Chapter 8 - Control of Gene Expression in Basal Ganglia by Adenosine Receptors

Abstract

This chapter discusses that neurons with axons extending to the internal segment of the globus palliudus (Gpi) and substantia nigra pars reticulata usually express substance P (SP) and dynorphin and at the same time form the striato-Gpi/ nigral pathway. Usually, neurons extending to the ipsilateral globus pallidus express enkephalin and form the striatopallidal pathway. The control of neuronal activity and neuropeptide gene expression in the striatum is inspired by the complex interplay among many neurotransmitter systems and their receptors of which dopamine is the one which holds the central position. At the same time, the expression of striatal enkephalin and SP are differentially regulated by the mesostriatal dopaminergic system. This chapter demonstrates that the blockade of adenosine A2A receptors in distinct neuronal populations helps to restore the balance of striatal function. The blockade also helps to increase the inhibition of both the striatopallidal and cholinergic interneurons while increasing the activity of striato- Gpi/ nigral neurons following striatal dopamine depletion or chronic D2 receptor blockade.