Astrocytic ALKBH5 in stress response contributes to depressive-like behaviors in mice.

Epigenetic mechanisms bridge genetic and environmental factors that contribute to the pathogenesis of major depression disorder (MDD). However, the cellular specificity and sensitivity of environmental stress on brain epitranscriptomics and its impact on depression remain unclear. Here, we found that ALKBH5, an RNA demethylase of N6-methyladenosine (m6A), was increased in MDD patients' blood and depression models. ALKBH5 in astrocytes was more sensitive to stress than that in neurons and endothelial cells. Selective deletion of ALKBH5 in astrocytes, but not in neurons and endothelial cells, produced antidepressant-like behaviors. Astrocytic ALKBH5 in the mPFC regulated depression-related behaviors bidirectionally. Meanwhile, ALKBH5 modulated glutamate transporter-1 (GLT-1) m6A modification and increased the expression of GLT-1 in astrocytes. ALKBH5 astrocyte-specific knockout preserved stress-induced disruption of glutamatergic synaptic transmission, neuronal atrophy and defective Ca2+ activity. Moreover, enhanced m6A modification with S-adenosylmethionine (SAMe) produced antidepressant-like effects. Our findings indicate that astrocytic epitranscriptomics contribute to depressive-like behaviors and that astrocytic ALKBH5 may be a therapeutic target for depression.

Preparation of Healthy Single Neuron or Astrocyte Suspension from Adult Mouse Brain for RNA-seq.

Single-cell RNA sequencing (scRNA-seq) has been widely applied in neuroscience research, enabling the investigation of cellular heterogeneity at the transcriptional level, the characterization of rare cell types, and the detailed analysis of the stochastic nature of gene expression. Isolation of single nerve cells in good health, especially from the adult rodent brain, is the most difficult and critical process for scRNA-seq. Here, we describe methods to optimize protease digestion of brain slices, which enable yield of millions of cells in good health from the adult brain.

Extracellular ATP is a homeostatic messenger that mediates cell‒cell communication in physiological processes and psychiatric diseases.

Neuronal activity is the basis of information encoding and processing in the brain. During neuronal activation, intracellular ATP is generated to meet the high-energy demands. Meantime, ATP is secreted, increasing the extracellular ATP concentration and acting as a homeostatic messenger that mediates cell‒cell communication to prevent aberrant hyperexcitability of the nervous system. In addition to the confined release and fast synaptic signaling of classic neurotransmitters within synaptic clefts, ATP can be released by all brain cells, diffuses widely and targets different types of purinergic receptors on neurons and glial cells, making it possible to orchestrate brain neuronal activity and participate in various physiological aspects, such as sleep and wakefulness, learning and memory, and feeding. Dysregulation of extracellular ATP leads to a "destabilizing" effect on the neural network, as found in the etiopathology of many psychiatric diseases, including depression, anxiety, schizophrenia, and autism spectrum disorder. This review summarizes advances in the understanding of the mechanisms by which extracellular ATP serves as an intercellular signaling molecule to regulate neural activity, with a focus on how it maintains the homeostasis of neural networks. In particular, we also focus on neural activity issues resulting from dysregulation of extracellular ATP and propose that aberrant levels of extracellular ATP may play a role in the etiopathology of some psychiatric diseases, highlighting the potential therapeutic targets of ATP signaling in the treatment of these psychiatric diseases. Finally, we suggest potential avenues to further elucidate the role of extracellular ATP in intercellular communication and psychiatric diseases.

Dopamine D2 receptors in pyramidal neurons in the medial prefrontal cortex regulate social behavior.

Drugs acting on dopamine D2 receptors are widely used for the treatment of several neuropsychiatric disorders, including schizophrenia and depression. Social deficits are a core symptom of these disorders. Pharmacological manipulation of dopamine D2 receptors (Drd2), a Gi-coupled subtype of dopamine receptors, in the medial prefrontal cortex (mPFC) has shown that Drd2 is implicated in social behaviors. However, the type of neurons expressing Drd2 in the mPFC and the underlying circuit mechanism regulating social behaviors remain largely unknown. Here, we show that Drd2 were mainly expressed in pyramidal neurons in the mPFC and that the activation of the Gi-pathway in Drd2+ pyramidal neurons impaired social behavior in male mice. In contrast, the knockdown of D2R in pyramidal neurons in the mPFC enhanced social approach behaviors in male mice and selectively facilitated the activation of mPFC neurons projecting to the nucleus accumbens (NAc) during social interaction. Remarkably, optogenetic activation of mPFC-to-NAc-projecting neurons mimicked the effects of conditional D2R knockdown on social behaviors. Altogether, these results demonstrate a cell type-specific role for Drd2 in the mPFC in regulating social behavior, which may be mediated by the mPFC-to-NAc pathway.

The decreased risk of hepatocellular carcinoma in hepatitis B virus-related cirrhotic portal hypertension patients after laparoscopic splenectomy and azygoportal disconnection.

BACKGROUND: Posthepatitic cirrhosis is one of the leading risk factors for hepatocellular carcinoma (HCC) worldwide, among which hepatitis B cirrhosis is the dominant one. This study explored whether laparoscopic splenectomy and azygoportal disconnection (LSD) can reduce the risk of HCC among patients with hepatitis B virus (HBV)-related cirrhotic portal hypertension (CPH). METHODS: A total of 383 patients with HBV-related CPH diagnosed as gastroesophageal variceal bleeding and secondary hypersplenism were identified in our hepatobiliary pancreatic center between April 2012 and April 2022, and conducted an 11-year retrospective follow-up. We used inverse probability of treatment weighting (IPTW) to correct for potential confounders, weighted Kaplan-Meier curves, and logistic regression to estimate survival and risk differences. RESULTS: Patients were divided into two groups based on treatment method: LSD (n = 230) and endoscopic therapy (ET; n = 153) groups. Whether it was processed through IPTW or not, LSD group showed a higher survival benefit than ET group according to Kaplan-Meier analysis (P < 0.001). The incidence density of HCC was higher in the ET group compared to LSD group at the end of follow-up [32.1/1000 vs 8.0/1000 person-years; Rate ratio: 3.998, 95% confidence intervals (CI) 1.928-8.293]. Additionally, in logistic regression analyses weighted by IPTW, LSD was an independent protective predictor of HCC incidence compared to ET (odds ratio 0.516, 95% CI 0.343-0.776; P = 0.002). CONCLUSION: Considering the ability of LSD to improve postoperative survival and prevent HCC in HBV-related CPH patients with gastroesophageal variceal bleeding and secondary hypersplenism, it is worth promoting in the context of the shortage of liver donors.

Increased NMDARs in neurons and glutamine synthetase in astrocytes underlying autistic-like behaviors of Gabrb1-/- mice.

Mutations of the GABA-A receptor subunit ß1 (GABRB1) gene are found in autism patients. However, it remains unclear how mutations in Gabrb1 may lead to autism. We generated Gabrb1-/- mouse model, which showed autistic-like behaviors. We carried out RNA-seq on the hippocampus and found glutamatergic pathway may be involved. We further carried out single-cell RNA sequencing on the whole brain followed by qRT-PCR, immunofluorescence, electrophysiology, and metabolite detection on specific cell types. We identified the up-regulated Glul/Slc38a3 in astrocytes, Grin1/Grin2b in neurons, glutamate, and the ratio of Glu/GABA in the hippocampus. Consistent with these results, increased NMDAR-currents and reduced GABAAR-currents in the CA1 neurons were detected in Gabrb1-/- mice. NMDAR antagonist memantine or Glul inhibitor methionine sulfoximine could rescue the abnormal behaviors in Gabrb1-/- mice. Our data reveal that upregulation of the glutamatergic synapse pathway, including NMDARs at neuronal synapses and glutamine exported by astrocytes, may lead to autistic-like behaviors.

A comparison of the impact on neuronal transcriptome and cognition of rAAV5 transduction with three different doses in the mouse hippocampus.

Introduction: Recombinant adeno-associated viruses (rAAVs) are widely used in genetic therapeutics. AAV5 has shown superior transduction efficiency, targeting neurons and glial cells in primate brains. Nonetheless, the comprehensive impact of AAV5 transduction on molecular and behavioral alterations remains unexplored. This study focuses on evaluating the effects of AAV5 transduction in the hippocampus, a critical region for memory formation and emotional processes. Methods: In this experiment, fluorescence-activated cell sorting (FACS) was utilized to isolate the mCherry-labeled pyramidal neurons in the hippocampus of CaMkIIα-cre mice following three different doses rAAV5-mCherry infusion after 3 weeks, which were then subjected to RNA sequencing (RNA-seq) to assess gene expression profiles. The cytokines concentration, mRNA expression, and glial response in hippocampi were confirmed by ELASA, digital droplet PCR and immunohistochemistry respectively. Locomotion and anxiety-like behaviors were elevated by Open Field Test and Elevated Plus Maze Test, while the Y-Maze were used to assessed spatial working memory. Recognition memory and fear responses were examined by the Novel Object Recognition Test and Fear Conditioning Test, respectively. Results: We found that 2.88 × 1010 v.g rAAV5 transduction significantly upregulated genes related to the immune response and apoptosis, and downregulated genes associated with mitochondrial function and synaptic plasticity in hippocampal pyramidal neurons, while did not induce neuronal loss and gliosis compared with 2.88 × 109 v.g and 2.88 × 108 v.g. Furthermore, the same doses impaired working memory and contextual fear memory, without effects on locomotion and anxiety-related behaviors. Discussion: Our findings highlight the detrimental impact of high-dose administration compared to median-dose or low-dose, resulting in increased neural vulnerability and impaired memory. Therefore, when considering the expression effectiveness of exogenous genes, it is crucial to also take potential side effects into account in clinical settings. However, the precise molecular mechanisms underlying these drawbacks of high-dose rAAV5-mCherry still require further investigation in future studies.

EphB6 deficiency in intestinal neurons promotes tumor growth in colorectal cancer by neurotransmitter GABA signaling.

EphB6 belongs to the receptor tyrosine kinase, whose low expression is associated with shorter survival of colorectal cancer (CRC) patients. But the role and mechanism of EphB6 in the progression of CRC need further study. In addition, EphB6 was mainly expressed in intestinal neurons. But how EphB6 is involved in functions of intestinal neurons has not been known. In our study, we constructed a mouse xenograft model of CRC by injecting CMT93 cells into the rectum of EphB6-deficient mice. We found that the deletion of EphB6 in mice promoted tumor growth of CMT93 cells in a xenograft model of CRC, which was independent of changes in the gut microbiota. Interestingly, inhibition of intestinal neurons by injecting botulinum toxin A into rectum of EphB6-deficient mice could eliminate the promotive effect of EphB6 deficiency on tumor growth in the xenograft model of CRC. Mechanically, the deletion of EphB6 in mice promoted the tumor growth in CRC by increasing GABA in the tumor microenvironment. Furthermore, EphB6 deficiency in mice increased the expression of synaptosomal-associated protein 25 in the intestinal myenteric plexus, which mediated the release of GABA. Our study concluded that EphB6 knockout in mice promotes tumor growth of CMT93 cells in a xenograft model of CRC by modulating GABA release. Our study found a new regulating mechanism of EphB6 on the tumor progression in CRC that is dependent on intestinal neurons.

Splenectomy and azygoportal disconnection decreases the risk of hepatocellular carcinoma for cirrhosis patients with portal hypertension bleeding: a 10-year retrospective follow-up study based on the inverse probability of treatment weighting method.

BACKGROUND: Liver cirrhosis is the highest risk factor for hepatocellular carcinoma (HCC) worldwide. However, etiological therapy is the only option in cirrhosis patients to decrease the HCC risk. The aim of this study was to explore whether laparoscopic splenectomy and azygoportal disconnection (LSD) decreases the risk of HCC for patients with cirrhotic portal hypertension (CPH). METHODS: Between April 2012 and April 2021, we identified 595 CPH patients in our hepatobiliary pancreatic center who were diagnosed with gastroesophageal variceal bleeding and secondary hypersplenism, and performed a 10-year retrospective follow-up. Inverse probability of treatment weighting (IPTW) was used to adjust for potential confounders, weighted Kaplan-Meier curves and logistic regression to estimate survival and risk differences. RESULTS: According to the method of therapy, patients were divided into LSD (n = 345) and endoscopic therapy (ET; n = 250) groups. Kaplan-Meier analysis revealed that patients who underwent LSD had higher survival benefit with those who underwent ET (P < 0.001). At the end of the follow-up, ET group was associated with a higher HCC incidence density compared with LSD group (28.1/1000 vs 9.6/1000 person-years; Rate ratio [RR] 2.922, 95% confidence intervals [CI] 1.599-5.338). In addition, logistic regression analyses weighted by IPTW revealed that, compared with ET, LSD was an independent protective predictor of HCC incidence (odds ratio [OR] 0.440, 95% CI 0.316-0.612; P < 0.001). CONCLUSIONS: Considering the better postoperative survival and the ability to prevent HCC in CPH patients with gastroesophageal variceal bleeding and secondary hypersplenism, LSD is worth popularization in situations where liver donors are scarce.

mGluR5 in hippocampal CA1 pyramidal neurons mediates stress-induced anxiety-like behavior.

Pharmacological manipulation of mGluR5 has showed that mGluR5 is implicated in the pathophysiology of anxiety and mGluR5 has been proposed as a potential drug target for anxiety disorders. Nevertheless, the mechanism underlying the mGluR5 involvement in stress-induced anxiety-like behavior remains largely unknown. Here, we found that chronic restraint stress induced anxiety-like behavior and decreased the expression of mGluR5 in hippocampal CA1. Specific knockdown of mGluR5 in hippocampal CA1 pyramidal neurons produced anxiety-like behavior. Furthermore, both chronic restraint stress and mGluR5 knockdown impaired inhibitory synaptic inputs in hippocampal CA1 pyramidal neurons. Notably, positive allosteric modulator of mGluR5 rescued stress-induced anxiety-like behavior and restored the inhibitory synaptic inputs. These findings point to an essential role for mGluR5 in hippocampal CA1 pyramidal neurons in mediating stress-induced anxiety-like behavior.

O-GlcNAc transferase in astrocytes modulates depression-related stress susceptibility through glutamatergic synaptic transmission.

Major depressive disorder is a common and devastating psychiatric disease, and the prevalence and burden are substantially increasing worldwide. Multiple studies of depression patients have implicated glucose metabolic dysfunction in the pathophysiology of depression. However, the molecular mechanisms by which glucose and related metabolic pathways modulate depressive-like behaviors are largely uncharacterized. Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) is a glucose metabolite with pivotal functions as a donor molecule for O-GlcNAcylation. O-GlcNAc transferase (OGT), a key enzyme in protein O-GlcNAcylation, catalyzes protein posttranslational modification by O-GlcNAc and acts as a stress sensor. Here, we show that Ogt mRNA was increased in depression patients and that astroglial OGT expression was specifically upregulated in the medial prefrontal cortex (mPFC) of susceptible mice after chronic social-defeat stress. The selective deletion of astrocytic OGT resulted in antidepressant-like effects, and moreover, astrocytic OGT in the mPFC bidirectionally regulated vulnerability to social stress. Furthermore, OGT modulated glutamatergic synaptic transmission through O-GlcNAcylation of glutamate transporter-1 (GLT-1) in astrocytes. OGT astrocyte-specific knockout preserved the neuronal morphology atrophy and Ca2+ activity deficits caused by chronic stress and resulted in antidepressant effects. Our study reveals that astrocytic OGT in the mPFC regulates depressive-like behaviors through the O-GlcNAcylation of GLT-1 and could be a potential target for antidepressants.

The Memory Orchestra: Contribution of Astrocytes.

For decades, memory research has centered on the role of neurons, which do not function in isolation. However, astrocytes play important roles in regulating neuronal recruitment and function at the local and network levels, forming the basis for information processing as well as memory formation and storage. In this review, we discuss the role of astrocytes in memory functions and their cellular underpinnings at multiple time points. We summarize important breakthroughs and controversies in the field as well as potential avenues to further illuminate the role of astrocytes in memory processes.

Vagus nerve-guided (modified Bai-Jiang-style) robotic-assisted laparoscopic splenectomy and azygoportal disconnection.

BACKGROUND: How to precisely protect and preserve anterior and posterior vagal trunks and all their branches during the procedure of splenectomy and azygoportal disconnection is studied rarely. We firstly developed a vagus nerve-guided robotic-assisted laparoscopic splenectomy and azygoportal disconnection (VGRSD). The aim of this study was to evaluate whether VGRSD is feasible and safe and to determine whether VGRSD can effectively eliminate postoperative digestive system complications by protecting vagal nerve precisely. METHOD: In this prospective clinical study, 10 cirrhotic patients with oesophagogastric variceal bleeding and hypersplenism who underwent VGRSD between January 2022 and March 2022 were gathered, and compared with a retrospective cohort who received a part of the vagus nerve-preserving robotic-assisted laparoscopic splenectomy and azygoportal disconnection (VPRSD). They were all followed up for 6 months. RESULTS: In VGRSD group, the operation time was 173.5 ± 16.2 min, blood loss was 68.0 ± 39.1 ml, VAS pain score on the first day was 1.9 ± 0.7, and the postoperative hospital stay was 7.7 ± 0.7 days. There was no incisional complications, pneumonia, gastric fistula, pancreatic fistula, and abdominal infection. No patients suffered from diarrhoea, delayed gastric emptying, and epigastric fullness. Compared with VPRSD, operation time was significantly longer for VGRSD (p < 0.05). However, VGRSD was significantly associated with less diarrhoea and shorter postoperative hospital stay (all p < 0.05). CONCLUSION: VGRSD procedure is not only technically feasible and safe, it also effectively eliminate postoperative digestive system complications. TRIAL REGISTRATION: We registered our research at https://www. CLINICALTRIALS: gov/. The name of research registered is 'Vagus Nerve-guided Robotic-assisted Splenectomy and Azygoportal Disconnection'. The trial registration identifier at clinicaltrials.gov is NCT05300516.

Novel Preoperative Type IV Collagen to Predict the Risk of Hepatocellular Carcinoma in Patients with Hepatitis B Virus-Related Cirrhotic Portal Hypertension After Laparoscopic Splenectomy and Azygoportal Disconnection.

Purpose: Although laparoscopic splenectomy and azygoportal disconnection (LSD) can significantly decrease portal vein pressure and even the incidence of hepatocellular carcinoma (HCC) in patients with cirrhotic portal hypertension (CPH), postoperative HCC inevitably occurs in certain patients. The purpose of this study was to seek a novel preoperative non-invasive predictive indicator to predict the occurrence of postoperative HCC. Patients and Methods: From April 2012 to April 2022, we collected clinical data of 178 hepatitis B virus (HBV)-related CPH patients. Based on inverse treatment probability weighting, candidate variables for predicting postoperative HCC were determined by means analysis. Then, a novel preoperative non-invasive prediction indicator (ie, type IV collagen-alpha fetoprotein-fibrosis-4 score [IVAF-FIB-4]) was established based on candidate variables, and its predictive ability was explored. Results: Postoperative HCC occurred in 9 (5.1%) patients. Correlation analyses showed that the IVAF-FIB-4 had a significant positive correlation with HCC (r = 0.835, P < 0.001). IVAF-FIB-4 showed a high accuracy (the area under the receiver operating characteristic curve: 0.939, 95% confidence interval [CI]: 0.818-1.000; sensitivity: 88.9%; specificity: 93.5%). At the end of follow-up, the incidence density of HCC in patients with IVAF-FIB-4 (1) was significant higher than that in patients with IVAF-FIB-4 (0) (138.1/1000 vs 1.1/1000 person-years; rate ratio: 130.475, 95% CI: 16.318-1043.227). In logistic regression, IVAF-FIB-4 was an independent risk factor for HCC (odds ratio: 668.000, 95% CI: 53.895-8279.541; P < 0.001). Conclusion: IVAF-FIB-4 is a novel preoperative noninvasive predictive indicator for predicting postoperative HCC in HBV-related CPH patients after LSD, with satisfactory predictive ability.

Astrocyte dysfunction drives abnormal resting-state functional connectivity in depression.

Major depressive disorder (MDD) is a devastating mental disorder that affects up to 17% of the population worldwide. Although brain-wide network-level abnormalities in MDD patients via resting-state functional magnetic resonance imaging (rsfMRI) exist, the mechanisms underlying these network changes are unknown, despite their immense potential for depression diagnosis and management. Here, we show that the astrocytic calcium-deficient mice, inositol 1,4,5-trisphosphate-type-2 receptor knockout mice (Itpr2-/- mice), display abnormal rsfMRI functional connectivity (rsFC) in depression-related networks, especially decreased rsFC in medial prefrontal cortex (mPFC)-related pathways. We further uncover rsFC decreases in MDD patients highly consistent with those of Itpr2-/- mice, especially in mPFC-related pathways. Optogenetic activation of mPFC astrocytes partially enhances rsFC in depression-related networks in both Itpr2-/- and wild-type mice. Optogenetic activation of the mPFC neurons or mPFC-striatum pathway rescues disrupted rsFC and depressive-like behaviors in Itpr2-/- mice. Our results identify the previously unknown role of astrocyte dysfunction in driving rsFC abnormalities in depression.