recapitulation of developmental-like mechanisms for neuronal survival and regeneration. Concurringly, ontogenic dependency of central neurons for brain-derived neurotrophic factor (BDNF) is lost during maturation, but is re-acquired after injury. Here we show in organotypic hippocampal slices that thyroxin, the thyroid hormone essential for normal CNS development, induces up-regulation of BDNF upon injury. This change in the effect of thyroxin is crucial to promote survival and regeneration of damaged central neurons. In addition, the effect of thyroxin on the expression of the K-Cl co-transporter (KCC2), a marker of neuronal maturation, is changed from down to up-regulation. Notably, previous results in humans have shown that during the first few days after traumatic brain injury or spinal cord injury, thyroid hormone levels are often diminished. Our data suggests that maintaining normal levels of thyroxin during the early posttraumatic phase of CNS injury could have a therapeutically positive effect.
Shulga A, Blaesse A, Kysenius K, Huttunen HJ, Tanhuanpää K, Saarma M, Rivera C. Thyroxin regulates BDNF expression to promote survival of injured neurons. Mol Cell Neurosci. 2009 September Institute of Biotechnology, University of Helsinki, Viikki Biocenter, FIN-00014, Helsinki, Finland.