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Abstract(s)
Apesar de não serem capazes de produzir potenciais de acção, é sabido que os astrócitos integram as sinapses, sendo capazes de detectar e responder a estímulos externos com dinâmicas de cálcio espaciotemporalmente complexas, podendo modelar a transmissão sináptica. O objectivo deste projecto é avaliar as dinâmincas de cálcio dos astrócitos através da modelação do seu microambiente electrofisiológico. Para tal, culturas de astrócitos foram estimuladas recorrendo a ThinMEAs©, monitorizando a actividade de cálcio. Os resultados obtidos demonstraram que os astrócitos respondem a estímulos de ±600mV ou ±800mV, gerando uma onda de cálcio que se propaga para células vizinhas. A amplitude, tempo de subida e velocidade de propagação da onda de cálcio está dependente do estímulo, sendo que um estímulo de maior amplitude resulta numa resposta de maior amplitude, demorando mais tempo a atingir o seu pico máximo mas atingindo distâncias mais longas. Apesar de preliminares, estes resultados indicam que os astrócitos são capazes de detectar e responder a mudanças eléctricas externas. Desta forma, os astrócitos são células electricamente excitáveis, possivelmente através do seguinte mecanismo: a estimulação leva à abertura dos canais de cálcio voltagem-dependentes de maneira dependente da voltagem, que irá sensibilizar o retículo endoplasmático resultando numa cascata de libertação de cálcio, gerando uma onda de cálcio que se irá propagar através de junções comunicantes ou gliotransmissão vesicular.
Although not able to generate action potentials, it is known that astrocytes integrate synapses, being able to sense and respond to external stimuli with complex calcium dynamics, having the ability to shape synaptic transmission. The aim of this project is to assess astrocytic calcium dynamics upon the modulation of their eletrophysiological microenvironment. To accomplish this, astrocyte cultures were electrically stimulated using ThinMEAs© while monitoring their calcium activity. Obtained data showed that astocytes respond to a ±600mV or ±800mV stimulus by generating a calcium wave which propagates to neighboring cells. The amplitude, rise time and propagation velocity of the calcium wave is dependent on the stimulus, with a higher stimulation amplitude leading to a higher response amplitude, wich takes longer to reach its maximum peak but reach a larger distance. Although preliminary, these results indicate that astrocytes are able to sense and respond to changes of the electrical environment. In this way, astrocytes are electrically excitable cells, possibly due to the following mechanism: electrical stimulation causes voltage-gated calcium channels to open in a voltage-dependent manner, which will sensitize the endoplasmic reticulum leading to a cascade of calcium releases, generating a calcium wave, which will propagate through gap junctions or vesicular gliotransmission.
Although not able to generate action potentials, it is known that astrocytes integrate synapses, being able to sense and respond to external stimuli with complex calcium dynamics, having the ability to shape synaptic transmission. The aim of this project is to assess astrocytic calcium dynamics upon the modulation of their eletrophysiological microenvironment. To accomplish this, astrocyte cultures were electrically stimulated using ThinMEAs© while monitoring their calcium activity. Obtained data showed that astocytes respond to a ±600mV or ±800mV stimulus by generating a calcium wave which propagates to neighboring cells. The amplitude, rise time and propagation velocity of the calcium wave is dependent on the stimulus, with a higher stimulation amplitude leading to a higher response amplitude, wich takes longer to reach its maximum peak but reach a larger distance. Although preliminary, these results indicate that astrocytes are able to sense and respond to changes of the electrical environment. In this way, astrocytes are electrically excitable cells, possibly due to the following mechanism: electrical stimulation causes voltage-gated calcium channels to open in a voltage-dependent manner, which will sensitize the endoplasmic reticulum leading to a cascade of calcium releases, generating a calcium wave, which will propagate through gap junctions or vesicular gliotransmission.
Description
Keywords
Astrocitos Imagens de cálcio Estimulação eletrica Análise de bioimagem Astrocytes calcium waves Calcium imaging Electrical stimulation microelectrode arrays Bioimage analysis