Geometry and kinetics of dopaminergic transmission in the rat striatum and in mice lacking the dopamine transporter

Abstract

Publisher Summary Several important observations have been reported concerning dopaminergic transmission in the striatum; all these data support the view that this transmission occurs outside the synaptic cleft. Therefore, according to the definition dopaminergic transmission must be considered of the volume transmission type. In this chapter, these data are reviewed and the spatiotemporal characteristics of dopaminergic transmission in the striatum are discussed in the light of a comparison between normal animals and mice lacking the dopamine transporter. In mice lacking dopamine transporter (DAt), the striatal dopamine signal exhibits all the spatial and temporal characteristics associated with a VT signal. In particular, the tonic transmission due to the basal extracellular dopamine level is exacerbated and this is in line with the hyperactive phenotype of these mice, but the phasic dopaminergic transmission triggered by bursts cannot be expressed. The disruption of this phasic function might be involved in the learning deficit of these mice. The comparison between normal and DAT -/- mice underlines the functional importance of the temporal characteristics of dopaminergic transmission in the striatum and the major role of the dopamine transporter in the control of these temporal characteristics. Interestingly, the amplitude and time course of the dopamine overflow in the striatum of mice lacking the dopamine transporter are close to those of the dopamine overflow evoked in the medial prefrontal cortex and in the basal amygdaloid nucleus of normal rats.