Thalamus nicotinic acetylcholine receptors

The thalamus has one of the highest densities of nicotinic acetylcholine receptors in the brain and is thought to be a critical structure in nicotine dependence (Clarke 2004 Rubboli et al. 1994a, b). As mentioned, Durazzo et al. (2004) obtained... 

Court J, Spurden D, Lloyd S, McKeith I, Ballard C, Cairns N, Kerwin R, Perry R, Perry E (1999) Neuronal nicotinic receptors in dementia with Lewy bodies and schizophrenia alpha-bungarotoxin and nicotine binding in the thalamus. J Neurochem 73 1590-1597 Couturier S, Bertrand D, Matter JM, Hernandez MC, Bertrand S, MiUar N, Valera S, Barkas T, Ballivet M (1990) A neuronal nicotinic acetylcholine receptor subunit (alpha 7) is devel-opmentally regulated and forms a homo-oligomeric channel blocked by alpha-BTX. Neuron 5 847-856... 

Ray MA, Graham AJ, Lee M, Perry RH, Court JA, Perry EK (2005) Neuronal nicotinic acetylcholine receptor subunits in autism an immunohistochemical investigation in the thalamus. Neurobiol Dis 19 366-377... 

Actions of acetylcholine (ACh) are referred to as muscarinic based on the observation that muscarine acts selectively at certain sites and, quahtatively, produces the same effects as ACh. Peripheral muscarinic acetylcholine receptors are found primarily on autonomic effector cells innervated by postganghonic parasympathetic nerves and on some cells that receive little or no cholinergic innervation but express muscarinic receptors e.g., vascular endothelial cells). There are also muscarinic receptors in ganglia and the adrenal meduUa, where muscarinic stimulation seems to modulate the effects of nicotinic stimulation. Within the central nervous system (CNS), the hippocampus, cortex, and thalamus have high densities of muscarinic receptors. 

Other approaches, some of which are still in clinical development, include restoration of the acetylcholine-dopamine balance in the basal ganglia, neuronal nicotinic receptor agonists, neurotrophic immunophilins, dopamine transport inhibitors, COMT-inhibitors, and adenosine A2A receptor antagonists.162,163 Also surgical therapies are used or under development, including stereotactic thalamotomy, continuous electric thalamus stimulation,164 posteroventral pallidotomy and transplantation of embryonal substantia nigra cells. 

In 1926, Otto Loewi discovered that acetylcholine was the principal neurotransmitter of the parasympathetic nervous system. As with other neurotransmitters, acetylcholine is synthesized and stored in vesicles within presynaptic neurons. Ninety percent of the cholinergic neurons in the brain are muscarinic, controlling salivation,sweating, dyspnea, diarrhea, vertigo, confusion, weakness and coma. Acetylcholine binds to muscarinic receptors on smooth muscle cells, innervated by post-synaptic fibers of the parasympathetic nervous system. The thalamus and cerebellar cortex have nicotinic receptors, i diile most other regions of the brain have muscarinic neurons. 

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