ACTIVITIES OF MONOAMINE-OXIDASE (MAO)-A AND (MAO)-B IN DISCRETE REGIONS OF RAT-BRAIN AFTER RAPID EYE-MOVEMENT (REM) SLEEP-DEPRIVATION

Rapid eye movement (REM) sleep deprivation increases monoaminergic (no radrenergic and serotonergic) turnover and their metabolites in whole brain of rats. This increase in metabolites may indicate increased act ivity of the enzymes responsible for the inactivation of monoamines. T o test this hypothesis, we assayed the activity of monoamineoxidases ( MAOs) A and B in hippocampus, hypothalamus, brainstem and its division s pens and medulla oblongata in rats deprived of REM sleep for 96h. RE M sleep deprivation was carried out by the newer-pot technique. A cont rol group remained in their home cages. MAO A was assayed by using [C- 14]-5-hydroxytryptamine as the substrate (50 mu M final concentration) and MAO B by using [C-14]-beta-phenylethylamine (2 mu M final concent ration). The enzymes were assayed in the mitochondrial fraction. The r esults obtained showed that a significant decrease in the activity of MAO A was obtained in the brainstem and an increase in medulla oblonga ta and no statistical differences in the activity of MAO B in brainste m, pens and medulla oblongata and MAO Pr in pons; there were also no d ifferences in the activities of both MAO A and B in hippocampus and hy pothalamus. Although our results confirmed previous data regarding cha nges in MAO A activity in brainstem and medulla oblongata, they did no t confirm our hypothesis that the increase in monamine turnover and me tabolites in the brain would be the result of increased MAO activity. (C) 1997 Elsevier Science Inc.