Komunikazio neuronala. Sare sinaptikoaren funtzionamendua eta agente neurotoxikoak

Abstract

[EUS] Nerbio sistemaren funtzionamenduaren inguruan hainbat hipotesi planteatu izan dira urteetan zehar, batez ere bere fisiologiaren eta komunikazio sistemari dagokionez. Gaur egun, argi dago nerbio sistemaren informazio transmisioaren oinarria zelula kitzikagarrietan ematen den ioi mugimendua eta zelula horien artean ematen diren loturak direla. Lotura hauek jarraikortasun zitoplasmatikoa ezarri dezakete edo ez. Horren arabera, sinapsi mota bi definituko dira: elektrikoa eta kimikoa. Sinapsi kimikoetan prozesu oso konplexu eta zehatzak ematen dira, eta horregatik, hain zuzen ere, izan da sinapsi mota hau agente neurotoxiko anitzen itu gunea. Hala ere, sinapsiekin erlazionatzen ez diren beste zenbait elementuk ere adierazten dute neurotoxinekiko afinitatea. Hala nola, kanal ionikoak. Egun, neurotoxina asko ezagutzen dira eta haien ekintza mekanismoen inguruko ezagutza emendatuz doa ikerketak aurreratu ahala. Hala ere, ez dago konposatu hauek era bateratu, ordenatu eta deskriptibo batean taldekatzen dituen sailkapenik. Lan honetan, erronka horri aurre eginez, agente neurotoxikoen sailkapen bat proposatzen da gaur egungo ezagumenduak jarraituz. Hau honela izanda, eta konposatuek azaltzen duten ekintza mekanismoaren arabera, hiru neurotoxina talde bereizi dira: kanal ionikoetan eragina duten neurotoxinak; neurotransmisoreen hidrolisia eragozten duten neurotoxinak eta neurotransmisoreen hartzaile espezifikoetan eragina duten neurotoxinak.

[EN] For years, many hypothesis have been proposed about the functioning of the nervous system, especially regarding its physiology and communication system. Nowadays, it is well understood that the unions between excitable cells and the ionic movement in them, are the basis for the transmission of the information. These unions can establish a cytoplasmic continuation or not. Depending on that, two synapse are described: electrical synapses and chemical synapses. In the case of the chemical synapses, a lot of complex and accurate processes take place, the reason why this type of synapses is the target for many different neurotoxic compounds. Nevertheless, some other elements like ion channels show affinity for neurotoxins, while they are not involved in the synapses. At the moment, a considerable number of neurotoxins are known, and as the studies about them increases, their action mechanisms are better known. However, as there is no an organized and descriptive classification of those neurotoxic compounds, a classification of these compounds will be proposed in this work considering the scientific knowledge. Consequently, on the basis of their action mechanism, three neurotoxin groups can be discriminated: neurotoxins that may have influence over ion channels, neurotoxins that avoid the hydrolysis of the neurotransmitters and neurotoxins that exert influence on the specific receivers of the neurotransmitters.