D2 receptor protein

Ultrastructural characterization of the D2 receptors have revealed that they are often present within the GABA-containing cells within the striatum, cerebral cortex, hippocampus, globus pallidus and thalamic reticular nucleus (Mrzljak et al., 1996). Thus, dopaminergic transmission via the D2 receptors predominantly provides inhibitory local intrinsic control in the cerebral cortex and inhibitory regulation of the projection pathways. 

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Immunohistochemical analysis with specific antibodies and in situ hybridization studies showed that D2 receptor protein and mRNA are located in about 50% of the medium sized neurons and in about 80% of the large cholinergic interneurons (Bouthenet et ah, 1987 Le Moine et ah, 1990a). 

Levey et al. (1993) found that axon terminals immunoreactive for D1 and D2 receptor proteins formed symmetrical synapses exclusively, and primarily with unlabeled dendritic shafts. In cultures, D1 and D2 receptors have been colocalized to terminals of intrinsic neurons (Wong et al., 1999). Functional D1 receptors have also been demonstrated on the terminals of striatal cells in the substantia nigra (Fiorillo and Williams, 1998). Collectively, the results for D1 and D2 receptors suggest their presence on the terminals of intrinsic GABA neurons. 

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