Dopamine molecular imaging

Molecular imaging with PET and SPECT of postsynaptic dopamine and serotonin receptors and presynaptic transporters help psychiatrists and psychologists go beyond subjective assessment of symptoms, signs, inappropriate thoughts, emotions, and behavior, but they have not yet begun to apply PET and SPECT in the every day clinical care of patients. They do use molecular imaging to differentiate mild cognitive impairment from AD. 

As a consequence of the important role it plays in the central nervous system, there has been very much interest in finding ways of monitoring the levels of dopamine and studying its metabolism in vivo. Molecular imaging techniques -PET in particular - have been increasingly useful in gaining a better understanding of these processes. 

Figure 4. DDC (A), serotonin (B), and tyrosine hydroxylase (C) immunore-activity in the posterior region of a wild-type Drosophila ventral ganglion. Tyrosine hydroxylase (TH) encodes the rate-limiting step in dopamine biosynthesis and is a marker for dopamine cells. B and C are the same CNS assayed for both serotonin and TH. M, medial dopamine neurons VL, ventrolateral serotonin neurons DL, dorsolateral dopamine neurons. Short unmarked arrows in C show vacuolated cells that do not contain DDC immunoreactivity. The immunoreactivity in these cells may represent a nonspecific cross-reactivity of the rat TH antibody. The length bar in A is 50 pM. The images are confocal projections generated on a Molecular Dynamics-2000 confocal laser scanning microscope.

To understand the long-term changes induced by drugs of abuse, their initial molecular and cellular targets must be identified. A combination of approaches in animals and humans, including functional imaging, has revealed the mesolimbic dopamine system as the prime target of addictive... 

Swanson JM, Kinsboume M, Nigg J, Lanphear B, Stefanatos GA, Volkow N, Taylor E, Casey BJ, Castellanos FX, Wadhwa PD. (2007) Etiologic subtypes of attention-deficit/hyperactivity disorder brain imaging, molecular genetic and environmental factors and the dopamine hypothesis. Neuropsychol Rev 17 39-59. 

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