Connexin switch in glial network maturation

LUCILA BROCARDO; LORENA RELA

Mar del Plata

Congreso; XXXII Congreso Anual; 2017

Sociedad Argentina de Investigación en Neurociencias

Connexin switch in glial network maturationOlfactory bulb innervation by olfactory sensory neurons (OSNs) refines post-natally and is a sensory activity-dependent process. OSNs associate to olfactory ensheathing cells (OECs), specialized glia organized in connexin 43 gap junction mediated networks. We propose that glial networks refine simultaneously with neuronal circuits. Previous results showed that OEC networks exist at neonatal ages, and that OEC sensitivity to meclofenamic acid (MFA, gap junction blocker) is comparable at neonate and juvenile stages. MFA-sensitivity is absent in OECs with deletion of the gap junction protein Cx43 at juvenile and adult ages. Strikingly, OECs show minimal Cx43 expression at P0-3 and higher levels from P4-30, suggesting a connexin switch during circuit refinement. By means of dye-coupling experiments we show that OEC network size diminishes with age. Surprisingly, dye-coupling is affected at P7 but not at P3 Cx43 KO OECs, indicating Cx43 independence at P3. To assess the molecular bases of these results, we used mice expressing a fluorescent reporter in OECs. mRNA was extracted from OEC-enriched samples by laser microdissection microscopy. We were able to specifically detect OEC markers and avoid contamination with neuronal transcripts. Cx29, a putative candidate to mediate OEC networks in the absence of Cx43 was not detected. These results suggest that OECs mature with the neuronal circuit, reflected in network selectivity and the molecular bases for connectivity.