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Behavioral changes or neuropsychiatric symptoms (NPSs) are common features in dementia and are associated with accelerated cognitive impairment and earlier deaths. However, how NPSs are intertwined with cognitive decline remains elusive. In this study, we identify that the basolateral amygdala (BLA) is a key brain region that is associated with mood disorders and memory decline in the AD course. During the process from pre‐ to post‐onset in AD, the dysfunction of parvalbumin (PV) interneurons and pyramidal neurons in the amygdala leads to hyperactivity of pyramidal neurons in the basal state and insensitivity to external stimuli. We further demonstrate that serotonin (5‐HT) receptors in distinct neurons synergistically regulate the BLA microcircuit of AD rather than 5‐HT levels, in which both restrained inhibitory inputs by excessive 5‐HT1AR signaling in PV interneurons and depolarized pyramidal neurons via upregulated 5‐HT2AR contribute to aberrant neuronal hyperactivity. Downregulation of these two 5‐HT receptors simultaneously enables neurons to resist β‐amyloid peptides (Aβ) neurotoxicity and ameliorates the mood and cognitive defects. Therefore, our study reveals a crucial role of 5‐HT receptors for regulating neuronal homeostasis in AD pathogenesis, and this would provide early intervention and potential targets for AD cognitive decline. [ABSTRACT FROM AUTHOR]

Background and Purpose: Atopic dermatitis is a common chronic pruritic inflammatory disease of the skin involving neuro‐immune communication. Neuronal mechanism‐based therapeutic treatments remain lacking. We investigated the efficacy of intravenous lidocaine therapy on atopic dermatitis and the underlying neuro‐immune mechanism. Experimental Approach: Pharmacological intervention, immunofluorescence, RNA‐sequencing, genetic modification and immunoassay were performed to dissect the neuro‐immune basis of itch and inflammation in atopic dermatitis‐like mouse model and in patients. Key Results: Lidocaine alleviated skin lesions and itch in both atopic dermatitis patients and calcipotriol (MC903)‐induced atopic dermatitis model by blocking subpopulation of sensory neurons. QX‐314, a charged NaV blocker that enters through pathologically activated large‐pore ion channels and selectivity inhibits a subpopulation of sensory neurons, has the same effects as lidocaine in atopic dermatitis model. Genetic silencing NaV1.8‐expressing sensory neurons was sufficient to restrict cutaneous inflammation and itch in the atopic dermatitis model. However, pharmacological blockade of TRPV1‐positive nociceptors only abolished persistent itch but did not affect skin inflammation in the atopic dermatitis model, indicating a difference between sensory neuronal modulation of skin inflammation and itch. Inhibition of activity‐dependent release of calcitonin gene‐related peptide (CGRP) from sensory neurons by lidocaine largely accounts for the therapeutic effect of lidocaine in the atopic dermatitis model. Conclusion and Implications: NaV1.8+ sensory neurons play a critical role in pathogenesis of atopic dermatitis and lidocaine is a potential anti‐inflammatory and anti‐pruritic agent for atopic dermatitis. A dissociable difference for sensory neuronal modulation of skin inflammation and itch contributes to further understanding of pathogenesis in atopic dermatitis. [ABSTRACT FROM AUTHOR]

Acid‐sensing ion channel 1a (ASIC1a) is well‐known to play a major pathophysiological role during brain ischemia linked to acute acidosis of ~pH 6, whereas its function during physiological brain activity, linked to much milder pH changes, is still poorly understood. Here, by performing live cell imaging utilizing Na+ and Ca2+ sensitive and spatially specific fluorescent dyes, we investigated the role of ASIC1a in cytosolic Na+ and Ca2+ signals elicited by a mild extracellular drop from pH 7.4 to 7.0 and how these affect mitochondrial Na+ and Ca2+ signaling or metabolic activity. We show that in mouse primary cortical neurons, this small extracellular pH change triggers cytosolic Na+ and Ca2+ waves that propagate to mitochondria. Inhibiting ASIC1a with Psalmotoxin 1 or ASIC1a gene knockout blocked not only the cytosolic but also the mitochondrial Na+ and Ca2+ signals. Moreover, physiological activation of ASIC1a by this pH shift enhances mitochondrial respiration and evokes mitochondrial Na+ signaling even in digitonin‐permeabilized neurons. Altogether our results indicate that ASIC1a is critical in linking physiological extracellular pH stimuli to mitochondrial ion signaling and metabolic activity and thus is an important metabolic sensor. [ABSTRACT FROM AUTHOR]

The photo‐manipulation of bioactive molecules provides unique advantages due to the high temporal and spatial precision of light. The first visible‐light uncaging reaction by photocatalytic deboronative hydroxylation in live cells is now demonstrated. Using Fluorescein and Rhodamine derivatives as photocatalysts and ascorbates as reductants, transient hydrogen peroxides were generated from molecular oxygen to uncage phenol, alcohol, and amine functional groups on bioactive molecules in bacteria and mammalian cells, including neurons. This effective visible‐light uncaging reaction enabled the light‐inducible protein expression, the photo‐manipulation of membrane potentials, and the subcellular‐specific photo‐release of small molecules. Visible‐light uncaging by photocatalysis: A visible‐light uncaging reaction using photocatalytic deboronative hydroxylation in live cells is demonstrated. This technology enabled visible‐light‐inducible protein expression, the photo‐manipulation of membrane potentials, and the subcellular‐specific photo‐release of small molecules. [ABSTRACT FROM AUTHOR]

Summary: Aims: Acid‐sensing ion channels (ASICs) are extracellular proton‐gated cation channels that have been implicated in multiple physiological and pathological processes, and peripheral ASIC3 prominently participate into the pathogenesis of chronic pain, itch, and neuroinflammation, which necessitates the need for discovery and development of novel modulators in a subtype‐specific manner. Methods: Whole‐cell patch clamp recordings and behavioral assays were used to examine the effect of several natural compounds on the ASIC‐mediated currents and acid‐induced nocifensive behavior, respectively. Results: We identified a natural flavonoid compound, (‐)‐epigallocatechin gallate (EGCG, compound 11), that acts as a potent inhibitor for the ASIC3 channel in an isoform‐specific way. The compound 11 inhibited ASIC3 currents with an apparent half maximal inhibitory concentration of 13.2 μmol/L when measured at pH 5.0. However, at the concentration up to 100 μmol/L, the compound 11 had no significant impacts on the homomeric ASIC1a, 1b, and 2a channels. In contrast to most of the known ASIC inhibitors that usually bear either basic or carboxylic groups, the compound 11 belongs to the polyphenolic family. In compound 11, both the chirality and the 3‐hydroxyl group of its pyrogallol part, in addition to the integrity of the gallate part, are crucial for the inhibitory efficacy. Finally, EGCG was found significantly to decrease the acid‐induced nocifensive behavior in mice. Conclusion: Taken together, these results thus defined a novel backbone structure for small molecule drug design targeting ASIC3 channels to treat pain‐related diseases. [ABSTRACT FROM AUTHOR]

Permafrost represents an important understudied genetic resource. Soil microorganisms play important roles in regulating biogeochemical cycles and maintaining ecosystem function. However, our knowledge of patterns and drivers of permafrost microbial communities is limited over broad geographic scales. Using high-throughput Illumina sequencing, this study compared soil bacterial, archaeal and fungal communities between the active and permafrost layers on the Tibetan Plateau. Our results indicated that microbial alpha diversity was significantly higher in the active layer than in the permafrost layer with the exception of fungal Shannon-Wiener index and Simpson's diversity index, and microbial community structures were significantly different between the two layers. Our results also revealed that environmental factors such as soil fertility (soil organic carbon, dissolved organic carbon and total nitrogen contents) were the primary drivers of the beta diversity of bacterial, archaeal and fungal communities in the active layer. In contrast, environmental variables such as the mean annual precipitation and total phosphorus played dominant roles in driving the microbial beta diversity in the permafrost layer. Spatial distance was important for predicting the bacterial and archaeal beta diversity in both the active and permafrost layers, but not for fungal communities. Collectively, these results demonstrated different driving factors of microbial beta diversity between the active layer and permafrost layer, implying that the drivers of the microbial beta diversity observed in the active layer cannot be used to predict the biogeographic patterns of the microbial beta diversity in the permafrost layer. [ABSTRACT FROM AUTHOR]

Aims To explore the role of histamine in acute pain perception and its possible mechanisms. Methods Pain-like behaviors induced by four types of noxious stimuli (hot-plate, tail-pressure, acetic acid, and formalin) were accessed in mice. Nav1.8 expression and functions in primary afferent neurons were compared between histidine decarboxylase knockout ( HDC−/−) mice and their wild-types. Results HDC−/− mice, lacking in endogenous histamine, showed elevated sensitivity to all these noxious stimuli, as compared with the wild-types. In addition, a depletion of endogenous histamine with α-fluoromethylhistidine (α- FMH), a specific HDC inhibitor, or feeding mice a low-histamine diet also enhanced nociception in the wild-types. Nav1.8 expression in primary afferent neurons was increased both in HDC−/− and in α- FMH-treated wild-type mice. A higher Nav1.8 current density, a lower action potential ( AP) threshold, and a higher firing rate in response to suprathreshold stimulation were observed in nociception-related small DRG neurons of HDC−/− mice. Nav1.8 inhibitor A-803467, but not TTX, diminished the hyperexcitability and blocked repetitive AP firing of these neurons. Conclusion Our results indicate that histamine participates in acute pain modulation in a dose-related manner. The regulation of Nav1.8 expression and the excitability of nociceptive primary afferent neurons may be involved in the underlying mechanisms. [ABSTRACT FROM AUTHOR]

Aim To investigate the effect of chronic H1-antihistamine treatment on seizure susceptibility after drug withdrawal in nonepileptic rats and to further study its relation to glutamine synthetase ( GS), which is the key enzyme for glutamate metabolism and gamma aminobutyric acid ( GABA) synthesis. Methods After drug withdrawal from a 2-week treatment with diphenhydramine or pyrilamine, seizure susceptibility was determined by amygdaloid kindling or pentylenetetrazol model; meanwhile, the GS expression or activity was analyzed. The glutamine, glutamate, and GABA contents were measured by high-performance liquid chromatography. Results Seizure susceptibility significantly increased in amygdaloid kindling and pentylenetetrazol model 10 days after drug withdrawal from a 2-week treatment with H1-antihistamines. Meanwhile, GS activity and expression in the cortex or hippocampus decreased simultaneously with a marked decline of glutamine and GABA content. Comparable inhibition of GS activity by methionine sulfoximine was also sufficient to increase the susceptibility, while supplementation with glutamine reversed the high susceptibility 10 days after diphenhydramine withdrawal. Moreover, the seizure susceptibility increased 10 days after diphenhydramine withdrawal in wild-type mice but not in histidine decarboxylase knockout mice, which lack histamine. Conclusions Chronic H1-antihistamine treatment produces long-lasting increase in seizure susceptibility in nonepileptic rodents after drug withdrawal and its mechanism involves impairment of GS through blocking the action of histamine. [ABSTRACT FROM AUTHOR]

The overall goal of this study was to determine the molecular basis by which mixed-lineage kinase 3 (MLK3) kinase and its signaling pathways are negatively regulated by the pro-survival Akt pathway in cerebral ischemia. We demonstrated that tyrosine phosphorylation of the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) underlies the increased Akt-Ser473 phosphorylation by orthovanadate. Co-immunoprecipitation analysis revealed that endogenous Akt physically interacts with Rac1 in the hippocampal CA1 region, and this interaction is promoted on tyrosine phosphatase inhibition. The elevated Akt activation can deactivate MLK3 by phosphorylation at the Ser71 residue of Rac1, a small Rho family of guanidine triphosphatases required for MLK3 autophosphorylation. Subsequently, inhibition of c-Jun N-terminal kinase 3 (JNK3) results in decreased serine phosphorylation of 14-3-3, a cytoplasmic anchor of Bax, and prevents ischemia-induced mitochondrial translocation of Bax, release of cytochrome c and activation of caspase 3. At the same time, the expression of Fas-ligand decreases in the CA1 region after inhibition of c-Jun activation. The neuroprotective effect of Akt activation is significant in the CA1 region after global cerebral ischemia. Our results suggest that the activation of the pro-apoptotic MLK3/JNK3 cascade induced by ischemic stress can be suppressed through activation of the anti-apoptotic phosphatidylinositol 3-kinase/Akt pathway, which provides a direct link between Akt and the family of stress-activated kinases. [ABSTRACT FROM AUTHOR]

Aims: To explore the role of histamine in acute pain perception and its possible mechanisms., Methods: Pain-like behaviors induced by four types of noxious stimuli (hot-plate, tail-pressure, acetic acid, and formalin) were accessed in mice. Nav 1.8 expression and functions in primary afferent neurons were compared between histidine decarboxylase knockout (HDC(-/-) ) mice and their wild-types., Results: HDC(-/-) mice, lacking in endogenous histamine, showed elevated sensitivity to all these noxious stimuli, as compared with the wild-types. In addition, a depletion of endogenous histamine with α-fluoromethylhistidine (α-FMH), a specific HDC inhibitor, or feeding mice a low-histamine diet also enhanced nociception in the wild-types. Nav 1.8 expression in primary afferent neurons was increased both in HDC(-/-) and in α-FMH-treated wild-type mice. A higher Nav 1.8 current density, a lower action potential (AP) threshold, and a higher firing rate in response to suprathreshold stimulation were observed in nociception-related small DRG neurons of HDC(-/-) mice. Nav 1.8 inhibitor A-803467, but not TTX, diminished the hyperexcitability and blocked repetitive AP firing of these neurons., Conclusion: Our results indicate that histamine participates in acute pain modulation in a dose-related manner. The regulation of Nav 1.8 expression and the excitability of nociceptive primary afferent neurons may be involved in the underlying mechanisms., (© 2013 John Wiley & Sons Ltd.)