Deiodinase 2 expression throughout perinatal stages of development in rodents

Resumen del póster presentado al 16th Congress of the Spanish Society for Neuroscience, celebrado en Granada del 23 al 25 de septiembre de 2015.Thyroid hormones (TH) play an essential role both in the developing and the adult central nervous system (CNS). The thyroid gland produces mainly thyroxine (T4) but the active hormone at a transcriptional level is the 3,5,3¿-triiodothyronine (T3). In the adult CNS 80% of the intracellular concentrations of T3 are modulated by the activity of type 2 deiodinase (D2) in astrocytes that converts T4 into T3. However, studies in rodents suggest that during embryonic development the only pathway for T3 availability in the brain is the one mediated by D2. Nevertheless, the timing and localization of the expression of D2 at perinatal stages of development in rodents still remains unknown. This is probably due to technical limitations because D2 has a very short half-life as it undergoes selective ubiquitination and proteasomal degradation. It is crucial to determine its location to fully understand T3 action. Here we have developed the necessary tools to study the mRNA and protein expression of D2 in vivo at a regional and cellular level. We have chosen several perinatal stages of development (Embryonic day15 (E15), E18, Postnatal day 1 (P1), P3 and P5) and we have successfully optimised immunohistochemistry and in situ hybridization techniques. We have characterised D2 expression pattern that changes throughout development especially from E15 to E18. Among other regions, D2 appears to be located at the Blood-Brain-Barrier and the Cerebrospinal-Fluid-Barrier. We have also obtained preliminary results of D2 protein expression with a commercial antibody that has provided additional information and better resolution. We are currently working on verifying the specificity of this antibody. In conclusion, D2 presents a dynamic expression throughout perinatal brain ontogeny, possibly adapting to meet the different cellular T3 requirements during development. The main role of D2 at early stages seems to be converting T3 into T4 at the brain barriers.Peer Reviewe