Activities of monoamine oxidase (MAO) A and B in discrete regions of rat brain after rapid eye movement (REM) sleep deprivation

Rapid eye movement (REM) sleep deprivation increases monoaminergic (noradrenergic and serotonergic) turnover and their metabolites in whole brain of rats. This increase in metabolites may indicate increased activity of the enzymes responsible for the inactivation of monoamines. To test this hypothesis, we assayed the activity of monoamineoxidases (MAOs) A and B in hippocampus, hypothalamus, brainstem and its divisions pens and medulla oblongata in rats deprived of REM sleep for 96h. REM sleep deprivation was carried out by the newer-pot technique. A control 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 concentration). the enzymes were assayed in the mitochondrial fraction. the results obtained showed that a significant decrease in the activity of MAO A was obtained in the brainstem and an increase in medulla oblongata and no statistical differences in the activity of MAO B in brainstem, pens and medulla oblongata and MAO Pr in pons; there were also no differences in the activities of both MAO A and B in hippocampus and hypothalamus. Although our results confirmed previous data regarding changes in MAO A activity in brainstem and medulla oblongata, they did not confirm our hypothesis that the increase in monamine turnover and metabolites in the brain would be the result of increased MAO activity. (C) 1997 Elsevier Science Inc.Universidade Federal de São Paulo,ESCOLA PAULISTA MED,DEPT PSYCHOBIOL,BR-04023062 São Paulo,BRAZILUniversidade Federal de São Paulo,ESCOLA PAULISTA MED,DEPT PSYCHOBIOL,BR-04023062 São Paulo,BRAZILWeb of Scienc