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

Article Abstract:

Monoamines are catecholamine compounds involved in the regulation of energy and feeling states. Abnormalities in the metabolic activity of monoamine oxidase (MAO) and serotonin (5-HT) have been reported in depression and other mental disorders. To evaluate differences in platelet MAO activity and platelet serotonin uptake, 20 agoraphobic outpatients, 16 neurotic depressive outpatients and 19 healthy comparison subjects (controls) were studied. All study subjects were screened so that no participants used medications or had any physical condition (e.g., anemia) which could alter normal MAO activity. Each patient completed a fear questionnaire to assess avoidance behavior, distress, other agoraphobic symptoms (e.g. fear of panic in a public space) and anxiety-depression. Blood samples were obtained from all participants, and MAO and 5-HT platelet assays were carried out. The agoraphobic patients had significantly higher average values of platelet MAO activity than both other groups. High situational anxiety, high degree of avoidance behavior, and high fear scores were also associated with high MAO activity, a finding thought to represent a biologic compensatory adaptation to stress. Sex differences were only significant in the healthy control group, where females tended to have higher platelet MAO levels. No significant changes in MAO activity were found in the neurotic depressive group and there were no associations found between 5-HT uptake and agoraphobia. The neurotic depressive group demonstrated significantly higher 5-HT platelet uptake and consequently had less available circulating brain serotonin. (Consumer Summary produced by Reliance Medical Information, Inc.)

Depression, Mental, Catecholamine metabolism, Panic disorder, Agoraphobia, Panic attacks, Monoamine oxidase

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Melatonin: a new probe in psychiatric investigation?

Article Abstract:

The most important function of the pineal gland is thought to be the transmission of information about length of day and seasonal cycles. Melatonin is synthesized from serotonin in the pineal gland. The major regulator of melatonin synthesis is the light-dark cycle, with synthesis being increased during darkness. Melatonin itself seems to play a central role in the regulation of both circadian rhythms and sexual maturation, and it is thought that episodes of depression and mania may be related to time-keeping disorders. Some evidence indicates that melatonin synthesis affects seasonal mood disorders because of its sensitivity to differences in the length of daytime of different seasons. Many studies have found that depressed patients have serotonin deficiencies. Since serotonin deficiencies can lower pineal melatonin production, this implicates melatonin deficiency in depression. Melatonin can now be reliably measured by radio-immunoassay, although this requires frequent blood sampling over a 24-hour period. Melatonin has been found to be effective in reducing sleep disturbance and in improving jet-lag fatigue. Based on these findings and a review of findings of studies related to the response of melatonin to different antidepressant treatments, it is conjectured that melatonin has therapeutic potential for the treatment of mild depression and insomnia. However, although melatonin carries a license from the U.S. Food and Drug Administration for human use, no clinical trials have been carried out to test this theory. (Consumer Summary produced by Reliance Medical Information, Inc.)

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The effect of moderate weight loss on overnight melatonin secretion

Article Abstract:

Melatonin is a neurohormone secreted by the pineal gland and synthesized from serotonin. Studies assessing the relationship of melatonin secretion with weight loss and depression have had confusing and inconsistent results. In an attempt to clarify some of these inconsistencies, the effect of moderate weight loss on melatonin secretion was studied in 10 female volunteers who met standards for normal height and weight, and had no personal or familial psychiatric history, or any history of endocrine abnormality. Overnight plasma melatonin levels were measured before and after weight loss. After following a diet containing approximately 1,000 calories daily over a three-week period, the average weight loss was 6.6 pounds. One woman was taking a contraceptive pill, but the other nine were all drug free. The diet plan provided 31 percent protein, 44 percent carbohydrate, and 25 percent fat. Weight loss was the only guarantee of diet compliance. Total overnight melatonin secretion before and after weight loss did not differ significantly. Average plasma melatonin concentration levels changed significantly during each measurement night, but there was no overall difference between the two measurement occasions. Total overnight melatonin secretion was not significantly related to weight. Results suggest that moderate weight loss through dieting in normal subjects does not alter overnight plasma melatonin concentration in females. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Weight loss

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