ABSTRACT
The functional role of dopamine in the striatum is intriguing. Clearly dopamine has a critical role in maintaining normal behaviour, as evidenced by the profound clinical movement disorders that accompany the degeneration of the nigrostriatal dopamine system in Parkinson’s disease (Albin, Young and Penney, 1989). Dopamine has also been implicated in mental disorders such as schizophrenia and attention deficit hyperactivity disorder (ADHD), as well as in the effects of abuse of psychostimulants such as cocaine and amphetamine. However, identifying the specific mechanisms by which dopamine effects such diverse behaviours has been difficult. Physiologic approaches have provided considerable advances in recent years, such that the long held view that dopamine acts to inhibit striatal neurone activity has yielded to more complex concepts, in which it is now appreciated that the effect which dopamine has on neuronal activity is dependent on many factors, involving the concurrent actions of other neurotransmitters. For example, while dopamine may inhibit the response of striatal neurones to glutamate input in some instances, in other instances, such as in combination with NMDA glutamate receptor activation, dopamine may enhance striatal neurone activity (Cepeda, Buchwald and Levine, 1993). An alternative approach to the study of dopamine function in the striatum utilises the effects of dopamine receptor activation on the regulation of genes expressed by striatal neurones. The rationale of this approach and the insights it provides to elucidating the functional role of dopamine in the striatum will be reviewed in this chapter.
