Multiple serum anti-glutamate receptor antibody levels in clozapine-treated/naïve patients with treatment-resistant schizophrenia.

BACKGROUND: Glutamatergic function abnormalities have been implicated in the etiology of treatment-resistant schizophrenia (TRS), and the efficacy of clozapine may be attributed to its impact on the glutamate system. Recently, evidence has emerged suggesting the involvement of immune processes and increased prevalence of antineuronal antibodies in TRS. This current study aimed to investigate the levels of multiple anti-glutamate receptor antibodies in TRS and explore the effects of clozapine on these antibody levels. METHODS: Enzyme linked immunosorbent assay (ELISA) was used to measure and compare the levels of anti-glutamate receptor antibodies (NMDAR, AMPAR, mGlur3, mGluR5) in clozapine-treated TRS patients (TRS-C, n = 37), clozapine-naïve TRS patients (TRS-NC, n = 39), and non-TRS patients (nTRS, n = 35). Clinical symptom severity was assessed using the Positive and Negative Symptom Scale (PANSS), while cognitive function was evaluated using the MATRICS Consensus Cognitive Battery (MCCB). RESULT: The levels of all four glutamate receptor antibodies in TRS-NC were significantly higher than those in nTRS (p < 0.001) and in TRS-C (p < 0.001), and the antibody levels in TRS-C were comparable to those in nTRS. However, no significant associations were observed between antibody levels and symptom severity or cognitive function across all three groups after FDR correction. CONCLUSION: Our findings suggest that TRS may related to increased anti-glutamate receptor antibody levels and provide further evidence that glutamatergic dysfunction and immune processes may contribute to the pathogenesis of TRS. The impact of clozapine on anti-glutamate receptor antibody levels may be a pharmacological mechanism underlying its therapeutic effects.

Expression and Functional Analysis of Ctenophore Glutamate Receptor Genes.

The functional analysis of ctenophore neurotransmitter receptors, transporters, and ion channels can be greatly simplified by use of heterologous expression systems. Heterologous expression allows the characterization of individual membrane proteins, expressed at high levels in cells, where background activity by endogenous ion channels and transporters is with few exceptions minimal. The goal of such experiments is to gain an in-depth understanding of the behavior and regulation of individual molecular species, which is challenging in native tissue, but especially so in the case of ctenophores and other marine organisms. Coupled with transcriptome analysis, and immunohistochemical studies of receptor expression in vivo, experiments with heterologous expression systems can provide valuable insight into cellular activity, prior to more challenging functional studies on native tissues.

Involvement of GLR-mediated nitric oxide effects on ROS metabolism in Arabidopsis plants under salt stress.

Plant glutamate receptor-like channels (GLRs) play important roles in plant development, immune response, defense signaling and Nitric oxide (NO) production. However, their involvement in abiotic stress responses, particularly in regulating Reactive Oxygen Species (ROS), is not well understood. This study aimed to investigate GLR-mediated NO production on ROS regulation in salt-stressed cells. To achieve this, Arabidopsis thaliana Columbia (Col-0) were treated with NaCl, glutamate antagonists [(DNQX (6,7-dinitroquinoxaline-2,3-dione and AP-5(D-2-amino-5-phosphono pentanoic acid)], and NO scavenger [cPTIO (2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt)]. Salt-stressed plants in combination with DNQX and AP-5 have exhibited higher increase in lipid peroxidation (TBARS), hydrogen peroxide (H2O2) and superoxide radical (O-2) contents as compared to solely NaCl-treated plants. Furthermore, NO and total glutathione contents, and S-nitrosoglutathione reductase (GSNOR) activity decreased with these treatments. AP-5 and DNQX increased the activities of NADPH oxidase (NOX), catalase (CAT), peroxidase (POX), cell wall peroxidase (CWPOX) in salt-stressed Arabidopsis leaves. However, their activities (except NOX) were significantly inhibited by cPTIO. Conversely, the combination of NaCl and GLR antagonists, NO scavenger decreased the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione reductase (GR), dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR) resulting in elevated GSSG levels, a low GSH/GSSG ratio, impaired ROS scavenging, excessive ROS accumulation and cell membrane damage. The findings of this study provide evidence that GLR-mediated NO plays a crucial role in improvement of the tolerance of Arabidopsis plants to salt-induced oxidative stress. It helps to maintain cellular redox homeostasis by reducing ROS accumulation and increasing the activity of SOD, GSNOR, and the ASC-GSH cycle enzymes.

Role of GLR-1 in Age-Dependent Short-Term Memory Decline.

As the global elderly population grows, age-related cognitive decline is becoming an increasingly significant healthcare issue, often leading to various neuropsychiatric disorders. Among the many molecular players involved in memory, AMPA-type glutamate receptors are known to regulate learning and memory, but how their dynamics change with age and affect memory decline is not well understood. Here, we examined the in vivo properties of the AMPA-type glutamate receptor GLR-1 in the AVA interneuron of the Caenorhabditis elegans nervous system during physiological aging. We found that both total and membrane-bound GLR-1 receptor levels decrease with age in wild-type worms, regardless of their location along the axon. Using fluorescence recovery after photobleaching, we also demonstrated that a reduction in GLR-1 abundance correlates with decreased local, synaptic GLR-1 receptor dynamics. Importantly, we found that reduced GLR-1 levels strongly correlate with the age-related decline in short-term associative memory. Genetic manipulation of GLR-1 stability, by either deleting msi-1 or expressing a ubiquitination-defective GLR-1 (4KR) variant, prevented this age-related reduction in receptor abundance and improved the short-term memory performance in older animals, which reached performance levels similar to those of young animals. Overall, our data indicate that AMPA-type glutamate receptor abundance and dynamics are key factors in maintaining memory function and that changes in these parameters are linked to age-dependent short-term memory decline.

Activity-dependent mitochondrial ROS signaling regulates recruitment of glutamate receptors to synapses.

Our understanding of mitochondrial signaling in the nervous system has been limited by the technical challenge of analyzing mitochondrial function in vivo. In the transparent genetic model Caenorhabditis elegans, we were able to manipulate and measure mitochondrial reactive oxygen species (mitoROS) signaling of individual mitochondria as well as neuronal activity of single neurons in vivo. Using this approach, we provide evidence supporting a novel role for mitoROS signaling in dendrites of excitatory glutamatergic C. elegans interneurons. Specifically, we show that following neuronal activity, dendritic mitochondria take up calcium (Ca2+) via the mitochondrial Ca2+ uniporter (MCU-1) that results in an upregulation of mitoROS production. We also observed that mitochondria are positioned in close proximity to synaptic clusters of GLR-1, the C. elegans ortholog of the AMPA subtype of glutamate receptors that mediate neuronal excitation. We show that synaptic recruitment of GLR-1 is upregulated when MCU-1 function is pharmacologically or genetically impaired but is downregulated by mitoROS signaling. Thus, signaling from postsynaptic mitochondria may regulate excitatory synapse function to maintain neuronal homeostasis by preventing excitotoxicity and energy depletion.

Targeting postsynaptic glutamate receptor scaffolding proteins PSD-95 and PICK1 for obesity treatment.

Human genome-wide association studies (GWAS) suggest a functional role for central glutamate receptor signaling and plasticity in body weight regulation. Here, we use UK Biobank GWAS summary statistics of body mass index (BMI) and body fat percentage (BF%) to identify genes encoding proteins known to interact with postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartate (NMDA) receptors. Loci in/near discs large homolog 4 (DLG4) and protein interacting with C kinase 1 (PICK1) reached genome-wide significance (P < 5 × 10-8) for BF% and/or BMI. To further evaluate the functional role of postsynaptic density protein-95 (PSD-95; gene name: DLG4) and PICK1 in energy homeostasis, we used dimeric PSD-95/disc large/ZO-1 (PDZ) domain-targeting peptides of PSD-95 and PICK1 to demonstrate that pharmacological inhibition of PSD-95 and PICK1 induces prolonged weight-lowering effects in obese mice. Collectively, these data demonstrate that the glutamate receptor scaffolding proteins, PICK1 and PSD-95, are genetically linked to obesity and that pharmacological targeting of their PDZ domains represents a promising therapeutic avenue for sustained weight loss.

Vagus nerve stimulation inhibits cortical spreading depression via glutamate-dependent TrkB activation mechanism in the nucleus tractus solitarius.

BACKGROUND: Vagus nerve stimulation (VNS) was recently found to inhibit cortical spreading depression (CSD), the underlying mechanism of migraine aura, through activation of the nucleus tractus solitarius (NTS), locus coeruleus (LC) and dorsal raphe nucleus (DRN). The molecular mechanisms underlying the effect of VNS on CSD in these nuclei remain to be explored. We hypothesized that VNS may activate glutamate receptor-mediated tropomyosin kinase B (TrkB) signaling in the NTS, thereby facilitating the noradrenergic and serotonergic neurotransmission to inhibit CSD. METHODS: To investigate the role of TrkB and glutamate receptors in non-invasive VNS efficacy on CSD, a validated KCl-evoked CSD rat model coupled with intra-NTS microinjection of selective antagonists, immunoblot and immunohistochemistry was employed. RESULTS: VNS increased TrkB phosphorylation in the NTS. Inhibition of intra-NTS TrkB abrogated the suppressive effect of VNS on CSD and CSD-induced cortical neuroinflammation. TrkB was found colocalized with glutamate receptors in NTS neurons. Inhibition of glutamate receptors in the NTS abrogated VNS-induced TrkB activation. Moreover, the blockade of TrkB in the NTS attenuated VNS-induced activation of the LC and DRN. CONCLUSIONS: VNS induces the activation of glutamate receptor-mediated TrkB signaling in the NTS, which might modulate serotonergic and norepinephrinergic innervation to the cerebral cortex to inhibit CSD and cortical inflammation.

Neuropharmacological Evidence Implicating Drug-Induced Glutamate Receptor Dysfunction in Affective and Cognitive Sequelae of Subchronic Methamphetamine Self-Administration in Mice.

Methamphetamine (MA) is a highly addictive drug, and MA use disorder is often comorbid with anxiety and cognitive impairment. These comorbid conditions are theorized to reflect glutamate-related neurotoxicity within the frontal cortical regions. However, our prior studies of MA-sensitized mice indicate that subchronic, behaviorally non-contingent MA treatment is sufficient to dysregulate glutamate transmission in mouse brain. Here, we extend this prior work to a mouse model of high-dose oral MA self-administration (0.8, 1.6, or 3.2 g/L; 1 h sessions × 7 days) and show that while female C57BL/6J mice consumed more MA than males, MA-experienced mice of both sexes exhibited some signs of anxiety-like behavior in a behavioral test battery, although not all effects were concentration-dependent. No MA effects were detected for our measures of visually cued spatial navigation, spatial learning, or memory in the Morris water maze; however, females with a history of 3.2 g/L MA exhibited reversal-learning deficits in this task, and mice with a history of 1.6 g/L MA committed more working-memory incorrect errors and relied upon a non-spatial navigation strategy during the radial-arm maze testing. Relative to naïve controls, MA-experienced mice exhibited several changes in the expression of certain glutamate receptor-related proteins and their downstream effectors within the ventral and dorsal areas of the prefrontal cortex, the hippocampus, and the amygdala, many of which were sex-selective. Systemic pretreatment with the mGlu1-negative allosteric modulator JNJ 162596858 reversed the anxiety-like behavior expressed by MA-experienced mice in the marble-burying test, while systemic pretreatment with NMDA or the NMDA antagonist MK-801 bi-directionally affected the MA-induced reversal-learning deficit. Taken together, these data indicate that a relatively brief history of oral MA is sufficient to induce some signs of anxiety-like behavior and cognitive dysfunction during early withdrawal that reflect, at least in part, MA-induced changes in the corticolimbic expression of certain glutamate receptor subtypes of potential relevance to treating symptoms of MA use disorder.

Rapid Propagation of Ca2+ Waves and Electrical Signals in the Liverwort Marchantia polymorpha.

In response to both biotic and abiotic stresses, vascular plants transmit long-distance Ca2+ and electrical signals from localized stress sites to distant tissues through their vasculature. Various models have been proposed for the mechanisms underlying the long-distance signaling, primarily centered around the presence of vascular bundles. We here demonstrate that the non-vascular liverwort Marchantia polymorpha possesses a mechanism for propagating Ca2+ waves and electrical signals in response to wounding. The propagation velocity of these signals was approximately 1-2 mm s-1, equivalent to that observed in vascular plants. Both Ca2+ waves and electrical signals were inhibited by La3+ as well as tetraethylammonium chloride, suggesting the crucial importance of both Ca2+ channel(s) and K+ channel(s) in wound-induced membrane depolarization as well as the subsequent long-distance signal propagation. Simultaneous recordings of Ca2+ and electrical signals indicated a tight coupling between the dynamics of these two signaling modalities. Furthermore, molecular genetic studies revealed that a GLUTAMATE RECEPTOR-LIKE (GLR) channel plays a central role in the propagation of both Ca2+ waves and electrical signals. Conversely, none of the three two-pore channels were implicated in either signal propagation. These findings shed light on the evolutionary conservation of rapid long-distance Ca2+ wave and electrical signal propagation involving GLRs in land plants, even in the absence of vascular tissue.

Ca2+/calmodulin-mediated desensitization of glutamate receptors shapes plant systemic wound signalling and anti-herbivore defence.

Plants rely on systemic signalling mechanisms to establish whole-body defence in response to insect and nematode attacks. GLUTAMATE RECEPTOR-LIKE (GLR) genes have been implicated in long-distance transmission of wound signals to initiate the accumulation of the defence hormone jasmonate (JA) at undamaged distal sites. The systemic signalling entails the activation of Ca2+-permeable GLR channels by wound-released glutamate, triggering membrane depolarization and cytosolic Ca2+ influx throughout the whole plant. The systemic electrical and calcium signals rapidly dissipate to restore the resting state, partially due to desensitization of the GLR channels. Here we report the discovery of calmodulin-mediated, Ca2+-dependent desensitization of GLR channels, revealing a negative feedback loop in the orchestration of plant systemic wound responses. A CRISPR-engineered GLR3.3 allele with impaired desensitization showed prolonged systemic electrical signalling and Ca2+ waves, leading to enhanced plant defence against herbivores. Moreover, this Ca2+/calmodulin-mediated desensitization of GLR channels is a highly conserved mechanism in plants, providing a potential target for engineering anti-herbivore defence in crops.

Adult rats sired by obese fathers present learning deficits associated with epigenetic and neurochemical alterations linked to impaired brain glutamatergic signaling.

AIM: Offspring of obese mothers are at high risk of developing metabolic syndrome and cognitive disabilities. Impaired metabolism has also been reported in the offspring of obese fathers. However, whether brain function can also be affected by paternal obesity has barely been examined. This study aimed to characterize the learning deficits resulting from paternal obesity versus those induced by maternal obesity and to identify the underlying mechanisms. METHODS: Founder control and obese female and male Wistar rats were mated to constitute three first-generation (F1) experimental groups: control mother/control father, obese mother/control father, and obese father/control mother. All F1 animals were weaned onto standard chow and underwent a learning test at 4 months of age, after which several markers of glutamate-mediated synaptic plasticity together with the expression of miRNAs targeting glutamate receptors and the concentration of kynurenic and quinolinic acids were quantified in the hippocampus and frontal cortex. RESULTS: Maternal obesity induced a severe learning deficit by impairing memory encoding and memory consolidation. The offspring of obese fathers also showed reduced memory encoding but not impaired long-term memory formation. Memory deficits in offspring of obese fathers and obese mothers were associated with a down-regulation of genes encoding NMDA glutamate receptors subunits and several learning-related genes along with impaired expression of miR-296 and miR-146b and increased concentration of kynurenic acid. CONCLUSION: Paternal and maternal obesity impair offspring's learning abilities by affecting different processes of memory formation. These cognitive deficits are associated with epigenetic and neurochemical alterations leading to impaired glutamate-mediated synaptic plasticity.

Anti-metabolic glutamate receptor 5 encephalitis with gangliocytoma: a case and review of the literature.

BACKGROUND: There are very limited reports on anti-metabolic glutamate receptor5 (mGluR5) encephalitis, especially lacking of pediatric research. The disease was mostly accompanied by tumors, mainly Hodgkin's lymphoma. No reports of other tumors, such as gangliocytoma have been reported to associate with anti-mGluR5 encephalitis so far. CASE PRESENTATION AND LITERATURE REVIEWS: We reported a case of a 12-year-old boy with anti-mGluR5 encephalitis complicated with gangliocytoma. The patient suffered from mental disorders including auditory hallucination, and sleep disorders. His cranial magnetic resonance imaging (MRI) showed an abnormality in the right insular lobe. Autoimmune encephalitis antibodies testing was positive for mGluR5 IgG antibody both in cerebrospinal fluid and serum (1:3.2, 1:100 respectively). Abdominal CT indicated a mass in left retroperitoneal confirmed with gangliocytoma via pathology. The patient underwent resection of gangliocytoma. After first-line immunotherapy (glucocorticoid, gamma globulin), his condition was improved. Furthermore, we provide a summary of 6 pediatric cases of Anti-mGluR5 encephalitis. Most of them complicated with Hodgkin's lymphoma, except the case currently reported comorbid with gangliocytoma. The curative effect is satisfactory. CONCLUSIONS: We report the first patient with anti-mGlur5 encephalitis complicated with gangliocytoma. It suggests that in addition to paying attention to the common lymphoma associated with anti-mGlur5 encephalitis, we should also screen the possibility of other tumors for early detection of the cause, active treatment and prevention of recurrence.

TRPM4 blocking antibody reduces neuronal excitotoxicity by specifically inhibiting glutamate-induced calcium influx under chronic hypoxia.

Excitotoxicity arises from unusually excessive activation of excitatory amino acid receptors such as glutamate receptors. Following an energy crisis, excitotoxicity is a major cause for neuronal death in neurological disorders. Many glutamate antagonists have been examined for their efficacy in mitigating excitotoxicity, but failed to generate beneficial outcome due to their side effects on healthy neurons where glutamate receptors are also blocked. In this study, we found that during chronic hypoxia there is upregulation and activation of a nonselective cation channel TRPM4 that contributes to the depolarized neuronal membrane potential and enhanced glutamate-induced calcium entry. TRPM4 is involved in modulating neuronal membrane excitability and calcium signaling, with a complex and multifaceted role in the brain. Here, we inhibited TRPM4 using a newly developed blocking antibody M4P, which could repolarize the resting membrane potential and ameliorate calcium influx upon glutamate stimulation. Importantly, M4P did not affect the functions of healthy neurons as the activity of TRPM4 channel is not upregulated under normoxia. Using a rat model of chronic hypoxia with both common carotid arteries occluded, we found that M4P treatment could reduce apoptosis in the neurons within the hippocampus, attenuate long-term potentiation impairment and improve the functions of learning and memory in this rat model. With specificity to hypoxic neurons, TRPM4 blocking antibody can be a novel way of controlling excitotoxicity with minimal side effects that are common among direct blockers of glutamate receptors.

Autoimmune Cerebellar Ataxia Associated with Anti-Glutamate Receptor δ2 Antibodies: a Rare but Treatable Entity.

We report two novel cases of autoimmune cerebellar ataxia (ACA) associated with anti-glutamate receptor δ2 antibodies (Gluδ2-Abs). The first case was confirmed by indirect immunofluorescence and cell-based assays: a 29-year-old woman presented after 5 days of headache and vomiting, a pancerebellar syndrome, downbeat nystagmus, decreased visual acuity linked to bilateral retrobulbar optic neuritis (RON), and lymphocytic pleocytosis in the cerebrospinal fluid (CSF) without any abnormality detected using cerebral magnetic resonance imaging (MRI). Second-line immunotherapy allowed progressive clinical improvement, with full recovery achieved after a 4-year follow-up. Thereafter, we retrospectively tested Gluδ2-Abs in 350 patients with a suspicion of autoimmune encephalitis without characterized autoantibody. We identified a second case, a 12-year-old boy who developed 10 days after a respiratory infection, a static cerebellar syndrome with lymphocytosis in the CSF, and right cerebellum hyperintensity in MRI. Five days of corticosteroid treatment allowed a quick clinical improvement. No tumor was identified in both cases, whereas laboratory analyses revealed autoimmune stigma. The present cases suggested that ACA associated with Gluδ2-Abs is an extremely rare but treatable disease. Therefore, testing for Gluδ2-Abs might be considered in the setting of suspected ACA and no initial antibody identification. The visual deficits and ocular motility abnormalities observed in the first reported case might be part of the clinical spectrum of Gluδ2-Abs ACA. Young age, infectious prodromes, lymphocytic pleocytosis, and autoimmune background usually appear together with this syndrome and should lead to discuss the initiation of immunotherapy (after ruling out differential diagnosis, especially infectious causes).

Clinical features, functional consequences, and rescue pharmacology of missense GRID1 and GRID2 human variants.

GRID1 and GRID2 encode the enigmatic GluD1 and GluD2 proteins, which form tetrameric receptors that play important roles in synapse organization and development of the central nervous system. Variation in these genes has been implicated in neurodevelopmental phenotypes. We evaluated GRID1 and GRID2 human variants from the literature, ClinVar, and clinical laboratories and found that many of these variants reside in intolerant domains, including the amino terminal domain of both GRID1 and GRID2. Other conserved regions, such as the M3 transmembrane domain, show different intolerance between GRID1 and GRID2. We introduced these variants into GluD1 and GluD2 cDNA and performed electrophysiological and biochemical assays to investigate the mechanisms of dysfunction of GRID1/2 variants. One variant in the GRID1 distal amino terminal domain resides at a position predicted to interact with Cbln2/Cbln4, and the variant disrupts complex formation between GluD1 and Cbln2, which could perturb its role in synapse organization. We also discovered that, like the lurcher mutation (GluD2-A654T), other rare variants in the GRID2 M3 domain create constitutively active receptors that share similar pathogenic phenotypes. We also found that the SCHEMA schizophrenia M3 variant GluD1-A650T produced constitutively active receptors. We tested a variety of compounds for their ability to inhibit constitutive currents of GluD receptor variants and found that pentamidine potently inhibited GluD2-T649A constitutive channels (IC50 50 nM). These results identify regions of intolerance to variation in the GRID genes, illustrate the functional consequences of GRID1 and GRID2 variants, and suggest how these receptors function normally and in disease.

The atypical 'hippocampal' glutamate receptor coupled to phospholipase D that controls stretch-sensitivity in primary mechanosensory nerve endings is homomeric purely metabotropic GluK2.

A metabotropic glutamate receptor coupled to phospholipase D (PLD-mGluR) was discovered in the hippocampus over three decades ago. Its pharmacology and direct linkage to PLD activation are well established and indicate it is a highly atypical glutamate receptor. A receptor with the same pharmacology is present in spindle primary sensory terminals where its blockade can totally abolish, and its activation can double, the normal stretch-evoked firing. We report here the first identification of this PLD-mGluR protein, by capitalizing on its expression in primary mechanosensory terminals, developing an enriched source, pharmacological profiling to identify an optimal ligand, and then functionalizing it as a molecular tool. Evidence from immunofluorescence, western and far-western blotting indicates PLD-mGluR is homomeric GluK2, since GluK2 is the only glutamate receptor protein/receptor subunit present in spindle mechanosensory terminals. Its expression was also found in the lanceolate palisade ending of hair follicle, also known to contain the PLD-mGluR. Finally, in a mouse model with ionotropic function ablated in the GluK2 subunit, spindle glutamatergic responses were still present, confirming it acts purely metabotropically. We conclude the PLD-mGluR is a homomeric GluK2 kainate receptor signalling purely metabotropically and it is common to other, perhaps all, primary mechanosensory endings.

Intravenous recombinant cerebellin 1 treatment restores signalling by spinal glutamate delta 1 receptors and mitigates chronic pain.

BACKGROUND AND PURPOSE: Chronic pain remains a major clinical problem that needs effective therapeutic agents. Glutamate delta 1 (GluD1) receptors and the protein cerebellin 1 (Cbln1) are down-regulated in the central amygdala (CeA) in models of inflammatory and neuropathic pain. One treatment with Cbln1, intracerebroventricularly (ICV) or in CeA, normalized GluD1 and reduced AMPA receptor expression, resulting in lasting (7-10 days) pain relief. Unlike many CNS-targeting biological agents, the structure of Cbln1 suggests potential blood-brain barrier penetration. Here, we have tested whether systemic administration of Cbln1 provides analgesic effects via action in the CNS. EXPERIMENTAL APPROACH: Analgesic effects of intravenous recombinant Cbln1 was assessed in complete Freund's adjuvant inflammatory pain model in mice. GluD1 knockout and a mutant form of Cbln1 were used. KEY RESULTS: A single intravenous injection of Cbln1 mitigated nocifensive and averse behaviour in both inflammatory and neuropathic pain models. This effect of Cbln1 was dependent on GluD1 receptors and required binding to the amino terminal domain of GluD1. Time course of analgesic effect was similar to previously reported ICV and intra-CeA injection. GluD1 in both spinal cord and CeA was down -regulated in the inflammatory pain model, whereas GluD1 expression in spinal cord but not in CeA, was partly normalized by intravenous Cbln1. Importantly, recombinant Cbln1 was detected in the synaptoneurosomes in spinal cord but not in the CeA. CONCLUSIONS AND IMPLICATIONS: Our results describe a novel mechanism by which systemic Cbln1 induces analgesia potentially by central actions involving normalization of signalling by spinal cord GluD1 receptors.

Comparative transcriptome analysis reveals growth and molecular pathway of body color regulation in turbot (Scophthalmus maximus) exposed to different light spectrum.

Fish body color changes play vital roles in adapting to ecological light environment and influencing market value. However, the initial mechanisms governing the changes remain unknown. Here, we scrutinized the impact of light spectrum on turbot (Scophthalmus maximus) body coloration, exposing them to red, blue, and full light spectra from embryo to 90 days post hatch. Transcriptome and quantitative real-time PCR (qRT-PCR) analyses were employed to elucidate underlying biological processes. The results showed that red light induced dimorphism in turbot juvenile skin pigmentation: some exhibited black coloration (Red_Black_Surface, R_B_S), while others displayed lighter skin (Red_White_Bottom, R_W_B), with red light leading to reduced skin lightness (L*) and body weight, particularly in R_B_S group. Transcriptomic and qRT-PCR analyses showcased upregulated gene expressions related to melanin synthesis in R_B_S individuals, notably tyrosinase (tyr), tyrosinase-related protein 1 (tyrp1), and dopachrome tautomerase (dct), alongside solute carrier family 24 member 5 (slc24a5) and oculocutaneous albinism type II (oca2) as pivotal regulators. Nervous system emerged as a critical mediator in spectral environment-driven color regulation. N-methyl d-aspartate (NMDA) glutamate receptor, and calcium signaling pathway emerged as pivotal links intertwining spectral conditions, neural signal transduction, and color regulation. The individual differences in NMDA glutamate receptor expression and subsequent neural excitability seemed responsible for dichromatic body coloration in red light-expose juveniles. This study provides new insights into the comprehending of fish adaptation to environment and methods for fish body color regulation and could potentially help enhance the economic benefit of fish farming industry.

An unexpected role for a glutamate receptor.

γ-Aminobutyric acid acts on a glutamate receptor, evoking synaptic plasticity.