In addition to Ret51, the TrkB receptors for BDNF are also downregulated under excitotoxic conditions and after transient MCAO,6, 44 suggesting that the impairment of the endogenous neuroprotective signaling mechanisms mediated by receptor tyrosine kinases may be a key event in neuronal death in brain ischemia. This evidence concerns the gene NTRK1 and brain ischemia.