A Prelimbic Cortex-Thalamus Circuit Bidirectionally Regulates Innate and Stress-Induced Anxiety-Like Behavior.

Anxiety-related disorders respond to cognitive behavioral therapies, which involved the medial prefrontal cortex (mPFC). Previous studies have suggested that subregions of the mPFC have different and even opposite roles in regulating innate anxiety. However, the specific causal targets of their descending projections in modulating innate anxiety and stress-induced anxiety have yet to be fully elucidated. Here, we found that among the various downstream pathways of the prelimbic cortex (PL), a subregion of the mPFC, PL-mediodorsal thalamic nucleus (MD) projection, and PL-ventral tegmental area (VTA) projection exhibited antagonistic effects on anxiety-like behavior, while the PL-MD projection but not PL-VTA projection was necessary for the animal to guide anxiety-related behavior. In addition, MD-projecting PL neurons bidirectionally regulated remote but not recent fear memory retrieval. Notably, restraint stress induced high-anxiety state accompanied by strengthening the excitatory inputs onto MD-projecting PL neurons, and inhibiting PL-MD pathway rescued the stress-induced anxiety. Our findings reveal that the activity of PL-MD pathway may be an essential factor to maintain certain level of anxiety, and stress increased the excitability of this pathway, leading to inappropriate emotional expression, and suggests that targeting specific PL circuits may aid the development of therapies for the treatment of stress-related disorders.

Mature astrocytes as source for astrocyte repopulation after deletion in the medial prefrontal cortex: Implications for depression.

The adult brain retains a high repopulation capacity of astrocytes after deletion, and both mature astrocytes in the neocortex and neural stem cells in neurogenic regions possess the potential to generate astrocytes. However, the origin and the repopulation dynamics of the repopulating astrocytes after deletion remain largely unclear. The number of astrocytes is reduced in the medial prefrontal cortex (mPFC) of patients with depression, and selective elimination of mPFC astrocytes is sufficient to induce depression-like behaviors in rodents. However, whether astrocyte repopulation capacity is impaired in depression is unknown. In this study, we used different transgenic mouse lines to genetically label different cell types and demonstrated that in the mPFC of normal adult mice of both sexes, mature astrocytes were a major source of the repopulating astrocytes after acute deletion induced by an astrocyte-specific toxin, L-alpha-aminoadipic acid (L-AAA), and astrocyte regeneration was accomplished within two weeks accompanied by reversal of depression-like behaviors. Furthermore, re-ablation of mPFC astrocytes post repopulation led to reappearance of depression-like behaviors. In adult male mice subjected to 14-day chronic restraint stress, a well-validated mouse model of depression, the number of mPFC astrocytes was reduced; however, the ability of mPFC astrocytes to repopulate after L-AAA-induced deletion was largely unaltered. Our study highlights a potentially beneficial role for repopulating astrocytes in depression and provides novel therapeutic insights into enhancing local mature astrocyte generation in depression.

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.

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.

Distinct roles of astroglia and neurons in synaptic plasticity and memory.

Long-term potentiation (LTP) in the hippocampus is the most studied form of synaptic plasticity. Temporal integration of synaptic inputs is essential in synaptic plasticity and is assumed to be achieved through Ca2+ signaling in neurons and astroglia. However, whether these two cell types play different roles in LTP remain unknown. Here, we found that through the integration of synaptic inputs, astrocyte inositol triphosphate (IP3) receptor type 2 (IP3R2)-dependent Ca2+ signaling was critical for late-phase LTP (L-LTP) but not early-phase LTP (E-LTP). Moreover, this process was mediated by astrocyte-derived brain-derived neurotrophic factor (BDNF). In contrast, neuron-derived BDNF was critical for both E-LTP and L-LTP. Importantly, the dynamic differences in BDNF secretion play a role in modulating distinct forms of LTP. Moreover, astrocyte- and neuron-derived BDNF exhibited different roles in memory. These observations enriched our knowledge of LTP and memory at the cellular level and implied distinct roles of astrocytes and neurons in information integration.

PV network plasticity mediated by neuregulin1-ErbB4 signalling controls fear extinction.

Neuroplasticity in the medial prefrontal cortex (mPFC) is essential for fear extinction, the process of which forms the basis of the general therapeutic process used to treat human fear disorders. However, the underlying molecules and local circuit elements controlling neuronal activity and concomitant induction of plasticity remain unclear. Here we show that sustained plasticity of the parvalbumin (PV) neuronal network in the infralimbic (IL) mPFC is required for fear extinction in adult male mice and identify the involvement of neuregulin 1-ErbB4 signalling in PV network plasticity-mediated fear extinction. Moreover, regulation of fear extinction by basal medial amygdala (BMA)-projecting IL neurons is dependent on PV network configuration. Together, these results uncover the local molecular circuit mechanisms underlying mPFC-mediated top-down control of fear extinction, suggesting alterative therapeutic approaches to treat fear disorders.

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.

The growth rate of hepatocellular carcinoma is different with different TNM stages at diagnosis.

BACKGROUND: Hepatocellular carcinoma (HCC) progresses fast and has a poor prognosis, but the growth rate in different TNM stages is not clear. The present study was to estimate the growth rate of HCC with different TNM stages at diagnosis. METHODS: Baseline demographics and tumor characteristics were analyzed for 10145 patients in Surveillance, Epidemiology, and End Results (SEER) Program-registered HCC. Multiple linear regression models were used for age adjustment with patient race, sex, marital status, and HCC grade. RESULTS: The age at diagnosis was younger in Caucasians and males. The adjusted average age of patients with stage I HCC was 65.26 years. The adjusted age of patients with stage II, IIIA, IIIB, and IIIC was -0.17, -0.25, -0.29, and -0.55 adjusted-year younger compared with patients with stage I HCC (all P < 0.001). The adjusted average age of patients with T1 was 65.26 years. The age adjustment was -0.17, -0.26, and -0.55 respectively (all P < 0.001) for T2, T3 or T4 tumors without distant metastases. CONCLUSIONS: These findings demonstrated that the more advanced the HCC stage at diagnosis, the younger the age at diagnosis and the faster the HCC growth from tumor occurrence.

erbb4 Deficits in Chandelier Cells of the Medial Prefrontal Cortex Confer Cognitive Dysfunctions: Implications for Schizophrenia.

erbb4 is a known susceptibility gene for schizophrenia. Chandelier cells (ChCs, also known as axo-axonic cells) are a distinct GABAergic interneuron subtype that exclusively target the axonal initial segment, which is the site of pyramidal neuron action potential initiation. ChCs are a source of ErbB4 expression and alterations in ChC-pyramidal neuron connectivity occur in the medial prefrontal cortex (mPFC) of schizophrenic patients and animal models of schizophrenia. However, the contribution of ErbB4 in mPFC ChCs to the pathogenesis of schizophrenia remains unknown. By conditional deletion or knockdown of ErbB4 from mPFC ChCs, we demonstrated that ErbB4 deficits led to impaired ChC-pyramidal neuron connections and cognitive dysfunctions. Furthermore, the cognitive dysfunctions were normalized by L-838417, an agonist of GABAAα2 receptors enriched in the axonal initial segment. Given that cognitive dysfunctions are a core symptom of schizophrenia, our results may provide a new perspective for understanding the etiology of schizophrenia and suggest that GABAAα2 receptors may be potential pharmacological targets for its treatment.

Neuronal mTORC1 Is Required for Maintaining the Nonreactive State of Astrocytes.

Astrocytes respond to CNS insults through reactive astrogliosis, but the underlying mechanisms are unclear. In this study, we show that inactivation of mechanistic target of rapamycin complex (mTORC1) signaling in postnatal neurons induces reactive astrogliosis in mice. Ablation of Raptor (an mTORC1-specific component) in postmitotic neurons abolished mTORC1 activity and produced neurons with smaller soma and fewer dendrites, resulting in microcephaly and aberrant behavior in adult mice. Interestingly, extensive astrogliosis without significant astrocyte proliferation and glial scar formation was observed in these mice. The inhibition of neuronal mTORC1 may activate astrogliosis by reducing neuron-derived fibroblast growth factor 2 (FGF-2), which might trigger FGF receptor signaling in astrocytes to maintain their nonreactive state, and FGF-2 injection successfully prevented astrogliosis in Raptor knock-out mice. This study demonstrates that neuronal mTORC1 inhibits reactive astrogliosis and plays an important role in CNS pathologies.