Dopamine and the Dopaminergic Receptors

Dopamine (3,4-dihydroxyphenyl-P-ethylamine, DA) (4.34) is a catecholamine intermediate in the biosynthesis of NE and epinephrine. There are several very important 

Dopamine metabolism was covered in the discussion of general catecholamine biochemistry. Dopamine is stored in synaptic vesicles, and this storage can be manipulated. Although the reuptake of released DA is the major deactivating mechanism, MAO and COMT act enzymatically on DA in the same way as on NE. However, following the degradative pathway of NE, DA will finally be metabolized to homovanillic acid (3-methoxy-4-hydroxy-phenylacetic acid), since it lacks the P-hydroxyl group. 

Parkinson s disease-like movement disorders. Therefore, the motor dysfunctions observed in patients chronically treated with antipsychotics are seemingly due to alterations in D2 receptor density. 

Presynaptic dopamineregic drug effects may be subdivided in the same way as that in which adrenergic drugs were classified in section 4.3.5  

These enable a logical, mechanistic understanding and will be discussed individually. 4.4.2.1 Dopamine Synthesis Inhibitors 

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While dopamine is an intermediate for NE and E, it is also a neurotransmitter in its own right. Dopamine and the dopaminergic receptor, as well as drugs that act on it, are discussed below. 

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