[Effect of short-term hypothermia on the monoamine oxidase system in the rat brain].

Concentrations of serotonin and of its metabolite 5-hydroxyindolyl acetic acid (5-HIAA) were shown to increase in rat brain stem after short-term hypothermia. At the same time, no distinct alterations could be found in the activity and kinetic parameters of the brain monoamine oxidase enzymatic system (MAO) catalyzing oxidative deamination of serotonin. Reduction of body temperature was accompanied by an increase in the MAO activity with serotonin as a substrate due to elevation in the enzyme-substrate affinity. Complete restoration of serotonin metabolism occurred within several days.