Microscopy Studies to Reveal Changes Induced by Perinatal Asphyxia

ANDREA AGUILAR ; CARLOS F KUSNIER; MARIA INÉS HERRERA ; LUCAS UDOVIN ; NICOLÁS TORO URREGO; CECILIA QUARRACINO ; TAMARA KOBIEC ; KÖLLIKER-FRERS RODOLFO; JUAN P. LUACES; FRANCISCO CAPANI

Congreso; XV Inter-American Congress of Microscopy Societies CIASEM XV ? SAMIC VI in Buenos Aires, Argentina from 1-4 of October 2019.; 2019

Diminish in the oxygen levels prompted short and long-term alterations in synapses and relatedstructures that are related to neuronal dysfunction and death. Perinatal asphyxia (PA) is an obstetriccomplication produced by an impaired gas exchange that lead to neonatal mortality and is a determinantfactor for neurodevelopmental disorders. Since pathophysiological mechanisms triggered by PA are not stilltotally unveiled, we investigated the changes in the cytoskeleton organization in the nervous tissue.For this study, we used a well-established murine model of PA [1]. After one, 2, 4 and 6 months ofsevere PA (20 min) rats were sacrificed and their brains were analyzed by combining photooxidation,conventional electron microscopy, and 3-D reconstruction techniques [1].After one month of PA, we found an increase in the F-actin staining in neostriatal and hippocampaldendritic spines together with some filopodia-likes structures, a typical embryonic type of spines inphotooxidated tissue [2] (Fig 1 A). In contrast, after second month of PA, spines were less consistent stained.In addition, we observed an increment of marker for neuronal and glial dysfunction such as GFAP,neurofilament and MAP-2 [4,5]. These modifications were more striking defined after 4 months of PA [3,4].After 6 months of PA post-synaptic densities (PSDs) in neostriatum were highly modified. Using three-Dreconstructions and electron tomography we were able to find clear signs of degeneration in the asphycticPSDs (Fig 1 B and C) [1].Therefore, we hypothesize that the cytoskeletal changes induced by PA in the rat CNS could lead tothe dramatic modifications in synapse and related structures that trigger neuronal damage. In addition,electron tomography, 3-D reconstruction and photooxidation contributed to dissect critical alterationsgenerated by PA that are not easily displayed using conventional microscopic techniques.