Both inorganic and organic selenium supplements can decrease brain monoamine oxidase B enzyme activity in adult rats.

It has been observed that the levels of brain monoamine oxidase B (MAO-B) increase during ageing. MAO catalyses the oxidative deamination of neurotransmitters, in which the by-product H2O2 is subsequently generated. Se exists naturally in inorganic and organic forms and is considered to play a key role in antioxidation functioning. The objective of the present study was to investigate two chemical forms of Se compounds for their inhibition effect on rat brain MAO-B. The total antioxidant capacity and lipid peroxidation of rats were also examined. The rats (age 7 weeks) were divided into four groups: the control group, tocopherol group (T group, positive control), selenite group (SE group, representing the inorganic Se group) and seleno-yeast group (SY group, representing the organic Se group). The rats were fed for 11 weeks with normal diets and 12 weeks with test diets. The serum total antioxidant capacity of the SE and SY groups was significantly higher than that in the control and T groups. In rat brains and livers, the lipid peroxidation levels were significantly decreased in the T, SE and SY groups. MAO-B activity showed a significant decrease in the T, SE and SY groups in rat brains but no significant change could be noted in the rat livers. In conclusion, the present study indicates that inorganic or organic Se supplementation can decrease the brain MAO-B enzyme activity in adult rats and can be accomplished by the effect of the Se antioxidation capability.