Unusual ultrastructural findings in dendrites of pyramidal neurons in the cerebral cortex of rabies-infected mice
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Abstract
Previous studies using the Golgi technique have demonstrated alterations in the dendritic morphology of pyramidal neurons of the cerebral cortex of mice inoculated with the rabies virus. However, knowledge about the fine structure of dendrites in rabies infection is scarce. This work had the aim of studying the ultrastructure of dendrites in cortical pyramidal neurons of rabies-infected mice. Mice were inoculated intramuscularly with a street rabies virus of canine origin. The animals that showed an advanced stage of disease were fixed by perfusion with glutaraldehyde and paraformaldehyde. Brains were removed and cut on a vibratome to obtain coronal slices of 200 micrometers of thickness. Vibratome slices were subjected to the following treatment: postfixation, dehydration, embedding in epoxy resin and polymerization between glass slides. Ultrathin sections of oriented tissue fragments from the cerebral cortex were obtained and observed under electron microscope. The most significant ultrastructural findings were located within distal dendrites of cortical pyramidal neurons: loss of mitochondria, disorganization and loss of microtubules, formation of vacuoles interrupting the continuity of the cytoplasm and formation of myelin-like figures. These strange myelin figures, which apparently had not been reported in previous studies of rabies, were the most noticeable ultrastructural feature. They also differ from the best known myelin figures formed by concentric lamellae. The possible origin of these myelin figures as result of mitochondrial degeneration is discussed.
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2015. Unusual ultrastructural findings in dendrites of pyramidal neurons in the cerebral cortex of rabies-infected mice. PeerJ PrePrints 3:e847v1 https://doi.org/10.7287/peerj.preprints.847v1Author comment
This is a submission to PeerJ for review.
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Competing Interests
The authors declare they have no competing interests.
Author Contributions
Orlando Torres-Fernández conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper.
Jeison Monroy-Gómez performed the experiments, analyzed the data, prepared figures and/or tables, reviewed drafts of the paper.
Ladys E Sarmiento performed the experiments, analyzed the data, prepared figures and/or tables, reviewed drafts of the paper.
Animal Ethics
The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):
This work was approved by the Ethics Committee of the Instituto Nacional de Salud (Bogotá, Colombia) according to Act No. 8 October 13 2011
Funding
This work was funded by Departamento Administrativo de Ciencias, Tecnología e Innovación COLCIENCIAS and the Instituto Nacional de Salud (INS, Colombia). Code of Grant 210454531601. Contract 378/2011. The participation of the second author (JMG) was financed by COLCIENCIAS and the INS under the 'Jóvenes Investigadores e Innovadores' Program (Contract 0237/2012). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
