Overview of D2 receptors

The D2 receptor is coupled to G protein and has been mainly characterized as an inhibitor of adenylyl cyclase. The D2 receptor also activates K+ channels, stimulates phospholipase A2 and affects Ca2+ channels. 

The highest density of D2 receptor, as measured by selective radiolabeled drugs or antibodies, was found in the NAc, olfactory tubercle, olfactory bulb (glomerular layer) and CPu. In the pituitary gland, D2 receptors were found to be present at a high level in the intermediate lobe. 

Medium-high density of D2 receptors was found in the islands of Calleja, ventral pallidum, zona incerta, GP, central amygdala, in some cells of the anterior lobe of the pituitary, and at several sites in the forebrain the laterodorsal septal area, hippocampus, subiculum, lateral habenula, STh, lateral mammillary bodies. D2 receptors were also found with a medium-high density in various cortical fields prefrontal, anterior cingulate, entorhinal and perirhinal cortices. In the brain stem, medium-high density of D2 receptors was found in the VTA, SNc, ventral SNr, parabrachial nucleus, superior and inferior colliculi, dorsal raphe nucleus and locus coeruleus. 

A medium-low density of D2 receptors was detected in the sensorymotor, visual, piriform and retrosplenial cortices, in the bed nucleus of the stria terminalis, basolateral amygdala, thalamus, EP, SNr, anterior hypothalamic area and cerebellar lobules 9 and 10. 

The D2 receptor distribution parallels, in general, the distribution of the D2 transcript (Mansour et al., 1990 Meador-Woodruff et ah, 1991a Weiner et ah, 1991). Good correspondence between the receptor binding sites and D2 mRNA was found in the prefrontal and cingulate cortex, NAc, olfactory tubercle, CPu, GP, SNc, VTA and in the 

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