Dopamine/dopaminergic system receptors

Dopamine is a catecholamine neurotransmitter in the CNS and at some ganglia in the autonomic nervous system. To date, three main types of receptors have been found D1( D2, and D3. The main dopaminergic systems in the brain are the nigro-neostriatal... 

The precise functions of the opioid receptor subtypes remain to be delineated. In many studies, it has been established that they modulate the functions of the dopaminergic system. For example, administration of morphine into the area 10 region results in a dopamine-dependent increase in locomotor activity. Electiophysiological studies of area 9 neurons suggest that p and k opioids have opposite effects on motor behaviors activation or sedation, respectively. The k and p agonists have also been found to exert opposite actions with respect to fluid regulation diuretic and... 

It is well known that typical neuroleptics, all of which have a high affinity for dopamine receptors (particularly D2 receptors), do not effectively treat all schizophrenic patients and have only limited beneficial effects on the negative symptoms of the illness. Furthermore, neither typical nor atypical neuroleptics have an immediate effect on the positive symptoms even though it can be shown by both experimental studies in animals and by imaging methods in schizophrenic patients that neuroleptics rapidly bind to dopamine receptors. Thus factors other than an overactive dopaminergic system are probably operative in this disorder. The question is which of the numerous neurotransmitters and modulatory neuropeptides are responsible for both the negative symptoms and the delay in onset of the therapeutic effects of neuroleptics on the positive symptoms ... 

Because of the discovery that all neuroleptics in clinical use are dopamine receptor antagonists, and that an abnormality in the dopaminergic system might underlie the pathology of the condition, the action of neuroleptics on the dopaminergic system has been extensively studied over the past two decades. Four major anatomical divisions of the dopaminergic system have been described ... 

---