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Increased platelet intracellular calcium concentration in patients with bipolar affective disorders
S L Dubovsky1, J Christiano, L C Daniell
1Department of Psychiatry, University of Colorado School of Medicine, Denver.
Insights
Blood platelets in patients with mania show increased intracellular calcium. Bipolar patients, both manic and depressed, exhibit heightened calcium responses to stimulation, unlike unipolar patients.
Area of Science:
- Neuroscience
- Biochemistry
- Psychiatry
Background:
- Intracellular calcium ions play a crucial role in platelet activation and signaling.
- Dysregulation of intracellular calcium has been implicated in various mood disorders.
- Platelets offer a accessible model for studying cellular mechanisms in psychiatric conditions.
Purpose of the Study:
- To investigate differences in free intracellular calcium ion concentration in blood platelets across various mood disorder states.
- To compare calcium mobilization responses to specific agonists between patients with mania, bipolar depression, unipolar depression, and healthy controls.
Main Methods:
- Utilized the fluorescent indicator Fura 2 to measure free intracellular calcium ion concentration.
- Assessed baseline calcium levels and responses to platelet-activating factor and thrombin stimulation.
- Included patients with untreated mania, bipolar depression, unipolar depression, recovered patients, and age/sex-matched controls.
Main Results:
- Significantly increased baseline intracellular calcium in platelets of patients with mania compared to controls.
- Significantly higher intracellular calcium after stimulation in platelets of manic and bipolar depressed patients versus other groups.
- A significantly lower increase in intracellular calcium over baseline upon stimulation in unipolar patients compared to bipolar patients.
Conclusions:
- Platelets from manic and bipolar depressed patients demonstrate enhanced intracellular calcium activity.
- Unipolar patients show a distinct impairment in intracellular calcium mobilization in response to stimulation.
- These findings suggest differential platelet calcium handling mechanisms in bipolar versus unipolar depression.
Abstract:
Using the fluorescent indicator Fura 2, we measured the free intracellular calcium ion concentration in blood platelets of patients with untreated mania, bipolar depression, and unipolar depression; patients who had recovered from bipolar depression or mania; and age- and sex-matched controls. The baseline intracellular calcium ion concentration was significantly increased in platelets from patients with mania compared with controls. The free intracellular calcium ion concentration after stimulation with platelet-activating factor and thrombin was significantly higher in platelets of manic and bipolar depressed patients than in all other groups. The degree to which intracellular calcium ion concentration increased over baseline after stimulation was significantly lower in unipolar than in bipolar patients. These findings suggest that platelets of manic and depressed bipolar patients have a similar enhancement of intracellular calcium ion activity that is distinctly different from the decreased ability of platelets of unipolar patients to mobilize intracellular calcium in response to stimulation.