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Possible relationship between pervasive developmental disorders and platelet monoamine oxidase activity
E J Filinger1, M A García-Cotto, S Vila
1Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.
Insights
Children with childhood-onset Pervasive Developmental Disorders (PDD) exhibit significantly lower platelet monoamine oxidase (MAO) activity compared to neurotypical children. This finding suggests a potential biomarker for PDD in pediatric populations.
Area of Science:
- Neuroscience
- Biochemistry
- Developmental Pediatrics
Background:
- Pervasive Developmental Disorders (PDD), including autism, are complex neurodevelopmental conditions.
- Platelet monoamine oxidase (MAO) is an enzyme involved in neurotransmitter metabolism, and its activity has been studied in various neurological conditions.
Purpose of the Study:
- To investigate whether platelet monoamine oxidase (MAO) activity differs between children diagnosed with PDD (including autism and atypical PDD) and typically developing children.
- To compare the kinetic parameters of MAO activity, specifically Km and Vmax, in these groups.
Main Methods:
- Platelet MAO activity was assessed in children aged 6-10 years, comprising groups with autism (N=6), childhood-onset PDD (N=6), atypical PDD (N=6), and 14 controls.
- Kinetic parameters (Km and Vmax) were determined using kynuramine as a substrate under controlled laboratory conditions (pH 7.4, 37°C).
Main Results:
- Children with PDD demonstrated significantly lower Km values (4.41 ± 0.26 µM) compared to controls (5.30 ± 0.23 µM).
- Vmax values were also significantly reduced in PDD children (16.77 ± 1.56 nmol/h/mg protein) versus controls (22.15 ± 2.16 nmol/h/mg protein).
- This reduction in Vmax was consistent when MAO activity was measured with a 100 µM substrate concentration.
Conclusions:
- Children with childhood-onset PDD, particularly those with the complete syndrome, exhibit markedly lower platelet MAO activity.
- These findings suggest that altered MAO activity may be a biological marker associated with PDD in children.
Abstract:
1. The present study was undertaken to determine if the platelet monoamine oxidase (MAO) activity of children with childhood-onset Pervasive Developmental Disorders (PDD), atypical PDD and autistic children differs from MAO of normal children of the same age. 2. The kinetic parameters of MAO activity (Km and Vmax for kynuramine as substrate in 100 mM sodium phosphate buffer, pH 7.4 at 37 degrees C) were determined for platelets from autistic (N = 6), childhood onset PDD (N = 6) and atypical PDD (N = 6) children and 14 controls aged 6-10 years. 3. PDD children had significantly lower Km (4.41 +/- 0.26 vs 5.30 +/- 0.23 microM) and Vmax (16.77 +/- 1.56 vs 22.15 +/- 2.16 nmol h-1 mg protein-1) than control children. The reduction in Vmax was demonstrable in MAO activity measured with 100 microM substrate (14.93 +/- 1.13 vs 20.96 +/- 2.10 nmol h-1 mg-1). 4. These data show that childhood-onset PDD patients, in which the syndrome was complete, presented the lowest levels of platelet MAO activity.