“…In vivo, stress increases BDNF expression in the PVN in a fast and transient manner [64], which could activate TRH neurons expressing TrkB receptor [63]. One could envisage situations where the TRHergic neuron receives diverse stimuli [65,66], simultaneously or in succession, adjusting the levels of immediate early genes expression, differentially modulating transcription factors as CREB, GR of AP-1 affecting thus, the inhibitory effect of rising corticosterone levels and, depending on the type of stress or previous history of the animal, alter the response to an incoming stimulus.…”