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Monoamine oxidase in chronic schizophrenia: Studies of hormonal and other factors affecting enzyme activity
Abstract:
Reported reductions in the activity of platelet monoamine oxidase (MAO) in chronic schizophrenic patients might be contributed to by alterations in hormones, platelet numbers or other non-specific factors thought to affect enzyme activity. In this study, MAO activity in 27 patients with chronic schizophrenia was measured, using benzylamine as the substrate in an assay based on platelet counts instead of platelet protein, and was found to be markedly lower than mean MAO activity in 375 normal controls. These results were similar to those previously reported with tryptamine as a substrate for the enzyme. Serum testosterone, triiodothyronine, iron and iron-binding capacity were within normal ranges in individuals with reduced MAO activities. Platelet MAO activity remained stable over time in patients and controls.
Insights
Platelet monoamine oxidase (MAO) activity is significantly reduced in chronic schizophrenia patients. This finding was consistent across different enzyme substrates and unaffected by common biological factors, suggesting a specific link to schizophrenia.
Area of Science:
- Neuroscience
- Biochemistry
- Psychiatry
Background:
- Reduced platelet monoamine oxidase (MAO) activity has been observed in chronic schizophrenic patients.
- Potential confounding factors include hormonal changes, platelet count variations, and other non-specific influences on enzyme assays.
Purpose of the Study:
- To investigate and confirm the reduction in platelet MAO activity in chronic schizophrenia.
- To assess the impact of using platelet counts versus protein in MAO assays.
- To evaluate the role of serum hormones and iron levels in observed MAO activity differences.
Main Methods:
- Platelet MAO activity was measured in 27 chronic schizophrenia patients and 375 healthy controls.
- Benzylamine was used as the substrate in an assay standardized by platelet count.
- Serum testosterone, triiodothyronine, iron, and iron-binding capacity were analyzed.
Main Results:
- Platelet MAO activity was markedly lower in chronic schizophrenic patients compared to controls, irrespective of the substrate used (benzylamine or tryptamine).
- Serum hormone and iron levels were within normal ranges in patients with reduced MAO activity.
- Platelet MAO activity demonstrated stability over time in both patient and control groups.
Conclusions:
- The study confirms significantly reduced platelet MAO activity in chronic schizophrenia.
- This reduction is unlikely to be explained by alterations in serum hormones or iron levels.
- The findings support a specific association between MAO activity and schizophrenia, independent of common confounding factors.