Epigenetic modulation of neural circuits facilitates learning and memory. Here, we examined specific inhibition of histone deacetylase 2 (HDAC2) expression in rats receiving a single intracerebroventricular injection of HDAC2-targeted anti-sense oligonucleotides (ASOs) one month prior to cognitive testing. The HDAC2 ASO-injected rats displayed increased novelty preference, decreased cortical and hippocampal HDAC2 mRNA and protein, and upregulated gene expression that persisted 1-month post-injection. Cortical RNA-seq revealed strongly increased transcription of a subset of cyclic adenosine monophosphate (cAMP)-response element binding (CREB) genes known to influence synaptic plasticity, along with dopamine (DRD1, DRD2) and adenosine (ADORA2A) G-protein-coupled receptors (GPCRs). Our analysis identified evidence of a positive-feedback loop that amplified expression of CREB-regulated Gs GPCRs and genes in cAMP/Gs/Gi signaling pathways. Additionally, we found differential expression of enzymes that shift neurotransmitter biosynthesis away from norepinephrine and toward dopamine and acetylcholine (DBH, CHAT). We also observed increased expression of genes important for neurotransmitter packaging (SV2C, VMAT) and release (SYT9). The data indicate that persistent inhibition of HDAC2 expression enables long-lived enhancement of aspects of cognition through increased cortical transcription of a subset of CREB-regulated genes amplified by a positive-feedback mechanism that increases synaptic plasticity and shifts neurotransmitter balance toward increased dopaminergic and cholinergic signaling.
bioRxiv Subject Collection: Neuroscience