Reduced platelet serotonergic responsivity as assessed by dense granule secretion in first-episode psychosis

Platelet haemostatic function in psychiatric disorders: Effects of antidepressants and antipsychotic drugs

Objectives Platelets, the smallest anucleated blood cells, play an essential role in the first step of complex haemostatic process. This review presents the haemostatic function of blood platelets related to their activation in psychiatric disorders (schizophrenia, depression), the role of antipsychotic and antidepressant medication, and introduces the mechanisms by which activated platelets may be involved in the pathophysiology of these disorders. Methods Platelets are interesting and easily accessible blood cells to study biochemical pathways related to schizophrenia and other psychiatric disorders, and their complex activation process might be useful as a diagnostic peripheral marker for studying psychiatric disorders and haemostatic complications. Results The excessive activation of platelets observed in patients with depression and schizophrenia is involved in cardiovascular diseases, stroke and increased risk of thrombotic complications that may be major causes of morbidity and mortality of patients. The use of antidepressants or antipsychotic drugs in depression and schizophrenia treatment is often associated with haematological side effects such as bleeding, venous thromboembolism and impaired platelet function. Conclusions Understanding the role of platelet activation in psychiatric disorders such as schizophrenia or depression and medication may improve therapies in the future.

Targeted multiplexed selected reaction monitoring analysis evaluates protein expression changes of molecular risk factors for major psychiatric disorders

BACKGROUND

Extensive research efforts have generated genomic, transcriptomic, proteomic, and functional data hoping to elucidate psychiatric pathophysiology. Selected reaction monitoring, a recently developed targeted proteomic mass spectrometric approach, has made it possible to evaluate previous findings and hypotheses with high sensitivity, reproducibility, and quantitative accuracy.

METHODS

Here, we have developed a labelled multiplexed selected reaction monitoring assay, comprising 56 proteins previously implicated in the aetiology of major psychiatric disorders, including cell type markers or targets and effectors of known psychopharmacological interventions. We analyzed postmortem anterior prefrontal cortex (Brodmann area 10) tissue of patients diagnosed with schizophrenia (n=22), bipolar disorder (n=23), and major depressive disorder with (n=11) and without (n=11) psychotic features compared with healthy controls (n=22).

RESULTS

Results agreed with several previous studies, with the finding of alterations of Wnt-signalling and glutamate receptor abundance predominately in bipolar disorder and abnormalities in energy metabolism across the neuropsychiatric disease spectrum. Calcium signalling was predominantly affected in schizophrenia and affective psychosis. Interestingly, we were able to show a decrease of all 4 tested oligodendrocyte specific proteins (MOG, MBP, MYPR, CNPase) in bipolar disorder and to a lesser extent in schizophrenia and affective psychosis. Finally, we provide new evidence linking ankyrin 3 specifically to affective psychosis and the 22q11.2 deletion syndrome-associated protein septin 5 to schizophrenia.

CONCLUSIONS

Our study highlights the potential of selected reaction monitoring to evaluate the protein abundance levels of candidate markers of neuropsychiatric spectrum disorders, providing a high throughput multiplex platform for validation of putative disease markers and drug targets.