Platelets: A possible glance into brain biological processes in schizophrenia

Table 1 Variations in monoamine oxidase activity in health and disease

High platelets MAO activity	Low platelets MAO activity
Women	Men
Elderly	Premenstrual phase in woman
Anxiety states	Bipolar disorder
Alzheimer disease	Alcoholism
	Schizophrenia

MAO: Monoamine oxidase.

Table 2 Low monoamine oxidase activity in schizophrenia

Subtype	Paranoid schizophrenia
Symptoms	Auditory hallucination
	Negative symptoms in unmedicated males
Prognosis	Better social adjustment and fewer symptoms at follow-up (other study reported higher symptomatology in senium)

Table 3 Platelet serotonin in schizophrenia

High platelet serotonin	Low platelet serotonin
Paranoid schizophrenia	Non-paranoid schizophrenia
Correlated with severity of auditory hallucinations	Correlated with lack of insight and with conceptual disorganization
Chronic active course
Higher levels in spring in patients with positive symptoms
Winter born patients

Table 4 Main methods used in psychiatry platelet research

Method	Brief description and representative references
MAO activity measuring	2-carbon14-tryptamine hydrochloride or carbon14-benzylamine as substrates[16,109]
Platelet 5-HT levels	High-performance liquid chromatography (HPLC) with fluorimetric or electrochemical detection[110]
Serotonin transporter binding sites	[3H] Imipramine binding assay[73]
Noradrenergic binding sites	Specific binding of 3H-clonidine and 3H-yohimbine to platelet membranes[111]
Prostaglandin E1 suppression of platelet aggregation response	Using PGE1 to suppress platelet aggregation in response to ADP[89]
Platelet Associated Antibodies 11	Enzyme linked immunoassay based on color development after reaction with anti-human immunoglobulin bound to horseradish peroxidase[112]
Platelet mitochondrial enzyme activity	Measuring different complexes of the respiratory system activity[100]

MAO: Monoamine oxidase; HPLC: High-performance liquid chromatography; PGE1: Prostaglandin E1.