Genetic Control of Platelet and Plasma Monoamine Oxidase Activity

Age and Sex Related Alterations in Serum and Platelet Monoamine Oxidase

“…These investigators proposed that the higher activity of the enzyme in females is the result of the interaction between female sex hormones and monoamine oxidase (26,36). However, in concordance with our results, most of the studies assaying serum monoamine oxidase activities reveal no significant differences related to age and sex (8,(27)(28)(29)(30).…”

“…One of the key enzymes in catecholamine metabolism is monoamine oxidase (EC 1.4.3.4) which is an oxidoreductase that deaminates monoamines such as adrenaline, noradrenaline and dopamine (7)(8). There are two types of monoamine oxidase, one being a FAD containing enzyme (intracellular) located in the outer membrane of the mitochondria of many tissues such as platelets (8)(9)(10)(11)(12) and the other, a Cu 2+ and pyridoxal phosphate containing enzyme found in serum (13).…”

“…There are two types of monoamine oxidase, one being a FAD containing enzyme (intracellular) located in the outer membrane of the mitochondria of many tissues such as platelets (8)(9)(10)(11)(12) and the other, a Cu 2+ and pyridoxal phosphate containing enzyme found in serum (13). It has been suggested that while tissue and serum monoamine oxidase activities manifest abnormal alterations in various disease states (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26), physiological fluctuations may also be detected in normals (8,(27)(28)(29)(30). The objective of this study has been to investigate the sex and age related fluctuations of platelet and serum monoamine oxidase in healthy volunteers.…”

Biochemistry of Mental Depression

“…Perhaps of greater importance is that there are genetic factors affecting the concentration of MAO in platelets (58,112). It is not known if brain MAO is similarly influenced, or whether these genetic factors are at all related to the genetic component in mental depression as suggested by response to drugs (63), by clinical-therapeutic studies (28), or epidemiological investigations in Iowa, Scandinavia and elsewhere (102), but this is obviously an important area for future exploration in biochemical psychiatry.…”

Biological markers and psychosis

“…However, interest in this potential marker has also spread into work on other conditions and low MAO activity has been associated with bipolar affective illness (Murphy & Weiss, 1972;Leckman et al 1977), with alcoholism (Major & Murphy, 1978;Sullivan et al 1979), as well as with high scores on Zuckerman's (1974) sensation-seeking personality scale and with having a family history of psychiatric disorder (Buchsbaum et al 1976;Haier et al 1980). Studies of platelet MAO in normal families (Pandey et al 1979) and twins (Nies et al 1973) strongly suggest that the level of activity is under genetic control. Furthermore, studies in twins discordant for schizophrenia (Wyatt et al 1973;Reveley et al 1983) have shown a high correlation for low activity between the schizophrenic probands and their well (and therefore unmedicated) co-twins, suggesting that low platelet MAO cannot be completely explained as an effect of drug treatment.…”