Mutations in the Shank3 gene are strongly associated with various neurodevelopmental disorders, particularly autism spectrum disorder (ASD). The R1117X mutation, which results in truncated SHANK3 protein, has been implicated in dysfunctions in the striatum and cortex. However, its effects on hippocampal function remain poorly understood. In this study, we performed a comprehensive behavioral and synaptic analysis of homozygous R1117X Shank3 mutant mice. These mice exhibited deficits in sensory gating, motor coordination, and pain perception, alongside severe anxiety in novel environment. Additionally, they showed significant impairments in learning and memory, as well as abnormal spontaneous fine motor behaviors. Histological analysis revealed morphological changes in the hippocampus, which were coupled with deficits in synaptic transmission and plasticity. Notably, we observed a downregulation of glutamatergic receptors in the hippocampus, particularly NMDA receptor subtypes. Taken together, these findings demonstrate that the homozygous R1117X Shank3 mutant mouse represents a valuable model for investigating schizophrenia associated with intellectual disability. The altered hippocampal morphology, impaired synaptic function, and deficits in learning and memory observed in this model provide new insights into the underlying mechanisms of Shank3-related neurodevelopmental disorders.

GABAergic signaling in the brain plays a key role in regulating synaptic transmission, neuronal excitability, and cognitive processes. Large-scale sequencing has revealed the diminished expression of GABA-related genes in Alzheimer's disease (AD), however, it is largely unclear about the epigenetic mechanisms that dysregulate the transcription of these genes in AD. We confirmed that GABA synthesizing enzymes, GAD1 and GAD2, were significantly downregulated in prefrontal cortex (PFC) of AD human postmortem tissues. A tauopathy mouse model also had the significantly reduced expression of GABA-related genes, as well as the diminished GABAergic synaptic transmission in PFC pyramidal neurons. To elevate endogenous Gad1 levels, we used the CRISPR/Cas9-based epigenome editing technology to recruit histone acetyltransferase p300 to Gad1. Cells transfected with a fusion protein consisting of the nuclease-null dCas9 protein and the catalytic core of p300 (dCas9p300), as well as a guide RNA targeting Gad1 promoter (gRNAGad1), had significantly increased Gad1 mRNA expression and histone acetylation at Gad1 promoter. Furthermore, the tauopathy mouse model with PFC injection of dCas9p300 and gRNAGad1 lentiviruses had significantly elevated GABAergic synaptic currents and improved spatial memory. These results have provided an epigenetic editing-based gene-targeting strategy to restore synaptic inhibition and cognitive function in AD and related disorders.

Post-traumatic stress disorder (PTSD) is one of the most serious and harmful stress-related emotion disorders resulting from traumatic experiences. Upregulation of autophagic flux in neuronal cells is believed to play a pivotal role in the pathogenesis of PTSD, however, the region-specific effects of autophagy upregulation in PTSD have not been fully investigated. In our study, inhibiting autophagy in the amygdala rather than in the medial prefrontal cortex or hippocampus of wild-type mice alleviated anxiety-like behaviors in a PTSD mouse model. Our results also suggested upregulating autophagic activity in the amygdala reversed the anxiolytic effect observed in Fmr1 knockout mice, which may have resulted from reduced autophagy levels in the brains of these mice. In conclusion, the impact of autophagy on PTSD may be region-dependent, even within PTSD-related neuronal circuits.

Chemogenetics is a rapidly advancing field that uses genetically engineered receptors to selectively modulate the activity of specific neuronal populations in the brain. This innovative approach allows for precise control of neural circuits, providing valuable insights into the roles of specific circuits in behavior and disease mechanisms. The potential of chemogenetics to transform our understanding of brain function could lead to novel therapeutic strategies for a wide range of neurological and psychiatric disorders. This review explores the fundamental mechanisms of chemogenetics, with a focus on Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) and their associated ligands. We provide a comprehensive overview of the various classes of DREADDs, detailing optimal ligand dosing and offering guidance for their integration into both research and clinical settings. Additionally, we examine the recent applications of DREADDs in psychiatry, particularly about brain regions and circuits involved in anxiety.

Stress is a high-risk factor for major depressive disorder (MDD) with hippocampal damage and monoamine deficiency. Surprisingly, the administration of gaseous or aqueous formaldehyde (FA) causes depressive symptoms in both animals and humans, though whether endogenous FA induces depression is unclear. Here, we report that stress-derived FA promotes depression onset. In this study, endogenous FA concentrations in mice and human induced by acute or chronic stress were quantified by a FA-sensitive fluorescence probe. Acute infusion and chronic FA injection were used to mimic depressive behaviors in mice under chronic unpredictable mild stress (CUMS). Patch clamp recorded FA-inhibited hippocampal CA1 discharges, while mass spectrometry and spectrophotometry examined FA-inactivated monoamine. The software of magnetic resonance imaging (MRI) was used to quantify hippocampal CA1 atrophy in adolescents with MDD. Biochemical tests were applied for evaluating the link between FA levels and depression severity in MDD patients. Various bioinformatics methods were used to explore FA’s connection to depression-related pathways. Metabolomics data from MENDA were used to identify FA accumulation and monoamine deficiency in depression models and MDD patients. Our results showed that in cellular and mouse models, glutamic acid and both acute and chronic stress triggered FA production in hippocampal CA1 neurons. Excessive FA indued depressive behaviors due to FA buildup and decreased serotonin, dopamine, and melatonin levels in the extracellular space. Especially, excessive FA deactivated these monoamines, damaged hippocampal CA1 structure, and reduced neuroexcitability. Remarkably, adolescent MDD patients showed hippocampal CA1 atrophy and monoamine deficiencies, with blood FA levels predicting depression severity. These findings suggest that stress-derived FA serves as a critical trigger of depression by inactivating monoamines and impairing hippocampal CA1.

Microglia’s P2X4 receptor may be a key target involved in the occurrence and development of pain–depression comorbidity. The objective of this study is to explore the possible mechanisms underlying the involvement of microglial P2X4 receptors in pain–depression comorbidity. Sixty male SD rats were randomly divided into six groups: normal control group (10), sham operation group (10), chronic constriction injury of sciatic nerve group (CCI group, 10), CCI + antagonist group (10), chronic unpredicted mild stress model group (CUMS group, 10), CUMS + antagonist group (10). The normal group received no treatment, the sham group was injected with normal saline through stereotaxic localisation, the CCI group was ligated with sciatic nerve of left leg, the CUMS group was stimulated by stress for 30 days. The rats in the CCI group and CUMS group were injected with P2X4 receptor antagonist 30 days later. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured in each group on different days, followed by forced swimming tests in all groups to measure floating immobility time in water. Finally, P2X4’s expression in rostral ventromedial medulla (RVM) and spinal lumbosacral swelling were detected by Western Blotting and immunofluorescence, respectively, whilst expression of 5-HT in the spinal dorsal horn was measured via immunohistochemistry. Compared with the sham group, both MWT and TWL in the CCI group exhibited a decreasing trend (lowest level at approximately 2 weeks before remaining stable). Floating state time in the forced swimming experiment was significantly prolonged. Simultaneously, P2X4’s expression increased in RVM, as did that of 5-HT in spinal cord, but the expression of 5-HT in spinal cord significantly decreased after injection of P2X4 receptor antagonist in RVM. Compared with the normal group, MWT and TWL in the CUMS group decreased gradually, and floating state time reached the longest. P2X4 receptor expression in the RVM increased more significantly than that in the CCI group, and that of 5-HT in the spinal cord increased. Post injection of the P2X4 receptor antagonist, the MWT and TWL were higher than those before injection, and forced swimming time decreased. Moreover, P2X4 receptor expression in RVM increased, and expression of 5-HT in the spinal cord decreased. P2X4 receptor in RVM may be involved in the pathogenesis of pain–depression comorbidity.

Alcohol withdrawal syndrome (AWS) is a poorly studied phenotype of alcohol use disorder. Understanding the relationship between allelic interactions and AWS-related impulsivity and aggression could have significant implications. This study aimed to investigate the main and interacting effects of ZNF804A and mTOR on impulsivity and aggression during alcohol withdrawal. 446 Chinese Han adult males with alcohol dependence were included in the study. Impulsivity and aggression were assessed, and genomic DNA was genotyped. Single gene analysis showed that ZNF804A rs1344706 (A allele/CC homozygote) and mTOR rs1057079 (C allele/TT homozygote) were strongly associated with AWS-related impulsivity and aggression. In the allelic group, MANOVA revealed a significant gene x gene interaction, suggesting that risk varied systematically depending on both ZNF804A and mTOR alleles. Additionally, a significant interactive effect of ZNF804A rs1344706 and mTOR rs7525957 was found on motor impulsivity and physical aggression, and the ZNF804A rs1344706 gene variant had significant effects on motor impulsivity and physical aggression only in mTOR rs7525957 TT homozygous carriers. The study showed that specific allelic combinations of ZNF804A and mTOR may have protective or risk-enhancing effects on AWS-related impulsivity and aggression.

Pleiotropic mechanisms have been implicated in Alzheimer’s disease (AD), including transcriptional dysregulation, protein misprocessing and synaptic dysfunction, but how they are mechanistically linked to induce cognitive deficits in AD is unclear. Here we find that the histone methyltransferase Smyd3, which catalyzes histone H3 lysine 4 trimethylation (H3K4me3) to activate gene transcription, is significantly elevated in prefrontal cortex (PFC) of AD patients and P301S Tau mice, a model of tauopathies. A short treatment with the Smyd3 inhibitor, BCI-121, rescues cognitive behavioral deficits, and restores synaptic NMDAR function and expression in PFC pyramidal neurons of P301S Tau mice. Fbxo2 , which encodes an E3 ubiquitin ligase controlling the degradation of NMDAR subunits, is identified as a downstream target of Smyd3. Smyd3-induced upregulation of Fbxo2 in P301S Tau mice is linked to the increased NR1 ubiquitination. Fbxo2 knockdown in PFC leads to the recovery of NMDAR function and cognitive behaviors in P301S Tau mice. These data suggest an integrated mechanism and potential therapeutic strategy for AD.

Cul3 encodes Cullin-3, a core component of the ubiquitin E3 ligase that is involved in protein ubiquitination. Recent studies have identified Cul3 as a high-confidence risk gene in neurodevelopmental disorders (NDDs), especially autism spectrum disorder (ASD). Different strategies have been used to generate animal models with Cul3 deficiency in the central nervous system, including whole-brain knockout (KO), cell-type specific conditional KO (cKO), and brain region-specific knockdown. In this review, we revisited the basic properties of CUL3 and its function under physiological and pathological conditions. Recent clinical studies including case reports and large cohort sequencing studies related to CUl3 in NDDs have been summarized. Moreover, we characterized the behavioral, electrophysiological, and molecular changes in newly developed Cul3 deficiency models. This would guide further studies related to Cul3 in CNS and provide potential therapeutic targets for Cul3-deficiency-induced NDDs, including ASD.

Neurodevelopmental disorders (NDDs) are a group of disorders induced by abnormal brain developmental processes. The prefrontal cortex (PFC) plays an essential role in executive function, and its role in NDDs has been reported. NDDs are associated with high-risk gene mutations and share partially overlapping genetic abnormalities. Neurexins (NRXNs) are related to autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD). NRXN1, an essential susceptibility gene for NDDs, has been reported to be associated with NDDs. However, little is known about its key role in NDDs. NRXN1 downregulation in the medial PFC induced anxiety-like behaviors and abnormal social phenotypes with impaired neurite outgrowth in Sh-NRXN1 in prefrontal neurons. Moreover, tandem mass tag (TMT)-based proteomic analysis of rat brain samples showed that NRXN1 downregulation led to significant proteome alterations, including pathways related to the extracellular matrix, cell membrane, and morphologic change. Furthermore, full-automatic immunoblotting analysis verified the differently expressed proteins related to cell morphology and membrane structure. Our results confirmed the association of NRXN1 with abnormal behaviors in NDDs and provided richer insights into specific prefrontal knockdown in adolescence, potentially expanding the NRXN1 interactome and contributing to human health.

The muscarinic acetylcholine receptor (mAChR) antagonist, scopolamine, has been shown to have a rapid antidepressant effect. And it is believed that GABAergic interneurons play a crucial role in this action. Therefore, characterizing the modulation effects of mAChR on GABAergic interneurons is crucial for understanding the mechanisms underlying scopolamine's antidepressant effects. In this study, we examined the effect of mAChR activation on the excitatory synaptic transmissions in two major subtypes of GABAergic interneurons, somatostatin (SST)- and parvalbumin (PV)-expressing interneurons, in the anterior cingulate cortex (ACC). We found that muscarine, a mAChR agonist, non-specifically facilitated the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) in both SST and PV interneurons. Scopolamine completely blocked the effects of muscarine, as demonstrated by recovery of sESPCs and mEPSCs in these two types of interneurons. Additionally, individual application of scopolamine did not affect the EPSCs of these interneurons. In inhibitory transmission, we further observed that muscarine suppressed the frequency of both spontaneous and miniature inhibitory postsynaptic currents (sIPSCs and mIPSCs) in SST interneurons, but not PV interneurons. Interestingly, scopolamine directly enhanced the frequency of both sIPSCs and mIPSCs mainly in SST interneurons, but not PV interneurons. Overall, our results indicate that mAChR modulates excitatory and inhibitory synaptic transmission to SST and PV interneurons within the ACC in a cell-type-specific manner, which may contribute to its role in the antidepressant effects of scopolamine.

ObjectiveAlcohol use disorder (AUD) is a common mental disorder characterized by repeated withdrawal episodes. Negative emotions during withdrawal are the primary factors affecting successful abstinence. Oxytocin is a critical modulator of emotions. OXTR, the oxytocin receptor, may also be a promising candidate for treating alcohol withdrawal symptoms. Previous studies indicated that people with different genotypes of OXTR rs2254298 were reported to suffer from more significant depressive or heightened anxiety symptoms when experiencing early adversity. The present study aims to explore the modulatory role of the polymorphism OXTR rs2254298 on mood disorders during alcohol withdrawal and to help researchers better understand and develop effective relapse prevention and interventions for alcohol use disorders.MethodsWe recruited 265 adult Chinese Han men with AUD. Anxiety and depressive symptoms were measured using the Self-Rating Anxiety Scale and Self-Rating Depression Scale. Alcohol dependence levels were measured using Michigan Alcoholism Screening Test. Genomic DNA extraction and genotyping from participants’ peripheral blood samples.ResultFirst, a multiple linear regression was used to set the alcohol dependence level, OXTR.rs2254298, interaction terms as the primary predictor variable, and depression or anxiety as an outcome; age and educational years were covariates. There was a significant interaction between OXTR rs2254298 and alcohol dependence level on anxiety (B = 0.23, 95% confidence interval [CI]: 0.01–0.45) but not on depression (B = −0.06, 95% CI: −0.30 – 0.18). The significance region test showed that alcohol-dependent men who are GG homozygous were more likely to experience anxiety symptoms than subjects with the A allele (A allele: β = 0.27, p < 0.001; GG homozygote: β = 0.50, p < 0.001). Finally, re-parameterized regression analysis demonstrated that this gene–environment interaction of OXTR rs2254298 and alcohol dependence on anxiety fits the weak differential susceptibility model (R2 = 0.17, F (5,259) = 13.46, p < 0.001).ConclusionThis study reveals a gene–environment interactive effect between OXTR rs2254298 and alcohol withdrawal on anxiety but not depression. From the perspective of gene–environment interactions, this interaction fits the differential susceptibility model; OXTR rs2254298 GG homozygote carriers are susceptible to the environment and are likely to experience anxiety symptoms of alcohol withdrawal.

CTNNB1 is the gene that encodes β-catenin which acts as a key player in the Wnt signaling pathway and regulates cellular homeostasis. Most CTNNB1-related studies have been mainly focused on its role in cancer. Recently, CTNNB1 has also been found involved in neurodevelopmental disorders (NDDs), such as intellectual disability, autism, and schizophrenia. Mutations of CTNNB1 lead to the dysfunction of the Wnt signaling pathway that regulates gene transcription and further disturbs synaptic plasticity, neuronal apoptosis, and neurogenesis. In this review, we discuss a wide range of aspects of CTNNB1 and its physiological and pathological functions in the brain. We also provide an overview of the most recent research regarding CTNNB1 expression and its function in NDDs. We propose that CTNNB1 would be one of the top high-risk genes for NDDs. It could also be a potential therapeutic target for the treatment of NDDs.

Loss-of-function mutations of the gene Cul3 have been identified as a risk factor for autism-spectrum disorder (ASD), but the pathogenic mechanisms are not well understood. Conditional Cul3 ablation in cholinergic neurons of mice (Chat CRE Cul3 F/+ ) recapitulated ASD-like social and sensory gating phenotypes and caused significant cognitive impairments, with diminished activity of cholinergic neurons in the basal forebrain (BF). Chemogenetic inhibition of BF cholinergic neurons in healthy mice induced similar social and cognitive deficits. Conversely, chemogenetic stimulation of BF cholinergic neurons in Chat CRE Cul3 F/+ mice reversed abnormalities in sensory gating and cognition. Cortical hypofunction was also found after ChAT-specific Cul3 ablation and stimulation of cholinergic projections from the BF to the prefrontal cortex (PFC) mitigated cognitive deficits. Overall, we demonstrate that cholinergic dysfunction due to Cul3 deficiency is involved in ASD-like behavioral abnormalities, and that BF cholinergic neurons are particularly critical for cognitive component through their projections to the PFC.

One of the major epigenetic mechanisms in gene regulation is histone modification, including histone methylation and acetylation. A new study [2] has found the increased histone H3 dimethylation at lysine 9 (H3K9me2, a repressive histone mark) and its catalyzing enzyme euchromatic histone-lysine Nmethyltransferase 2 (EHMT2) in prefrontal cortex (PFC) of the P301S Tau AD mouse model. Consistently, the elevated H3K9me2 and EHMT1/2, as well as the excessive suppression of glutamate receptor genes, are also found in PFC of a familial AD model with APP/PS1 mutations [3]. It provides a potential mechanism underlying the diminished expression of synaptic genes that are important for cognitive stability in AD patients uncovered by bioinformatics analyses [4]. A short treatment with the EHMT inhibitor UNC0642 not only ameliorates synaptic and behavioral deficits in both AD models [2, 3], but also significantly reduces hyperphosphorylated tau in the P301S Tau AD mouse model [2]. Transcriptomic analysis reveals that a large number of downregulated genes, which are enriched in synaptic organization and plasticity, is restored by UNC0642 treatment in both AD models [2, 3]. These studies highlight the therapeutic potential of targeting epigenetic enzymes to normalize downregulated genes in AD [5].

The expression of glutathione transferase isoenzymes has been investigated in embryo and adult liver of the frog Xenopus laevis. By analysing the GST isoenzymes recovered from GSH-affinity chromatography in terms of electrophoretic mobility, HPLC elution profile, immunological reactivity, N-terminal amino acid sequence and mass spectrometry molecular mass no significant difference in the GST subunit composition between embryos and liver was found. In both tissues the same three subunits, showing similarity to mu, alpha and sigma class GSTs, are present. These results, together with those previously reported for toad (Bufo bufo), strongly support the notion that the transition from an aquatic environment to a terrestrial atmosphere containing high oxygen concentration has accompanied specific GST gene expression.

Epigenetic abnormality is implicated in neurodegenerative diseases associated with cognitive deficits, such as Alzheimer's disease (AD). A common feature of AD is the accumulation of neurofibrillary tangles composed of hyperphosphorylated tau. Transgenic mice expressing mutant P301S human tau protein develop AD-like progressive tau pathology and cognitive impairment. Here, we show that the euchromatic histone-lysine N-methyltransferase 2 (EHMT2) is significantly elevated in the prefrontal cortex (PFC) of P301S Tau mice (5-7 months old), leading to the increased repressive histone mark, H3K9me2, which is reversed by treatment with the selective EHMT inhibitor UNC0642. Behavioral assays show that UNC0642 treatment induces the robust rescue of spatial and recognition memory deficits in P301S Tau mice. Concomitantly, the diminished PFC neuronal excitability and glutamatergic synaptic transmission in P301S Tau mice are also normalized by UNC0642 treatment. In addition, EHMT inhibition dramatically attenuates the hyperphosphorylated tau level in PFC of P301S Tau mice. Transcriptomic analysis reveals that UNC0642 treatment of P301S Tau mice has normalized a number of dysregulated genes in PFC, which are enriched in cytoskeleton and extracellular matrix organization, ion channels and transporters, receptor signaling, and stress responses. Together, these data suggest that targeting histone methylation enzymes to adjust gene expression could be used to treat cognitive and synaptic deficits in neurodegenerative diseases linked to tauopathies.

Exposure to prolonged stress in critical developmental periods induces heightened vulnerability to psychiatric disorders, which may have sex-specific consequences. Here we investigate the neuronal circuits mediating behavioral changes in mice after chronic adolescent social isolation stress. Escalated aggression is exhibited in stressed males, while social withdrawal is shown in stressed females. In vivo multichannel recordings of free-moving animals indicate that pyramidal neurons in prefrontal cortex (PFC) from stressed males exhibit the significantly decreased spike activity during aggressive attacks, while PFC pyramidal neurons from stressed females show a blunted increase of discharge rates during sociability tests. Chemogenetic and electrophysiological evidence shows that PFC hypofunctioning and BLA principal neuron hyperactivity contribute to the elevated aggression in stressed males, while PFC hypofunctioning and VTA dopamine neuron hypoactivity contribute to the diminished sociability in stressed females. These results establish a framework for understanding the circuit and physiological mechanisms underlying sex-specific divergent effects of stress.

Uncontrolled drug-seeking and -taking behaviors are generally driven by maladaptive corticostriatal synaptic plasticity. The orbital frontal cortex (OFC) and its projections to the dorsomedial striatum (DMS) have been extensively implicated in drug-seeking and relapse behaviors. The influence of the synaptic plasticity of OFC projections to the DMS (OFC→DMS) on drug-seeking and -taking behaviors has not been fully characterized. To investigate this, we trained rats to self-administer 20% alcohol and then delivered an in vivo optogenetic protocol designed to induce long-term potentiation (LTP) selectively at OFC→DMS synapses. We selected LTP induction because we found that voluntary alcohol self-administration suppressed OFC→DMS transmission and LTP may normalize this transmission, consequently reducing alcohol-seeking behavior. Importantly, ex vivo slice electrophysiology studies confirmed that this in vivo optical stimulation protocol resulted in a significant increase in excitatory OFC→DMS transmission strength on day two after stimulation, suggesting that LTP was induced in vivo. Rat alcohol-seeking and -taking behaviors were significantly reduced on days 1–3, but not on days 7–11, after LTP induction. Striatal synaptic plasticity is modulated by several critical neurotransmitter receptors, including dopamine D1 receptors (D1Rs) and adenosine A2A receptors (A2ARs). We found that delivery of in vivo optical stimulation in the presence of a D1R antagonist abolished the LTP-associated decrease in alcohol-seeking behavior, whereas delivery in the presence of an A2AR antagonist may facilitate this LTP-induced behavioral change. These results demonstrate that alcohol-seeking behavior was negatively regulated by the potentiation of excitatory OFC→DMS neurotransmission. Our findings provide direct evidence that the OFC exerts “top-down” control of alcohol-seeking behavior via the DMS.