high density lipoprotein (HDL)-cholesterol were studied in normal, non-diabetic female rats. In all treated groups a significant increase of plasma BuChE activity was obtained after 6 weeks of either OXP (46%), or GL (36%) treatment, or of their concurrent application (24%). After 12 weeks of treatment, the increase in enzyme activity was significant only in the OXP group. The BuChE activity in the liver was increased (between 3-25%) in all treated groups except in one during 6 and 12 weeks of treatment. These effects of either OXP or GL, or their combination on BuChE activity in liver suggest their stimulating effects on enzyme synthesis. The changes of total plasma cholesterol in all groups were insignificant. On the other hand, HDLcholesterol was significantly decreased in all treated groups. After 6 weeks of treatment, GL, OXP, or their combination caused a decrease in plasma HDL cholesterol by 19, 50 or 22% respectively, when compared with the control group.After 12 weeks of GL, OXP, or GL+OXP administration, HDL-cholesterol plasma levels in treated groups were 32, 25 and 22% lower than in the control group.Treatment with GL, OXP, or GL+OXP during 6 weeks had no significant effect on triglycerides level. However, after 12 weeks of GL, OXP, or GL+OXP administration, the triglycerides levels were significantly increased (9, 47 and 36%) when compared with the control group. These results have shown, that the increase in BuChE activity might be the first sign of altered triglyceride and lipoprotein metabolism.3

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 5 pancreatic, membrane bound enzymes in female Fisher rats that were given low oral doses of ochratoxin A (120 Mg/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-Ca 2+ /Mg 2 " l "-ATPase, γ-glutamyl transferase and ecto-5 f -nucleotidase. Treatment lasting 20 days caused a strong decrease in the activity of alanine aminopeptidase, Ca 2H~/ 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 γ-glutamyl transferase and 5 1nucleotidase 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 Ca 2+ /Mg 2 " H -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.