Autophagy Enhances Memory Erasure through Synaptic Destabilization.

There is substantial interest in memory reconsolidation as a target for the treatment of anxiety disorders, such as post-traumatic stress disorder. However, its applicability is restricted by reconsolidation-resistant boundary conditions that constrain the initial memory destabilization. In this study, we investigated whether the induction of synaptic protein degradation through autophagy modulation, a major protein degradation pathway, can enhance memory destabilization upon retrieval and whether it can be used to overcome these conditions. Here, using male mice in an auditory fear reconsolidation model, we showed that autophagy contributes to memory destabilization and its induction can be used to enhance erasure of a reconsolidation-resistant auditory fear memory that depended on AMPAR endocytosis. Using male mice in a contextual fear reconsolidation model, autophagy induction in the amygdala or in the hippocampus enhanced fear or contextual memory destabilization, respectively. The latter correlated with AMPAR degradation in the spines of the contextual memory-ensemble cells. Using male rats in an in vivo LTP reconsolidation model, autophagy induction enhanced synaptic destabilization in an NMDAR-dependent manner. These data indicate that induction of synaptic protein degradation can enhance both synaptic and memory destabilization upon reactivation and that autophagy inducers have the potential to be used as a therapeutic tool in the treatment of anxiety disorders.SIGNIFICANCE STATEMENT It has been reported that inhibiting synaptic protein degradation prevents memory destabilization. However, whether the reverse relation is true and whether it can be used to enhance memory destabilization are still unknown. Here we addressed this question on the behavioral, molecular, and synaptic levels, and showed that induction of autophagy, a major protein degradation pathway, can enhance memory and synaptic destabilization upon reactivation. We also show that autophagy induction can be used to overcome a reconsolidation-resistant memory, suggesting autophagy inducers as a potential therapeutic tool in the treatment of anxiety disorders.

Does autophagy work in synaptic plasticity and memory?

Many studies have reported the roles played by regulated proteolysis in neural plasticity and memory. Within this context, most of the research focused on the ubiquitin-proteasome system and the endosome-lysosome system while giving lesser consideration to another major protein degradation system, namely, autophagy. Although autophagy intersects with many of the pathways known to underlie synaptic plasticity and memory, only few reports related autophagy to synaptic remodeling. These pathways include PI3K-mTOR pathway and endosome-dependent proteolysis. In this review, we will discuss several lines of evidence supporting a physiological role of autophagy in memory processes, and the possible mechanistic scenarios for how autophagy could fulfill this function.

Neuronal stimulation induces autophagy in hippocampal neurons that is involved in AMPA receptor degradation after chemical long-term depression.

Many studies have reported the roles played by regulated proteolysis in synaptic plasticity and memory, but the role of autophagy in neurons remains unclear. In mammalian cells, autophagy functions in the clearance of long-lived proteins and organelles and in adaptation to starvation. In neurons, although autophagy-related proteins (ATGs) are highly expressed, autophagic activity markers, autophagosome (AP) number, and light chain protein 3-II (LC3-II) are low compared with other cell types. In contrast, conditional knock-out of ATG5 or ATG7 in mouse brain causes neurodegeneration and behavioral deficits. Therefore, this study aimed to test whether autophagy is especially regulated in neurons to adapt to brain functions. In cultured rat hippocampal neurons, we found that KCl depolarization transiently increased LC3-II and AP number, which was partially inhibited with APV, an NMDA receptor (NMDAR) inhibitor. Brief low-dose NMDA, a model of chemical long-term depression (chem-LTD), increased LC3-II with a time course coincident with Akt and mammalian target of rapamycin (mTOR) dephosphorylation and degradation of GluR1, an AMPA receptor (AMPAR) subunit. Downstream of NMDAR, the protein phosphatase 1 inhibitor okadaic acid, PTEN inhibitor bpV(HOpic), autophagy inhibitor wortmannin, and short hairpin RNA-mediated knockdown of ATG7 blocked chem-LTD-induced autophagy and partially recovered GluR1 levels. After chem-LTD, GFP-LC3 puncta increased in spines and in dendrites when AP-lysosome fusion was blocked. These results indicate that neuronal stimulation induces NMDAR-dependent autophagy through PI3K-Akt-mTOR pathway inhibition, which may function in AMPAR degradation, thus suggesting autophagy as a contributor to NMDAR-dependent synaptic plasticity and brain functions.

Combined rectal indomethacin and intravenous saline hydration in post-ERCP pancreatitis prophylaxis.

BACKGROUND AND STUDY AIM: Acute pancreatitis (AP) is a potentially life-threatening complication of endoscopic retrograde cholangiopancreatography (ERCP). There is a lack of effective measures to prevent post-ERCP pancreatitis (PEP), except NSAIDs. Aggressive hydration for AP can be considered, given the frequency of hemoconcentration, hypovolemia, and hypoperfusion in pancreatitis. We aimed to clarify the clinical utility of combined indomethacin and saline hydration for preventing PEP. PATIENTS AND METHOD: In this cross-sectional study, 120 patients undergoing ERCP for the first time at the Gastrointestinal Endoscopy Unit and Liver Unit Kasralainy (GIELUKA) were enrolled and then randomly allocated into two groups: indomethacin and indomethacin-hydration groups. Intravenous (IV) saline was given to the latter at a rate of 10 ml/kg/h after the ERCP for 2 h. RESULTS: The age of the studied patients was 43.8 ± 14.9 years, with 55% of them being female. The patient-related risk factors for PEP were older age (p = 0.039), higher pre-ERCP urea level (p = 0.032), and less choledocholithiasis (p = 0.028). The patients with PEP had a higher frequency of biliary cannulation attempts (p = 0.004) and accidental pancreatic duct cannulation (p = 0.003), required a longer cannulation time (p = 0.021), had undergone precut knife and transpancreatic sphincterotomy at a higher rate (p = 0.032; and p = 0.001, respectively), and had a significantly longer procedure time (p = 0.006). PEP occurred in only five patients in the indomethacin group, while it did not occur in the indomethacin-hydration group (8% vs. 0%, p = 0.022). Serum amylase and lipase elevation 2 h after ERCP were predictors of PEP. However, serum amylase only was significantly lower 2 h post-ERCP in the indomethacin-hydration group than in the indomethacin group (p = 0.045). Moreover, abdominal pain and vomiting on the first day of ERCP were good predictors of PEP. CONCLUSION: Aggressive IV saline hydration with rectal indomethacin can more effectively prevent PEP than indomethacin alone.

Spontaneous motor tempo contributes to preferred music tempo regardless of music familiarity.

Music, and listening to music, has occurred throughout human history. However, it remains unclear why people prefer some types of music over others. To understand why we listen to a certain music, previous studies have focused on preferred tempo. These studies have reported that music components (external), as well as participants' spontaneous motor tempo (SMT; internal), determine tempo preference. In addition, individual familiarity with a piece of music has been suggested to affect the impact of its components on tempo preference. However, the relationships among participants' SMT, music components, and music familiarity as well as the influence of these variables on tempo preference have not been investigated. Moreover, the music components that contribute to tempo preference and their dependence on familiarity remain unclear. Here, we investigate how SMT, music components, and music familiarity simultaneously regulate tempo preference as well as which music components interact with familiarity to contribute to tempo preference. A total of 23 participants adjusted the tempo of music pieces according to their preferences and rated the familiarity of the music. In addition, they engaged in finger tapping at their preferred tempo. Music components, such as the original tempo and the number of notes, were also analyzed. Analysis of the collected data with a linear mixed model showed that the preferred tapping tempo of participants contributed to the preferred music tempo, regardless of music familiarity. In contrast, the contributions of music components differed depending on familiarity. These results suggested that tempo preference could be affected by both movement and memory.

Team Flow Is a Unique Brain State Associated with Enhanced Information Integration and Interbrain Synchrony.

Team flow occurs when a group functions in a high task engagement to achieve a goal, commonly seen in performance and sports. Team flow can enable enhanced positive experiences, as compared with individual flow or regular socializing. However, the neural basis for this enhanced behavioral state remains unclear. Here, we identified neural correlates (NCs) of team flow in human participants using a music rhythm task with electroencephalogram hyperscanning. Experimental manipulations held the motor task constant while disrupting the corresponding hedonic music to interfere with the flow state or occluding the partner's positive feedback to impede team interaction. We validated these manipulations by using psychometric ratings and an objective measure for the depth of flow experience, which uses the auditory-evoked potential (AEP) of a task-irrelevant stimulus. Spectral power analysis at both the scalp sensors and anatomic source levels revealed higher ß-γ power specific to team flow in the left middle temporal cortex (L-MTC). Causal interaction analysis revealed that the L-MTC is downstream in information processing and receives information from areas encoding the flow or social states. The L-MTC significantly contributes to integrating information. Moreover, we found that team flow enhances global interbrain integrated information (II) and neural synchrony. We conclude that the NCs of team flow induce a distinct brain state. Our results suggest a neurocognitive mechanism to create this unique experience.

Enhancement of hyperthermia-induced apoptosis by sanazole in human lymphoma U937 cells.

Sanazole has been tested clinically as a hypoxic cell radiosensitizer. The aim of the present study was to investigate whether sanazole enhances apoptosis induced by hyperthermia at 44 degrees C for 20 min in human lymphoma U937 cells. Sanazole alone induced continuous increase in the intracellular superoxide generation in a time-dependent manner and transient increase in the peroxide formation, which further were enhanced at 1 hour after HT treatment. Moreover, when the cells were treated first with 10 mM sanazole for 40 min, exposed to HT at 44 degrees C for 20 min and the cells were further treated with the drug at 37 degrees C for 6 h, a significant enhancement of HT-induced apoptosis was evidenced by DNA fragmentation, morphological changes and phosphatidylserine externalization. Studying the apoptotic pathways involved in this enhancement, we found that loss of the mitochondrial membrane potential, release of cytochrome c from mitochondria to cytosol, and activation of caspase-3 and caspase-8 was enhanced significantly in the U937 cells after the combined treatment. Moreover, this combination enhanced activation of Bid, and down regulation of Hsp70. In addition, an increase in the intracellular Ca(2+) concentration ([Ca(2+)](i)), and externalization of Fas were observed immediately after sanazole and HT treatment. Our data indicate that sanazole can enhance the hyperthermia induced-apoptosis through the Fas-caspase-8- and [Ca(2+)](i)-dependent apoptotic pathways. In addition, the down regulation of Hsp70 contributed to this enhancement.

Low-intensity ultrasound adjuvant therapy: enhancement of doxorubicin-induced cytotoxicity and the acoustic mechanisms involved.

PURPOSE: In this study, the effects of low-intensity pulsed ultrasound (LIU) as an adjuvant to doxorubicin (DOX) treatment was further investigated in comparison to hyperthermia as another widely used adjuvant. The effects were compared with respect to cell killing and apoptosis induction in U937 cells. Human primary liver cancer (PLC) cells were also used to evaluate the effects of the combinations. The use of an echo contrast agent was investigated for further enhancement of cytotoxicity. Finally, the acoustic mechanisms involved were investigated. METHODS: The effects of different treatment regimens on cell viability were determined using the Trypan blue dye-exclusion test. Apoptosis induction was detected by flow cytometry using fluorescein isothiocyanate-annexin V and propidium iodide staining. The mechanistic study involved electron paramagnetic spin trapping for detecting free radical formation as an indicator of the occurrence of inertial cavitation and spectrophotometry for sucrose hydrolysis as an indicator for noncavitational effects. RESULTS: The combination treatments exerted synergistic effects on cytotoxicity depending on the acoustic conditions used. The use of LIU as an adjuvant to DOX treatment was shown to be superior to the use of hyperthermia as an adjuvant. Moreover, the combination seems to be promising for other cancer types provided that the acoustic conditions are properly selected with respect to drug concentration. The key ultrasound mechanism responsible for the synergism observed was shown to be the production of free radicals by inertial cavitation. Non-cavitational forces were also shown to contribute to the effect. CONCLUSION: This study is motivating to engage in in vivo research with various cancer types as a step toward clinical applicability and is emphasizing on the importance of developing therapeutic protocols for setting LIU parameters with respect to other therapeutic conditions.

Powerful Homeostatic Control of Oligodendroglial Lineage by PDGFRα in Adult Brain.

Oligodendrocyte progenitor cells (OPCs) are widely distributed cells of ramified morphology in adult brain that express PDGFRα and NG2. They retain mitotic activities in adulthood and contribute to oligodendrogenesis and myelin turnover; however, the regulatory mechanisms of their cell dynamics in adult brain largely remain unknown. Here, we found that global Pdgfra inactivation in adult mice rapidly led to elimination of OPCs due to synchronous maturation toward oligodendrocytes. Surprisingly, OPC densities were robustly reconstituted by the active expansion of Nestin+ immature cells activated in meninges and brain parenchyma, as well as a few OPCs that escaped from Pdgfra inactivation. The multipotent immature cells were induced in the meninges of Pdgfra-inactivated mice, but not of control mice. Our findings revealed powerful homeostatic control of adult OPCs, engaging dual cellular sources of adult OPC formation. These properties of the adult oligodendrocyte lineage and the alternative OPC source may be exploited in regenerative medicine.

Synapse-specific representation of the identity of overlapping memory engrams.

Memories are integrated into interconnected networks; nevertheless, each memory has its own identity. How the brain defines specific memory identity out of intermingled memories stored in a shared cell ensemble has remained elusive. We found that after complete retrograde amnesia of auditory fear conditioning in mice, optogenetic stimulation of the auditory inputs to the lateral amygdala failed to induce memory recall, implying that the memory engram no longer existed in that circuit. Complete amnesia of a given fear memory did not affect another linked fear memory encoded in the shared ensemble. Optogenetic potentiation or depotentiation of the plasticity at synapses specific to one memory affected the recall of only that memory. Thus, the sharing of engram cells underlies the linkage between memories, whereas synapse-specific plasticity guarantees the identity and storage of individual memories.

Cryobiopsy versus forceps biopsy in endobronchial lesions, diagnostic yield and safety.

INTRODUCTION: This study aimed to evaluate the safety and diagnostic yield of CB in comparison to forceps biopsy in endobronchial lesions. MATERIAL AND METHODS: Patients with suspected endobronchial lesions were enrolled. Two forceps biopsies and one cryobiopsy were done in the same patient with randomized sequence. The largest diameter of the samples was measured in mm by electronic caliper. Diagnostic yield of each technique and postbronchoscopy bleeding were evaluated. RESULTS: Samples obtained by CB was significantly larger than that of the forceps biopsy (5.9 ± 2.3 vs 2.5 ± 0.8), (p = 0.001). Diagnostic yield of CB was significantly higher than forceps biopsy 74.5% versus 51.1% (p = 0.001). Mild and moderate bleeding grades were reported in both techniques with no significant difference (p = 0.063) (p = 0.5) respectively. Severe bleeding was not recorded in both techniques. CONCLUSIONS: CB represents a safe and effective tool to obtain a larger tissue samples of a good quality with higher diagnostic yield in comparison to standard forceps samples. On the other hand, bleeding occurred more frequently after CB than forceps biopsy. However, without severe adverse effects.

Frequency-specific stimulations induce reconsolidation of long-term potentiation in freely moving rats.

BACKGROUND: When consolidated memories are retrieved, they become labile and a new protein synthesis-dependent reconsolidation process is required to restabilize these memories. So far, most studies conducted on reconsolidation rely on the analyses of animal behavior, leaving the synaptic mechanisms that underlie reconsolidation largely unclear. Here, we examined whether the reconsolidation process occurs in hippocampal long term potentiation (LTP), as a synaptic model that is correlated with long term memories (LTM). RESULTS: We employed LTP system in the dentate gyrus of freely moving rats that lasts for weeks simulating LTM. LTP was induced by high frequency stimulation at 400 Hz (HFS400), and as a reactivation stimulation, we tested a low frequency stimulation at 0.1 Hz (LFS0.1), a theta stimulation at 8 Hz (TS8), or HFS400. Unlike HFS400 reactivation, both LFS0.1 and TS8 induced a reconsolidation-like phenomenon and rendered the LTP labile to protein synthesis inhibition by anisomycin. Without reactivation, LTP remained unaffected by protein synthesis inhibition. In addition, the TS8-induced LTP reconsolidation was NMDAR dependent. CONCLUSION: Our results indicate that, as with behavioral LTM, there are boundary conditions for LTP reconsolidation where only a certain range of frequency stimulations as reactivation can destabilize the consolidated LTP. This LTP reconsolidation system will be useful for future elucidation of the synaptic reconsolidation mechanism.

Mutation-, aging-, and gene dosage-dependent accumulation of neuroserpin (G392E) in endoplasmic reticula and lysosomes of neurons in transgenic mice.

Mutations in human neuroserpin gene cause an autosomal dementia, familial encephalopathy with neuroserpin inclusion bodies (FENIB). We generated and analyzed transgenic mice expressing high levels of either FENIB-type (G392E) or wild-type human neuroserpin in neurons of the central nervous system. G392E neuroserpin accumulated age-dependently in neurons of the neocortex, thalamus, amygdala, pons, and spinal cord of homozygous transgenic mice. Such accumulations were not observed in hemizygous transgenic mice nor in transgenic mice for wild-type neuroserpin. In differential centrifugation of brain homogenates, G392E neuroserpin recovered in the nucleus-rich fraction dramatically increased along with aging, suggesting that the aggregations gradually increase their densities presumably by their conversion into heavier and more compact configurations. In immunoelectron microscopical analyses, immunopositivities for G392E neuroserpin were found not only in endoplasmic reticulum but also in lysosomes. G392E neuroserpin transgenic mice were much more susceptible to seizures induced by kainate administration than nontransgenic mice. Overall, G392E neuroserpin accumulated in the central nervous system neurons of transgenic mice in mutation-, aging-, and gene dosage-dependent manners. The established transgenic mice will be valuable to elucidate not only mechanisms for the formation of G392E neuroserpin aggregations but also pathways for the degradation and/or clearance of the already formed aggregations in neurons.