Nicotinic acetylcholine receptors envolvement in Central Nervous System disorders [La participación de los receptores de acetilcolina nicotínicos en trastornos del Sistema Nervioso Central]
Por:
López-Valdés H.E., García-Colunga J.
Publicada:
1 ene 2003
Resumen:
Nicotinic acetylcholine receptors (nAChRs) are cationic channels opened after binding of the neurotransmitter acetylcholine (ACh). These receptors are membrane proteins composed of five subunits and are the key for the cholinergic nicotinic transmission in the neuromuscular junction as well as in different areas of the peripheral and central nervous system (PNS and CNS respectively), where they are widely distributed. Muscle and PNS nAChRs are located postsynaptically, mediating excitatory responses. In the CNS the nAChRs are preferentially located in presynaptic neurons, modulating the release of neurotransmitters such as dopamine, serotonin, ?-aminobutiric acid, noradrenaline, ACh and glutamate. Up to this day, 17 different genes encoding nAChR subunits have been identified. The subunits that form fetal skeletal muscle nAChRs are ?1, ?1, ? and ?. The ? subunit is changed by ? subunit in adult muscle nAChRs. In the nervous system the ?2-?10 and ?2-?4 nAChR subunits have been identified, being ?4 and ?2 the predominant subunits in the brain. In the CNS, different combinations of subunits produce multiple nAChR subtypes, showing different functional properties. Each nAChR subtype may present different regional, cellular and subcellular distribution, which may help to explain the involvement of nAChRs in different physiological and pathological processes: muscle contraction, memory, attention, learning, the Alzheimer's and Parkinson's diseases, schizophrenia, anxiety and depression. Alzheimer's disease is a neurodegenerative condition that mainly affects persons older than sixty-five years. It is characterized by a progressive cognitive impairment, including loss of memory. On the other hand, Parkinson's disease produces degeneration of dopaminergic neurons in the substantia nigra and a motor dysfunction (muscular rigidity, tremor and bradykinesia). Patients with Parkinson's disease frequently present also cognitive dysfunctions or dementia. In patients with Alzheimer's and Parkinson's diseases have been identified a decrease of both, cholinergic projections and quantity of nAChRs. The use of nicotine and nAChR agonists has beneficial effects in patients with these diseases. Furthermore, the treatment with nicotine increases the memory capacity and prevents the neurotoxin-induc
Filiaciones:
López-Valdés H.E.:
Instituto de Neurobiología, Univ. Nacional Autonoma de Mexico, Campus Juriquilla, Apartado Postal 1-1141, 76001, Juriquilla, Querétaro, Mexico
García-Colunga J.:
Instituto de Neurobiología, Univ. Nacional Autonoma de Mexico, Campus Juriquilla, Apartado Postal 1-1141, 76001, Juriquilla, Querétaro, Mexico
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