Cellular and Molecular Neurobiology
Author: Javier Hernan Fotti | Email: jfotti@fmed.uba.ar
Javier Fotti1°2°, Lucía Garbini1°2°, Juan Belforte1°2°, Lorena Rela1°2°
1° Universidad de Buenos Aires. Facultad de Ciencias Médicas. Departamento de Ciencias Fisiológicas. Buenos Aires, Argentina.
2° CONICET-Universidad de Buenos Aires. Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO). Buenos Aires, Argentina.
After damage to sensory neurons in the olfactory nerve (ON), stem cells proliferate in the olfactory epithelium and complete regeneration occurs in ~two months. Immune myeloid cells in the ON react to damage with hypertrophy and proliferation. Olfactory ensheathing cells (OECs), ON glia known for their neurotrophic properties, also react to damage. The relative timing of immune and OEC responses to damage is unknown and is relevant to understand possible interactions between them in the regenerative process. We propose that an early response of immune cells triggers the response of OECs. In this study, we evaluated the morphological changes of immune myeloid cells at early stages after ON damage, following administration of methimazole. Analysis of immunostained tissue sections reveals that methimazole-treated mice exhibit higher density of Iba1+ cells in the nerve layer of the olfactory bulb, when compared to control mice (37.91±11.54 versus 10.13±4.12 cells/mm2; p<0,0001, after significant interaction in 2-way ANOVA), as well as reduced cell complexity (6,64±2.96 versus 13,76±6.58 total intersections in sholl analysis; p<0,001), as early as day 3 post-injury. A qualitative analysis of the response of OECs in reporter mice (PLP-CreERT-Tomflox) suggests an earlier (2 days post-injury) hypertrophic response of these cells. These preliminary results allow us to consider a more complex scenario in which OECs may recruit immune cells as an early step in the repair process.