Non-coding enhancer RNA regulates NPAS4 in the mPFC to control chronic stress-induced anhedonia-like behavior

Chronic stress can produce reward system deficits (i.e. anhedonia) and other common symptoms associated with depressive disorders, as well as neural circuit hypofunction in the medial prefrontal cortex (mPFC). However, the molecular mechanisms by which chronic stress promotes depressive-like behavior and hypofrontality remain poorly understood.C57BL/6 adult male mice were subjected to chronic social defeat stress (CSDS). Neuronal PAS domain-containing protein 4 (NPAS4) or the Npas4 lnc-eRNA were reduced using a viral-mediated shRNA approach. CSDS-induced behaviors, including social avoidance, sucrose preference, natural reward motivation, and anxiety-like behavior, were then measured. CSDS-induced changes in mPFC dendritic spine density were assessed using confocal imaging, and the mPFC NPAS4-regulated transcriptome was assessed using RNA-seq analysis.Social defeat stress induced transient expression of NPAS4 in the mPFC. Viral-mediated knockdown of mPFC NPAS4 blocked CSDS-induced reduction in sucrose preference and changes in natural reward motivation, but without influencing social avoidance. NPAS4 was also required for CSDS-induced reduction of pyramidal neuron dendritic spine density in mPFC. RNA-seq analysis from mPFC tissues revealed that NPAS4 influences expression of numerous genes linked to glutamatergic synapses and ribosomal function, and to genes dysregulated in multiple neuropsychiatric disorders, including depression. Finally, we found that stress-induced expression of NPAS4 in mPFC requires a novel, activity-regulated lnc-eRNA, and that this Npas4 lnc-eRNA in mPFC was required for CSDS-induced anhedonia-like behavior.Together our findings reveal a novel, stress-regulated and lnc-eRNA-dependent transcriptional mechanism in the mPFC that promotes dendritic spine loss and development of anhedonia-like behaviors.