Hypothermia prevents synaptic actin cytoskeletal modifications induced by hypoxia

MARÍA INÉS HERRERA, MARÍA LAURA AÓN-BERTOLINO, JUAN ROMERO, MARIANA HOLUBIEC, L GIRALDEZ, G SANTOS, GEORGE BARRETO, F CAPANI

Congreso; Meeting of the American Society for Neuroscience; 2014

Perinatal asphyxia (PA) damages synaptic proteins, resulting in cytoskeletal alterations, protein aggregation and neuronal death. In the previous works, we have shown neuronal and synaptic changes in rat neostriatum subjected to hypoxia that leads to ubi-protein accumulation. Recently, we also showed that, changes in F-actin organization could be related to early alterations induced by hypoxia in the central nervous system. In addition, little is known about effective treatment to diminish the damage. The main aim of this work is to study the effects of birth hypothermia on the actin cytoskeleton of neostriatal post-synaptic densities (PSD) in 60 days olds rats by immunohistochemistry, photooxidation and western blot. We used 2 different protocols of hypothermia: (a) intrahypoxic hypothermia at 15 °C and (b) post-hypoxia hypothermia at 32 °C. Consistent with previous data at 30 days, staining with phalloidin-Alexa(488) followed by confocal microscopy analysis showed an increase of F-actin fluorescent staining in the neostriatum of hypoxic animals. Correlative phalloidin-eosin photooxidation and electron microscopy confirmed these observations showing an increment in the number of mushroom-shaped F-actin staining spines in neostriatal excitatory synapses in PA rats. In addition, western blot revealed β-actin increase in PSDs in hypoxic animals. When hypoxia was done under hypothermic conditions, changes observed in actin cytoskeleton were blocked. Post-hypoxic hypothermia showed similar answer but actin cytoskeleton modifications were not totally reverted as we observed at 15°C. These data suggest that the decrease of the body temperature blocked the actin modifications in dendritic spines preventing the neuronal death. Supported by CONICET, UBACYT and UAJFK.