Dopamine dopaminergic neuron

Neuromelanin, a dark colored pigment and product of the oxidative metabolism of dopamine, is found in the cytoplasm of dopaminergic neurons of the human substantia nigra pars compacta. Neuromelanin deposits increase with age, matching the age distribution of Parkinson s disease. In the absence of significant quantities of iron, neuromelanin can act as an antioxidant in... 

Kaxp channels under investigation resulted in selective rescue of substantia nigra dopaminergic neurons does not prove a deleterious, neurodegeneration-promoting role of Katp channels, but may simply mean that the dopamine neurons, lacking KATP channels, have developed other, undetected self-protection mechanisms. 

The dopamine precursor l-DOPA (levodopa) is commonly used in TH treatment of the symptoms of PD. l-DOPA can be absorbed in the intestinal tract and transported across the blood-brain barrier by the large neutral amino acid (LNAA) transport system, where it taken up by dopaminergic neurons and converted into dopamine by the activity of TH. In PD treatment, peripheral AADC can be blocked by carbidopa or benserazide to increase the amount of l-DOPA reaching the brain. Selective MAO B inhibitors like deprenyl (selegiline) have also been effectively used with l-DOPA therapy to reduce the metabolism of dopamine. Recently, potent and selective nitrocatechol-type COMT inhibitors such as entacapone and tolcapone have been shown to be clinically effective in improving the bioavailability of l-DOPA and potentiating its effectiveness in the treatment of PD. 

DAT (SLC6A3) Dopamine -5 CNS dopaminergic neurons (emanate from substantia nigra, other mid brain nuclei, hypothalamus) ... 

Conserved dopamine neurotrophic factor (CDNF) is a newly discovered growth factor with a high specificity and activity to promote survival of dopaminergic neurons in vitro and in vivo. CDNF is homologous to an astrocyte-derived growth factor, MANF-1. 

The nigrostriatal tract is one of the four main dopaminergic pathways in the central nervous system. About 75% of the dopamine in the brain occurs in the nigrostriatal pathway with its cell bodies in the substantia nigra, whose axons project in the corpus striatum. Degeneration of the dopaminergic neurons in the nigrostriatal system results in Parkinsons disease. 

Momiyama, T, Nao5uiki, T and Saso, M (1993) A mechanism underl5dng dopamine Di and D2 receptor-mediated inhibition of dopaminergic neurons in the ventral tegmental area in vitro. Br. J. Pharmacol. 109 933-940. 

COMMENT You have presented some evidence that dopamine may be involved in the neurotoxic action of methamphetamine in terms of dopaminergic neurons, and you presented evidence suggesting that it may be involved in not only the dopamine system but also the serotonin system. 

This benzylisoquinoline alkaloid inhibits in vitro the specific bonding of [3H] dopamine to dopamine receptors and abrogates amphetamine-induced circling behavior in rodents with unilateral degeneration of dopaminergic neurons in the corpus striatum (109). 

These symptoms are alleviated by administering levodopa (L-dopa), a precursor for dopamine. L-dopa is taken up by the axon terminals of dopaminergic neurons and used to form dopamine. Interestingly, in some patients, a side effect of dopamine replacement therapy is the development of symptoms characteristic of schizophrenia. (Recall that this mental disorder is caused by overactive dopaminergic neurons.) On the other hand, drugs used to treat schizophrenia — dopamine receptor antagonists — may elicit symptoms of Parkinson s disease. 

The histaminergic neurons have several well-developed primary and secondary dendrites that overlap with each other. Furthermore, long dendrites from histaminergic neurons located close to the mammillary recess or to the basal surface of the mammillary body appear to penetrate into the ependymal layer and make contact with cerebrospinal fluid. Thus, it is likely that neuroactive substances such as cytokines, present in the cerebrospinal fluid, may influence the discharge activity of TMN neurons (Wada et al., 1991). Unlike the dopaminergic neurons, which are known to release dopamine from their dendrites, there is no evidence that these histaminergic dendrites store and/or release HA. 

In rats, lesions targeting presumptively wake-active dopaminergic neurons that extend dorsally from the VTA into the ventral periaqueductal gray have recently been shown to result in c. 20% reductions in wakefulness (Lu et al. 2006). Daytime sleepiness and SOREMs were reported in a non-human primate following systemic delivery of the dopamine neurotoxin MPTP (Daley et al. 1999), and this was subsequently confirmed in two additional animals (Daley... 

Seutin V. (2005). Dopaminergic neurones much more than dopamine Br. J. 

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