IBCN   20355
INSTITUTO DE BIOLOGIA CELULAR Y NEUROCIENCIA "PROFESOR EDUARDO DE ROBERTIS"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Hypoxic cell death shares a common execution pathway with naturally occurring cell death
Autor/es:
POZO DEVOTO, V M; FISZER DE PLAZAS, S
Lugar:
Buzios, Brasil.
Reunión:
Congreso; I IBRO/LARC Congress of Neurosciences of Latin America, The Caribbean and Iberian Peninsula, Buzios, Brazil; 2008
Resumen:
&lt;!-- /* Font Definitions */ @font-face {font-family:Verdana; panose-1:2 11 6 4 3 5 4 4 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:536871559 0 0 0 415 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0pt; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 85.05pt 70.85pt 85.05pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --&gt; The aim of the present work was to compare mechanisms involved in the execution of the naturally ocurring cell death (NOCD) and in the hypoxic cell death (HxCD). Also, we have tested the influence of the fibers of the retinal ganglion cells (RGC) on the HxCD that occurs in the optic tectum (OT). In previous works we have found that TUNEL+ nuclei, active caspase-3 and nuclear pyknosis colocalize for both control (C) and hypoxic (Hx) (8% [O2], 60 min) embryos of embryonic day (ED) 12. However, only at 6 h post-hypoxia (p-hx) a significant increase in cell death rate was observed (Neuroscience, 142,645. 2006). In the present study, a co-immunofluorescence anti-cytochrome C and anti-active caspase-9 was performed in C and Hx OT. Both treatments present colocalization of cytoplasmatic cytochrome C and active caspase-9, observed with confocal microscopy and nuclear pyknosis was detected with Hoechst stain. In Hx embryos the increase in the presence of both markers was observed at 4 and 6 h p-hx. Electron microscopy was performed to analyze differences in cell degeneration phenotype for C and Hx embryos. Both treatments showed figures clearly apoptotic, with dense circular-shaped nuclear material, absence of a regular nuclear membrane and absence of organelles . To test the influence of the RGC fibers on the HxCD, the right eye of ED4 embryos was removed and then left to develop until ED12 where cuantification of TUNEL+ nuclei of entire OT sections was performed in C and Hx embryos. We have found no significant differences between contralateral (without fibers) and ipsilateral (with fibers) OT in neither of the treatments (CC:233 ±25 vs. CI:255 ±36; HxC:416 ±55 vs. HxI:388 ±56; p>0,05 for both comparisons). However, Hx OT had a significant increase in TUNEL+ nuclei compared to C for both sides (same values as above: CC vs. HxC, p<0,05; CI vs. HxI, p<0,05). Colocalization and electron microscopy results suggest that the same execution pathway of cell death is shared by both the NOCD and the HxCD, namely the intrinsic mitochondrial pathway. Enucleation experiments show that retinal fibers are not involved in HxCD (i.e. via excitotoxicity or neurotrophic factors).