Modulation of cytochrome P450-dependent monooxygenases in streptozotocin-induced diabetic hamster: II. Reverse role of insulin in P450 activity and defluorination.
BACKGROUND
Metabolic activities of cytochrome (cyt) P450-dependent monooxygenase could be modulated by diabetic state in experimental diabetic animals. The purpose of this study is to validate the effect of insulin on the modulation of the metabolic activity of cyt P450 and the defluorination ability to inhalational anesthetics in diabetic animals.


METHODS
Diabetic state in golden Syrian hamsters was achieved by intraperitoneal injection of streptozotocin 40 mg/kg once a day for 4 days. After stabilization of diabetic state for 6 weeks, a regimen of insulin treatment given subcutaneously was carried out. Metabolic activities of cyt P450 were assessed by the reaction with benzo(a) pyrene, pentoxyresorufin, aniline and erythromycin (specific substrates). The metabolic activities of cyt 1A1, 2B1, 2E1 and 3A4 respectively in a NADPH-generating system in microsomal preparations of the diabetic hamsters were observed before and after insulin treatment, and were compared with the control group. The ability of defluorination was evaluated by measuring the free fluoride metabolites after incubating the microsomes with enflurane in diabetic and insulin-treated hamsters. Contents of cyt P450 isozymes were measured by electrophoresis and immunoblotting before and after insulin treatment. Pathological features of hepatocytes in diabetic hamsters were evaluated microscopically before and after insulin treatment.


RESULTS
The defluorination of enflurane and activity of aniline hydroxylase (cyt 2E1) were successfully induced by diabetic state (P < 0.01). The pentoxyresorufin O-dealkylase (cyt 2B1) was inhibited nearly 50% in the diabetic hamster liver when compared with that of control (P < 0.01). While the activities of benzo(a)pyrene hydroxylase (cyt 1A1) and the erythromycin N-demethylase (cyt 3A4) were basically unaffected by diabetes, alterations in content of cyt P450 were parallel to the alterations in enzyme activities. Microscopically, diabetes induced vacuolization with fatty droplets in the hepatocytes. After treatment with insulin injection, the enzyme activities, protein content and pathologic features returned to the baseline similar to the control.


CONCLUSIONS
Our data demonstrated that under diabetic state, metabolic activities of cyt P450 and its extent of defluorination would be polymorphically modulated. After administration of insulin, the activities of cyt P450 and defluorination of enflurane returned to baseline as the blood sugar level had been normalized. This could remind the clinicians of the importance of insulin treatment in the potential drug-to-drug interactions in the diabetic patients.
Chen
T G
TG
Department of Anesthesiology, Wan-Fang Hospital, Taiwan, R.O.C.
Tai
Y T
YT
Chang
H C
HC
Hong
C T
CT
Chen
R M
RM
Chen
T L
TL
D000818:Animals; D006224:Cricetinae; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004737:Enflurane / Q000378:metabolism*; D005461:Fluorine / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D007527:Isoenzymes / Q000378:metabolism; D008647:Mesocricetus; D013311:Streptozocin
D007328:Insulin; D007527:Isoenzymes; D005461:Fluorine; D013311:Streptozocin; D003577:Cytochrome P-450 Enzyme System; D004737:Enflurane