Depression and monoamine oxidase

The Antidepressant-like Effect of Ethanol Extract of Daylily Flowers ( Jīn Zhēn Huā) in Rats

According to the prediction of the 2008 World Health Organization (WHO) report, depression will be the highest burden disease by the year 2030. Daylily flower ( Jīn Zhēn Huā ; the flower of Hemerocallis fulva) is traditionally used for soothing in Chinese dietary therapy. The major flavonoid of daylily flowers, rutin, is also characterized to be an antidepressant. In this study, we investigated the antidepressant effects of ethanol extract of daylily flowers (DFEtoH) and rutin by forced swimming test (FST) and neurotransmitter metabolism of brain regions (frontal cortex, hippocampus, striatum, and amygdala). Results show that either short- or long-term tests, the extract and rutin significantly reduce the immobility time and increased swimming time of FST, which are compared with the vehicle (P < 0.05). The extract and rutin also increase the serotonin, norepinephrine, and dopamine concentration of these brain regions (P < 0.05). In long-term tests, the daylily flowers extract markedly increased serotonin concentration and reduced serotonin turnover rate in these brain regions but not frontal cortex. In conclusion, present data illustrated that DFEtoH does have antidepressant-like effects possibly via the regulation of serotonergic system. Moreover, rutin might be playing a very important role in the antidepressant-like effects of DFEtoH.

The emerging therapeutic potential of histone methyltransferase and demethylase inhibitors

Epigenetics is defined as heritable changes to the transcriptome that are independent of changes in the genome. The biochemical modifications that govern epigenetics are DNA methylation and posttranslational histone modifications. Among the histone modifications, acetylation and deacetylation are well characterized, whereas the fields of histone methylation and especially demethylation are still in their infancy. This is particularly true with regard to drug discovery. There is strong evidence that these modifications play an important role in the maintenance of transcription as well as in the development of certain diseases. This article gives an overview of the mechanisms of action of histone methyltransferases and demethylases, their role in the formation of certain diseases, and available inhibitors. Special emphasis is placed on the strategies that led to the first inhibitors which are currently available and the screening approaches that were used in that process.

Specific binding of [3H]Ro 19-6327 (lazabemide) to monoamine oxidase B is increased in frontal cortex of suicide victims after controlling for age at death

Previous studies have reported negative findings for the association among brain monoamine oxidase B (MAO-B) and suicidal behaviour. However those studies did not adequately control their main results for the influence of confounding variables such as age at death. We have evaluated the association of MAO-B density (assessed by [3H]Ro 19-6327 - lazabemide - binding) with type of death (suicide victims vs non-suicide controls) after controlling for age at death. Frontal cortex samples from 43 subjects (21 suicides, 22 controls) were assayed for MAO-B density at a single concentration of lazabemide (8 nM). A linear regression modelling approach comparing nested models resulted with both type of death (p<0.05) and age of death (p<0.01) as main explanatory variables for the variability of MAO-B density. Suicide victims had >30% more binding sites for lazabemide than controls. Contrary to previous reports, MAO-B density seems to increase in suicide victims.

Effects of past history of major depression on smoking characteristics, monoamine oxidase-A and -B activities and withdrawal symptoms in dependent smokers

Past history of major depression is more common in smokers than in non-smokers. We have shown in a previous study that lifetime prevalence of major depression is higher in dependent smokers and they have lower monoamine oxidase-A and -B activities than non-smokers. Because several studies have found an association between MAO-B activity and depression we analysed data of these smokers to assess whether past history of major depression is associated with reduced monoamine oxidase activities (A and B) or not. Further, we tried to characterize smokers with past history of major depression and its effect on withdrawal symptoms. The data of 88 dependent smokers (Fagerström Tolerance Questionnaire score > or = 6 and smoking > or = 20 cigarettes/day) who participated in a smoking cessation study were analysed. Smokers with past history of major depression but without current illness did not differ in demographic and smoking characteristics from smokers without past history of major depression. Smokers with past history of major depression were mainly women and had lower body mass index. Adjusted for gender and body mass index dependent smokers with or without past history of depression had similar MAO-A and MAO-B activities but smokers with past history of major depression had significantly lower resting plasma norepinephrine levels. Smokers with past history of depression had not significantly higher ratings for depression (Montgomery-Asberg Depression Rating Scales) and anxiety (Hamilton Anxiety Scales) and smoking cessation did not exacerbate these ratings (assessed up to 3 months) and none had depressive episode during the postcessation period up to one year. Past history of depression was associated with higher scores on 'expressed sadness' and 'depressive mood'. Abstinent smokers with past history of depression had significantly higher ratings in one of the seven ratings of a 6 months period for craving (day 28), anxiety (day 7) and total withdrawal symptom score (day 7) when compared to those who had no past history of major depression. It is concluded that (i) past history of major depression is more frequent in female smokers; (ii) smokers with past history of depression may have more intense withdrawal symptoms (craving and anxiety) at some time after cessation: and (iii) past history of depression does not affect monoamine oxidase activities, therefore, reduced monoamine oxidase activities found in previous studies are possibly characteristic features of smoking.

Platelet monoamine oxidase activity and 5-hydroxytryptamine uptake in agoraphobic patients

Platelet MAO activity and platelet serotonin uptake were determined in 20 agoraphobic and 16 neurotic depressive out-patients, and 19 healthy volunteers. Agoraphobic patients were characterised by significantly higher mean values of platelet MAO activity compared with the other two groups, while neurotic depressive patients exhibited significantly higher maximum platelet serotonin uptake velocity. These findings are compatible with an abnormality in the uptake and metabolism of serotonin.

Platelet MAO activity in clinical subtypes of depression and DST suppression

Platelet MAO activity was measured in 75 hospitalized depressed patients and in 31 healthy subjects. Plasmas post dexamethasone cortisol levels were examined in 73 patients. Results indicate that higher platelet MAO activity does not occur in all, but only in male major depressed patients. No relationship between changes of MAO activity and specific clinical subtypes was found. Platelet MAO activity is not different between DST suppressors and DST non suppressors. The authors suggest that platelet MAO activity may be related to non specific factors such as sex, age, but not to diagnosis of depression.

Neurochemical aspects of depression: the past and the future?

The role of aberrant neurochemical substrates in the etiology of depression and the neurochemical mechanisms of antidepressant therapies have been the subjects of many hypotheses in the last 30 years. Pharmacological studies of early antidepressant drugs indicated that brain monoamines were significantly affected by these drugs and these led to the formulation of the biogenic amine hypothesis of depression. Although this hypothesis has been of heuristic value in the study of drug mechanisms and has provided a basis for screening drugs for antidepressant potential, deficiencies in it have become apparent. Neuroanatomical and neurochemical considerations favour the view that brain noradrenaline and serotonin systems may serve as bias adjusting systems for each other and numerous other neural systems. As a consequence of such a relationship, a primary defect in some other neural system would appear amplified in measurements of serotonin or noradrenaline. A possible site for this primary defect may be in membrane composition and function. Recent studies have found that typical and other antidepressant therapies have a pronounced effect on membrane lipids. Thus, in view of the important functions of membrane lipids and the fact that they have been linked to the initiation and development of a number of other disease processes, it is now suggested that consideration be given to them as playing primary causal roles in the etiology of depression and as a site of action for antidepressant drugs.

Life events and biological vulnerability: a study of life events and platelet MAO activity in depressed patients

The present study investigated the possible relationship between platelet monoamine oxidase (MAO) activity and life events. From the general hypothesis that the impact of life events should be seen against the background of an individual's vulnerability, it was assumed that low platelet MAO patients would need fewer life events to develop a psychopathological condition and that they would experience more negatively those events that occurred. Patients (n = 127) of both sexes suffering from various kinds of depressive disorders participated in the study. There were 39 unipolar patients, 11 bipolar patients, 43 patients suffering from neurotic-reactive disorder, and 34 patients suffering from an unspecified depressive disorder. No statistically significant differences in MAO activity were found in this series among the diagnostic subgroups. Younger patients predominated among those with the lowest MAO values. As expected, low MAO patients reported a lower number of life events than patients in the highest MAO quartile, and had experienced those events more negatively.

Psychiatric clinic of the Free University of Berlin; Department of Clinical Psychiatry and Polyclinic

The Department of Psychiatry in its present form has developed since 1968, when the psychiatric branch of the Psychiatrische und Neurologische Klinik (Psychiatric and Neurological Clinic), the traditional type of a West German university hospital comprising psychiatry and neurology in one chair, became autonomous with the establishment of an independent chair of psychiatry. This was an early step in the separation of psychiatry and neurology, a situation which is now to be seen in all German universities. Moreover, during the last decade almost all psychiatric university departments have been more or less sub-divided into sub-specialities. This process has been carried to its furthest extreme in West Berlin which now has departments of clinical psychiatry, geronto-psychiatry, social psychiatry, psychosomatics, child and adolescent psychiatry, neuropsychopharmacology, psychophysiology, student mental health, and forensic psychiatry. The lines of demarcation have been drawn according to somewhat divergent (historical, personal, conceptual) criteria, so that the individual departments differ in size, research interests and research facilities. More than 10 professors, 15 senior doctors and about 50 assistants (physicians, psychologists, sociologists, mathematicians, chemists and engineers) make up a critical mass, but centrifugal forces are often dominant and restrain the optimal use of all facilities for real interdisciplinary collaboration in the sense of what has been described as the ‘agricultural’ approach to research (Shepherd, 1981).

Neurotransmitter functions in depression

1. Subgroups of depressions may be identified and treated based on MHPG execution. 2. HVA correlates more with activity than with mood. 3. CSF-5HIAA may be helpful in categorising some depressions. 4. Acetylcholine has some effect on mood most probably through indirect action on other neurotransmitters. 5. GABA is still not adequately investigated. 6. Desensitization of presynaptic adrenergic autoreceptors may explain some of the mechanisms of antidepressant action of drugs. 7. Decreased post-synaptic adrenergic activity is a common effect of most antidepressants and of ECT.