[Comparative study of the effect of vitamin B12 coenzymes on monooxygenase system and lipid peroxidation in the liver of rabbits poisoned with phenylhydrazine].

Distinct activation of lipid peroxidation, reduction in N-demethylation of dimethyl aniline and in NADPH-dependent electron transport chain were observed in liver microsomes of rabbits poisoned with phenyl hydrazine. Methylcobalamine and adenosyl-cobalamine, two coenzyme forms of vitamin B12, were firstly shown to serve as modulators of the monooxygenase system, whereas methyl-cobalamine proved to be inductor and adenosylcobalamine-repressor of the system. Administration of methylcobalamine into the poisoned rabbits stimulated much higher the activities of dimethyl aniline N-demethylase, aniline p-hydroxylase, NADPH-cytochrome P-450- and NODH-cytochrome b5 reductases as compared with normal state, while adenosylcobalamine inhibited the reduction of all the monooxygenase system patterns studied. At the same time, both these coenzymes contributed to normalization of lipid peroxidation in liver microsomes of poisoned rabbits.