Low Monoamine Oxidase Activity Research Articles

Usability of MAO-A gene in the judicial process

Monoamine oxidase (MAO-A) is an enzyme found in the nervous system and plays an important role in the breakdown of monoamine neurotransmitters. This enzyme varies among individuals depending on genetic factors. The monoamine oxidase-A (MAO-A) gene has been studied by various researchers to understand behavioral differences between individuals and evaluate crime propensity. However, serious ethical and legal problems may arise regarding the use of genetic factors alone in the judicial process. In this context, considering environmental factors as well as the MAO-A gene may contribute to the development of a more comprehensive approach. The role of the MAO-A gene in the judgment process has created an area of research that allows us to understand behavioral differences. The MAO-A gene has been associated with various behavioral traits. It has particular effects on aggressive behavior, antisocial behavior, and emotional reactions. In this context, the MAO-A gene may be an important factor in determining how individuals respond to environmental factors and guide their judgment processes. Some studies show that individuals with low MAO-A activity may be prone to antisocial behavior and crime. Thus, the MAO-A gene can be taken into consideration in determining guilt in legal processes. Assessing individuals' criminal propensity based on genetic factors can make the justice system more effective and fair. For example, harsh childhood conditions or traumatic experiences can trigger genetic predispositions and increase criminal propensity. In this case, it is important to take environmental factors into account when evaluating the genetic profile of the individual during the judicial process. Many ethical and legal issues need to be carefully considered on how to integrate the MAO-A gene into the judicial system. Therefore, research on the usability of the MAO-A gene in the judicial process should be continued.

EFFECT OF UROKINASE GENE KNOCKOUT ON TISSUE LEVELS OF BIOGENIC AMINES IN MICE WITH MELANOMA

The research aim was to study the dynamics of biogenic amines in the brain, tumor and intact skin of urokinase (uPA) gene knockout mice on day 21 of the B16/F10 melanoma growth. Material and methods. The study included male and female uPA gene knockout (-uPA, n = 38) and wild type mice (+uPA, n = 61). Melanoma was transplanted subcutaneously. Levels of biogenic amines were studied by ELISA in tissues obtained on day 21 of carcinogenesis. Results and discussion . Intact (-uPA) mice showed an increased total content of biogenic amines: in the skin - due to noradrenaline increase by 4.8 times in males and by 4.9 times in females, histamine - by 3.6 times in males and by 1.6 times (p < 0.05) in females, serotonin - by 3.4 times in males and by 8.3 times in females; in the brain - due to noradrenaline increase by 3.5 times in males and by 3.2 times in females, dopamine by 2.1 times in males and by 2.9 times in females, while histamine content decreased. Melanoma development in (-uPA) mice was characterized by: lower levels of adrenaline with high NA concentrations and an increase in the serotonin metabolism in the brain; higher histamine concentrations in the tumor and higher serotonin levels in the skin; similar to (+uPA) mice levels of adrenaline (males) and noradrenaline in the tumor and higher levels of adrenaline in the tumor and histamine in the skin in (-uPA) females. Conclusions. The uPA gene knockout limits the development of stress at the central regulatory level due to lower levels of A together with increasing serotoninergic mediation in the brain, as well as modulates the immune antitumor response due to higher levels of histamine in the tumor and 5 serotonin in the skin, as a result of lower monoamine oxidase activity, in mice with B16/F10 melanoma.

The putative catalytic role of higher serotonin bioavailability in the clinical response to exposure and response prevention in obsessive-compulsive disorder.

Objective:Exposure and response prevention (ERP) is effective to treat obsessive-compulsive disorder (OCD), but the lack of tolerance to the aversion nature of exposure techniques results in a high drop-out rate. There have been reports of a generic stress endurance effect of serotonin (5-HT) in the central nervous system (CNS) which might be explained by suppression of defensive fixed action patterns. Previous studies have proposed that higher baseline 5-HT concentration and slow decrease in concentration during drug treatment of OCD were predictors of good clinical response to 5-HT reuptake inhibitors. The objective of this study was to investigate whether pre-treatment platelet rich plasma (PRP) 5-HT concentration is associated with latency of treatment response and final response to an ERP protocol for obsessive-compulsive disorder (OCD).Methods:Thirty adult and treatment-free OCD patients were included in an 8-week, 16-session ERP protocol. 5-HT concentration was determined at baseline and after treatment. Patients with a reduction ≥30% on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) at the end of ERP were defined as responders.Results:A positive correlation between baseline 5-HT concentration and reduction of symptoms on the Y-BOCS was observed after 4 weeks. Baseline 5-HT concentration was not correlated with clinical response after 8 weeks of ERP, possibly due to the similar though delayed clinical response of patients with lower (compared to those with higher) baseline 5-HT concentration. Patients with higher 5-HT baseline concentration also showed more improvement in depressive symptoms with treatment.Conclusion:The present results partially support the hypothesis of a stress endurance effect of 5-HT in OCD patients. According to the literature, fast onset responders possibly have more or larger 5-HT containing neurons, higher endogenous 5-HT synthesis or lower monoamine oxidase activity; all these hypotheses remain to be investigated.

A mutation in the enzyme monoamine oxidase explains part of the Astyanax cavefish behavioural syndrome

We use Astyanax mexicanus, a single species with surface-dwelling forms (SF) and blind de-pigmented cave forms (CF), to study mechanisms underlying the evolution of brain and behaviour. In CF, the origin of changes in complex motivated behaviours (social, feeding, sleeping, exploratory) is unknown. Here we find a hyper-aminergic phenotype in CF brains, including high levels and neurotransmission indexes for serotonin, dopamine and noradrenaline, and low monoamine oxidase (MAO) activity. Although MAO expression is unchanged in CF, a pro106leu mutation is identified in the MAO coding sequence. This mutation is responsible for low MAO activity and high serotonin neurotransmission index in CF brains. We find the same mutated allele in several natural CF populations, some being independently evolved. Such occurrence of the same allele in several caves may suggest that low MAO activity is advantageous for cave life. These results provide a genetic basis for several aspects of the cavefish 'behavioural syndrome'.

Platelet monoamine oxidase activity in association with adolescent inattentive and hyperactive behaviour: A prospective longitudinal study

Platelet monoamine oxidase (MAO) activity is a peripheral marker of central serotonergic activity, and has been associated with psychiatric vulnerability. This longitudinal investigation studied the relationship between aggressive and hyperactive behaviour and platelet MAO activity in adolescents at age 15 and 18 years. The psychological data were obtained from teachers by using the Hyperactivity Scale ( af Klinteberg, 1988) and, at the age of 18 years, the teacher-report version of the SNAP-IV. Female subjects had significantly higher platelet MAO activity levels than males, and regular smokers had significantly lower MAO activity levels than nonsmokers. Low levels of platelet MAO and smoking at the age of 15 years were independently associated with Motor Restlessness and Inattention symptoms at the age of 18 years. These longitudinal data suggest that specific aspects of hyperactivity and attention deficit are associated with platelet MAO activity independently of smoking.

Psychological traits and platelet monoamine oxidase activity in eating disorder patients: Their relationship and stability

Self-reported behavior and attitudes towards eating [Eating Disorder Invetory-2; Garner DM (1991). Eating Disorder Inventory-2: Professional Manual. Odessa, Fl.: Psychological Assessment Resources; Estonian version Podar I, Hannus A, Allik J (1999). Personality and Affectivity Characteristics Associated With Eating Disorders: a Comparison of Eating Disordered, Weight-Preoccupied, and Normal Samples. J Pers Assess; 73(1), 133–147] and the activity of platelet monoamine oxidase (MAO) was studied in 11 patients with anorexia nervosa (AN), 43 patients with bulimia nervosa (BN) and a healthy control group ( n = 138). Nineteen patients filled in the EDI-2 questionnaire and donated blood samples three times with three month intervals in order to determine platelet MAO activity. Eating disordered (ED) patients scored higher on all EDI-2 subscales and had lower MAO activity compared to the control group. They also scored higher than the control group on the Neuroticism domain but lower on the Extraversion, Openness, and Conscientiousness domains of the NEO-PI-R questionnaire. The average stability of MAO on different occasions ( r = .56) was slightly smaller than the stability of the EDI-2 scores ( r = .70). The lack of correlations between personality dispositions and MAO activity indicates that they have independent influence on eating disorders. A possible relationship between neurochemical mechanisms and psychological symptoms of eating disordered behavior is discussed.

Monoamine Oxidase Activity and Tri-Iodothyronine Level in Violent Offenders with Early Behavioural Problems

The focus is on evaluating the relationships between early behavioural problems and biochemical variables at adult age and their significance for early criminality and violent behaviour in a life perspective. In the present study, using prospective longitudinal data, a sample of males with a history of early criminal behaviour and male controls (n = 103) were investigated concerning (1) teacher-rated behaviours at age 11–14 years; (2) platelet monoamine oxidase (MAO) activity and tri-iodothyronine (T₃) level at adult age; (3) registered early criminality (11–14 years); (4) records of violent offending up to age 35 years, and (5) interview data on smoking. The main finding was that a combined risk level pattern of low MAO activity and high T₃ level was found significantly more frequently than expected in violent offenders with an early behavioural risk pattern. Furthermore, there was a significant interaction effect between early attention difficulties and smoking on MAO activity, as well as an effect by smoking on MAO activity. The findings are discussed in terms of the possible influence of biological vulnerability to certain behaviours, which in combination with possible childhood stress, enhance the risk for antisocial behaviours and subsequent violence.

Panic disorder: Psychobiological aspects of personality dimensions

Attempts to understand the underlying mechanisms of association between psychological factors and panic disorder have been mostly based on psychodynamic description. Evidence of the importance of serotonergic (5-HT) system in panic disorder (PD), however, has substanti ally increased in recent years. The objective of our study was to determine whether there was a specific personality profile of panic disorder patients and how it was related to possible neurobiological mechanisms underlying personality dimensions. Sample consisted of 14 inpatients with ICD-X diagnosis of panic disorder and 34 healthy control subjects. Personality dimensions were assessed by Minnesota Multiphasic Personality Inventory (MMPI-201) and Tridimensional Personality Questionnaire (TPQ). To assess central 5-HT function, platelet monoamine-oxidase (MAO) activity was measured. In panic disorder group, higher scores of histrionic, depressive and hypochondriac subscales and significant increase of harm avoidance (HA) scale as well as low MAO activity were found. Negative correlation was established between MAO activity and psychopathic deviance MMPI scale. The obtained results might indicate a specific personality profile of patients with panic disorder, which is characterized by high neuroticism, fearfulness, inhibition, shyness and apprehensive worry. Low MAO activity and high HA scores possibly indicate underlying hyperserotonergic state. The observed correlation between personality traits and MAO activity provide additional support for the hypothesized functional relationship between underlying central monoaminergic activity and temperament traits associated with anxiety, depression and impulsivity.

Antisocial alcoholism and serotonin-related polymorphisms: association tests.

Central serotonin dysfunction appears to be related to a subtype of alcoholism with antisocial impulsive features (type II; antisocial alcoholism). The serotonergic deficit may be associated with greater impulsivity, which in turn facilitates both alcohol dependence and antisocial behavior. The present study tested association of antisocial impulsive alcoholism with candidate genes related to serotonergic neurotransmission, using families. Eight markers were assayed using polymerase chain reaction: tryptophan hydroxylase (intron 7), the serotonin transporter SLC6A4 (VNTR 9/12), HTTLPR, the three serotonin receptor types HTR1B (G861C), HTR2A (T102C) and HTR2C (Cys23Ser), monoamine oxidase A (T1460C), and (CA)(n). Eligible probands had early age of onset of alcoholism, child conduct disorder, and two or more symptoms of adult Antisocial Personality Disorder. This sample included 35 probands, their parents, and some siblings (n = 116). Association tests were conducted using the Haplotype Relative Risk method for antisocial alcoholism diagnosis and the George-Elston regression method (the S.A.G.E. program ASSOC) for quantitative antisocial alcoholism severity. Haplotype Relative Risk analyses were not significant at the 0.05 level for any of the markers. Trends suggestive for future research occurred for tryptophan hydroxylase and HTR2A. Quantitative ASSOC analyses showed significant marker effects (P < 0.05) for both monoamine oxidase A markers, which were in linkage disequilibrium. Antisocial alcoholism symptom severity was higher with monoamine oxidase A C homozygotes or hemizygotes, indicating that low monoamine oxidase activity may be important. Future studies are needed to examine joint and interactive effects of serotonin-related markers.

Platelet monoamine oxidase activity in association with childhood aggressive and hyperactive behaviour: the effect of smoking?

Monoamine oxidase (MAO) activity in platelets is known to be a marker of certain personality traits and behavioural preferences in adults, but less is known of the association of platelet MAO and behaviour in children. Platelet MAO activity was measured in 1129 randomly sampled 9- and 15-year old children by a radioenzymatic method with β-phenylethylamine as the substrate. Ratings of children’s Aggressiveness, Motor Restlessness and Concentration Difficulties were obtained from teachers. Smokers had significantly lower MAO activity and they were also given significantly higher scores in Aggressiveness, Motor Restlessness and Concentration Difficulties than non-smokers. In 15-year but not 9-year-old children, significant associations were found between platelet MAO activity and behavioural ratings. However, these associations disappeared when smokers were excluded from the analysis. It is concluded that the causal relationship between behavioural measures and platelet MAO can only be revealed with longitudinal studies, considering smoking as a confounding factor.

Relationships Between Effects of Smoking, Gender, and Alcohol Dependence on Platelet Monoamine Oxidase-B: Activity, Affinity Labeling, and Protein Measurements

Background Many studies have reported apparent associations between platelet monoamine oxidase (MAO) activity and susceptibility to alcoholism and other psychiatric conditions. Alcohol-dependent individuals generally exhibit lower platelet MAO activity compared with controls, and on this basis, platelet MAO has been proposed as a potential genetic marker for predisposition to alcoholism. However, several lines of evidence also suggest that MAO activity is reduced in both the brain and platelets of smokers. Many alcohol-dependent individuals are also tobacco users, and few studies have attempted to dissociate the effect of alcohol and tobacco use on MAO activity. Methods Platelet MAO-B activity in 629 subjects recruited as part of the WHO/ISBRA Study of State and Trait Markers of Alcohol Use and Dependence was assayed by using a high throughput fluorescence assay. Platelet MAO-B protein concentrations were measured by analysis of immunoblots probed with a polyclonal antibody selective for MAO. Quantitative measurements of affinity labeling of platelet MAO were made by using the selective MAO-B catalytic site antagonist [3H]Ro 19–6327. Results Multiple regression analysis revealed that subjects’ gender, cigarette smoking, lifetime alcohol dependence, and recruitment site each contributed independently to the variance in platelet MAO activity levels. Female subjects had significantly higher MAO activity levels than males, whereas heavy smokers had significantly lower MAO activity levels than nonsmokers. Immunoblot measurement of platelet MAO-B protein demonstrated that females had significantly higher MAO-B protein concentrations. Platelet MAO-B protein concentrations did not differ significantly between smokers and nonsmokers but were lower in subjects with a diagnosis of lifetime alcohol dependence (DSM-IV) compared with subjects who were never alcohol dependent. Measurements of affinity labeling by [3H]Ro 19–6327 of platelet MAO correlated significantly with MAO activity levels (i.e., the lower MAO-B activity in smokers was mirrored by lower levels of [3H]Ro 19–6327 binding). Conclusions In this international population, gender, cigarette smoking, lifetime history of alcohol dependence, and recruitment site were associated with lower platelet MAO activity levels. Differences in MAO activity associated with gender and lifetime alcohol dependence can be attributed largely to differences in MAO-B protein concentration, whereas those associated with smoking behavior may be the result of binding of an inhibitor contained in cigarette smoke to platelet MAO-B at catalytic site of MAO.

Relationships Between Effects of Smoking, Gender, and Alcohol Dependence on Platelet Monoamine Oxidase‐B: Activity, Affinity Labeling, and Protein Measurements

Many studies have reported apparent associations between platelet monoamine oxidase (MAO) activity and susceptibility to alcoholism and other psychiatric conditions. Alcohol-dependent individuals generally exhibit lower platelet MAO activity compared with controls, and on this basis, platelet MAO has been proposed as a potential genetic marker for predisposition to alcoholism. However, several lines of evidence also suggest that MAO activity is reduced in both the brain and platelets of smokers. Many alcohol-dependent individuals are also tobacco users, and few studies have attempted to dissociate the effect of alcohol and tobacco use on MAO activity. Platelet MAO-B activity in 629 subjects recruited as part of the WHO/ISBRA Study of State and Trait Markers of Alcohol Use and Dependence was assayed by using a high throughput fluorescence assay. Platelet MAO-B protein concentrations were measured by analysis of immunoblots probed with a polyclonal antibody selective for MAO. Quantitative measurements of affinity labeling of platelet MAO were made by using the selective MAO-B catalytic site antagonist [3H]Ro 19-6327. Multiple regression analysis revealed that subjects' gender, cigarette smoking, lifetime alcohol dependence, and recruitment site each contributed independently to the variance in platelet MAO activity levels. Female subjects had significantly higher MAO activity levels than males, whereas heavy smokers had significantly lower MAO activity levels than nonsmokers. Immunoblot measurement of platelet MAO-B protein demonstrated that females had significantly higher MAO-B protein concentrations. Platelet MAO-B protein concentrations did not differ significantly between smokers and nonsmokers but were lower in subjects with a diagnosis of lifetime alcohol dependence (DSM-IV) compared with subjects who were never alcohol dependent. Measurements of affinity labeling by [3H]Ro 19-6327 of platelet MAO correlated significantly with MAO activity levels (i.e., the lower MAO-B activity in smokers was mirrored by lower levels of [3H]Ro 19-6327 binding). In this international population, gender, cigarette smoking, lifetime history of alcohol dependence, and recruitment site were associated with lower platelet MAO activity levels. Differences in MAO activity associated with gender and lifetime alcohol dependence can be attributed largely to differences in MAO-B protein concentration, whereas those associated with smoking behavior may be the result of binding of an inhibitor contained in cigarette smoke to platelet MAO-B at catalytic site of MAO.

Human fear conditioning is related to dopaminergic and serotonergic biological markers.

Biological markers for acquisition and extinction of fear conditioning were studied in 40 individuals selected for displaying either good or poor acquisition of fear conditioning. as estimated by the skin conductance response. Participants with a short serotonin transporter (5-HTT) promoter allele or low monoamine oxidase activity in platelets (trbc-MAO) displayed better acquisition than those with only long alleles or high trbc-MAO, whereas participants with a long dopamine D4 receptor (D4DR) exon III allele showed delayed extinction compared with those with only short alleles. The findings, that D4DR exon III and 5-HTT promoter genotypes and trbc-MAO activity are related to human fear conditioning, a basic form of associative learning, are consistent with animal studies suggesting a genetic contribution to fear conditioning. The authors suggest that in humans these genetic mechanisms are partly dopaminergic and serotonergic in origin.

Adrenergic and noradrenergic plasma levels in Lesch-Nyhan disease.

Noradrenergic dysfunction and abnormality in monoamine oxidase (MAO) enzyme activity have been reported previously in Lesch-Nyhan (LN) disease. This study examines peripheral indices of adrenergic, noradrenergic, and MAO function in children and young adults with LN disease (n = 11), and healthy subjects (n = 9). Blood samples, collected in identical conditions prior to a positron emission tomography (PET) study, were assayed for concentrations of epinephrine (EPI), norepinephrine (NE), and 3-methoxy-4-hydroxyphenylglycol (DHPG) (which results from the degradation of NE by monoamine oxidase type A [MAO-A]). The LN subjects had significantly higher EPI levels by 245% (p < .00) and lower DHPG levels by 42% (p < .00) compared to the control group. No group differences were noted in NE plasma levels. Cognitive function (IQ tested by Stanford Binet Intelligence Scale) was associated with EPI in the LN group (r = 0.77, p = .009), but not in the control group. The abnormally high EPI plasma concentrations may indicate another biochemical dysfunction secondary to the absence of the HPRT enzyme in LN patients. Such a biochemical deficit is likely to originate from the adrenal medulla, which is the primary site of EPI synthesis. The adrenal medulla may be directly affected by the absence of hypoxanthine guanine phosphoribosyl transferase (HPRT) enzyme, or may receive inappropriately high descending activation input from the brain. The abnormally low DHPG levels, in the context of normal NE levels, indicates low MAO activity, either as a primary deficit, or as secondary adaptive changes to spare NE levels that would otherwise be too low for adequate noradrenergic function.

Platelet monoamine oxidase (MAO) activity and alcoholism: is there a genuine association?

Monoamine oxidase (MAO) is a particle-bound flavoenzyme principally located in the outer mitochondrial membrane, which catalyzes the oxidative deamination of a variety of the amine transmitters in the central nervous system. There have been many reports from different groups around the world over the last 20 years that indicated a lower platelet MAO activity was associated with alcoholism. As there are multiple influences upon measured MAO activity, this article attempts to address each of the issues in turn for potential confounding of the reported association. These issues include: the duration of abstinence from alcohol, the substrate used for analysis, gender issues, association with different subtypes of alcoholics, the influence of other psychopathology, personality traits of alcoholics, the question of smoking, and proposed modes of transmission of MAO activity. The initial promise about MAO activity being a possible marker for alcoholism or a least a genetically predisposed subgroup has receded as the number of negative typology-based studies increases. The failure to account for a major confounding variable, e.g. smoking and other minor but possibly vital confounds in almost all these studies leaves the whole hypothesis open to criticism. However, the possible association between personality traits that might predispose to some if not all substances of addiction to low MAO activity may make it possible to reframe the hypothesized association in the setting of a generalized predisposition to addictions in particular, and to psychopathology in general. Nonetheless the association remains of great interest and may yet yield vital genetic and clinical information.

The Marke-Nyman Temperament (MNT) scale in relationship with monoamine metabolism and corticosteroid measures in suicide attempters

Various monoaminergic measures as well as corticosteroid deviances have repeatedly been linked to depression or suicidal behavior. With the purpose to study these biological markers in relationship with temperament, the Marke-Nyman Temperament (MNT) questionnaire was administered in a sample of 89 suicide attempters. The subjects were diagnosed according to the DSM-III-R and subgrouped according to suicide method into 'violent' and 'nonviolent' attempters, and into 'repeaters' (with previous attempt) and 'nonrepeaters' (without previous attempts). The subjects were also subgrouped according to MNT patterns into 5 MNT clusters. Lumbar punctures were performed and the monoamine metabolites homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycole (MHPG) in the cerebrospinal fluid (CSF) were analysed. The levels of plasma cortisol and 24 h. urinary cortisol were determined and dexamethasone suppression tests (DST) were performed. The activity of the enzyme monoamine oxidase (MAO) in platelets was determined. Among the alcoholic patients, the biological markers showed several specific correlations with temperament. In this group, low Solidity (reflecting impulsiveness) was significantly associated with low levels of CSF HVA, CSF 5-HIAA, urinary cortisol and low platelet MAO activity. The Stability (reflecting emotional distance towards others) was significantly and positively associated with urinary cortisol and platelet MAO activity. This seems to reflect the two previously described subgroups of alcoholism, with early and late onset, respectively. In the whole sample, we found a positive correlation between urinary cortisol and Stability. The biological markers showed no clear differences between the MNT clusters. We could not replicate earlier findings of an association between impulsiveness (low solidity) and low levels of 5-HIAA or low MAO activity in platelets in the whole sample of suicide attempters.

Platelet monoamine oxidase in attempted suicide. Relations to sex, psychiatric diagnosis, mode of attempt, and previous attempts

Platelet monoamine oxidase (MAO) activities were assessed in 82 patients, 57 females and 25 males, who were admitted to the medical ward of a general hospital after a suicide attempt. The enzyme activities were compared to the activities of healthy subjects, 35 females and 26 males. In addition, MAO activities were analyzed in relation to sex, psychiatric diagnosis, mode of attempt, drugs ingested, and previous attempts. Compared to normal controls, only female patients showed lower MAO activities. In the male population, lower activities were found in the subgroup of patients who had made previous attempts. In relation to diagnosis, analysis performed in the female population revealed lower MAO activities in the dysthymic and personality disorder, and not in the adjustment or major affective disorder subgroups. MAO activities were not related to the violent mode of attempt, the type of medication used, or the score in the Beck Suicidal Intent scale. The finding of low platelet MAO activities in dysthymic disorder, indicates the need for further studies of biological variables in this underdiagnosed and undertreated diagnostic group.

Alcohol consumption: Biochemical and personality correlates in a college student population

The frequency of alcohol use among a subject population of 28 male and 60 female college students was assessed using the Student Alcohol and Drug Use Survey (STADUS). Data were also collected on personality traits as measured by the Sensation Seeking Scale V (SSSV) and the Eysenck Personality Questionnaire (EPQ). Finally, three biochemical variables were assessed: monoamine oxidase (MAO) activity, dopamine beta hydroxylase (DBH) activity, and testosterone levels. Among males, high SSSV scores, high testosterone levels, and low MAO activity contributed to the variance in alcohol use, whereas among females, a significant proportion of the variability in alcohol use was accounted for by high SSSV scores, high DBH activity, and younger age.

Purification of soluble monoamine oxidase in rat liver cytosol by countercurrent chromatography

An endogenous monoamine oxidase (MAO) inhibitory modulator and cytosolic MAO coexisting in the rat liver cytosol were fractionated by gel filtration following ultracentrifugation. High molecular weight fractions exhibiting MAO activity were further purified by countercurrent chromatography (CCC). MAO activity, detected using beta-phenylethylamine (β-PEA) and 5-hydroxytryptamine (5-HT) as substrates, was eluted in two separate peaks (fractions M-1, M-2) from the CCC column. Both the M-1 and M-2 fractions displayed high enzymatic activities on β-PEA whereas the M-2 fraction showed a very low MAO activity on 5-HT. This result might indicate a lack of type A MAO in the M-2 fraction due to the selective separation of endogenous MAO inhibitor. We may conclude that “endogenous MAO modulator” is present in rat liver cytosol.

Platelet monoamine oxidase activity and temperament and personality in adolescent female substance abusers

Platelet monoamine oxidase (MAO) activities were compared between female adolescent substance abusers and normal control females. No differences were observed on this biochemical trait. The two groups were discriminable on psychosocial, and behavioral adjustment, personality traits measuring aggression, self control, and stress reactivity, and on the temperament constellations of difficult temperament index, dysrythmicity, and difficult affective temperament. Platelet MAO activity was associated with difficult affective temperament only in the substance abuse group but not in the controls, suggesting that this temperament variant and lower MAO activities may comprise one form of predisposition to substance abuse.