Autism is a neurodevelopmental disorder characterised by impaired social skills, communication deficits and repetitive behaviours. Alterations in a number of neurotransmitter signalling systems and neuroregulatory proteins have been reported in individuals with autism spectrum disorders (ASD). The most compelling evidence seems to suggest an imbalance in excitatory and inhibitory impulses in the premature autistic brain, combined with defects in secondary neurotransmitter systems, resulting in autistic traits. Serotonin, known to be disrupted in ASD, facilitates the release of both reelin and oxytocin, with excessive levels of serotonin resulting in a decrease in reelin and oxytocin. Deficits in developmental growth factors, such as reelin, may regulate or be regulated by oxytocin, thus contributing to both neurodevelopmental arrest and altered social behaviour, characteristic for the autistic spectrum. In this review we therefore concentrate on the role of the serotonin neurotransmitter and the two neuroregulatory proteins (reelin and oxytocin), and evaluate the pharmacological interventions available at the moment, associated with the latter neurochemical changes in autism.

Introduction

Autism is regarded as a heterogeneous neurodevelopmental disorder, characterised by a spectrum of impaired social skills, communication deficits, repetitive behaviour and frequently associated with co-morbid disorders (e.g. obsessive compulsive disorder, epilepsy, Tourette syndrome, attention deficit hyperactivity disorder, tuberous sclerosis and Fragile X syndrome, among others; Gillberg and Billstedt, 2000). A significant number of individuals with autism also show hyperactivity, anxiety and self-injurious behaviours.