INVESTIGADORES
TORBIDONI Ana vanesa
congresos y reuniones científicas
Título:
Expression of Endothelin and its Receptors in Light-Injured Retina.
Autor/es:
AM SUBURO, V TORBIDONI, M IRIBARNE, G PRASANNA.
Lugar:
Florida, United States.
Reunión:
Congreso; Association for Research in Vision and Ophthalmology, Annual meeting; 2004
Institución organizadora:
Association for Research in Vision and Ophthalmology
Resumen:
Purpose: Endothelins are powerful vasoconstrictor peptides, that also act as astrocytic growth factors, regulators of gap junctions conductance and bloodretinal barrier permeability. Since they could be involved in the glial response to retinal injury, we have studied the expression of endothelins and their receptors in mouse retinas submitted to constantlightinduced photoreceptor degeneration.
Methods:BALBc mice were bred under cyclic low level illumination. Experimental animals were kept under 1,500 lux for periods of 3, 6, 9 and 18 days. Retinas obtained from perfusionfixed mice were incubated with antibodies against glial fibrillary acidic protein (GFAP), endothelins 1 and 3 (ET1 and ET3) or their receptors ETA, ETB. Areas of astrocyte immunoreactivity (ir) were measured in retinal wholemounts using Kontron 400. For RTPCR, RNA was extracted from nonfixed retinas.
Results:Almost half of the outer nuclear layer disappeared after 6 days of constant illumination, whereas only a single layer of cell nuclei remained after 18 days. Gliosis, as evidenced by the area of GFAP immunoreactivity, increased after 3 days of illumination. In normal retinas, ET1ir was only detected in astrocytes, as shown by colocalization with GFAP. ET3ir could not be observed. ETAir and ETBir appeared on endothelial cells. ETAir was also present in ganglion cells and outer plexiform layer (OPL). Astrocytes exhibited very low levels of ETBir. In lightinjured retinas, astrocytic ET1ir area steadily increased during the experimental period. Significant changes, however, were only present at the 18 day stage. The ratio ET1/actin mRNA increased in a similar fashion. By contrast, area of astrocytic ETBir showed an early increase, significant differences being detected by the 6 day stage. No changes in endothelial and ganglion cell immunoreactivities could be detected, but ETAir disappeared from OPL.
Conclusions:Gliosis, affecting both Müller cells and astrocytes, was an early event in our experimental model. The endothelinergic system seemed to be specifically associated to astrocytes, since neither the ligands nor the receptors could be detected in Müller cells. The early increase in astrocytic ETB immunoreactivity suggests that this receptor might probably be involved in the gliotic response.