Pars compacta

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... 

ANSWER I think that is controversial right now. Yes, I think there is a projection system that runs from the pars reticulata to pars compacta, but the consequences of activation of that system and how you would get access to it are not well understood at this time. 

Bums, R.S. Chieuh, C.C. Markey, S.P. Ebert, M.H. Jacobowitz, D.M. and Kopin, I.J. A primate model of parkinsonism Selective destraction of dopaminergic neurons in the pars compacta of the substantia nigra by n-methyl-4-phenyl-l,2,3,6-tetrahydropyridine.. Proc Natl Acad Sci USA 80 4546-4550, 1983. 

The neural structures involved in the promotion of the waking (W) state are located in the (1) brainstem [dorsal raphe nucleus (DRN), median raphe nucleus (MRN), locus coeruleus (LC), laterodorsal and pedunculopontine tegmental nuclei (LDT/PPT), and medial-pontine reticular formation (mPRF)] (2) hypothalamus [tuberomammillary nucleus (TMN) and lateral hypothalamus (LH)[ (3) basal forebrain (BFB) (medial septal area, nucleus basalis of Meynert) and (4) midbrain ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) (Pace-Schott Hobson, 2002 Jones, 2003). The following neurotransmitters function to promote W (1) acetylcholine (ACh LDT/PPT, BFB) (2) noradrenaline (NA LC) (3) serotonin (5-HT DRN, MRN) (4) histamine (HA TMN) (5) glutamate (GLU mPRF, BFB, thalamus) (6) orexin (OX LH) and (7) dopamine (DA VTA, SNc) (Zoltoski et al, 1999 Monti, 2004). 

Consistent with receptor binding studies, k receptor mRNA is expressed in the claustrum and interpeduncular nucleus as well as the ventral tegmental area. High levels of k receptor mRNA levels are expressed in the substantia nigra pars compacta, suggestive that k receptors may be expressed in dopaminergic neurons with a presynaptic location. 

The two hallmark features in the substantia nigra pars compacta are loss of neurons and the presence of Lewy bodies. There is a positive correlation between the degree of nigrostriatal dopamine loss and severity of motor symptoms. PD is relatively asymptomatic until profound depletion (70% to 80%) of substantia nigra pars compacta neurons has occurred. 

Tsuneki H, Klink R, Ldna C, Kom H, Changeux JP (2000) Calcium mobilization ehcited by two types of nicotinic acetylcholine receptors in mouse substantia nigra pars compacta. Eur J Neurosci 12 2475-2485... 

In contrast to acetylcholine, dopamine has both excitatory (Dl) and inhibitory (D2 and D3) receptors. Dopaminergic neurons occur in two closely connected groups AlO—ventral tegmental area (VTA), and A9—substantia nigra, pars compacta (Fig. 3). While substantia nigra neurons project to the striatum, VTA... 

Paolncd E, Berretta N, Tozzi A, et al (2003) Depression of mGlnR-mediated IPSCs by 5-HT in dopamine nenrons of the rat snbstantia nigra pars compacta. Eim J Neimosci 18 2743-2750... 

Inputs from ascending dopamine pathways originating in the substania nigra, pars compacta, play a crucial role in coordinating the output from the striatum (Aosaki et ah, 1994). Explicit dopamine hypotheses for Tourette s syndrome posit either an excess of dopamine or an increased sensitivity of D2 dopamine re-... 

Functional circuitry between the cortex, basal ganglia, and thalamus. The major neurotransmitters are indicated. In Parkinson s disease, there is degeneration of the pars compacta of the substantia nigra, leading to overactivity in the indirect pathway (red) and increased glutamatergic activity by the subthalamic nucleus. 

Dopamine receptors are discussed in detail in Chapters 21 and 29. Dopamine receptors of the Di type are located in the pars compacta of the substantia nigra and presynaptically on striatal axons coming from cortical neurons and from dopaminergic cells in the substantia nigra. The D2 receptors are located postsynaptically on striatal neurons and... 

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