DOPAMINE IS RELEASED SPONTANEOUSLY FROM DEVELOPING MIDBRAIN NEURONS IN ORGANOTYPIC CULTURE

While neuronal activity is important in CNS development, little is kno wn of the behaviour of the actual neurotransmitters released during th is period. None the less, indirect evidence has suggested that the neu rotransmitter dopamine actually has a morphogenic role. This study is the first attempt to monitor directly and in real-time, the release of dopamine from midbrain neurons developing as an isolated organotypic slice culture. The observed release of dopamine was both spontaneous a nd synchronized and occurred with an average periodicity that is two o rders of magnitude longer than the characteristic neuronal discharge a ctivity of midbrain dopamine cells. Moreover, elevations in the extrac ellular concentrations of dopamine were markedly more prolonged in the se and other developing systems than in axon terminal regions in matur e striatum in which dopaminergic innervation is fully established. Thu s, dopamine may have an action in developing circuits over spatial and temporal scales that vastly exceed those in mature, synaptic-like tra nsmission. (C) 1998 IBRO. Published by Elsevier Science Ltd.