Project description:Understanding the mechanisms by which long-term memories are formed and stored in the brain represents a central aim of neuroscience. Prevailing theory suggests that long-term memory encoding involves early plasticity within hippocampal circuits, while reorganization of the neocortex is thought to occur weeks to months later to subserve remote memory storage. Here we report that long-term memory encoding can elicit early transcriptional, structural and functional remodeling of the neocortex. Parallel studies using genome-wide RNA-sequencing, ultrastructural imaging, and whole-cell recording in wild-type mice suggest that contextual fear conditioning initiates a transcriptional program in the medial prefrontal cortex (mPFC) that is accompanied by rapid expansion of the synaptic active zone and postsynaptic density, enhanced dendritic spine plasticity, and increased synaptic efficacy. To address the real-time contribution of the mPFC to long-term memory encoding, we performed temporally precise optogenetic inhibition of excitatory mPFC neurons during contextual fear conditioning. Using this approach, we found that real-time inhibition of the mPFC inhibited activation of the entorhinal-hippocampal circuit and impaired the formation of long-term associative memory. These findings suggest that encoding of long-term episodic memory is associated with early remodeling of neocortical circuits, identify the prefrontal cortex as a critical regulator of encoding-induced hippocampal activation and long-term memory formation, and have important implications for understanding memory processing in healthy and diseased brain states. 4 biological replicates per group were analyzed. The material analyzed was medial prefrontal cortex (mPFC; anterior cingulate cortex subregion) from both brain hemispheres, from which total RNA was extracted.
Project description:Background: Extinction-based exposure therapy is used in treating anxiety- and trauma-related disorders, however there is the need to improve its limited efficacy in individuals with impaired fear extinction learning and to facilitate the inadequate protection against return-of-fear phenomena. Methods: Spontaneous recovery and fear renewal tests, assessed persistence and context-independence of treatments rescuing deficient fear extinction in 129S1/SvImJ mice. To reveal neurobiological mechanisms supporting long-lasting extinction rescue, whole-genome expression profiling, qRT-PCR, immunohistochemistry and chromatin immunoprecipitation were used. Results: Persistent and context-independent rescue of deficient fear extinction induced by dietary zinc-restriction was associated with enhanced expression of dopamine-related genes, such as genes encoding the dopamine- D1 (Drd1a) and -D2 (Drd2) receptor in the medial prefrontal cortex (mPFC) and amygdala. Moreover, enhanced histone acetylation was observed in the promoter of the extinction-regulated Drd2 gene in the mPFC, revealing a possibly involved gene regulatory mechanism. While enhancing histone acetylation, via administering the HDAC inhibitor MS275, does not induce successful fear reduction during extinction training, it promoted enduring and context-independent rescue of deficient fear extinction consolidation/retrieval once extinction learning was initiated. This was associated with enhanced neuronal histone acetylation in the mPFC and amygdala. Finally, as a proof of principle, mimicking enhanced dopaminergic signaling by L-dopa treatment rescued deficient fear extinction and co-administration of MS-275 rendered this effect enduring and context-independent. Conclusion: Current data reveal that combining dopaminergic and epigenetic mechanisms is a promising strategy to improve exposure-based behavior therapy in extinction-impaired individuals by initiating the formation of an enduring and context-independent fear inhibitory memory.
Project description:Background: Extinction-based exposure therapy is used in treating anxiety- and trauma-related disorders, however there is the need to improve its limited efficacy in individuals with impaired fear extinction learning and to facilitate the inadequate protection against return-of-fear phenomena. Methods: Spontaneous recovery and fear renewal tests, assessed persistence and context-independence of treatments rescuing deficient fear extinction in 129S1/SvImJ mice. To reveal neurobiological mechanisms supporting long-lasting extinction rescue, whole-genome expression profiling, qRT-PCR, immunohistochemistry and chromatin immunoprecipitation were used. Results: Persistent and context-independent rescue of deficient fear extinction induced by dietary zinc-restriction was associated with enhanced expression of dopamine-related genes, such as genes encoding the dopamine- D1 (Drd1a) and -D2 (Drd2) receptor in the medial prefrontal cortex (mPFC) and amygdala. Moreover, enhanced histone acetylation was observed in the promoter of the extinction-regulated Drd2 gene in the mPFC, revealing a possibly involved gene regulatory mechanism. While enhancing histone acetylation, via administering the HDAC inhibitor MS275, does not induce successful fear reduction during extinction training, it promoted enduring and context-independent rescue of deficient fear extinction consolidation/retrieval once extinction learning was initiated. This was associated with enhanced neuronal histone acetylation in the mPFC and amygdala. Finally, as a proof of principle, mimicking enhanced dopaminergic signaling by L-dopa treatment rescued deficient fear extinction and co-administration of MS-275 rendered this effect enduring and context-independent. Conclusion: Current data reveal that combining dopaminergic and epigenetic mechanisms is a promising strategy to improve exposure-based behavior therapy in extinction-impaired individuals by initiating the formation of an enduring and context-independent fear inhibitory memory.
Project description:Understanding the mechanisms by which long-term memories are formed and stored in the brain represents a central aim of neuroscience. Prevailing theory suggests that long-term memory encoding involves early plasticity within hippocampal circuits, while reorganization of the neocortex is thought to occur weeks to months later to subserve remote memory storage. Here we report that long-term memory encoding can elicit early transcriptional, structural and functional remodeling of the neocortex. Parallel studies using genome-wide RNA-sequencing, ultrastructural imaging, and whole-cell recording in wild-type mice suggest that contextual fear conditioning initiates a transcriptional program in the medial prefrontal cortex (mPFC) that is accompanied by rapid expansion of the synaptic active zone and postsynaptic density, enhanced dendritic spine plasticity, and increased synaptic efficacy. To address the real-time contribution of the mPFC to long-term memory encoding, we performed temporally precise optogenetic inhibition of excitatory mPFC neurons during contextual fear conditioning. Using this approach, we found that real-time inhibition of the mPFC inhibited activation of the entorhinal-hippocampal circuit and impaired the formation of long-term associative memory. These findings suggest that encoding of long-term episodic memory is associated with early remodeling of neocortical circuits, identify the prefrontal cortex as a critical regulator of encoding-induced hippocampal activation and long-term memory formation, and have important implications for understanding memory processing in healthy and diseased brain states.
Project description:Histone acetylation is a key component in the consolidation of long-term fear memories, which are models for highly resilient and durable memory. Histone acetylation is fueled by acetyl-CoA and recently, nuclear-localized metabolic enzymes that produce this metabolite have emerged as direct and local regulators of histone acetylation. In particular, Acetyl-coA synthetase 2 (ACSS2) mediates histone acetylation in the mouse hippocampus. However, whether ACSS2 regulates long-term fear memory remains to be determined. Here, we show that Acss2 knockout is well-tolerated in mice, yet the Acss2 null mouse exhibits reduced acquisition of long-term fear memory. Loss of Acss2 leads to reductions in both histone acetylation and expression of critical learning and memory-related genes in the dorsal hippocampus, specifically following fear conditioning. Further, systemic administration of blood-brain-barrier (BBB)-permeable Acss2 inhibitors during the consolidation window reduces fear memory formation in mice and rats, and reduces anxiety in a predator-scent-stress (PSS) paradigm. Our findings suggest that nuclear acetyl-CoA metabolism via ACSS2 plays a critical, previously unappreciated role in the formation of fear memories.
Project description:Background: The present study investigated a role of proteins from BET family (epigenetic readers) in schizophrenia-like abnormalities in MAM-E17 model of schizophrenia. Methods: An inhibitor of BET proteins, JQ1, was given during adolescence in postnatal days (P) 23-P30, and behavioral response (sensorimotor gating, recognition memory) and prefrontal cortex (mPFC) function (long-term potentiation (LTP), molecular and proteomic studies) were performed in adult males and females. Results: Deficits in sensorimotor gating and recognition memory were observed only in MAM-treated males. However, adolescent JQ1 treatment affected control, but MAM-treated groups in both sexes. Electrophysiological study showed an LTP impairment only in male MAM-treated animals, and JQ1 did not have any effect on LTP in the mPFC. In contrast, MAM did not affect immediate early gene expression (markers of neuronal and synaptic activity), but JQ1 altered them in both sexes. Proteomic study revealed alterations in MAM-treated groups only in males, while JQ1 affected both sexes. Conclusions: Prenatal MAM administration induced schizophrenia-like abnormalities only in males. In contrast, adolescent JQ1 treatment affected both sexes and induced behavioral changes in control groups, altered a markers of neuronal and synaptic activity and proteomic landscape in the mPFC of both groups (VEH- and MAM-treated). Thus, adolescent inhibition of BET family might change neuroplasticity in the mPFC.
Project description:N-octanoyl dopamine (NOD), but not dopamine dose dependently induces the UPR. This was also found for other synthetic N-Acyl dopamine derivates (NADD). Induction of the UPR was dependent on the redox activity of NADD and was not caused by selective activation of a particular UPR sensor. UPR induction did not result in cell apoptosis, yet NOD strongly impaired cell proliferation by attenuation of cells in the S-G2/M phase. Long-term treatment of HUVEC with low NOD concentration showed decreased intracellular ATP concentration paralleled with activation of AMPK. These cells were significantly more resistant to cold inflicted injury. N-octanoyl dopamine (NOD) and other synthetic N-Acyl dopamine derivates (NADD), but not dopamine dose dependently induces the UPR. Long-term treatment of HUVEC with low NOD concentration showed decreased intracellular ATP concentration paralleled with activation of AMPK. Genome wide gene expression profiling, confirmatory qPCR and reporter assays were employed on human umbilical vein endothelial cells (HUVEC) to validate induction of UPR target genes and UPR sensor activation by NOD
Project description:The heterogeneity of cortical dopamine D2 receptor expressing cells is not well characterized We performed microarrays to study expression of all the transcriprts specifically from Drd2+ neurons of mouse mPFC. For this we immunoprecipitated ribosomes from mPFC of D2Cre::RiboTag mouse, where ribosomal subunit Rpl22 is tagged with HA epitope specifically in Drd2+ neurons