Quisqualate Research Articles

Improved synthesis of two quisqualic acid analogs containing hydantoin and imidazolidinone moieties

Improved synthesis of two quisqualic acid analogs containing hydantoin and imidazolidinone moieties

Investigating post-traumatic syringomyelia and local fluid osmoregulation via a rat model

BackgroundSyringomyelia (SM) is characterized by the development of fluid-filled cavities, referred to as syrinxes, within the spinal cord tissue. The molecular etiology of SM post-spinal cord injury (SCI) is not well understood and only invasive surgical based treatments are available to treat SM clinically. This study builds upon our previous omics studies and in vitro cellular investigations to further understand local fluid osmoregulation in post-traumatic SM (PTSM) to highlight important pathways for future molecular interventions.MethodsA rat PTSM model consisting of a laminectomy at the C7 to T1 level followed by a parenchymal injection of 2 μL quisqualic acid (QA) and an injection of 5 μL kaolin in the subarachnoid space was utilized 6 weeks after initial surgery, parenchymal fluid and cerebrospinal fluid (CSF) were collected, and the osmolality of fluids were analyzed. Immunohistochemistry (IHC), metabolomics analysis using LC–MS, and mass spectrometry-based imaging (MSI) were performed on injured and laminectomy-only control spinal cords.ResultsWe demonstrated that the osmolality of the local parenchymal fluid encompassing syrinxes was higher compared to control spinal cords after laminectomy, indicating a local osmotic imbalance due to SM injury. Moreover, we also found that parenchymal fluid is more hypertonic than CSF, indicating establishment of a local osmotic gradient in the PTSM injured spinal cord (syrinx site) forcing fluid into the spinal cord parenchyma to form and/or expand syrinxes. IHC results demonstrated upregulation of betaine, ions, water channels/transporters, and enzymes (BGT1, AQP1, AQP4, CHDH) at the syrinx site as compared to caudal and rostral sites to the injury, implying extensive local osmoregulation activities at the syrinx site. Further, metabolomics analysis corroborated alterations in osmolality at the syrinx site by upregulation of small molecule osmolytes including betaine, carnitine, glycerophosphocholine, arginine, creatine, guanidinoacetate, and spermidine.ConclusionsIn summary, PTSM results in local osmotic disturbance that propagates at 6 weeks following initial injury. This coincides with and may contribute to syrinx formation/expansion.

Biogenic one-step synthesis of silver nanoparticles using Quisqualis indica linn flower extract: Characterization, molecular docking, and DFT studies

The present study reports a one-step, eco-friendly, and green synthesis route of silver nanoparticles (AgNPs) from the flower extract of Quisqualis indica Linn. Analytical techniques like Ultraviole-visible (UV–Vis), Field emission scanning electron microscope (FESEM), and X-ray diffraction (XRD) were used to investigate different physicochemical characteristics of AgNPs. The UV–Vis spectrum revealed the maximum absorption at 455 nm and FESEM images confirmed that the synthesis produces stable, polydisperse with a spherical, rod-shaped, triangular, and hexagon shape. XRD analysis at 2θ degrees of 38.1o, 44.3o, 64.7o, and 77.7o corresponding to the (111), (200), (220), and (311) planes, respectively, Bragg’s reflections of the face-centered cubic crystalline structure. Fourier transform infrared spectroscopy (FTIR) analysis suggested that the carbonyl and alcoholic groups of the different compounds of the extract of Quisqualis indica Linn flowers were majorly responsible for being the stabilizer and a capping agent of AgNPs. Furthermore, the quantum chemical parameters of β-Sitosterol (1), Brinzolamide (2), Gallic Acid (3), L-Asparagine (4), L-Proline (5), Quisqualic Acid (6), Quinoline-4-Carbonitrile (7), Quercetin (8), and Rutin (9) compounds present in the flowers of Quisqualis indica Linn are also calculated based on density functional theory (DFT). In silico study, a method such as molecular docking was carried out to determine the binding affinity of compounds (1–9) with presentations of Gram-positive bacteria (PDB ID: 2MLM) and Gram-negative bacteria (PDB ID-1KZN). Compounds (1), (2), (7) and (8) had a better score of binding toward the selected proteins. Overall, our findings shed light on the green synthesis of silver nanoparticles and it could be a potential candidate for the pharmaceutical industry against topical pathogens.

149 Effects of quisqualic acid and L-α-amino butyrate supplementation during in vitro oocyte maturation on embryonic development in pigs.

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

PSV-11 Efficacy of Quisqualic Acid as an Amino Acid Transporter Inhibitor in Pig Oocytes

Abstract Quisqualic acid is a known inhibitor of sodium-dependent amino acid transporters. However, it is unknown if quisqualic acid has similar effects in in vitro mature oocytes. Therefore, the objective of this study was to determine the optimal dose and effects of quisqualic acid supplemented during maturation. Oocytes (n=362) were supplemented during maturation with quisqualic acid (0, 0.5, 0.75, 1.0, 2.5 mM) to determine the minimum concentration of quisqualic acid that had no effect on oocyte maturation but significantly decreased the intracellular glutathione concentration. The addition of 1.0 mM quisqualic acid was the lowest concentration observed to cause intracellular glutathione levels to be significantly less (P < 0.05) without affecting maturation compared to no quisqualic acid. Based on those results, oocytes were supplemented with or without 1.0 mM quisqualic acid then evaluated for cumulus cell expansion (n=410) and stage of meiosis (n=380) at the end of maturation. Additional oocytes were fertilized and assessed for cortical granule exocytosis (n=400) and kinetics at 12 h after IVF (n=420). Supplementing quisqualic acid to the media did not have an effect on stage of meiosis, fertilization, polyspermic penetration, or cortical granule exocytosis. Supplementing 1.0 mM quisqualic acid significantly decreased (P < 0.05) cumulus cell expansion by the end of maturation and male pronuclear formation by 12 h after IVF. These results suggest that quisqualic acid supplementation during maturation in pigs inhibits sodium-dependent amino acid transporters.

PSV-10 Effects of l-α-amino Butyrate Supplementation on Oocyte Maturation

Abstract L-α-amino butyrate is a low-molecular weight thiol compound that acts to increase the levels of glutathione in the oocyte. Glutathione acts as an antioxidant during oocyte maturation and promotes male pronuclear formation during fertilization. Supplementing the L-α-amino butyrate helps to decrease polyspermic penetration rates and improve early embryonic development in swine. However, it is unknown if L-α-amino butyrate supplementation affects the environment of the oocyte or the oocyte directly. Therefore, the objective of this study was to determine if L-α-amino butyrate supplementation to the maturation media acted on the oocyte or had alternative beneficial effects in the surrounding environment. Oocytes were randomly assigned to a maturation media containing an amino acid transport inhibitor, quisqualic acid (QA) (0 or 1 mM) and then supplemented with L-α-amino butyrate (0 or 3.3 mM). Oocytes were evaluated for stage of meiosis (n=380) and cumulus cell expansion (n=411) at the end of maturation. The remaining oocytes were fertilized and evaluated for cortical granule exocytosis (n=400) and IVF kinetics (n=456). Supplementation of L-α-amino butyrate with or without QA significantly increased (P < 0.05) cumulus cell expansion, cortical granule exocytosis and male pronuclear formation compared to no supplementation or QA supplementation. There was no difference in meiotic progression, fertilization or polyspermic penetration rates between the treatment groups. Results suggest that when L-α-amino butyrate is supplemented during maturation, it improves the maturation of the oocyte by acting directly on the oocyte and not through the surrounding environment of the oocyte.

DFT Calculations and In silico Study of Chlorogenic, Ellagic and Quisqualic acids as Potential Inhibitors of SARS-CoV-2 Main Protease Mpro

In the present work, at first, density functional theory calculations were performed to investigate the molecular structure of the Chlorogenic, Ellagic, and Quisqualic acids by CAM-B3LYP/MidiX level of theory. A detail of quantum molecular descriptors of the title compounds such as ionization potential (IP) and Electron Affinities (EA), Hardness (η), Softness (S), Electronegativity (μ), Electrophilic Index (ω), Electron Donating Power (ω-), Electron Accepting Power (ω+) and Energy Gap (Eg) have been calculated. Pharmacokinetic properties of the title compounds and their bioactivity were investigated. In the following, a molecular docking study was carried out to screen for an effective available compound that may work as a strong inhibitor for the SARS-CoV-2 main protease Mpro. The binding energy between SARS-CoV-2 main protease Mpro and title organic acids showed a good binding affinity. Therefore, the Chlorogenic, Ellagic, and Quisqualic acids can be used for potential application against the SARS-CoV-2 main protease Mpro.

Validation of Analytical Method of Quisqualic Acid for Standardization of Quisqualis indica Extract Powder (HU033)

Validation of Analytical Method of Quisqualic Acid for Standardization of <i>Quisqualis indica</i> Extract Powder (HU033)

DMSO Delays Alzheimer Disease Causing Aβ-induced Paralysis in C. elegans Through Modulation of Glutamate/Acetylcholine Neurotransmission.

Background:Alzheimer’s disease (AD), a prevalent neurodegenerative disease with progressive dementia and neurotransmission (NT)-dysfunction-related complications in older adults, is known to be caused by abnormal Amyloid-β (Aβ) peptide and associated amyloid plaques in the brain. Drugs to cure AD are not in sight. Two major excitatory neurotransmitters, glutamate (Glu) and acetylcholine (ACh), and their signaling systems are implicated in AD.Objective:To determine the effect of various NT-altering compounds including fenobam, quisqualic acid, and dimethyl sulfoxide (DMSO) in the protection against Aβ toxicity. Further, to identify the potential mechanism through which the protection happens.Methods:The well-known C. elegans AD model, CL4176, in which human Aβ expression is turned on upon a temperature shift to 25 °C that leads to paralysis, was screened for protection/delay in paralysis because of Αβ toxicity. While screening the compounds, dimethyl sulfoxide (DMSO), a universal solvent used to solubilize compounds, was identified to provide protection. Aldicarb and levamisole assays were performed to identify the contribution of ACh neurotransmission in Αβ toxicity protection by DMSO.Results:One percent and two percent DMSO delayed paralysis by 48% and 90%, respectively. DMSO was dominant over one of the Glu-NT pathway-related compounds, Fenobam-Group I mGluR antagonist. But DMSO provided only 30% to 50% protection against Quisqualic acid, the Glu-agonist. DMSO (2%) delayed ACh-NT, both presynaptic acetylcholine esterase inhibitor (AchEi)-aldicarb and postsynaptic-iAChR-agonst-levamisole induced paralysis, by ∼70% in CL4176. DMSO seems to be altering Ca2+ ion permeability essential for NT as EthyleneDiamine Tetra-Acetic acid (EDTA) and DMSO provided similar aldicarb resistance either combined or alone in wildtype worms. But postsynaptic Ca2+ depletion by EDTA could reverse DMSO-induced levamisole hypersensitivity. Surprisingly, the absence of FOrkhead boXO (FOXO) transcription factor homolog, daf-16 (loss-of-function mutant), a critical transcription factor in the reduced IIS-mediated longevity in C. elegans, abolished DMSO-mediated AldR.Conclusion:DMSO and Fenobam protect against Aβ toxicity through modulation of NT.

Determination of Quisqualic Acid in quisqualis fructus by Pre-column Derivatization and High Performance Liquid Chromatography

A convenient, cheap and accurate method for the determination of quisqualic acid in traditional Chinese medicine Quisqualis fructus by pre-column derivatization with 2-nitrobenzenesulfonyl chloride and HPLC was established. Quisqualis fructus samples were homogenised in water after being crushed and degreased with petroleum ether. Target compounds were separated and detected on a C18 column using gradient elution. The recovery rates were in the range of 90–103%. Good linearity within the range of 0.2–20 mg/mL for quisqualic acid with correlation coefficients of ≥0.98 was observed. The relative standard deviations (RSDs) of the within-day and between-day retention time precisions were 0.15–0.17% and 0.8–0.9%, respectively. The RSDs of the within-day and between-day integrated area precisions were 2.3–6.4% and 4.8–9.8%, respectively. The concentrations of quisqualic acid (1.5 mg/g) from Quisqualis fructus were conveniently measured without any expensive photodiode array detector but with a common UV–visible detector.

Retinal control of lens-induced astigmatism in chicks

PurposeAstigmatism is a refractive error due to meridional differences in refractive powers of lens or cornea. The resulting failure to focus image points in a single plane causes blurred vision at all distances. In this study, using an animal model of lens-induced astigmatism, we tested the hypothesis that induced astigmatism is due to processing of astigmatic retinal image information by the brain, which causes distorted growth in the anterior segment via centrifugal neural projections. MethodsTo induce astigmatism, +4.00DS/-8.00DC crossed-cylinder-lens goggles were affixed over the right eyes of 7-day-old chicks (P7), with the -8.00DC axis oriented vertically (at 90°) or horizontally (180°) (n = 12 each); the left eyes were without goggles (non-goggled). For all experiments, refractive errors of both eyes were measured by streak retinoscopy, before and after 1 week of lens wear. To test whether neuronal pathways between retina and brain are required, axonal conduction within the eye was blocked by intravitreal injections of tetrodotoxin (TTX; 7 μL of 10-4M) in phosphate-buffered saline (PBS), or of PBS alone (7 μL); fellow open eyes received PBS alone. Pupillary light reflex (PLR) and optokinetic response (OKR) were measured, to assess the efficacy and duration of TTX action. To test whether retinal circuitry is required, groups of chicks (n = 12 each) were treated at P7 by intravitreal injection of 20 μL of mixed excitotoxins (2 μmol N-methyl-D-aspartate, 0.2 μmol quisqualic acid, 0.2 μmol kainic acid; in water) into goggled or non-goggled eyes, to compromise retinal circuitry needed for emmetropization. ResultsCrossed-cylinder goggles reliably induced refractive astigmatism. Maximum astigmatic error was induced when the cylindrical axis was oriented at 90° (vertically). TTX effectively blocked nerve conduction within the eye for 48 h after injection. Goggled eyes developed astigmatism after treatment with TTX or PBS, but not after excitotoxins. ConclusionOur hypothesis was rejected. In this model, the compensatory astigmatism induced by crossed-cylinder lenses is intrinsic to the eye, and mediated by visual processing in the retina.

Involvement of glutamatergic mechanisms in the median preoptic nucleus in the dipsogenic response induced by angiotensinergic activation of the subfornical organ in rats.

Experiments were done to investigate the role of glutamatergic systems in the median preoptic nucleus (MnPO) in the water ingestion induced by administration of angiotensin II (ANG II) in the subfornical organ (SFO) in the awake rat. Microdialysis methods were utilized to quantify the extracellular content of glutamate (Glu) in the region of MnPO. Microinjection of ANG II (10-10M) into the SFO significantly increased the release of Glu in the MnPO in the rats under the condition that water is available for drinking and the rats under the condition that water is not available for drinking. The amount of initial maximal increases in the Glu levels elicited by the ANG II injection was quite similar in drinking and non-drinking rats, whereas the duration of the response was much longer in non-drinking than in drinking rats. The amount of water ingestion in 20min immediately after the ANG II injection was significantly enhanced by previous injections of N-methyl-D-aspartate (NMDA, 10μM) into the MnPO, while the ANG II-induced water ingestion was attenuated by pretreatment with the NMDA antagonist dizocilpine (MK-801, 10μM). The amount of water intake elicited by the ANG II injection into the SFO was enhanced by previous injections of either the non-NMDA agonist kainic acid (KA, 50μM) or quisqualic acid (QA, 50μM) into the MnPO. On the contrary, the ANG II-induced drinking response was diminished by pretreatment with the non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10μM) in the MnPO. Each injection of NMDA, KA, and QA into the MnPO produced drinking behavior. These results imply that the glutamatergic neural pathways to the MnPO may transmit the information for eliciting drinking in response to ANG II acting at the SFO. Our data further provide evidence that the ANG II-induced dipsogenic response may be mediated through both NMDA and non-NMDA glutamatergic receptor mechanisms in the MnPO.

The Novel Direct Modulatory Effects of Perampanel, an Antagonist of AMPA Receptors, on Voltage-Gated Sodium and M-type Potassium Currents.

Perampanel (PER) is a selective blocker of AMPA receptors showing efficacy in treating various epileptic disorders including brain tumor-related epilepsy and also potential in treating motor neuron disease. However, besides its inhibition of AMPA-induced currents, whether PER has any other direct ionic effects in different types of neurons remains largely unknown. We investigated the effects of PER and related compounds on ionic currents in different types of cells, including hippocampal mHippoE-14 neurons, motor neuron-like NSC-34 cells and U87 glioma cells. We found that PER differentially and effectively suppressed the amplitude of voltage-gated Na+ currents (INa) in mHippoE-14 cells. The IC50 values required to inhibit peak and late INa were 4.12 and 0.78 μM, respectively. PER attenuated tefluthrin-induced increases in both amplitude and deactivating time constant of INa. Importantly, PER also inhibited the amplitude of M-type K+ currents (IK(M)) with an IC50 value of 0.92 μM. The suppression of IK(M) was attenuated by the addition of flupirtine or ZnCl2 but not by L-quisqualic acid or sorafenib. Meanwhile, in cell-attached configuration, PER (3 μM) decreased the activity of M-type K+ channels with no change in single-channel conductance but shifting the activation curve along the voltage axis in a rightward direction. Supportively, PER suppressed IK(M) in NSC-34 cells and INa in U87 glioma cells. The inhibitory effects of PER on both INa and IK(M), independent of its antagonistic effect on AMPA receptors, may be responsible for its wide-spectrum of effects observed in neurological clinical practice.

Increased [³H]quisqualic acid binding density in the dorsal striatum and anterior insula of alcoholics: A post-mortem whole-hemisphere autoradiography study

The function of group I metabotropic glutamate receptors mGluR1 and mGluR5 is involved in the hyperglutamatergic state caused by chronic alcohol. Preclinical studies suggest that group I mGluR modulation could serve as a novel treatment of alcoholism. Considering the wide role of glutamatergic neurochemistry in addiction, group I mGluR binding was studied in brain areas involved in decision-making, learning and memory.Post-mortem whole hemisphere autoradiography was used to study the binding density of [³H]quisqualic acid, a potent group I mGluR agonist, in 9 Cloninger type 1 alcoholics, 8 Cloninger type 2 alcoholics and 10 controls. Binding was studied in the dorsal striatum, hippocampus and cortex.Alcoholics displayed a trend towards increased [³H]quisqualic acid binding in all brain areas. The most robust findings were in the putamen (p = 0.006) and anterior insula (p = 0.005), where both alcoholic subtypes displayed increased binding compared to the controls.These findings suggest altered group I mGluR function in alcoholic subjects in the dorsal striatum, which is involved in habitual learning, and in the anterior insula, which has a pivotal role in the perception of bodily sensations. Increased [³H]quisqualic acid binding might suggest a beneficial impact of mGluR1/5 modulators in the treatment of alcoholism.

Geranium intoxication induces detoxification enzymes in the Japanese beetle, Popillia japonica Newman

Popillia japonica is a generalist herbivore that feeds on >300 host plant species in at least 72 plant families. It is unknown why P. japonica, despite possessing active detoxification enzymes in its gut, is paralyzed when feeding on the petals of one of its preferred host plant, Pelargonium×hortorum, or on artificial diet containing quisqualic acid (QA), the active compound in zonal geranium. We hypothesized that Pelargonium×hortorum or QA do not induce activity of the cytochrome P450, glutathione S transferase (GST), and carboxylesterase (CoE) detoxification enzymes in P. japonica. In this study, P. japonica were fed petals of zonal geranium or agar plugs containing QA, or rose petals, another preferred but non-toxic host. Midgut enzyme activities of P450, GST, and CoE were then assayed after 6, 12, or 24h of feeding. In most cases, P450, GST, and CoE activities were significantly induced in P. japonica midguts by geranium petals and QA, though the induction was slower than with rose petals. Induced enzyme activity reached a peak at 24h after consumption, which coincides with the period of highest recovery from geranium and QA paralysis. This study shows that toxic geranium and QA induce detoxification enzyme activity, but the induced enzymes do not effectively protect P. japonica from paralysis by QA. Further investigation is required through in vitro studies to know if the enzymes induced by geranium are capable of metabolizing QA. This study highlights a rare physiological mismatch between the detoxification tool kit of a generalist and its preferred host.

Harmful Effects of Neonatal Epileptic Seizures on Cerebrovascular Functions: Does Sex Matter?

There is a growing interest in the potential contribution of sex‐related variables to cerebrovascular functions in healthy and sick neonates. Epileptic seizures, the most common adverse neurological event in human newborns, may lead to cerebrovascular injury and abnormalities in cerebral blood flow regulation. Clinical studies suggest that male neonates are more susceptible to seizures, with a higher incidence of neurological complications. Cerebral vascular health is an important contributing factor to brain homeostasis and neuronal health. Newborn piglets provide a valuable and translationally relevant animal model for studying the cerebrovascular effects of epileptic seizures in the neonatal brain. This study in newborn pigs (2–5 days old) was designed to investigate whether sex‐related differences contribute to systemic parameters and cerebrovascular functions in: 1) control healthy animals and 2) piglets subjected to bicuculline‐induced epileptic seizures leading to prolonged cerebral vascular dysfunction during the delayed postictal period. After a 48‐h recovery period from epileptic seizures, postictal cerebrovascular functions were tested using intravital microscopy via the closed cranial window technique. We recorded the responses of small‐ and medium‐sized pial cerebral arterioles (50–100 μm) to a battery of vasodilator stimuli including: A) endothelium‐dependent hypercapnia and bradykinin; B) dual endothelium/astrocyte‐dependent stimuli glutamate, ionotropic glutamate receptor agonist quisqualic acid, and hemin; C) astrocyte‐dependent vasodilator adenosine diphosphate, and D) endothelium/astrocyte‐independent vasodilator sodium nitroprusside (SNP). We found no sex‐related differences in cardiovascular parameters (mean arterial blood pressure, heart rate), arterial blood gases, or core body temperature in either control or postictal groups of newborn piglets. A significant reduction (50–70%) in responses of pial arterioles to endothelium‐ and/or astrocyte‐dependent vasodilators was observed 48 h after seizures (delayed postictal period) in both male and female piglets. In piglets of both sexes, vasodilation to SNP was preserved during the delayed postictal period, suggesting that vascular smooth muscle contractility was not affected by seizures. An antioxidant and cytoprotective compound, the carbon‐monoxide (CO)‐releasing molecule CORM‐A1 (3 mg/kg i.p.) that was administered shortly before and/or during seizures, prevented postictal loss of cerebrovascular functions in both male and female piglets. Overall, we observed no sex‐specific differences in selected systemic cardiovascular parameters and cerebrovascular dilator functions in control and epileptic newborn pigs. In both male and female piglets, epileptic seizures lead to severe cerebral vascular dysfunction during the delayed postictal period. Antioxidant therapy with CORM‐A1 is neuroprotective in both male and female newborn pigs because it effectively prevents deleterious effects of epileptic seizures on cerebral blood flow regulation in a sex‐independent manner.Support or Funding InformationThe study was supported by NIH/NHLBI/NINDS.

Glutamatergic modulation of noradrenaline release in the rat median preoptic area

The present study was carried out to investigate whether glutamatergic receptor mechanisms modulate the release of noradrenaline (NA) in the region of the median preoptic nucleus (MnPO) using intracerebral microdialysis techniques in freely moving rats. Perfusion of N-methyl-d-asparatate (NMDA, 10 and 50μM) through the microdialysis probe significantly enhanced dialysate NA concentration in the region of the MnPO. Local perfusion of the NMDA antagonist dizocilpine (MK801, 10 and 50μM) did not change the basal release of NA in the MnPO area. MK801 (10μM) administered together with NMDA antagonized the stimulant effect of NMDA (50μM). Perfusion of the non-NMDA agonist quisqualic acid (QA, 10 and 50μM) or kainic acid (KA, 10 and 50μM) significantly increased the NA release in the MnPO area. Perfusion of the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 and 50μM) had no effect on the NA release. CNQX (10μM) administered together with either QA (50μM) or KA (50μM) in the MnPO area prevented the stimulant effect of the agonists on the NA release. Nonhypotensive hypovolemia following subcutaneous injections of polyethylene glycol (PEG, 30%, 5ml) significantly elevated the NA level in the MnPO area. The PEG-induced elevation in the NA release was attenuated by perfusion of either MK801 (10μM) or CNQX (10μM). The present results suggest that glutamatergic synaptic inputs may act to enhance the release of NA in the MnPO area through both NMDA and non-NMDA receptors, and imply that these glutamatergic receptor mechanisms may be involved in the noradrenergic reguratory system for the body fluid balance.

Spinal Cord Transcriptomic and Metabolomic Analysis after Excitotoxic Injection Injury Model of Syringomyelia.

Syringomyelia is a condition of the spinal cord in which a syrinx, or fluid-filled cavity, forms from trauma, malformation, or general disorder. Previous work has shown that in noncanalicular syringomyelia irregular flow and pressure conditions enhance the volumetric growth of syrinxes. A better understanding of the underlying molecular pathways associated with syrinx formation will unveil targets for treatments and possibly prevention of syringomyelia in the future. In this study, we performed an established surgical induction of a syrinx using quisqualic acid and kaolin injections in rats to characterize the injury at the molecular level by RNA sequencing and metabolomics techniques at three and six weeks post-injury. Syrinxes averaging nearly 10 mm in length formed in the rats' spinal cords; however, smaller syrinxes were also detected in saline injected surgical shams, complicating interpretation of results. Our current results indicate a robust immune response coupled with overall decreases in neuronal signal transmission of syrinx containing animals compared with controls. Although transcriptional changes indicated gliosis and loss of neurons, no neuropathic pain was detected by von Frey allodynia testing. Unique transporters were revealed to be highly dysregulated, including significant increases in betaine/glycine transporter (BGT-1), K+/Cl- co-transporter (KCC4), and aquaporin 1 (AQP1), along with the upregulation of small molecule osmolytes taurine and betaine. The identified metabolites are of particular interest because of their involvement in osmotic homeostasis and need to be investigated further for their specific involvement in trauma-induced syrinxes.

P.1.g.086 - Pharmacological investigation of alpha7 nAChR and mGluR2 in human pluripotent stem cell derived dentate gyrus neurons: implications for schizophrenia

We have studied the effects of groups I, II, and III metabotropic glutamate receptor (mGluR) agonists and antagonists on pyloric activity in the stomatogastric ganglion (STG) of the Caribbean spiny lobster Panulirus argus. We have found that agonists for all three groups of mGluRs modify the pyloric output. The group I agonist, l-quisqualic acid (l-QA), activated the pyloric central pattern generator (CPG). When the pyloric rhythm was partially suppressed by sucrose-block of input fibers in the stomatogastric nerve (stn), l-QA accelerated the rhythmic activity. In addition, the number of spike discharges was increased in pyloric motoneurons: pyloric (PY), and lateral pyloric (LP). In completely blocked preparations, a slow pyloric rhythm was initiated by l-QA. Groups II and III agonists exerted an inhibitory effect on pyloric activity. The group II agonist, (2S,1′S,2′S)-2-(Carboxycyclopropyl)glycine (L-CCG-I), decreased both the frequency of the pyloric rhythm and the number of spike discharges in the motoneurons: ventricular dilator (VD), PY, and LP. The effects of L-CCG-I were dose-dependent. The group III agonist, l-(+)-2-Amino-4-phosphonobutyric acid (l-AP4), slightly decreased the frequency of the pyloric rhythm and suppressed spike discharges in the VD neuron. All effects of mGluR agonists were reversible. The effect of l-QA was blocked by the broad spectrum mGluR antagonist (S)-Methyl-4-carboxyphenylglycine (MCPG). The inhibitory effect of L-CCG-I was prevented by MCPG and by the group II/III mGluR antagonist (RS)-α-Methyl-4-phosphonophenylglycine (MPPG), and was partially blocked by the group II mGluR antagonist (RS)-1-amino-5-phosphonoindan-1-carboxylic acid (APICA). The inhibitory effect of l-AP4 was blocked by MPPG and partially blocked by APICA.

Spinal Cord Injury Induced Hyperalgesia is Associated with Increased Levels of Let-7 Family of MicroRNAs

Title: Spinal cord injury induced hyperalgesia is associated with increased levels of Let-7 family of MicroRNAs. Background: Spinal cord injury (SCI) results in chronic pain syndromes that are often refractory to treatment with opioids, and may represent mu opioid receptor (MOR) dysfunction. MicroRNAs play a role in gene regulation by binding to target mRNA, causing translational repression or mRNA degradation. Let-7 family microRNAs have been shown to target MOR suggesting they may influence the development of pain states and opioid responsiveness. This study sought to determine temporal changes in Let-7 family miRNA and correlate them to the onset of pain behaviors in a rodent model of post-SCI pain. Methods and findings: Thermal thresholds (evoked pain) were assessed in rats before and after intramedullary injection of quisqualic acid (n=18) or sham laminectomy (n=18). Three of the Let-7 family miRNA levels were determined (Let-7a, Lets-7c and Let 7g) using RT-PCR and qRT-PCR on spinal cord segments caudal to lesion at 7, 14 and 21 days after injury. Thermal thresholds were significantly reduced compared to baseline in injured animals at day 21 (mean decrease of 1.9 sec; p=0.02; 95% CI=0.41-3.3). Sham animals showed no significant change in thermal thresholds over time (p=0.77; 95% CI=3.2-4.2). SCI led to a trend in increasing Let-7 family miRNA levels over time. Compared to sham animals, miRNA levels studied increased in injured animals at 14 and 21 days, corresponding to the period during which post-injury pain developed. Conclusions: Our data suggests that increased levels of Let-7 family miRNAs are involved in behavioral responses to SCI. Future work will examine if inhibition of Let-7 family miRNAs alters the behavioral and cellular response to SCI.