Neuroprotective Effect of Chrysophanol as a PI3K/AKT/mTOR Signaling Inhibitor in an Experimental Model of Autologous Blood-induced Intracerebral Hemorrhage

OBJECTIVE

Intracerebral hemorrhage (ICH) refers to predominant, sporadic, and non-traumatic bleeding in the brain parenchyma. The PI3K/AKT/mTOR signaling pathway is an important signal transduction pathway regulated by enzyme-linked receptors and has many biological functions in mammals. It plays a key role in neuronal metabolism, gene expression regulation, and tissue homeostasis in the healthy and diseased brain.

METHODS

In the present study, the role of the PI3K/AKT/mTOR pathway inhibitor chrysophanol (CPH) (10 mg/kg and 20 mg/kg, orally) in the improvement of ICH-associated neurological defects in rats was investigated. Autologous blood (20 µL/5 min/unilateral/intracerebroventricular) mimics ICH-like defects involving cellular and molecular dysfunction and neurotransmitter imbalance. The current study also included various behavioral assessments to examine cognition, memory, and motor and neuromuscular coordination. The protein expression levels of PI3K, AKT, and mTOR as well as myelin basic protein and apoptotic markers, such as Bax, Bcl-2, and caspase-3, were examined using ELISA kits. Furthermore, the levels of various neuroinflammatory cytokines and oxidative stress markers were assessed. Additionally, the neurological severity score, brain water content, gross brain pathology, and hematoma size were used to indicate neurological function and brain edema.

RESULTS

CPH was found to be neuroprotective by restoring neurobehavioral alterations and significantly reducing the elevated PI3K, AKT, and mTOR protein levels, and modulating the apoptotic markers such as Bax, Bcl-2, and caspase-3 in rat brain homogenate. CPH substantially reduced the inflammatory cytokines like interleukin (IL)-1β, IL-6, and tumor necrosis factor-α. CPH administration restored the neurotransmitters GABA, glutamate, acetylcholine, dopamine, and various oxidative stress markers.

CONCLUSION

Our results show that CPH may be a promising therapeutic approach for overcoming neuronal damage caused by the overexpression of the PI3K/AKT/mTOR signaling pathway in ICH-induced neurological dysfunctions in rats.

Total Triterpenes of Wolfiporia cocos (Schwein.) Ryvarden & Gilb Exerts Antidepressant-Like Effects in a Chronic Unpredictable Mild Stress Rat Model and Regulates the Levels of Neurotransmitters, HPA Axis and NLRP3 Pathway

Purpose:Wolfiporia cocos is frequently used in traditional Chinese medicine to treat depression. However, antidepressant-like effects of the main active ingredients of Wolfiporia cocos, total triterpenes of Wolfiporia cocos (TTWC), are not well studied. This study aimed to investigate those effects and explore their specific mechanisms of action in depth.

Methods: Chemical components of TTWC were analyzed using LC-MS. Depression-like behavior in rats were induced by chronic unpredictable mild stress (CUMS). The suppressive effects of TTWC (60, 120, 240 mg/kg) against CUMS-induced depression-like behavior were evaluated using the forced swimming test (FST), open field test (OFT) and sucrose preference test (SPT). Levels of 5-hydroxytryptamine (5-HT), glutamate (GLU), corticotropin-releasing hormone (CRH), interleukin-1 beta (IL-1beta), interleukin-18 (IL-18), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in different groups were determined by ELISA. Western blotting (WB) was used to detect the expression of NLRP3, ASC, pro-caspase-1, caspase-1, pro-IL-1beta, IL-1beta, pro-IL-18, and IL-18 in the prefrontal cortex. Additionally, the mRNA levels of NLRP3, ASC, caspase-1, IL-1beta and IL-18 were detected by RT-PCR.

Results: A total of 69 lanostane-type triterpene acids of TTWC were identified. The results showed that TTWC exhibited an antidepressant-like effect in CUMS rats, reversed the decreased sugar preference in the SPT, reduction of immobility time in the FST, reduced the rest time, increased the total moving distance in the OFT. TTWC increased 5-HT levels and decreased GLU levels in the hippocampus. Moreover, TTWC decreased CRH levels in serum, indicating the regulation of over-activation of the hypothalamic-pituitary-adrenal (HPA) axis. In addition, reduced serum levels of IL-1beta, IL-18, IL-6, and TNF-alpha. The WB results implied that TTWC inhibited the expression of NLRP3, ASC, caspase-1, IL-1beta, and IL-18 in the prefrontal cortex and enhanced the expression of pro-caspase-1, pro-IL-1beta, and pro-IL-18. Although most of the results were not significant, PCR results showed that TTWC inhibited the expression of NLRP3, ASC, caspase-1, IL-1beta, and IL-18 in the prefrontal cortex.

Conclusion: TTWC treatment exerted an antidepressant-like effect and regulates neurotransmitters, HPA axis and NLRP3 signaling pathway. These results indicated the potential of TTWC in preventing the development of depression.

Therapeutic potential of nociceptin/orphanin FQ peptide (NOP) receptor modulators for treatment of traumatic brain injury, traumatic stress, and their co-morbidities

The nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor is a member of the opioid receptor superfamily with N/OFQ as its endogenous agonist. Wide expression of the NOP receptor and N/OFQ, both centrally and peripherally, and their ability to modulate several biological functions has led to development of NOP receptor modulators by pharmaceutical companies as therapeutics, based upon their efficacy in preclinical models of pain, anxiety, depression, Parkinson's disease, and substance abuse. Both posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) are debilitating conditions that significantly affect the quality of life of millions of people around the world. PTSD is often a consequence of TBI, and, especially for those deployed to, working and/or living in a war zone or are first responders, they are comorbid. PTSD and TBI share common symptoms, and negatively influence outcomes as comorbidities of the other. Unfortunately, a lack of effective therapies or therapeutic agents limits the long term quality of life for either TBI or PTSD patients. Ours, and other groups, demonstrated that PTSD and TBI preclinical models elicit changes in the N/OFQ-NOP receptor system, and that administration of NOP receptor ligands alleviated some of the neurobiological and behavioral changes induced by brain injury and/or traumatic stress exposure. Here we review the past and most recent progress on understanding the role of the N/OFQ-NOP receptor system in PTSD and TBI neurological and behavioral sequelae. There is still more to understand about this neuropeptide system in both PTSD and TBI, but current findings warrant further examination of the potential utility of NOP modulators as therapeutics for these disorders and their co-morbidities. We advocate the development of standards for common data elements (CDE) reporting for preclinical PTSD studies, similar to current preclinical TBI CDEs. That would provide for more standardized data collection and reporting to improve reproducibility, interpretation and data sharing across studies.

Multimodal MRI data fusion reveals distinct structural, functional and neurochemical correlates of heavy cannabis use

Heavy cannabis use (HCU) is frequently associated with a plethora of cognitive, psychopathological and sensorimotor phenomena. Although HCU is frequent, specific patterns of abnormal brain structure and function underlying HCU in individuals presenting without cannabis-use disorder or other current and life-time major mental disorders are unclear at present. This multimodal magnetic resonance imaging (MRI) study examined resting-state functional MRI (rs-fMRI) and structural MRI (sMRI) data from 24 persons with HCU and 16 controls. Parallel independent component analysis (p-ICA) was used to examine covarying components among grey matter volume (GMV) maps computed from sMRI and intrinsic neural activity (INA), as derived from amplitude of low-frequency fluctuations (ALFF) maps computed from rs-fMRI data. Further, we used JuSpace toolbox for cross-modal correlations between MRI-based modalities with nuclear imaging derived estimates, to examine specific neurotransmitter system changes underlying HCU. We identified two transmodal components, which significantly differed between the HCU and controls (GMV: p = 0.01, ALFF p = 0.03, respectively). The GMV component comprised predominantly cerebello-temporo-thalamic regions, whereas the INA component included fronto-parietal regions. Across HCU, loading parameters of both components were significantly associated with distinct HCU behavior. Finally, significant associations between GMV and the serotonergic system as well as between INA and the serotonergic, dopaminergic and μ-opioid receptor system were detected. This study provides novel multimodal neuromechanistic insights into HCU suggesting co-altered structure/function-interactions in neural systems subserving cognitive and sensorimotor functions.

Exercise to spot the differences: a framework for the effect of exercise on hippocampal pattern separation in humans

Exercise has a beneficial effect on mental health and cognitive functioning, but the exact underlying mechanisms remain largely unknown. In this review, we focus on the effect of exercise on hippocampal pattern separation, which is a key component of episodic memory. Research has associated exercise with improvements in pattern separation. We propose an integrated framework mechanistically explaining this relationship. The framework is divided into three pathways, describing the pro-neuroplastic, anti-inflammatory and hormonal effects of exercise. The pathways are heavily intertwined and may result in functional and structural changes in the hippocampus. These changes can ultimately affect pattern separation through direct and indirect connections. The proposed framework might guide future research on the effect of exercise on pattern separation in the hippocampus.

Frequency-dependent characteristics of nerve-mediated ATP and acetylcholine release from detrusor smooth muscle

NEW FINDINGS

The frequency-dependencies of acetylcholine (ACh) and ATP co-transmitter release are different. ACh release can be modelled to a one-compartment process, whereas ATP release requires a two-compartment model. Nerve-mediated release of ACh and ATP can be independently regulated, for example by the phosphodiesterase-type 5 inhibitor, sildenafil. What is the central question of this study? Is the frequency-dependency of co-transmitter release from postganglionic nerve fibres different for each transmitter? What is the main finding and its importance? Release of co-transmitters from the parasympathetic supply to detrusor smooth muscle can be independently regulated. This offers a targeted drug model to reduce selectively the release of transmitter associated with human pathologies (ATP) and may also be applicable to other smooth muscle-based disorders of visceral tissues.

ABSTRACT

Nerve-mediated contractions of detrusor smooth muscle are mediated by acetylcholine (ACh) and ATP release in most animals. However, with the normal human bladder only ACh is a functional transmitter but in benign pathologies such as overactive bladder (OAB), ATP re-emerges a secondary transmitter. The selective regulation of ATP release offers a therapeutic approach to manage OAB, in contrast to current primary strategies that target ACh actions. However, the release characteristics of nerve-mediated ACh and ATP are poorly defined and this study aimed to measure the frequency-dependence of ACh and ATP release and determine if selective regulation of ATP or ACh was possible. Experiments were carried out in vitro with mouse detrusor with nerve-mediated ATP and ACh release measured, simultaneously with tension recording. ATP was released in two frequency-dependent components, both at lower frequencies (mid-range 0.4 and 5.5 Hz stimulation) compared to a single compartment release of ACh at 14 Hz. Intervention with the phosphodiesterase type-5 inhibitor, sildenafil, attenuated ATP release, equally from both components, but had no effect on ACh release. These data demonstrate that nerve-mediated ACh and ATP release characteristics are distinct and may be separately manipulated. This offers a potential targeted drug model to manage benign lower urinary tract conditions such as OAB. This article is protected by copyright. All rights reserved.

The distinct roles of various neurotransmitters in modulating methamphetamine-induced conditioned place preference in relevant brain regions in mice

OBJECTIVES

Previous studies have shown that methamphetamine (METH) can induce complex adaptive changes in the reward system in the brain, including the changes in the content of neurotransmitters in the signal transduction pathway. However, how the changes of various neurotransmitters in relevant brain reward circuits contribute to METH-induced conditioned place preference (CPP) remains unclear.

METHODS

In this study, first, we designed an animal model of METH-induced CPP. Then we used liquid chromatography-mass spectrometry (LC-MS) to simultaneously determine the contents of various neurotransmitters - dopamine (DA), norepinephrine (NE), 5-hydroxytryptamine (5-HT), 5-hydroxyindole acetic acid (5-HIAA), glutamic acid (Glu) and glutamine (Gln) - in different brain regions of the prefrontal cortex (PFc), nucleus accumbens (NAc), caudate-putamen (CPu) and hippocampus (Hip), which are believed to be relevant to the drug's reward effect.

RESULTS

The results of the behavioral experiment suggested that 1.0 mg/kg METH could induce obvious CPP in mice. The results about various neurotransmitters showed that: DA significantly increased in NAc in the METH group; Glu increased significantly in the METH group in PFc and NAc and Gln increased significantly in the METH group in PFc.

CONCLUSIONS

These results suggested that the neurotransmitters of DA, Glu and Gln may work together and play important roles in METH-induced CPP in relevant brain reward circuits, especially in PFc and NAc. These findings therefore could help to advance the comprehensive understanding of the neurochemic and psychopharmacologic properties of METH in reward effect, which is important for future improvements in the treatment of drug addiction.

Neuroprotective Effect of Chrysophanol as a PI3K/AKT/mTOR Signaling Inhibitor in an Experimental Model of Autologous Blood-induced Intracerebral Hemorrhage

OBJECTIVE

Intracerebral hemorrhage (ICH) refers to predominant, sporadic, and non-traumatic bleeding in the brain parenchyma. The PI3K/AKT/mTOR signaling pathway is an important signal transduction pathway regulated by enzyme-linked receptors and has many biological functions in mammals. It plays a key role in neuronal metabolism, gene expression regulation, and tissue homeostasis in the healthy and diseased brain.

METHODS

In the present study, the role of the PI3K/AKT/mTOR pathway inhibitor chrysophanol (CPH) (10 mg/kg and 20 mg/kg, orally) in the improvement of ICH-associated neurological defects in rats was investigated. Autologous blood (20 µL/5 min/unilateral/intracerebroventricular) mimics ICH-like defects involving cellular and molecular dysfunction and neurotransmitter imbalance. The current study also included various behavioral assessments to examine cognition, memory, and motor and neuromuscular coordination. The protein expression levels of PI3K, AKT, and mTOR as well as myelin basic protein and apoptotic markers, such as Bax, Bcl-2, and caspase-3, were examined using ELISA kits. Furthermore, the levels of various neuroinflammatory cytokines and oxidative stress markers were assessed. Additionally, the neurological severity score, brain water content, gross brain pathology, and hematoma size were used to indicate neurological function and brain edema.

RESULTS

CPH was found to be neuroprotective by restoring neurobehavioral alterations and significantly reducing the elevated PI3K, AKT, and mTOR protein levels, and modulating the apoptotic markers such as Bax, Bcl-2, and caspase-3 in rat brain homogenate. CPH substantially reduced the inflammatory cytokines like interleukin (IL)-1β, IL-6, and tumor necrosis factor-α. CPH administration restored the neurotransmitters GABA, glutamate, acetylcholine, dopamine, and various oxidative stress markers.

CONCLUSION

Our results show that CPH may be a promising therapeutic approach for overcoming neuronal damage caused by the overexpression of the PI3K/AKT/mTOR signaling pathway in ICH-induced neurological dysfunctions in rats.

Occlusion of the human serotonin transporter is mediated by serotonin-induced conformational changes in the bundle domain

The human serotonin transporter (hSERT) terminates neurotransmission by removing serotonin (5HT) from the synaptic cleft, an essential process for proper functioning of serotonergic neurons. Structures of the hSERT have revealed its molecular architecture in four conformations, including the outward-open and occluded states, and show the transporter’s engagement with co-transported ions and the binding mode of inhibitors. In this study, we investigated the molecular mechanism by which the hSERT occludes and sequesters the substrate 5HT. This first step of substrate uptake into cells is a structural change consisting of the transition from the outward-open to the occluded state. Inhibitors such as the antidepressants citalopram, fluoxetine, and sertraline inhibit this step of the transport cycle. Using molecular dynamics simulations, we reached a fully occluded state, in which the transporter-bound 5HT becomes fully shielded from both sides of the membrane by two closed hydrophobic gates. Analysis of 5HT-triggered occlusion showed that bound 5HT serves as an essential trigger for transporter occlusion. Moreover, simulations revealed a complex sequence of steps and showed that movements of bundle domain helices are only partially correlated. 5HT-triggered occlusion is initially dominated by movements of transmembrane helix 1b, while in the final step, only transmembrane helix 6a moves and relaxes an intermediate change in its secondary structure.

Presynaptic mechanisms underlying GABAB-receptor-mediated inhibition of spontaneous neurotransmitter release

Inhibition of neurotransmitter release by neurotransmitter substances constitutes a fundamental means of neuromodulation. In contrast to well-delineated mechanisms that underlie inhibition of evoked release via suppression of voltage-gated Ca²⁺ channels, processes that underlie neuromodulatory inhibition of spontaneous release remain unclear. Here, we interrogated inhibition of spontaneous glutamate and GABA release by presynaptic metabotropic GABA_B receptors. Our findings show that this inhibition relies on Gβγ subunit action at the membrane, and it is largely independent of presynaptic Ca²⁺ signaling for both forms of release. In the case of spontaneous glutamate release, inhibition requires Gβγ interaction with the C terminus of the key fusion machinery component SNAP25, and it is modulated by synaptotagmin-1. Inhibition of spontaneous GABA release, on the other hand, is independent of these pathways and likely requires alternative Gβγ targets at the presynaptic terminal.

Synthesis, Crystallographic, Quantum Chemical, Antitumor, and Molecular Docking/Dynamic Studies of 4-Hydroxycoumarin-Neurotransmitter Derivatives

In this contribution, four new compounds synthesized from 4-hydroxycoumarin and tyramine/octopamine/norepinephrine/3-methoxytyramine are characterized spectroscopically (IR and NMR), chromatographically (UHPLC-DAD), and structurally at the B3LYP/6-311++G*(d,p) level of theory. The crystal structure of the 4-hydroxycoumarin-octopamine derivative was solved and used as a starting geometry for structural optimization. Along with the previously obtained 4-hydroxycoumarin-dopamine derivative, the intramolecular interactions governing the stability of these compounds were quantified by NBO and QTAIM analyses. Condensed Fukui functions and the HOMO-LUMO gap were calculated and correlated with the number and position of OH groups in the structures. In vitro cytotoxicity experiments were performed to elucidate the possible antitumor activity of the tested substances. For this purpose, four cell lines were selected, namely human colon cancer (HCT-116), human adenocarcinoma (HeLa), human breast cancer (MDA-MB-231), and healthy human lung fibroblast (MRC-5) lines. A significant selectivity towards colorectal carcinoma cells was observed. Molecular docking and molecular dynamics studies with carbonic anhydrase, a prognostic factor in several cancers, complemented the experimental results. The calculated MD binding energies coincided well with the experimental activity, and indicated 4-hydroxycoumarin-dopamine and 4-hydroxycoumarin-3-methoxytyramine as the most active compounds. The ecotoxicology assessment proved that the obtained compounds have a low impact on the daphnia, fish, and green algae population.

Positron Emission Tomography in Animal Models of Tauopathies

The microtubule-associated protein tau (MAPT) plays an important role in Alzheimer's disease and primary tauopathy diseases. The abnormal accumulation of tau contributes to the development of neurotoxicity, inflammation, neurodegeneration, and cognitive deficits in tauopathy diseases. Tau synergically interacts with amyloid-beta in Alzheimer's disease leading to detrimental consequence. Thus, tau has been an important target for therapeutics development for Alzheimer's disease and primary tauopathy diseases. Tauopathy animal models recapitulating the tauopathy such as transgenic, knock-in mouse and rat models have been developed and greatly facilitated the understanding of disease mechanisms. The advance in PET and imaging tracers have enabled non-invasive detection of the accumulation and spread of tau, the associated microglia activation, metabolic, and neurotransmitter receptor alterations in disease animal models. In vivo microPET studies on mouse or rat models of tauopathy have provided significant insights into the phenotypes and time course of pathophysiology of these models and allowed the monitoring of treatment targeting at tau. In this study, we discuss the utilities of PET and recently developed tracers for evaluating the pathophysiology in tauopathy animal models. We point out the outstanding challenges and propose future outlook in visualizing tau-related pathophysiological changes in brain of tauopathy disease animal models.

Gut Microbiota Metabolites in Major Depressive Disorder-Deep Insights into Their Pathophysiological Role and Potential Translational Applications

The gut microbiota is a complex and dynamic ecosystem essential for the proper functioning of the organism, affecting the health and disease status of the individuals. There is continuous and bidirectional communication between gut microbiota and the host, conforming to a unique entity known as "holobiont". Among these crosstalk mechanisms, the gut microbiota synthesizes a broad spectrum of bioactive compounds or metabolites which exert pleiotropic effects on the human organism. Many of these microbial metabolites can cross the blood-brain barrier (BBB) or have significant effects on the brain, playing a key role in the so-called microbiota-gut-brain axis. An altered microbiota-gut-brain (MGB) axis is a major characteristic of many neuropsychiatric disorders, including major depressive disorder (MDD). Significative differences between gut eubiosis and dysbiosis in mental disorders like MDD with their different metabolite composition and concentrations are being discussed. In the present review, the main microbial metabolites (short-chain fatty acids -SCFAs-, bile acids, amino acids, tryptophan -trp- derivatives, and more), their signaling pathways and functions will be summarized to explain part of MDD pathophysiology. Conclusions from promising translational approaches related to microbial metabolome will be addressed in more depth to discuss their possible clinical value in the management of MDD patients.

The intestinal microbiota and metabolites in patients with anorexia nervosa

Brain-gut microbiota interactions are intensively studied in connection with various neurological and psychiatric diseases. While anorexia nervosa (AN) pathophysiology is not entirely clear, it is presumably linked to microbiome dysbiosis. We aimed to elucidate the gut microbiota contribution in AN disease pathophysiology. We analyzed the composition and diversity of the gut microbiome of patients with AN (bacteriome and mycobiome) from stool samples before and after renourishment, and compared them to healthy controls. Further, levels of assorted neurotransmitters and short-chain fatty acids (SCFA) were analyzed in stool samples by MS and NMR, respectively. Biochemical, anthropometric, and psychometric profiles were assessed. The bacterial alpha-diversity parameter analyses revealed only increased Chao 1 index in patients with AN before the realimentation, reflecting their interindividual variation. Subsequently, core microbiota depletion signs were observed in patients with AN. Overrepresented OTUs (operation taxonomic units) in patients with AN taxonomically belonged to Alistipes, Clostridiales, Christensenellaceae, and Ruminococcaceae. Underrepresented OTUs in patients with AN were Faecalibacterium, Agathobacter, Bacteroides, Blautia, and Lachnospira. Patients exhibited greater interindividual variation in the gut bacteriome, as well as in metagenome content compared to controls, suggesting altered bacteriome functions. Patients had decreased levels of serotonin, GABA, dopamine, butyrate, and acetate in their stool samples compared to controls. Mycobiome analysis did not reveal significant differences in alpha diversity and fungal profile composition between patients with AN and healthy controls, nor any correlation of the fungal composition with the bacterial profile. Our results show the changed profile of the gut microbiome and its metabolites in patients with severe AN. Although therapeutic partial renourishment led to increased body mass index and improved psychometric parameters, SCFA, and neurotransmitter profiles, as well as microbial community compositions, did not change substantially during the hospitalization period, which can be potentially caused by only partial weight recovery.

Relaxation Effects of Essential Oils Are Explained by Their Interactions with Human Brain Neurotransmitter Receptors and Electroencephalography Rhythms

Inhaled essential oils (EOs) are bioavailable to the brain and are consistently reported to promote relaxation effects. Their mechanisms of action are however not well understood. The aim of this investigation was to assess the neuroactivity of EOs based on their (i) binding interactions to neurotransmitter receptors and (ii) bioelectrical activities in the brain as measured by electroencephalography (EEG). These EO properties were compared to those of reference pharmaceutical compounds with effects also measured by EEG. Relative receptor binding efficacies of 10 reference compounds, 180 EOs, and 9 EO extracts with 7 different neurotransmitter receptors were calculated using in silico molecular docking procedures. Changes in brain EEG rhythms, as standardized changes in absolute power, were determined for the reference compounds and selected EOs and compared to receptor binding efficacy results. The reference compounds had diverse receptor binding patterns, with EEG responses dominated by EEG-delta wave frequencies. In contrast, the receptor binding pattern of the EOs was remarkably consistent and replicated a subclinical affinity pattern corresponding to the inhibitory glycine-α-GLRA3 and dopamine-D2 receptors, producing responses dominated by EEG-alpha wave frequencies. The results support the hypothesis that EOs stimulate neuroactivity by modulating patterns of neurotransmission affecting alpha wave EEG responses.

Neural plasticity of the uterus: New targets for endometrial cancer?

Endometrial carcinoma is the most common gynecological malignancy in Western countries and is expected to increase in the following years because of the high index of obesity in the population. Recently, neural signaling has been recognized as part of the tumor microenvironment, playing an active role in tumor progression and invasion of different solid tumor types. The uterus stands out for the physiological plasticity of its peripheral nerves due to cyclic remodeling brought on by estrogen and progesterone hormones throughout the reproductive cycle. Therefore, a precise understanding of nerve-cancer crosstalk and the contribution of the organ-intrinsic neuroplasticity, mediated by estrogen and progesterone, of the uterine is urgently needed. The development of new and innovative medicines for patients with endometrial cancer would increase their quality of life and health. This review compiles information on the architecture and function of autonomous uterine neural innervations and the influence of hormone-dependent nerves in normal uterus and tumor progression. It also explores new therapeutic possibilities for endometrial cancer using these endocrine and neural advantages.

Immunohistochemical Characterization of the Nervous System of Culex pipiens (Diptera, Culicidae)

Arthropod-borne diseases represent one of the greatest infection-related threats as a result of climate change and globalization. Repeatedly, arbovirus-infected mosquitoes show behavioral changes whose underlying mechanisms are still largely unknown, but might help to develop control strategies. However, in contrast to well-characterized insects such as fruit flies, little is known about neuroanatomy and neurotransmission in mosquitoes. To overcome this limitation, the study focuses on the immunohistochemical characterization of the nervous system of Culex pipiens biotype molestus in comparison to Drosophila melanogaster using 13 antibodies labeling nervous tissue, neurotransmitters or neurotransmitter-related enzymes. Antibodies directed against γ-aminobutyric acid, serotonin, tyrosine-hydroxylase and glutamine synthetase were suitable for investigations in Culex pipiens and Drosophila melanogaster, albeit species-specific spatial differences were observed. Likewise, similar staining results were achieved for neuronal glycoproteins, axons, dendrites and synaptic zones in both species. Interestingly, anti-phosphosynapsin and anti-gephyrin appear to represent novel markers for synapses and glial cells, respectively. In contrast, antibodies directed against acetylcholine, choline acetyltransferase, elav and repo failed to produce a signal in Culex pipiens comparable to that in Drosophila melanogaster. In summary, present results enable a detailed investigation of the nervous system of mosquitoes, facilitating further studies of behavioral mechanisms associated with arboviruses in the course of vector research.

Molecular Engineered Carbon-Based Sensor for Ultrafast and Specific Detection of Neurotransmitters

In the quest for designing affordable diagnostic devices with high performance, precisely functionalized carbon-based materials with high accuracy and selectivity are required. Every material has its own unique ability to interact with the analyte, and its performance can be enhanced by probing the interaction mechanism. Herein, p-aminophenol (PAP)-functionalized reduced graphene oxide (rGO) nanoscale material is developed by a one-step synthetic route as an all-organic-based sensor. As the PAP molecules are precisely covalently interacted with the rGO at the basal plane and form a wrinkled-paper-like structure, the functionalized material exhibits an outstanding sensing ability (7.5 nM neurotransmitter dopamine (DA) at a wide linear range, 0.01-100 μM) with fast electrical transduction (<3 s) and good recyclability (∼10 cycles) in a real sample. Combining various analytical and density functional theory (DFT) calculation methods, physicochemical properties and the interaction mechanism of analyte-materials transduction are discussed exclusively. Besides, the potential application of the well-dispersed rGO-PAP gravure ink in flexible-printed electronics fields is explored. This study not only provides new insights into the surface/interface chemistry and working principle of this unique anchoring of PAP on rGO but also offers a new pathway for developing other forms of metal-free/organic functionalized biosensors with high efficiency.

Neuronal exposure induces neurotransmitter signaling and synaptic mediators in tumors early in brain metastasis

BACKGROUND

Brain metastases (BM) are responsible for neurological decline and poor overall survival. Although the pro-metastatic roles of glial cells, and the acquisition of neuronal attributes in established BM tumors have been described, there are no studies that investigate the initial interplay between neurons and brain-seeking tumor cells. The aim of this study was to characterize early tumor-neuron interactions and the induced CNS-adaptive changes in tumor cells prior to macro-colonization.

METHODS

Utilizing pure neuronal cultures and brain-naïve and patient-derived BM tumor cells, we surveyed the early induction of mediators of neurotransmitter (NT) and synaptic signaling in breast and lung tumor cells. Reliance on microenvironmental GABA in breast-to-brain metastatic cells (BBMs) was assessed in vitro and in vivo.

RESULTS

Co-culture with neurons induces early expression of classical NT receptor genes (HTR4, GRIA2, GRIN2B, GRM4, GRM8, DRD1) and neuronal synaptic mediators (CNR1, EGR2, ARC, NGFR, NRXN1) in breast and lung cancer cells. NT-dependent classification of tumor cells within the neuronal niche shows breast cancer cells become GABAergic responsive brain metastases (GRBMs) and transition from relying on autocrine GABA, to paracrine GABA from adjacent neurons; while autocrine Dopaminergic breast and lung tumor cells persist. In vivo studies confirm reliance on paracrine GABA is an early CNS-acclimation strategy in breast cancer. Moreover, neuronal contact induces early resurgence in Reelin expression in tumor cells through epigenetic activation, facilitating CNS adaptation.

CONCLUSION

Tumor-neuron interactions allow for CNS-adaptation early in the course of brain metastasis.

Identification of the Nerve-Cancer Cross-Talk-Related Prognostic Gene Model in Head and Neck Squamous Cell Carcinoma

The incidence of head and neck squamous cell carcinoma (HNSC) is increasing year by year. The nerve is an important component of the tumor microenvironment, which has a wide range of cross-talk with tumor cells and immune cells, especially in highly innervated organs, such as head and neck cancer and pancreatic cancer. However, the role of cancer-nerve cross-talk-related genes (NCCGs) in HNSC is unclear. In our study, we constructed a prognostic model based on genes with prognostic value in NCCGs. We used Pearson’s correlation to analyze the relationship between NCCGs and immune infiltration, microsatellite instability, tumor mutation burden, drug sensitivity, and clinical stage. We used single-cell sequencing data to analyze the expression of genes associated with stage in different cells and explored the possible pathways affected by these genes via gene set enrichment analysis. In the TCGA-HNSC cohort, a total of 23 genes were up- or downregulated compared with normal tissues. GO and KEGG pathway analysis suggested that NCCGs are mainly concentrated in membrane potential regulation, chemical synapse, axon formation, and neuroreceptor-ligand interaction. Ten genes were identified as prognosis genes by Kaplan-Meier plotter and used as candidate genes for LASSO regression. We constructed a seven-gene prognostic model (NTRK1, L1CAM, GRIN3A, CHRNA5, CHRNA6, CHRNB4, CHRND). The model could effectively predict the 1-, 3-, and 5-year survival rates in the TCGA-HNSC cohort, and the effectiveness of the model was verified by external test data. The genes included in the model were significantly correlated with immune infiltration, microsatellite instability, tumor mutation burden, drug sensitivity, and clinical stage. Single-cell sequencing data of HNSC showed that CHRNB4 was mainly expressed in tumor cells, and multiple metabolic pathways were enriched in high CHRNB4 expression tumor cells. In summary, we used comprehensive bioinformatics analysis to construct a prognostic gene model and revealed the potential of NCCGs as therapeutic targets and prognostic biomarkers in HNSC.

Droplet Microfluidics with MALDI-MS Detection: The Effects of Oil Phases in GABA Analysis

Microfluidic and mass spectrometry (MS) methods are widely used to sample and probe the chemical composition of biological systems to elucidate chemical correlates of their healthy and disease states. Though matrix-assisted laser desorption/ionization-mass spectrometry (MALDI)-MS has been hyphenated to droplet microfluidics for offline analyses, the effects of parameters related to droplet generation, such as the type of oil phase used, have been understudied. To characterize these effects, five different oil phases were tested in droplet microfluidics for producing samples for MALDI-MS analysis. Picoliter to nanoliter aqueous droplets containing 0.1 to 100 mM γ-aminobutyric acid (GABA) and inorganic salts were generated inside a polydimethylsiloxane microfluidic chip and deposited onto a conductive glass slide. Optical microscopy, Raman spectroscopy, and MALDI-mass spectrometry imaging (MSI) of the droplet samples and surrounding areas revealed patterns of solvent and oil evaporation and analyte deposition. Optical microscopy detected the presence of salt crystals in 50-100 μm diameter dried droplets, and Raman and MSI were used to correlate GABA signals to the visible droplet footprints. MALDI-MS analyses revealed that droplets prepared in the presence of octanol oil led to the poorest detectability of GABA, whereas the oil phases containing FC-40 provided the best detectability; GABA signal was localized to the footprint of 65 pL droplets with a limit of detection of 23 amol. The effect of the surfactant perfluorooctanol on analyte detection was also investigated.

Striatonigrostriatal Spirals in Addiction

A biological reward system is integral to all animal life and humans are no exception. For millennia individuals have investigated this system and its influences on human behavior. In the modern day, with the US facing an ongoing epidemic of substance use without an effective treatment, these investigations are of paramount importance. It is well known that basal ganglia contribute to rewards and are involved in learning, approach behavior, economic choices, and positive emotions. This review aims to elucidate the physiological role of striatonigrostriatal (SNS) spirals, as part of basal ganglia circuits, in this reward system and their pathophysiological role in perpetuating addiction. Additionally, the main functions of neurotransmitters such as dopamine and glutamate and their receptors in SNS circuits will be summarized. With this information, the claim that SNS spirals are crucial intermediaries in the shift from goal-directed behavior to habitual behavior will be supported, making this circuit a viable target for potential therapeutic intervention in those with substance use disorders.

Fluorescent Nanozeolite Receptors for the Highly Selective and Sensitive Detection of Neurotransmitters in Water and Biofluids

The design and preparation of synthetic binders (SBs) applicable for small biomolecule sensing in aqueous media remains very challenging. SBs designed by the lock-and-key principle can be selective for their target analyte but usually show an insufficient binding strength in water. In contrast, SBs based on symmetric macrocycles with a hydrophobic cavity can display high binding affinities but generally suffer from indiscriminate binding of many analytes. Herein, a completely new and modular receptor design strategy based on microporous hybrid materials is presented yielding zeolite-based artificial receptors (ZARs) which reversibly bind the neurotransmitters serotonin and dopamine with unprecedented affinity and selectivity even in saline biofluids. ZARs are thought to uniquely exploit both the non-classical hydrophobic effect and direct non-covalent recognition motifs, which is supported by in-depth photophysical, and calorimetric experiments combined with full atomistic modeling. ZARs are thermally and chemically robust and can be readily prepared at gram scales. Their applicability for the label-free monitoring of important enzymatic reactions, for (two-photon) fluorescence imaging, and for high-throughput diagnostics in biofluids is demonstrated. This study showcases that artificial receptor based on microporous hybrid materials can overcome standing limitations of synthetic chemosensors, paving the way towards personalized diagnostics and metabolomics.

Anti-depressant effects of ethanol extract from Cannabis sativa (hemp) seed in chlorpromazine-induced Drosophila melanogaster depression model

CONTEXT

Depression is a severe mental illness caused by a deficiency of dopamine and serotonin. Cannabis sativa L. (Cannabaceae) has long been used to treat pain, nausea, and depression.

OBJECTIVE

This study investigates the anti-depressant effects of C. sativa (hemp) seed ethanol extract (HE) in chlorpromazine (CPZ)-induced Drosophila melanogaster depression model.

MATERIALS AND METHODS

The normal group was untreated, and the control group was treated with CPZ (0.1% of media) for 7 days. The experimental groups were treated with a single HE treatment (0.5, 1.0, and 1.5% of media) and a mixture of 0.1% CPZ and HE for 7 days. The locomotor activity, behavioural patterns, depression-related gene expression, and neurotransmitters level of flies were investigated.

RESULTS

The behavioural patterns of individual flies were significantly reduced with 0.1% CPZ treatment. In contrast, combination treatment of 1.5% HE and 0.1% CPZ significantly increased subjective daytime activity (p < 0.001) and behavioural factors (p < 0.001). These results correlate with increased transcript levels of dopamine (p < 0.001) and serotonin (p < 0.05) receptors and concentration of dopamine (p < 0.05), levodopa (p < 0.001), 5-HTP (p < 0.05), and serotonin (p < 0.001) compared to those in the control group.

DISCUSSION AND CONCLUSIONS

Collectively, HE administration alleviates depression-like symptoms by modulating the circadian rhythm-related behaviours, transcript levels of neurotransmitter receptors, and neurotransmitter levels in the CPZ-induced Drosophila model. However, additional research is needed to investigate the role of HE administration in behavioural patterns, reduction of the neurotransmitter, and signalling pathways of depression in a vertebrate model system.

DOPA Homeostasis by Dopamine: A Control-Theoretic View

Dopamine (DA) is an important signal mediator in the brain as well as in the periphery. The term "dopamine homeostasis" occasionally found in the literature refers to the fact that abnormal DA levels can be associated with a variety of neuropsychiatric disorders. An analysis of the negative feedback inhibition of tyrosine hydroxylase (TH) by DA indicates, with support from the experimental data, that the TH-DA negative feedback loop has developed to exhibit 3,4-dihydroxyphenylalanine (DOPA) homeostasis by using DA as a derepression regulator. DA levels generally decline when DOPA is removed, for example, by increased oxidative stress. Robust DOPA regulation by DA further implies that maximum vesicular DA levels are established, which appear necessary for a reliable translation of neural activity into a corresponding chemical transmitter signal. An uncontrolled continuous rise (windup) in DA occurs when Levodopa treatment exceeds a critical dose. Increased oxidative stress leads to the successive breakdown of DOPA homeostasis and to a corresponding reduction in DA levels. To keep DOPA regulation robust, the vesicular DA loading requires close to zero-order kinetics combined with a sufficiently high compensatory flux provided by TH. The protection of DOPA and DA due to a channeling complex is discussed.

The combined use of gamma-aminobutyric acid and walnut peptide enhances sleep in mice

BACKGROUND

γ-aminobutyric acid (GABA) is a naturally occurring non-protein amino acid in the nervous system and has a wide range of physiological functions in the body. Walnut peptide (WP) contains high levels of arginine, aspartic acid, and glutamate, and has been shown to improve cognitive deficits and memory impairment in mice, while restoring antioxidant enzyme levels and reducing brain inflammatory mediators.

METHODS

This study investigated the effects of GABA and WP, either alone or in combination, on sleep disturbances in mice. The pentobarbital-prolonged sleep test, pentobarbital-threshold sleep test, and barbital-induced sleep test were conducted to assess the effects of GABA and WP on sleep quality by gavage for 30 days as follows: GABA (102.25 mg/kg), WP (102.25 mg/kg), GABA (33.95, 102.25, 306.75 mg/kg)/WP (102.25 mg/kg) mixture. Furthermore, neurotransmitter tests were performed using mice brain tissue to investigate the possible mechanisms of GABA and WP on sleep status.

RESULTS

The results showed that the combined use of GABA and WP significantly increased sleep duration compared with single administration of either WP or GABA. Increasing doses of GABA in mice treated with combined GABA and WP elevated the sleep rate to 50.00%, 64.28%, and 64.28%, respectively, compared to mice treated with GABA alone (35.71%) or mice treated with WP alone (28.57%). In mice that received a combination of GABA and WP orally, the latency time was significantly decreased after 30 days compared to control mice (P<0.05). Additionally, in mice treated with GABA, WP, or the combination of GABA and WP, the concentrations of GABA and acetylcholine (Ach) in the brain were significantly elevated and the concentration of serotonin (5-HT) was decreased compared to untreated mice.

CONCLUSIONS

These results demonstrated that the combined administration of GABA and WP could prolong the sleep duration, increase sleep rate, and shorten the sleep latency more effectively than the administration of either GABA or WP alone. The mechanisms of action may be related to the regulation of neurotransmitters in the brain tissue by the combination of GABA and WP.

Effects of fastigial nucleus electrostimulation on cardiac nerve regeneration, neurotransmitter release, and malignant arrhythmia inducibility in a post-infarction rat model

The reduced density of cardiac autonomic nerves plays an important role in malignant arrhythmia after myocardial infarction (MI). Previous studies have shown that there is an interaction between the brain and the heart, and fastigial nucleus electrostimulation (FNS) promotes central nerve regeneration. Whether and how it can promote cardiac nerve regeneration after MI and the underlying mechanisms remain unknown. This study investigated whether FNS promotes cardiac nerve regeneration and reduces malignant arrhythmia inducibility in a post-infarction rat model. Ninety-eight Wistar rats were randomly assigned to Sham control, MI (left anterior descending coronary artery ligation without FNS), FNS (MI plus FNS), and FNL (fastigial nucleus lesion plus FNS plus MI) groups. The frequency of malignant arrhythmia was significantly lower in the FNS group than in the MI and FNL groups. The density of cardiac autonomic nerves was less in the MI group than in the Sham group, which was promoted by FNS. The nerve growth factor (NGF) mRNA expression was downregulated in the MI group compared to the Sham group, which was significantly enhanced by FNS. The expression levels of norepinephrine (NE) and acetylcholine (ACh) were higher and lower respectively in the MI and FNL groups than in the Sham group. After FNS, NE concentration was reduced and Ach level was elevated compared to the MI group. These data suggested that FNS promoted the regeneration of cardiac autonomic nerves and reduced the incidence of malignant arrhythmias in MI rat model. The mechanisms might involve up-regulation of NGF mRNA expression, decrease of NE release and increase of ACh release.

The dopamine membrane transporter plays an active modulatory role in synaptic dopamine homeostasis

Modulatory mechanisms of neurotransmitter release and clearance are highly controlled processes whose finely tuned regulation is critical for functioning of the nervous system. Dysregulation of the monoamine neurotransmitter dopamine can lead to several neuropathies. Synaptic modulation of dopamine is known to involve pre-synaptic D2 auto-receptors and acid sensing ion channels. In addition, the dopamine membrane transporter (DAT), which is responsible for clearance of dopamine from the synaptic cleft, is suspected to play an active role in modulating release of dopamine. Using functional imaging on the Caenorhabditis elegans model system, we show that DAT-1 acts as a negative feedback modulator to neurotransmitter vesicle fusion. Results from our fluorescence recovery after photo-bleaching (FRAP) based experiments were followed up with and reaffirmed using swimming-induced paralysis behavioral assays. Utilizing our numerical FRAP data we have developed a mechanistic model to dissect the dynamics of synaptic vesicle fusion, and compare the feedback effects of DAT-1 with the dopamine auto-receptor. Our experimental results and the mechanistic model are of potential broader significance, as similar dynamics are likely to be used by other synaptic modulators including membrane transporters for other neurotransmitters across species.

Electromagnetic Field Stimulation Attenuates Phasic Nociception after Complete Spinal Cord Injury in Rats

Traumatic spinal cord injury (SCI) is one of the most incapacitating pathologies, leading to huge rehabilitation challenges besides a social-economic burden on SCI patients and their families. There is no complete curative treatment available so far. Non-invasive and patient-friendly use of extremely low-frequency electromagnetic field stimulation (EMF) has emerged as a therapeutic and rehabilitation option. In this study, we tested whole-body EMF stimulation on thoracic complete SCI-induced nociception including sensorimotor deficits in rats. The EMF application significantly attenuated hyperalgesia and allodynia to thermal, electrical, and chemical stimuli from 6 weeks onwards as well as restoration of spinal reflexes, viz., H-reflex and nociceptive flexion reflex at the study endpoint (week 8). Besides, massively increased glutamate at the SCI injury site was observed in SCI rats with no treatment, which was also attenuated significantly by EMF stimulation. Spinal cord histology of the injury area showed a decrease in lesion volume and glial population in the EMF-stimulated rats. These findings indicate the beneficial role of EMF stimulation after thoracic complete SCI in adult male rats and, thereby, a beneficial patient-friendly rehabilitation tool.

Cerebrospinal Fluid Pterins, Pterin-Dependent Neurotransmitters, and Mortality in Pediatric Cerebral Malaria

BACKGROUND

Cerebral malaria (CM) pathogenesis remains incompletely understood. Having shown low systemic levels of tetrahydrobiopterin (BH4), an enzymatic cofactor for neurotransmitter synthesis, we hypothesized that BH4 and BH4-dependent neurotransmitters would likewise be low in cerebrospinal fluid (CSF) in CM.

METHODS

We prospectively enrolled Tanzanian children with CM and children with nonmalaria central nervous system conditions (NMCs). We measured CSF levels of BH4, neopterin, and BH4-dependent neurotransmitter metabolites, 3-O-methyldopa, homovanillic acid, and 5-hydroxyindoleacetate, and we derived age-adjusted z-scores using published reference ranges.

RESULTS

Cerebrospinal fluid BH4 was elevated in CM (n = 49) compared with NMC (n = 51) (z-score 0.75 vs -0.08; P < .001). Neopterin was increased in CM (z-score 4.05 vs 0.09; P < .001), and a cutoff at the upper limit of normal (60 nmol/L) was 100% sensitive for CM. Neurotransmitter metabolite levels were overall preserved. A higher CSF BH4/BH2 ratio was associated with increased odds of survival (odds ratio, 2.94; 95% confidence interval, 1.03-8.33; P = .043).

CONCLUSION

Despite low systemic BH4, CSF BH4 was elevated and associated with increased odds of survival in CM. Coma in malaria is not explained by deficiency of BH4-dependent neurotransmitters. Elevated CSF neopterin was 100% sensitive for CM diagnosis and warrants further assessment of its clinical utility for ruling out CM in malaria-endemic areas.

Reciprocal signals between nerve and epithelium: how do neurons talk with epithelial cells?

Most epithelium tissues continuously undergo self-renewal through proliferation and differentiation of epithelial stem cells (known as homeostasis), within a specialized stem cell niche. In highly innervated epithelium, peripheral nerves compose perineural niche and support stem cell homeostasis by releasing a variety of neurotransmitters, hormones, and growth factors and supplying trophic factors to the stem cells. Emerging evidence has shown that both sensory and motor nerves can regulate the fate of epithelial stem cells, thus influencing epithelium homeostasis. Understanding the mechanism of crosstalk between epithelial stem cells and neurons will reveal the important role of the perineural niche in physiological and pathological conditions. Herein, we review recent discoveries of the perineural niche in epithelium mainly in tissue homeostasis, with a limited touch in wound repair and pathogenesis.

GABA Neurotransmission of the Suprachiasmatic Nucleus Is Modified During Rat Postnatal Development

The suprachiasmatic nucleus (SCN) of the hypothalamus is the brain structure that controls circadian rhythms in mammals. The SCN is formed by two neuroanatomical regions: the ventral and dorsal. Gamma-aminobutyric acid (GABA) neurotransmission is important for the regulation of circadian rhythms. Excitatory GABA effects have been described in both SCN regions displaying a circadian variation. Moreover, the GABAergic system transfers photic information from the ventral to the dorsal SCN. However, there is almost no knowledge about GABA neurotransmission during the prenatal or postnatal development of the SCN. Here, we used whole-cell patch-clamp recordings to study spontaneous inhibitory postsynaptic currents (IPSCs) in the two SCN regions, at two zeitgeber times (day or night), and at four postnatal (P) ages: P3-5, P7-9, P12-15, and P20-25. The results herein show that the three analyzed parameters of the IPSCs, frequency, amplitude, and decay time, were significantly affected by the postnatal age: mostly, the IPSC frequency increased with age, principally in the ventral SCN in both day and night recordings; similarly, the amplitude of IPSCs augmented with age, especially at night, whereas the IPSC decay time was reduced (it was faster) with postnatal age, mainly during the day. Our findings first reveal that parameters of GABA neurotransmission are modified by postnatal development, implying that synaptic adjustments are required for an appropriate maturation of the GABAergic system in the SCN.

Molecular Link between Circadian Rhythmicity and Mood Disorders

BACKGROUND

The internal clock is driven by circadian genes [e.g., Clock, Bmal1, Per1-3, Cry1-2], hormones [e.g., melatonin, cortisol], as well as zeitgeber ['synchronisers']. Chronic disturbances in the circadian rhythm in patients diagnosed with mood disorders have been recognised for more than 50 years.

OBJECTIVES

The aim of this review is to summarise the current knowledge and literature regarding circadian rhythms in the context of mood disorders, focussing on the role of circadian genes, hormones, and neurotransmitters.

METHOD

The review presents the current knowledge and literature regarding circadian rhythms in mood disorders using the Pubmed database. Articles with a focus on circadian rhythms and mood disorders [n=123], particularly from 1973 to 2020, were included.

RESULTS

The article suggests a molecular link between disruptions in the circadian rhythm and mood disorders. Circadian disturbances, caused by the dysregulation of circadian genes, hormones, and neurotransmitters, often result in a clinical picture resembling depression.

CONCLUSION

Circadian rhythms are intrinsically linked to affective disorders, such as unipolar depression and bipolar disorder.

GABAergic signaling in human and murine NK cells upon challenge with Toxoplasma gondii

Protective cytotoxic and proinflammatory cytokine responses by NK cells impact the outcome of infections by Toxoplasma gondii, a common parasite in humans and other vertebrates. However, T. gondii can also sequester within NK cells and downmodulate their effector functions. Recently, the implication of GABA signaling in infection and inflammation-related responses of mononuclear phagocytes and T cells has become evident. Yet, the role of GABAergic signaling in NK cells has remained unknown. Here, we report that human and murine NK cells synthesize and secrete GABA in response to infection challenge. Parasitized NK cells secreted GABA, whereas activation stimuli, such as IL-12/IL-18 or parasite lysates, failed to induce GABA secretion. GABA secretion by NK cells was associated to a transcriptional up-regulation of GABA synthesis enzymes (glutamate decarboxylases [GAD65/67]) and was abrogated by GAD inhibition. Further, NK cells expressed GABA-A receptor subunits and GABA signaling regulators, with transcriptional modulations taking place upon challenge with T. gondii. Exogenous GABA and GABA-containing supernatants from parasitized dendritic cells (DCs) impacted NK cell function by reducing the degranulation and cytotoxicity of NK cells. Conversely, GABA-containing supernatants from NK cells enhanced the migratory responses of parasitized DCs. This enhanced DC migration was abolished by GABA-A receptor antagonism or GAD inhibition and was reconstituted by exogenous GABA. Jointly, the data show that NK cells are GABAergic cells and that GABA hampers NK cell cytotoxicity in vitro. We hypothesize that GABA secreted by parasitized immune cells modulates the immune responses to T. gondii infection.

Opposing Actions of Octopamine and Tyramine on Honeybee Vision

The biogenic amines octopamine and tyramine are important neurotransmitters in insects and other protostomes. They play a pivotal role in the sensory responses, learning and memory and social organisation of honeybees. Generally, octopamine and tyramine are believed to fulfil similar roles as their deuterostome counterparts epinephrine and norepinephrine. In some cases opposing functions of both amines have been observed. In this study, we examined the functions of tyramine and octopamine in honeybee responses to light. As a first step, electroretinography was used to analyse the effect of both amines on sensory sensitivity at the photoreceptor level. Here, the maximum receptor response was increased by octopamine and decreased by tyramine. As a second step, phototaxis experiments were performed to quantify the behavioural responses to light following treatment with either amine. Octopamine increased the walking speed towards different light sources while tyramine decreased it. This was independent of locomotor activity. Our results indicate that tyramine and octopamine act as functional opposites in processing responses to light.

Cross-Validation of the Foundation Pain Index with PROMIS-29 in Chronic Pain Patients

Purpose

Discovery and validation of pragmatic biomarkers represent significant advancements in the field of pain management. Evaluating relationships between objective biomarkers and patient-reported outcomes (PROs) is an effective way to gain mechanistic insight into the potential role of biochemistry in chronic pain. The aim of this study was to validate the Foundation Pain Index (FPI) by evaluating associations between deranged biochemical function and PROMIS-29 domains in individuals living with chronic pain.

Patients and Methods

PROMIS-29 scores and FPI test results were obtained from 298 patients with chronic pain in this retrospective, observational study. Statistical analysis was performed using clinical test data to evaluate relationships between deranged biochemical function and quality of life measures across 8 universal domains.

Results

FPI scores significantly associated with multiple PROMIS-29 domains including physical function, impact score, fatigue, pain interference, and depression (P < 0.05). Moreover, specific analytes that comprise the FPI significantly correlated with PROMIS-29 domains, including 5-hydroxyindolacetic acid (pain interference, physical function, and pain impact scores), hydroxymethylglutarate (physical function), homocysteine (pain impact scores), kynurenic acid (pain interference and physical function), and quinolinic acid (physical function) (P < 0.05).

Conclusion

Cross-validation of the FPI with PROMIS-29 domains further supports the role of deranged biochemical function in the etiology of chronic pain. Objective identification of atypical biochemical function and subsequent correction holds tremendous promise for the non-opioid management of pain. Continued research efforts will aim to determine the impact of biochemical optimization in pre-surgical periods and post-surgical outcomes in patients with chronic pain.

Effects of Radiofrequency Electromagnetic Radiation on Neurotransmitters in the Brain

With the rapid development of electronic information in the past 30 years, technical achievements based on electromagnetism have been widely used in various fields pertaining to human production and life. Consequently, electromagnetic radiation (EMR) has become a substantial new pollution source in modern civilization. The biological effects of EMR have attracted considerable attention worldwide. The possible interaction of EMR with human organs, especially the brain, is currently where the most attention is focused. Many studies have shown that the nervous system is an important target organ system sensitive to EMR. In recent years, an increasing number of studies have focused on the neurobiological effects of EMR, including the metabolism and transport of neurotransmitters. As messengers of synaptic transmission, neurotransmitters play critical roles in cognitive and emotional behavior. Here, the effects of EMR on the metabolism and receptors of neurotransmitters in the brain are summarized.

Neurotransmitter Precursor Amino Acid Ratios Show Differential, Inverse Correlations with Depression Severity in the Low and High Depression Score Range

The immunomodulatory capacity of mental stress is one of the basic concepts of psychoneuroimmunology. The current prospective longitudinal study was designed to evaluate the effect of acute mental stress on neurotransmitter precursor amino acid levels in individuals with depression at 2 time points. Ten physically healthy patients with a diagnosis of major depressive episode and Montgomery–Åsberg Depression Rating Scale scores (MADRAS) ⩾20 points at inclusion were assessed on 2 study days (once with higher MADRAS scores, once with lower MADRAS scores; median 34.5 days apart) and subjected to a standardized acute mental stress test on each study day. Blood was collected at 4 time points: once prior to and at 3 time points (0, 30 minutes, 60 minutes) following mental stress. Neurotransmitter precursor amino acid levels, that is kynurenine/tryptophan (KYN/TRP) and phenylalanine/tyrosine (PHE/TYR), as well as neopterin and nitrite were analyzed in a total of 80 individual blood samples. Regression and correlation analyses were performed. Regression analyses of PHE/TYR (R² = .547) and KYN/TRP (R² = .440) in relation to MADRAS depression severity showed a quadratic curve fit. This was reflected by a negative linear correlation between MADRAS scores and PHE/TYR as well as KYN/TRP in the lower score range (r = −.805, P < .001 and r = −.586, P < .001 respectively) and a positive correlation in the higher MADRAS score range (r = .713, P < .001 and r = .379, P = .016 respectively). No effect of acute mental stress was found. This analysis exemplifies the implications of sampling as well as data distributions on results. The crosstalk of biological mechanisms that orchestrate metabolic and immunological signaling may vary depending on depression severity resulting in non-linear associations that may explain the heterogeneity of results found in the literature.

Effect of Anesthesia/Surgery on Gut Microbiota and Fecal Metabolites and Their Relationship With Cognitive Dysfunction

Aims: Post-operative cognitive dysfunction (POCD) is the decline in cognitive function of the central nervous system (CNS) after anesthesia/surgery. The present study explored whether anesthesia/surgery altered gut microbiota and fecal metabolites, examining their associations with risk factors of cognitive dysfunction in aged mice.

Methods: Sixteen-month-old C57BL/6 mice underwent abdominal surgery under isoflurane anesthesia to establish an animal model of POCD. The Morris water maze test (MWMT) was used as an indicator of memory after surgery. The effects of anesthesia/surgical interventions on gut microbiota, fecal metabolites, hippocampus, and serum levels of inflammatory factors were examined.

Results: The anesthesia/surgery induced more serious POCD behavior, increasing brain interleukin (IL)-6, and IL-1β levels than sham control mice. The relative abundance of bacterial genera Bacteroidales_unclassified, Mucispirillum, and Clostridiales_unclassified declined, whereas that of Escherichia–Shigella, actinomyces, Ruminococcus_gnavus_group, and Lachnospiraceae_FCS020_group were enriched after anesthesia/surgery compared to the baseline controls. Liquid chromatography–mass spectrometry (LC–MS) showed that the metabolites differed between post-anesthesia+surgery (post_A + S) and baseline samples and were associated with the fecal metabolism of tryptophan, kynurenic acid, N-oleoyl γ-aminobutyric acid (GABA), 2-indolecarboxylic acid, and glutamic acid. Furthermore, the differential metabolites were associated with alterations in the abundance of specific bacteria. These results indicate that the POCD intervention may be achieved by targeting specific bacteria associated with neurotransmitter metabolism.

Conclusions: A transient cognitive disturbance induced by anesthesia/surgery may be associated with unfavorable alterations in gut microbiota and fecal metabolites, thereby contributing to the POCD development.

Effects of Sleep Deprivation by Olfactorily Induced Sexual Arousal Compared to Immobilization Stress and Manual Sleep Deprivation on Neuromessengers and Time Keeping Genes in the Suprachiasmatic Nuclei and Other Cerebral Entities of Syrian Hamsters-An Immunohistochemical Study

We investigated the effects of sexual arousal induced by olfactory stimuli on the expression of neuromodulators, neurotransmitters and sexual steroid receptors in the suprachiasmatic nucleus (SCN, the circadian pacemaker of mammals) and other cerebral entities of Syrian hamsters (Mesocricetus auratus) compared to manual sleep deprivation and immobilization stress. The hamsters kept under a 12:12 hours (h) light:dark cycle were deprived of sleep by sexual stimulation, gentle manual handling or immobilization stress for 1 h at the beginning of the light phase and subsequently sacrificed at zeitgeber time 01:00, respectively; for comparison, hamsters were manually sleep deprived for 6 or 20 h or sacrificed after completing a full sleep phase. As demonstrated by immunohistochemistry, apart from various alterations after manual sleep deprivation, sexual stimulation caused down-regulation of arginine-vasopressin (AVP), vasointestinal peptide (VIP), serotonin (5-HT), substance P (SP), and met-enkephalin (ME) in the SCN. Somatostatin (SOM) was diminished in the medial periventricular nucleus (MPVN). In contrast, an increase in AVP was observed in the PVN, that of oxytocin (OXY) in the supraoptic nucleus (SON), of tyrosine-hydroxylase (TH) in the infundibular nucleus (IN), and dopamine beta-hydroxylase (DBH) in the A7 neuron population of the brain stem (A7), respectively. Testosterone in plasma was increased. The results indicate that sexual arousal extensively influences the neuropeptide systems of the SCN, suggesting an involvement of the SCN in reproductive behavior.

mTOR Knockdown in the Infralimbic Cortex Evokes A Depressive-like State in Mouse

Fast and sustained antidepressant effects of ketamine identified the mammalian target of rapamycin (mTOR) signaling pathway as the main modulator of its antidepressive effects. Thus, mTOR signaling has become integral for the preclinical evaluation of novel compounds to treat depression. However, causality between mTOR and depression has yet to be determined. To address this, we knocked down mTOR expression in mice using an acute intracerebral infusion of small interfering RNAs (siRNA) in the infralimbic (IL) or prelimbic (PrL) cortices of the medial prefrontal cortex (mPFC), and evaluated depressive- and anxious-like behaviors. mTOR knockdown in IL, but not PrL, cortex produced a robust depressive-like phenotype in mice, as assessed in the forced swimming test (FST) and the tail suspension test (TST). This phenotype was associated with significant reductions of mTOR mRNA and protein levels 48 h post-infusion. In parallel, decreased brain-derived neurotrophic factor (BDNF) expression was found bilaterally in both IL and PrL cortices along with a dysregulation of serotonin (5-HT) and glutamate (Glu) release in the dorsal raphe nucleus (DRN). Overall, our results demonstrate causality between mTOR expression in the IL cortex and depressive-like behaviors, but not in anxiety.

Pharmacological Modulation of Behaviour, Serotonin and Dopamine Levels in Daphnia magna Exposed to the Monoamine Oxidase Inhibitor Deprenyl

This study assessed the effects of the monoamine oxidase (MAO) inhibitor deprenyl in Daphnia magna locomotor activity. The mechanisms of action of deprenyl were also determined by studying the relationship between behaviour, MAO activity and neurotransmitter levels. Modulation of the D. magna monoamine system was accomplished by 24 h exposure to two model psychotropic pharmaceuticals with antagonistic and agonistic serotonin signalling properties: 10 mg/L of 4-chloro-DL-phenylalanine (PCPA) and 1 mg/L of deprenyl, respectively. Contrasting behavioural outcomes were observed for deprenyl and PCPA reflected in decreased basal locomotor activity and enhanced habituation for the former compound and delayed habituation for the latter one. Deprenyl exposure inhibited monoamine oxidase (MAO) activity and increased the concentrations of serotonin, dopamine and the dopamine metabolite 3-methoxytyramine in whole D. magna extracts. Our findings indicate that D. magna is a sensitive and useful nonvertebrate model for assessing the effects of short-term exposure to chemicals that alter monoamine signalling changes.

Nonselective cation permeation in an AMPA-type glutamate receptor

Fast excitatory synaptic transmission in the central nervous system relies on the AMPA-type glutamate receptor (AMPAR). This receptor incorporates a nonselective cation channel, which is opened by the binding of glutamate. Although the open pore structure has recently became available from cryo-electron microscopy (Cryo-EM), the molecular mechanisms governing cation permeability in AMPA receptors are not understood. Here, we combined microsecond molecular dynamic (MD) simulations on a putative open-state structure of GluA2 with electrophysiology on cloned channels to elucidate ion permeation mechanisms. Na⁺, K⁺, and Cs⁺ permeated at physiological rates, consistent with a structure that represents a true open state. A single major ion binding site for Na⁺ and K⁺ in the pore represents the simplest selectivity filter (SF) structure for any tetrameric cation channel of known structure. The minimal SF comprised only Q586 and Q587, and other residues on the cytoplasmic side formed a water-filled cavity with a cone shape that lacked major interactions with ions. We observed that Cl^- readily enters the upper pore, explaining anion permeation in the RNA-edited (Q586R) form of GluA2. A permissive architecture of the SF accommodated different alkali metals in distinct solvation states to allow rapid, nonselective cation permeation and copermeation by water. Simulations suggested Cs⁺ uses two equally populated ion binding sites in the filter, and we confirmed with electrophysiology of GluA2 that Cs⁺ is slightly more permeant than Na⁺, consistent with serial binding sites preferentially driving selectivity.

Impaired learning and memory in mice induced by nano neodymium oxide and possible mechanisms

A growing number of individuals are now exposed to neodymium (Nd) owing to its extensive applications. However, the biological effects of Nd on humans, especially on learning and memory, remain elusive. To investigate whether Nd exposure affects learning and memory, in this study female ICR mice were exposed to nano Nd₂ O₃ via intranasal instillation at doses of 50, 100, and 150 mg/kg body weight, daily for 45 days. According to Morris water maze data, learning and memory parameters were significantly reduced in the 150 mg/kg nano-Nd₂ O₃ group than the sham control. Furthermore, inductively coupled plasma-mass spectroscopy analysis revealed that Nd levels were significantly higher in the hippo campus of the 100 and 150 mg/kg exposed group than the sham control; however, no significant differences were observed in the hippocampal histopathology between these groups. Furthermore, reactive oxygen species were elevated in hippocampal tissues of experimental groups than the sham control, 447.3 in high dose group and 360.0 in control group; however, malondialdehyde levels were significantly increased and superoxide dismutase activities were decreased only in mice exposed to 100 and 150 mg/kg Nd₂ O₃ . High-performance liquid chromatography data demonstrated that levels of glutamic acid, glycine, and gamma-aminobutyric acid were higher in the hippocampus of mice exposed to 150 mg/kg Nd₂ O₃ than the sham control. Our findings indicated that the neuronal injury was induced by disruption of the oxidation-antioxidation homeostasis and altered amino acid neurotransmitter levels in the hippocampus, which could result in the poor cognitive performance demonstrated by exposed mice.

Longitudinal Analysis of Multiple Neurotransmitter Metabolites in Cerebrospinal Fluid in Early Parkinson's Disease

BACKGROUND

Cerebrospinal fluid (CSF) levels of monoamine metabolites may represent biomarkers of Parkinson's disease (PD).

OBJECTIVE

The aim of this study was quantification of multiple metabolites in CSF from PD versus healthy control subjects (HCs), including longitudinal analysis.

METHODS

Absolute levels of multiple monoamine metabolites in CSF were quantified by liquid chromatography coupled with tandem mass spectrometry from 161 individuals with early PD and 115 HCs from the Parkinson's Progression Marker Initiative and de novo PD (DeNoPA) studies.

RESULTS

Baseline levels of homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were lower in individuals with PD compared with HCs. HVA levels correlated with Movement Disorder Society Unified Parkinson's Disease Rating Scale total scores (P < 0.01). Both HVA/dopamine and DOPAC/dopamine levels correlated with caudate nucleus and raw DOPAC with putamen dopamine transporter single-photon emission computed tomography uptake ratios (P < 0.01). No metabolite changed over 2 years in drug-naive individuals, but some changed on starting levodopa treatment.

CONCLUSIONS

HVA and DOPAC CSF levels mirrored nigrostriatal pathway damage, confirming the central role of dopaminergic degeneration in early PD. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Shedding Light on the Role of Neurotransmitters in the Microenvironment of Pancreatic Cancer

Pancreatic cancer (PC) is a highly lethal malignancy with a 5-year survival rate of less than 8%. The fate of PC is determined not only by the malignant behavior of the cancer cells, but also by the surrounding tumor microenvironment (TME), consisting of various cellular (cancer cells, immune cells, stromal cells, endothelial cells, and neurons) and non-cellular (cytokines, neurotransmitters, and extracellular matrix) components. The pancreatic TME has the unique characteristic of exhibiting increased neural density and altered microenvironmental concentration of neurotransmitters. The neurotransmitters, produced by both neuron and non-neuronal cells, can directly regulate the biological behavior of PC cells via binding to their corresponding receptors on tumor cells and activating the intracellular downstream signals. On the other hand, the neurotransmitters can also communicate with other cellular components such as the immune cells in the TME to promote cancer growth. In this review, we will summarize the pleiotropic effects of neurotransmitters on the initiation and progression of PC, and particularly discuss the emerging mechanisms of how neurotransmitters influence the innate and adaptive immune responses in the TME in an autocrine or paracrine manner. A better understanding of the interplay between neurotransmitters and the immune cells in the TME might facilitate the development of new effective therapies for PC.

Reciprocal regulation of spontaneous synaptic vesicle fusion by Fragile X mental retardation protein and group I metabotropic glutamate receptors

Fragile X mental retardation protein (FMRP) is a neuronal protein mediating multiple functions, with its absence resulting in one of the most common monogenic causes of autism, Fragile X syndrome (FXS). Analyses of FXS pathophysiology have identified a range of aberrations in synaptic signaling pathways and plasticity associated with group I metabotropic glutamate (mGlu) receptors. These studies, however, have mostly focused on the post-synaptic functions of FMRP and mGlu receptor activation, and relatively little is known about their presynaptic effects. Neurotransmitter release is mediated via multiple forms of synaptic vesicle (SV) fusion, each of which contributes to specific neuronal functions. The impacts of mGlu receptor activation and loss of FMRP on these SV fusion events remain unexplored. Here we combined electrophysiological and fluorescence imaging analyses on primary hippocampal cultures prepared from an Fmr1 knockout (KO) rat model. Compared to wild-type (WT) hippocampal neurons, KO neurons displayed an increase in the frequency of spontaneous excitatory post-synaptic currents (sEPSCs), as well as spontaneous SV fusion events. Pharmacological activation of mGlu receptors in WT neurons caused a similar increase in spontaneous SV fusion and sEPSC frequency. Notably, this increase in SV fusion was not observed when spontaneous activity was blocked using the sodium channel antagonist tetrodotoxin. Importantly, the effect of mGlu receptor activation on spontaneous SV fusion was occluded in Fmr1 KO neurons. Together, our results reveal that FMRP represses spontaneous presynaptic SV fusion, whereas mGlu receptor activation increases this event. This reciprocal control appears to be mediated via their regulation of intrinsic neuronal excitability.

Improving the Utility of a Dynorphin Peptide Analogue Using Mannosylated Glycoliposomes

Peptide therapeutics offer numerous advantages in the treatment of diseases and disorders of the central nervous system (CNS). However, they are not without limitations, especially in terms of their pharmacokinetics where their metabolic lability and low blood–brain barrier penetration hinder their application. Targeted nanoparticle delivery systems are being tapped for their ability to improve the delivery of therapeutics into the brain non-invasively. We have developed a family of mannosylated glycoliposome delivery systems for targeted drug delivery applications. Herein, we demonstrate via in vivo distribution studies the potential of these glycoliposomes to improve the utility of CNS active therapeutics using dynantin, a potent and selective dynorphin peptide analogue antagonist of the kappa opioid receptor (KOR). Glycoliposomal entrapment protected dynantin against known rapid metabolic degradation and ultimately improved brain levels of the peptide by approximately 3–3.5-fold. Moreover, we linked this improved brain delivery with improved KOR antagonist activity by way of an approximately 30–40% positive modulation of striatal dopamine levels 20 min after intranasal administration. Overall, the results clearly highlight the potential of our glycoliposomes as a targeted delivery system for therapeutic agents of the CNS.

Dopaminergic brainstem disconnection is common to pharmacological and pathological consciousness perturbation

Understanding the neural bases of consciousness is of basic scientific and clinical importance. Human neuroimaging has established that a network of interconnected brain regions known as the default mode network disintegrates in anesthesia and after brain damage that causes disorders of consciousness. However, the neurochemical underpinnings of this network change remain largely unknown. Motivated by preclinical animal work and clinical observations, we found that across pharmacological (sedation) and pathological (disorders of consciousness) consciousness perturbation, the dopaminergic source nucleus, the ventral tegmental area, disconnects from the main nodes of the default mode network. As the severity of this dopaminergic disconnection was associated with default mode network disintegration, we propose that dopaminergic modulation may be a central mechanism for consciousness maintenance.

Clinical research into consciousness has long focused on cortical macroscopic networks and their disruption in pathological or pharmacological consciousness perturbation. Despite demonstrating diagnostic utility in disorders of consciousness (DoC) and monitoring anesthetic depth, these cortico-centric approaches have been unable to characterize which neurochemical systems may underpin consciousness alterations. Instead, preclinical experiments have long implicated the dopaminergic ventral tegmental area (VTA) in the brainstem. Despite dopaminergic agonist efficacy in DoC patients equally pointing to dopamine, the VTA has not been studied in human perturbed consciousness. To bridge this translational gap between preclinical subcortical and clinical cortico-centric perspectives, we assessed functional connectivity changes of a histologically characterized VTA using functional MRI recordings of pharmacologically (propofol sedation) and pathologically perturbed consciousness (DoC patients). Both cohorts demonstrated VTA disconnection from the precuneus and posterior cingulate (PCu/PCC), a main default mode network node widely implicated in consciousness. Strikingly, the stronger VTA–PCu/PCC connectivity was, the more the PCu/PCC functional connectome resembled its awake configuration, suggesting a possible neuromodulatory relationship. VTA-PCu/PCC connectivity increased toward healthy control levels only in DoC patients who behaviorally improved at follow-up assessment. To test whether VTA–PCu/PCC connectivity can be affected by a dopaminergic agonist, we demonstrated in a separate set of traumatic brain injury patients without DoC that methylphenidate significantly increased this connectivity. Together, our results characterize an in vivo dopaminergic connectivity deficit common to reversible and chronic consciousness perturbation. This noninvasive assessment of the dopaminergic system bridges preclinical and clinical work, associating dopaminergic VTA function with macroscopic network alterations, thereby elucidating a critical aspect of brainstem–cortical interplay for consciousness.