This is an historical archive of the activities of the MRC Anatomical Neuropharmacology Unit (MRC ANU) that operated at the University of Oxford from 1985 until March 2015. The MRC ANU established a reputation for world-leading research on the brain, for training new generations of scientists, and for engaging the general public in neuroscience. The successes of the MRC ANU are now built upon at the MRC Brain Network Dynamics Unit at the University of Oxford.

Synaptic connections between spiny neurons of the direct and indirect pathways in the neostriatum of the rat: evidence from dopamine receptor and neuropeptide immunostaining.

Eur. J. Neurosci. 1996;8(5):861-9.

Synaptic connections between spiny neurons of the direct and indirect pathways in the neostriatum of the rat: evidence from dopamine receptor and neuropeptide immunostaining.

Yung KK, Smith AD, Levey AI, Bolam JP
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Abstract:
The flow of cortical information through the basal ganglia occurs through the so-called 'direct pathway' and 'indirect pathways'. The object of the present work was to attempt to determine whether spiny neurons in the neostriatum that give rise to the direct pathway (i.e. the striatonigral/entopeduncular pathway) and those giving rise to the indirect pathways (i.e. striatopallidal pathway) are synaptically interconnected. The approach was to carry out double immunocytochemistry at the electron microscopic level using antibodies against peptides or dopamine receptor subtypes that are selectively associated with the neurons that give rise to the direct (substance P or D1 receptors) and indirect pathways (enkephalin or D2 receptors). Sections of perfuse-fixed rat neostriatum were immunostained to reveal both substance P immunoreactivity and D2 receptor immunoreactivity or enkephalin and D1 receptor immunoreactivity, respectively. Double peroxidase methods were employed using different chromogens that were distinguishable at both the light and electron microscopic levels. In the electron microscope substance P-immunoreactive terminals were seen in synaptic contact with dendritic structures that displayed immunoreactivity for D2 receptor. Similarly, enkephalin-immunoreactive terminals were seen in synaptic contact with D1-immunoreactive dendritic structures. Thus, axon collaterals of neurons giving rise to the direct pathway form synaptic contacts with neurons that give rise to the indirect pathway and axon collaterals of neurons giving rise to the indirect pathway form synaptic contact with neurons that give rise to the direct pathway. These results indicate that the two pathways of information flow through the basal ganglia are synaptically linked at the level of the neostriatum. Keywords: spiny neurons, direct pathway,indirect pathways, rat neostriatum