Increased monoamine oxidase activity following repeated electroshock seizures

Abstract

W e H ave recently reported that chronic electroconvulsive seizures (ECS) lead to a long‐lasting increase (up to 6 weeks) in the activity of monoamine oxidase (MAO) in the brain of rats (P ryor and O tis , 1970). Other investigators have shown increased levels of norepinephrine (NE) and 5‐HT, more rapid clearance of intracisternally‐injected [ 3 H]HNE (K ety , J avoy , T hierry , J ulou and G lowinski , 1967), and increased tyrosine hydroxylase activity (M usacchio , J ulou , K ety and G lowinski , 1969) at 24 h after a series of two ECS daily for 7 days. Together, these data suggest a sustained activation of the 5‐HT and/or NE systems following chronic ECS. We now report the results of a series of experiments in which some of the potential variables that may be involved in the MAO response were investigated and that indicate some biochemical specificity of the response. In these experiments, succinate dehydrogenase (SDH) activity was also assayed to assess possible nonspecific effects of repeated seizures on mitochondrial metabolism and catechol O ‐methyltransferase (COMT) activity was determined to see if this extracellular degradative enzyme for NE was affected in the same way as MAO located intracellularly in the mitochondria.