Imaging dopamine metabolism with PET

Dopamine is a chemical messenger produced within the nerve cells that is essential for the transmission of the nerve impulse and hence involved in a wide range of important functions, including movement, cognition and behaviour. Dysfunctions in the central nervous dopamine system can lead to diseases such as Parkinson s and schizophrenia. Alterations in the levels of this neurotransmitter have also been implicated in a variety of behavioural problems such as attention deficit and hyperactivity. 

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. 

AAAD = Aromatic L-amino acid decarboxylase TH = Tyrosine hydroxylase 

These examples show how PET can provide valuable information on the metabolism and the molecular events associated with the function of an important neurotransmitter. Besides providing a better molecular understanding of the central nervous system, these radiotracers can also be of great help at the time of designing and developing drugs to treat diseases associated with dysfunctions in the central nervous dopamine system (see Section 13.3.4). 

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