A role for eukaryotic translation initiation factor 2B (eIF2B) in taste memory consolidation and in thermal control establishment during the critical period for sensory development

All species exhibit critical periods for sensory development, yet very little is known about the molecules involved in the changes in the network wiring that underlies this process. Here the role of transcription regulation of the translation machinery was determined by evaluating the expression of eIF2Bε, an essential component of translation initiation, in both taste-preference development and thermal control establishment in chicks. Analysis of the expression pattern of this gene after passive-avoidance training revealed clear induction of eIF2Bε in both the mesopallium intermediomediale (IMM) and in the striatum mediale (StM). In addition, a correlation was found between the concentration of methylanthranilate (MeA), which was the malaise substrate in the passive-avoidance training procedure, the duration of memory, and the expression level of eIF2Bε. Training chicks on a low concentration of MeA induced short-term memory and low expression level of eIF2Bε, whereas a high concentration of MeA induced long-term memory and a high expression level of eIF2Bε in both the IMM and StM. Furthermore, eIF2Bε-antisense "knock-down" not only reduced the amount of eIF2Bε but also attenuated taste memory formation. In order to determine whether induction of eIF2Bε is a general feature of neuronal plasticity, we checked whether it was induced in other forms of neuronal plasticity, with particular attention to its role in temperature control establishment, which represents hypothalamic-related plasticity. It was established that eIF2Bε-mRNA was induced in the preopotic anterior hypothalamus during heat conditioning. Taken together, these results correlate eIF2Bε with sensory development.