Catechol‐O‐methyl transferase and monoamine oxidase activities in brains of mice susceptible and resistant to audiogenic seizures

Abstract

The activities of catechol-O-methyl transferase (COMT), monoamine oxidase (MAO), and a methanol forming enzyme were studied in whole brain homogenates and in livers obtained from DBA/2J, C57B1/6J, and F1 hybrid mice. DBA/2J mice are extremely susceptible to audiogenic seizures, whereas C57B1/6J mice are resistant to sound-induced convulsions. C57B1/6J mice were found to have significantly higher brain levels of COMT, while MAO activities were not different in animals of these genotypes. No methanol forming activity was detected in animals of either strain. No differences were found in hepatic activities of either COMT or MAO. Pyrogallol was shown to protect DBA/2J animals against audiogenic seizures.

Differences in activity in cerebral methyltransferases and monoamine oxidases between audiogenic seizure susceptible and resistant mice and deermice

“…The DBA/2J animals exhibited significantly lower COMT values than the C57B1/6J mice at both 21 and 70 days, confirming the work of Schlesinger et al. [18]; there was, however, no significant difference in the DBA/2J mice at 21 vs 70 days. Table 3 shows that MAO, type B (substrate phenylethylamine) was also significantly lower in the brains of the 21-day old SS DBA/2J mice when compared to either 21-day old SR C57B1/6J or 70-day old SR DBA/2J animals.…”

“…Table 3 also shows a difference in the specific activity of MAO, type A between 21-and 70-day old DBA/2J mice. This observation is to be compared to the findings of Schlesinger et al [18] who reported no difference in the activity of cerebral 5-hydroxytryptamine-preferring (MAO, type A) enzyme between C57BI/6J and DBA/2J mice and of Kellogg [6] who described significantly higher MAO, type A values in 21-day old SR C57B1/6J mice relative to DBA/2J SS mice of the same age. 75.55 _+ 0.45 (8) *nmoles product/hr/mg of protein of mean _+ SEM.…”

Seizure proneness and neurotransmitter uptake

“…Several neurotransmitter-related enzymes have been found to have differing levels in these strains of mice (5)(6)(7). A relation between seizure susceptibility and reduced levels of monoamine transmitters has been proposed (5,8), but changes in cholinergic system enzymes have also been suggested as the underlying cause of audiogenic seizure sensitivity (9,10).…”