DECREASED ACTIVITY OF STRIATAL MONOAMINE-OXIDASE-B AFTER RAPID-EYE-MOVEMENT (REM) SLEEP-DEPRIVATION IN RATS

The striatum seems to be the main brain region involved in stereotyped behavior induced by dopaminergic agonists. Rapid eye movement (REM) s leep deprivation increases dopaminergic agonist-induced stereotypy and produces biochemical changes in striatal dopaminergic neurotransmissi on. However, the mechanism underlying the increased dopaminergic sensi tivity induced by REM sleep deprivation has not been elucidated. In an attempt to determine some of the biochemical changes in striatal dopa minergic neurotransmission that could contribute to REM sleep deprivat ion effects, we measured the activity of monoamine oxidase (MAO) A and B, the enzymes responsible for dopamine and beta-phenylethylamine (be ta-PEA) deamination in striatum. Male adult rats were deprived of REM sleep for 96 h by the newer-pot technique. MAO A and B were assayed ra dioisotopically in the mitochondrial fraction by standard laboratory p rocedures, using [C-14]-5-hydroxytryptamine (5-MT) and [C-14]-beta-phe nylethylamine (beta-PEA), as substrates for MAO A and MAO B, respectiv ely. The results showed no significant statistical differences in stri atal MAO A activity, whereas a significant decrease in MAO B activity was observed. The results are discussed in terms of the possible invol vement of beta-PEA, a striatal endogenous trace amine, which potentiat es dopaminergic neurotransmission and may participate in the increased dopaminergic sensitivity observed after REM sleep deprivation. (C) 19 98 Elsevier Science Inc.