Abstract
Evidence is growing that the exposure to anesthetics and sedatives in the neonatal period, which is the "window of vulnerability" during which they are particularly susceptible to disturbance factors, induce neurodevelopmental disorders long after the causative event. We found that rats neonatally treated with midazolam, a common sedative using in pediatric clinical settings, showed changes in sociality and deficits in social novelty discrimination behavior in adulthood. The decrement of the number of positive cells for tyrosine hydroxylase, the rate-limiting enzyme for dopamine synthesis, in the ventral tegmental area and substantia nigra pars compacta observed in these rats suggested that long-lasting decrease of dopamine release is involved in the mechanisms of deficits in social behavior. Furthermore, we revealed that correction of dopamine homeostasis by acute systemic administration of methylphenidate, a dopamine and noradrenaline reuptake inhibitor, restored the impaired social novelty discrimination behavior in neonatal midazolam treated rats. In this symposium, we would like to introduce a new probable mechanism concerning hypofunction of dopaminergic system underlies the impairment induced by exposure to anesthetics in neonatal period.
