eIF4E-Dependent Translation Potentially Regulates Apoptosis and BDNF/TrkB Signaling in the Medial Prefrontal Cortex During Morphine-Induced CPP.

Morphine addiction is driven in part by persistent reward-associated memory, yet the molecular mechanisms linking translational control to cellular stress responses remain unclear. In the present study, using a mouse morphine-induced conditioned place preference and N2a cell model, we investigated apoptosis-related alterations in the medial prefrontal cortex and the involvement of eIF4E-dependent translational regulation and BDNF/TrkB signaling. Morphine-induced conditioned place preference was associated with an increase in TUNEL-positive cells in the medial prefrontal cortex, accompanied by upregulation of Bax and downregulation of Bcl-2. In N2a cells, morphine induced apoptosis in a dose-dependent manner. Morphine also increased neuronal eIF4E expression in both mPFC tissue and N2a cells, accompanied by upregulation of BDNF and TrkB. Inhibition of the eIF4E/eIF4G interaction with 4EGI-1 significantly affected morphine-induced CPP formation and altered apoptosis-related markers and BDNF/TrkB expression. Notably, intra-mPFC administration of 4EGI-1 suppressed morphine-induced CPP without affecting anxiety-like behavior, locomotor activity, or general learning and memory performance. These findings suggest that eIF4E-dependent translational regulation is functionally associated with morphine-induced reward memory and apoptosis, potentially in association with changes in BDNF/TrkB molecular expression. This study offers novel insight into the molecular basis of morphine addiction and highlights a potentially targetable translational regulatory pathway for therapeutic intervention.