Elevated prelimbic cortex-to-basolateral amygdala circuit activity mediates comorbid anxiety-like behaviors associated with chronic pain.

Chronic pain can cause both hyperalgesia and anxiety symptoms. However, how the two components are encoded in the brain remains unclear. The prelimbic cortex (PrL), a critical brain region for both nociceptive and emotional modulations, serves as an ideal medium for comparing how the two components are encoded. We report that PrL neurons projecting to the basolateral amygdala (PrLBLA) and those projecting to the ventrolateral periaqueductal gray (PrLl/vlPAG) were segregated and displayed elevated and reduced neuronal activity, respectively, during pain chronicity. Consistently, optogenetic suppression of the PrL-BLA circuit reversed anxiety-like behaviors, whereas activation of the PrL-l/vlPAG circuit attenuated hyperalgesia in mice with chronic pain. Moreover, mechanistic studies indicated that elevated TNF-α/TNFR1 signaling in the PrL caused increased insertion of GluA1 receptors into PrLBLA neurons and contributed to anxiety-like behaviors in mice with chronic pain. Together, these results provide insights into the circuit and molecular mechanisms in the PrL for controlling pain-related hyperalgesia and anxiety-like behaviors.

Astrocytic lactate dehydrogenase A regulates neuronal excitability and depressive-like behaviors through lactate homeostasis in mice.

Alterations in energy metabolism are associated with depression. However, the role of glycolysis in the pathogenesis of depression and the underlying molecular mechanisms remain unexplored. Through an unbiased proteomic screen coupled with biochemical verifications, we show that the levels of glycolysis and lactate dehydrogenase A (LDHA), a glycolytic enzyme that catalyzes L-lactate production, are reduced in the dorsomedial prefrontal cortex (dmPFC) of stress-susceptible mice in chronic social defeat stress (CSDS) model. Conditional knockout of LDHA from the brain promotes depressive-like behaviors in both male and female mice, accompanied with reduced L-lactate levels and decreased neuronal excitability in the dmPFC. Moreover, these phenotypes could be duplicated by knockdown of LDHA in the dmPFC or specifically in astrocytes. In contrast, overexpression of LDHA reverses these phenotypic changes in CSDS-susceptible mice. Mechanistic studies demonstrate that L-lactate promotes neuronal excitability through monocarboxylic acid transporter 2 (MCT2) and by inhibiting large-conductance Ca2+-activated potassium (BK) channel. Together, these results reveal a role of LDHA in maintaining neuronal excitability to prevent depressive-like behaviors.

The ketogenic diet increases Neuregulin 1 expression via elevating histone acetylation and its anti-seizure effect requires ErbB4 kinase activity.

BACKGROUND: The ketogenic diet (KD)has been considered an effective treatment for epilepsy, whereas its underlying mechanisms remain obscure. We have previously reported that the KD feeding increased Neuregulin 1 (NRG1) expression in the hippocampus; disruption of NRG1 signaling by genetically deleting its receptor-ErbB4 abolished KD's effects on inhibitory synaptic activity and seizures. However, it is still unclear about the mechanisms underlying the effect of KD on NRG1 expression and whether the effects of KD require ErbB4 kinase activity. METHODS: The effects of the KD on NRG1 expression were assessed via western blotting and real-time PCR. Acetylation level at the Nrg1 promoter locus was examined using the chromatin immunoprecipitation technique. Kainic acid (KA)-induced acute seizure model was utilized to examine the effects of KD and histone deacetylase inhibitor-TSA on seizures. Synaptic activities in the hippocampus were recorded with the technique of electrophysiology. The obligatory role of ErbB4 kinase activity in KD's effects on seizures and inhibitory synaptic activity was evaluated by using ErbB kinase antagonist and transgenic mouse-T796G. RESULTS: We report that KD specifically increases Type I NRG1 expression in the hippocampus. Using the chromatin immunoprecipitation technique, we observe increased acetylated-histone occupancy at the Nrg1 promoter locus of KD-fed mice. Treatment of TSA dramatically elevates NRG1 expression and diminishes the difference between the effects of the control diet (CD) and KD. These data indicate that KD increases NRG1 expression via up-regulating histone acetylation. Moreover, both pharmacological and genetic inhibitions of ErbB4 kinase activity significantly block the KD's effects on inhibitory synaptic activity and seizure, suggesting an essential role of ErbB4 kinase activity. CONCLUSION: These results strengthen our understanding of the role of NRG1/ErbB4 signaling in KD and shed light on novel therapeutic interventions for epilepsy.

Neuregulin 1/ErbB4 signaling contributes to the anti-epileptic effects of the ketogenic diet.

BACKGROUND: The ketogenic diet (KD) has been recognized as a potentially effective therapy to treat neuropsychiatric diseases, including epilepsy. Previous studies have indicated that KD treatment elevates γ-Amino butyric acid (GABA) levels in both human and murine brains, which presumably contributes to the KD's anti-seizure effects. However, this has not been systematically investigated at the synaptic level, and the underlying molecular mechanisms remain to be elucidated. METHODS: Kainic acid (KA)-induced acute and chronic seizure models were utilized to examine the effects of KD treatment on seizure threshold and epileptogenesis. Synaptic activities in the hippocampus were recorded with the technique of electrophysiology. The effects of the KD on Neuregulin 1 (Nrg1) expression were assessed via RNA sequencing, real-time PCR and Western blotting. The obligatory role of Nrg1 in KD's effects on seizures was evaluated through disruption of Nrg1 signaling in mice by genetically deleting its receptor-ErbB4. RESULTS: We found that KD treatment suppressed seizures in both acute and chronic seizure models and enhanced presynaptic GABA release probability in the hippocampus. By screening molecular targets linked to GABAergic activity with transcriptome analysis, we identified that KD treatment dramatically increased the Nrg1 gene expression in the hippocampus. Disruption of Nrg1 signaling by genetically deleting its receptor-ErbB4 abolished KD's effects on GABAergic activity and seizures. CONCLUSION: Our findings suggest a critical role of Nrg1/ErbB4 signaling in mediating KD's effects on GABAergic activity and seizures, shedding light on developing new therapeutic interventions to seizure control.

Flagellum Malfunctions Trigger Metaboly as an Escape Strategy in Euglena gracilis.

Euglenoids present the ability to alter the shape of their bodies, a process referred to as metaboly. Metaboly is usually used by phagotrophic cells to engulf their prey. However, Euglena gracilis is osmotrophic and photosynthetic. Though metaboly was discovered centuries ago, it remains unclear why E. gracilis undergo metaboly and what causes them to deform, and some consider metaboly to be a functionless ancestral vestige. Here, we discover that flagellum malfunctions trigger metaboly and metaboly is a smart escape strategy adopted by E. gracilis when the proper rotation and beating of the flagellum are hindered by restrictions including surface obstruction, sticking, resistance, or limited space. Metaboly facilitates escape in five ways: (i) detaching the body from the surface; (ii) enlarging the space between flagellum and the restricting surface which restores beating and rotation of the flagellum; (iii) decreasing the torque of viscous resistance for rotation of the body; (iv) decreasing the length of the body; and (v) crawling backwards on a surface or swimming backwards if the flagellum completely malfunctions or has broken off. Our findings suggest that metaboly plays a key role in enabling E. gracilis to escape from harmful conditions when flagellar functions are impaired or absent.

Anti-depression effects of ketogenic diet are mediated via the restoration of microglial activation and neuronal excitability in the lateral habenula.

Depression is a severe neuropsychiatric disorder, of which the underlying pathological mechanisms remain unclear. The ketogenic diet (KD) has been reported to exhibit preventative effects on depressive-like behaviors in rodents. However, the therapeutic effects of KD on depressive-like behaviors have not been illustrated thus far. Here, we found that KD treatment dramatically ameliorated depressive-like behaviors in both repeated social defeat stress (R-SDS) and lipopolysaccharide (LPS) models, indicating the potential therapeutic effects of KD on depression. Our electrophysiological studies further showed that neuronal excitability was increased in the lateral habenula (LHb) of mice exposed to R-SDS or LPS, which can be reversed in the presence of KD treatment. Moreover, R-SDS and LPS were also found to induce robust microglial inflammatory activation in the LHb. Importantly, these phenotypes were rescued in mice fed with KD. In addition, we found that the protein level of innate immune receptor Trem2 in the LHb was significantly decreased in depression models. Specific knockdown of Trem2 in LHb microglia induced depressive-like behaviors, increased neuronal excitability as well as robust microglial inflammatory activation. Altogether, we demonstrated the therapeutic effects of KD on depressive-like behaviors, which are probably mediated via the restoration of microglial inflammatory activation and neuronal excitability. Besides, we also proposed an unrecognized function of Trem2 in the LHb for depression. Our study sheds light on the pathogenesis of depression and thereby offers a potential therapeutic intervention.

Social Company by a Receptive Mating Partner Facilitates Fear Extinction.

Fear extinction remains an unresolved challenge for behavioral exposure therapy in patients with post-traumatic stress disorder (PTSD). Previous reports have suggested that social support from either familiar or unfamiliar same-sex partners is beneficial to attenuating fear responses during fear extinction and renewal. Despite that, few studies have examined the effects of social support in advance on fear extinction and/or retrieval. It is also not clear whether social company by a receptive mating partner in advance facilitates fear extinction. In the present study, we address these questions by introducing a co-housing method, where fear-conditioned male mice are co-housed with or without a receptive mating partner prior to fear extinction. We found that while co-housing with an ovariectomized female mouse showed little effect on fear extinction or retrieval, social company by a receptive mating partner in advance dramatically facilitates fear extinction. In addition, the number of cFos-positive neurons in the basolateral amygdala (BLA) were also found to be reduced in male mice accompanied with receptive mating partner in response to fear extinction and retrieval, indicating diminished neuronal activation. Electrophysiological studies further showed that the excitability of excitatory neurons in BLA was decreased, which is probably due to the attenuated basal level of excitatory synaptic transmission. Together, our observations demonstrate an effect of social company by a receptive mating partner can facilitate fear extinction and afford a possible cellular mechanism.

Synthesis, self-assembly and nonlinear optical activity of selenium-annulated perylene diimide.

A novel Se-annulated perylene diimide derivative tethered with polyhedral oligosilsesquioxane (POSS) nanoparticles (POSS-2SePDI-POSS) was designed and prepared. The introduction of selenium atoms endows POSS-2SePDI-POSS with significant fluorescence quenching but enhanced excited-state absorption. As a result, POSS-2SePDI-POSS exhibits a distinct reverse saturable absorption characteristic, suggesting its potential application in optical limiting.

X-linked inhibitor of apoptosis-associated factor l (XAFl) enhances the sensitivity of colorectal cancer cells to cisplatin.

The purpose of present study was to investigate the roles of X-linked inhibitor of apoptosis-associated factor l (XAFl) in regulation apoptosis of colorectal cancer (CRC) cells after treatment with cisplatin (DDP). A total of ten paired cancerous and non-cancerous tissues were collected from patients with CRC after surgery. The levels of XAFl protein were detected by Western blot. Primary CRC cells were separated from cancer tissues, and its viability or apoptosis after treatment with DDP was determined with MTT or Annexin V/PI assays, respectively. Furthermore, we either up-regulated transfecting a XAF1 overexpression vector or down-regulated XAF1 by siRNA interference. And then, the XAF1 levels and its sensitivity to cisplatin were assessed. XAFl had a lower expression in the cancerous tissues from samples T1, T2 and T3 than their paired non-cancerous tissues N1, N2 and N3. However, the expression of XAF1 was not detected in samples T4 and N1. XAF1 levels in cancer tissues significantly decreased in comparison with normal tissues. Cell abilities of primary cells were significantly decreased in a dose-dependent manner, after treatment with a series concentrations of cisplatin (2, 5, 10 µg/mL) for 48 h. Although, after down-expression of XAFl by siRNA, cisplatin caused a significant decreases in apoptosis rates in CRC cells. The up-regulation of XAF1 distinctly increased apoptosis in CRC cells administered by cisplatin (P < 0.001). The XAFl could promoted apoptosis and enhanced chemotherapy sensitivity to cisplatin in CRC cells.

Combination of gefitinib and DNA methylation inhibitor decitabine exerts synergistic anti-cancer activity in colon cancer cells.

Despite recent advances in the treatment of human colon cancer, the chemotherapy efficacy against colon cancer is still unsatisfactory. In the present study, effects of concomitant inhibition of the epidermal growth factor receptor (EGFR) and DNA methyltransferase were examined in human colon cancer cells. We demonstrated that decitabine (a DNA methyltransferase inhibitor) synergized with gefitinib (an EGFR inhibitor) to reduce cell viability and colony formation in SW1116 and LOVO cells. However, the combination of the two compounds displayed minimal toxicity to NCM460 cells, a normal human colon mucosal epithelial cell line. The combination was also more effective at inhibiting the AKT/mTOR/S6 kinase pathway. In addition, the combination of decitabine with gefitinib markedly inhibited colon cancer cell migration. Furthermore, gefitinib synergistically enhanced decitabine-induced cytotoxicity was primarily due to apoptosis as shown by Annexin V labeling that was attenuated by z-VAD-fmk, a pan caspase inhibitor. Concomitantly, cell apoptosis resulting from the co-treatment of gefitinib and decitabine was accompanied by induction of BAX, cleaved caspase 3 and cleaved PARP, along with reduction of Bcl-2 compared to treatment with either drug alone. Interestingly, combined treatment with these two drugs increased the expression of XIAP-associated factor 1 (XAF1) which play an important role in cell apoptosis. Moreover, small interfering RNA (siRNA) depletion of XAF1 significantly attenuated colon cancer cells apoptosis induced by the combination of the two drugs. Our findings suggested that gefitinib in combination with decitabine exerted enhanced cell apoptosis in colon cancer cells were involved in mitochondrial-mediated pathway and induction of XAF1 expression. In conclusion, based on the observations from our study, we suggested that the combined administration of these two drugs might be considered as a novel therapeutic regimen for treating colon cancer.