Clinical observations on iproniazid in idiots with epilepsy

In contradistinction to the observation made before that iproniazid has a potentiating effect on certain amines in guinea pigs, human studies have shown that this effect has very little clinical importance, when both the amines and the amine oxidase inhibitor are given in the usual therapeutic doses. However, neither in man nor in the guinea pig pretreatment with iproniazid showed a potentiating effect on amines which are not substrates of monoamine oxidase (ephedrine and amphetamine). Patients with epilepsy and allergic disease may receive iproniazid.

The inhibition of amine oxidase and the central stimulating action of the stereoisomeric amphetamines and 1-phenylethylamines

The stereoisomers of amphetamine and 1-phenylethylamine have been studied in the rat both as central stimulants and as inhibitors of amine oxidase from brain, liver, and kidney. There was no correlation between these two effects; thus it is unlikely that the central stimulating action of amphetamine is due to inhibition of amine oxidase.

Monoamine oxidase, thyroid activity and hyperglycaemia in the frog

1. Estimations of monoamine oxidase (m.o.) activity in suspensions of frog liver taken at monthly intervals showed that activity was relatively constant during the greater part of the year (mean value 8·6 ± 0·332 μl. O2/15 min/mg colloid nitrogen), but it rose to a significantly higher level from August to November inclusive (mean 11·7 ± 0·513 μl. O2/15 min/mg colloid nitrogen).

2. The pattern of seasonal variation in enzyme activity showed no correspondence with the annual cycle of change in the thyroid gland, nor was there any correlation between m.o. activity of the liver and the histological appearance of the thyroid in individual frogs.

3. Inhibition of m.o. in vivo by iproniazid elicited a hyperglycaemic response to excitement in previously unresponsive frogs which was almost identical with that obtained after treatment with thyroxine and iproniazid.

4. There was no evidence that treatment with thyroxine led to any alteration in the activity of liver m.o.

5. It is concluded that m.o. is not an important factor in the inactivation of catechol amines in the strongly stimulated frog, but the possibility is discussed that under natural conditions of lower stress the high enzyme activity from August to November might be one factor tending to limit mobilization of liver glycogen.

Monoamine Oxidase, Psychoenergizers, and Tranquilizers

1-Benzyl-2-methyl-5-methoxytryptamine (BAS) inhibits monoamine oxidase in man. This finding confirms the findings of Woolley in mice. Since BAS, a tranquilizing agent, and Marsilid, a psychoenergizer, are both monoamine oxidase inhibitors, doubt is cast upon the hypothesis, that the stimulatory effect of Marsilid is due to its ability to inhibit monoamine oxidase.