4 research outputs found
Organizaci贸n funcional de las ves铆culas sin谩pticas en neuronas de hipocampo y su participaci贸n en los fen贸menos de facilitaci贸n y depresi贸n de la sinapsis
Los Objetivos de la Tesis son: 1.C谩lculo de la fracci贸n en la superficie de la Sinaptofisina-fluorina `SypHy226}0en la membrana de neuronas de hipocampo en cultivo y la evaluaci贸n de la resoluci贸n y la sensibilidad de esta sonda para el estudio de las disLos Objetivos de la Tesis son:
I. C谩lculo de la fracci贸n en la superficie de la Sinaptofisina-fluorina `SypHy麓 en la membrana de neuronas de ...
II. An谩lisis de los fen贸menos de fusi贸n y de reciclaje en condiciones de estimulaciones m铆nimas (un 煤nico potencial de acci贸n) y de altas estimulaciones (10, 40 y 100 PA), cuantificaci贸n de la amplitud de la respuesta cuantal y de las constantes de endocitosis y de exocitosis.
III. Estudio del efecto del calcio a una alta concentraci贸n de 10mM sobre la actividad sin谩ptica en distintas intensidades de estimulaci贸n.
IV. Caracterizaci贸n y cuantificaci贸n del tama帽o de los distintos contingentes vesiculares presin谩pticos y determinaci贸n del n煤mero de ves铆culas del terminal presin谩ptico y su distribuci贸n en los distintos contingentes.
V. An谩lisis de la heterogeneidad entre distintas neuronas y distintas sinapsis y el estudio de su relaci贸n con la ubicaci贸n espacial dentro de una misma neurona y el efecto de una alta concentraci贸n de calcio de 10mM sobre esta heterogeneidad.
VI. Monitorizaci贸n de distintos fen贸menos de plasticidad sin谩ptica tanto depresi贸n como facilitaci贸n y an谩lisis del papel del contingente de reposo en la transmisi贸n sin谩ptica y pl谩stica en neuronas de hipocampo en cultivo
G protein-coupled receptor signalling potentiates the osmo-mechanical activation of TRPC5 channels
TRPC5 is an ion channel permeable to monovalent and divalent cations that is widely expressed in different tissues. Although implicated in the control of neurite extension and in the growth cone morphology of hippocampal neurons, as well as in fear-related behaviour, the mechanisms by which TRPC5 is activated remain poorly understood. TRPC5 is known to be activated downstream of Gq-coupled receptors and by membrane stretch, and since there is evidence that mechanical stress may directly activate Gq-coupled receptors, we examined the relationship between the activation of TRPC5 by the type 1 histamine receptor and osmotic stress. Using calcium imaging and patch clamp recordings, we found that a higher proportion of cells expressing TRPC5 respond to hypoosmotic solution when they co-express H1R. This response is associated with a phospholipase C-dependent increase in the cells internal calcium concentration, which is abolished on depletion of calcium stores. We also found that the hypoosmotic stimulus that provokes mechanical stress drives the translocation of TRPC5 to the plasma membrane by a mechanism dependent on PI3K. This increase in TRPC5 at the plasma membrane augments the proportion of cells that respond to hypoosmotic stimulation. Together, these results suggest that hypoosmotic cell-swelling activates Gq-coupled receptors, which in turn enhance the activation of TRPC5 by regulating this channel membrane trafficking. Gq-coupled receptors and TPRC5 are co-expressed in several tissues such as those of the vascular system and in somatosensory neurons, suggesting that this mechanism of TRPC5 activation may have interesting and important implications in arterial pressure sensing and mechanotransduction.The work was supported by grants from the Spanish government (BFU2009-07835 and CONSOLIDER-INGENIO 2010 CSD2007-0023). A-L.C holds a JAE (Junta de Ampliaci贸n de Estudios) predoctoral fellowship from the Spanish Research Council, cofinanced by the European Social Fund