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Sample records for gabab receptors play

  1. GABAB Receptors, Schizophrenia and Sleep Dysfunction

    PubMed Central

    Kantrowitz, Joshua; Citrome, Leslie; Javitt, Daniel

    2016-01-01

    Evidence for an intrinsic relationship between sleep, cognition and the symptomatic manifestations of schizophrenia is accumulating. This review presents evidence for the possible utility of GABAB receptor agonists for the treatment of subjective and objective sleep abnormalities related to schizophrenia. At the phenotypic level, sleep disturbance occurs in 16–30% of patients with schizophrenia and is related to reduced quality of life and poor coping skills. On the neurophysiological level, studies suggest that sleep deficits reflect a core component of schizophrenia. Specifically, slow-wave sleep deficits, which are inversely correlated with cognition scores, are seen. Moreover, sleep plays an increasingly well documented role in memory consolidation in schizophrenia. Correlations of slow-wave sleep deficits with impaired reaction time and declarative memory have also been reported. Thus, both behavioural insomnia and sleep architecture are critical therapeutic targets in patients with schizophrenia. However, long-term treatment with antipsychotics often results in residual sleep dysfunction and does not improve slow-wave sleep, and adjunctive GABAA receptor modulators, such as benzodiazepines and zolpidem, can impair sleep architecture and cognition in schizophrenia. GABAB receptor agonists have therapeutic potential in schizophrenia. These agents have minimal effect on rapid eye movement sleep while increasing slow-wave sleep. Preclinical associations with increased expression of genes related to slow-wave sleep production and circadian rhythm function have also been reported. GABAB receptor deficits result in a sustained hyperdopaminergic state and can be reversed by a GABAB receptor agonist. Genetic, postmortem and electrophysiological studies also associate GABAB receptors with schizophrenia. While studies thus far have not shown significant effects, prior focus on the use of GABAB receptor agonists has been on the positive symptoms of schizophrenia, with

  2. GABA(B) receptors and synaptic modulation.

    PubMed

    Kornau, Hans-Christian

    2006-11-01

    GABA(B) receptors modulate transmitter release and postsynaptic membrane potential at various types of central synapses. They function as heterodimers of two related seven-transmembrane domain receptor subunits. Trafficking, activation and signalling of GABA(B) receptors are regulated both by allosteric interactions between the subunits and by the binding of additional proteins. Recent studies have shed light on the roles of GABA(B) receptors in plasticity processes at excitatory synapses. This review summarizes our knowledge of the localization, structure and function of GABA(B) receptors in the central nervous system and their use as drug targets for neurological and psychiatric disorders. PMID:16932937

  3. Chemistry and pharmacology of GABAB receptor ligands.

    PubMed

    Froestl, Wolfgang

    2010-01-01

    This chapter presents new clinical applications of the prototypic GABA(B) receptor agonist baclofen for the treatment of addiction by drugs of abuse, such as alcohol, cocaine, nicotine, morphine, and heroin, a novel baclofen prodrug Arbaclofen placarbil, the GABA(B) receptor agonist AZD3355 (Lesogabaran) currently in Phase 2 clinical trials for the treatment of gastroesophageal reflux disease, and four positive allosteric modulators of GABA(B) receptors (CGP7930, GS39783, NVP-BHF177, and BHFF), which have less propensity for the development of tolerance due to receptor desensitization than classical GABA(B) receptor agonists. All four compounds showed anxiolytic affects. In the presence of positive allosteric modulators the "classical" GABA(B) receptor antagonists CGP35348 and 2-hydroxy-saclofen showed properties of partial GABA(B) receptor agonists. Seven micromolar affinity GABA(B) receptor antagonists, phaclofen; 2-hydroxy-saclofen; CGP's 35348, 36742, 46381, 51176; and SCH50911, are discussed. CGP36742 (SGS742) showed statistically significant improvements of working memory and attention in a Phase 2 clinical trial in mild, but not in moderate Alzheimer patients. Eight nanomolar affinity GABA(B) receptor antagonists are presented (CGP's 52432, 54626, 55845, 56433, 56999, 61334, 62349, and 63360) that were used by pharmacologists for numerous in vitro and in vivo investigations. CGP's 36742, 51176, 55845, and 56433 showed antidepressant effects. Several compounds are also available as radioligands, such as [(3)H]CGP27492, [(3)H]CGP54626, [(3)H]CGP5699, and [(3)H]CGP62349. Three novel fluorescent and three GABA(B) receptor antagonists with very high specific radioactivity (>2,000 Ci/mmol) are presented. [(125)I]CGP64213 and the photoaffinity ligand [(125)I]CGP71872 allowed the identification of GABA(B1a) and GABA(B1b) receptors in the expression cloning work. PMID:20655477

  4. GABA(B) receptors play an essential role in maintaining sleep during the second half of the night in Drosophila melanogaster.

    PubMed

    Gmeiner, Florian; Kołodziejczyk, Agata; Yoshii, Taishi; Rieger, Dirk; Nässel, Dick R; Helfrich-Förster, Charlotte

    2013-10-15

    GABAergic signalling is important for normal sleep in humans and flies. Here we advance the current understanding of GABAergic modulation of daily sleep patterns by focusing on the role of slow metabotropic GABAB receptors in the fruit fly Drosophila melanogaster. We asked whether GABAB-R2 receptors are regulatory elements in sleep regulation in addition to the already identified fast ionotropic Rdl GABAA receptors. By immunocytochemical and reporter-based techniques we show that the pigment dispersing factor (PDF)-positive ventrolateral clock neurons (LNv) express GABAB-R2 receptors. Downregulation of GABAB-R2 receptors in the large PDF neurons (l-LNv) by RNAi reduced sleep maintenance in the second half of the night, whereas sleep latency at the beginning of the night that was previously shown to depend on ionotropic Rdl GABAA receptors remained unaltered. Our results confirm the role of the l-LNv neurons as an important part of the sleep circuit in D. melanogaster and also identify the GABAB-R2 receptors as the thus far missing component in GABA-signalling that is essential for sleep maintenance. Despite the significant effects on sleep, we did not observe any changes in circadian behaviour in flies with downregulated GABAB-R2 receptors, indicating that the regulation of sleep maintenance via l-LNv neurons is independent of their function in the circadian clock circuit. PMID:24068350

  5. Specific roles of GABAB(1) receptor isoforms in cognition

    PubMed Central

    Jacobson, Laura H.; Kelly, Peter H.; Bettler, Bernhard; Kaupmann, Klemens; Cryan, John F.

    2010-01-01

    The GABAB receptor is a heterodimer of GABAB(1) and GABAB(2) subunits. There are two isoforms of the GABAB(1) subunit: GABAB(1a) and GABAB(1b). Recent studies with mutant mice suggest a differential role for the two GABAB(1) isoforms in behavioural processes. As pharmacological and genetic studies have implicated GABAB receptors in cognition we investigated the behaviour of GABAB(1a) −/− and GABAB(1b) −/− mice in different types of cognitive paradigms. GABAB(1a) −/− and GABAB(1b) −/− mice were both impaired relative to wildtype controls in a continuous spontaneous alternation behaviour test of working spatial memory. In contrast to the reported phenotype of GABAB(1) −/− mice, however, neither GABAB(1a) −/− nor GABAB(1b) −/− mice were deficient in a passive avoidance task. On the other hand, GABAB(1a) −/− mice were impaired in familiar and novel object recognition. We conclude that GABAB(1) isoforms contribute differentially to GABAB receptor-mediated cognitive processes. PMID:17498817

  6. Regulating hippocampal hyperexcitability through GABAB Receptors

    PubMed Central

    Lang, Min; Moradi‐Chameh, Homeira; Zahid, Tariq; Gane, Jonathan; Wu, Chiping; Valiante, Taufik; Zhang, Liang

    2014-01-01

    Abstract Disturbances of GABAergic inhibition are a major cause of epileptic seizures. GABA exerts its actions via ionotropic GABAA receptors and metabotropic G protein‐coupled GABAB receptors. Malfunction of GABAA inhibition has long been recognized in seizure genesis but the role of GABAB receptors in controlling seizure activity is still not well understood. Here, we examined the anticonvulsive, or inhibitory effects, of GABAB receptors in a mouse model of hippocampal kindling as well as mouse hippocampal slices through the use of GS 39783, a positive allosteric GABAB receptor modulator, and CGP 55845, a selective GABAB receptor antagonist. When administered via intraperitoneal injections in kindled mice, GS 39783 (5 mg/kg) did not attenuate hippocampal EEG discharges, but did reduce aberrant hippocampal spikes, whereas CGP 55845 (10 mg/kg) prolonged hippocampal discharges and increased spike incidences. When examined in hippocampal slices, neither GS 39783 at 5 μmol/L nor the GABAB receptor agonist baclofen at 0.1 μmol/L alone significantly altered repetitive excitatory field potentials, but GS 39783 and baclofen together reversibly abolished these field potentials. In contrast, CGP 55845 at 1 μmol/L facilitated induction and incidence of these field potentials. In addition, CGP 55845 attenuated the paired pulse depression of CA3 population spikes and increased the frequency of EPSCs in individual CA3 pyramidal neurons. Collectively, these data suggest that GABABB receptors regulate hippocampal hyperexcitability by inhibiting CA3 glutamatergic synapses. We postulate that positive allosteric modulation of GABAB receptors may be effective in reducing seizure‐related hyperexcitability. PMID:24771688

  7. GABAB Receptor-Positive Modulators: Enhancement of GABAB Receptor Agonist Effects In Vivo

    PubMed Central

    France, Charles P.; Cheng, Kejun; Rice, Kenner C.

    2010-01-01

    In vivo effects of GABAB receptor-positive modulators suggest that they have therapeutic potential for treating central nervous system disorders such as anxiety, depression, and drug abuse. Although these effects generally are thought to be mediated by positive modulation of GABAB receptors, such modulation has been examined primarily in vitro. The present study was aimed at further examining the in vivo positive modulatory properties of the GABAB receptor-positive modulators, 2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethylpropyl) phenol (CGP7930) and (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF). Both compounds enhanced loss of righting induced by baclofen in mice. However, CGP7930 was less effective and rac-BHFF was less potent for enhancing loss of righting induced by γ-hydroxybutyrate (GHB), which, like baclofen, has GABAB receptor agonist properties. In contrast with baclofen- and GHB-induced loss of righting, the hypothermic effects of baclofen and GHB were not enhanced by rac-BHFF but were enhanced by CGP7930 only at doses that produced hypothermia when given alone. CGP7930-induced hypothermia was not attenuated by the GABAB receptor antagonist 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348), at doses that blocked baclofen-induced hypothermia, and was not increased by the nitric-oxide synthase inhibitor Nω-nitro-l-arginine methyl ester, at doses that increased the hypothermic effects of baclofen and GHB. The results provide evidence that CGP7930 and rac-BHFF act in vivo as positive modulators at GABAB receptors mediating loss of righting, but not at GABAB receptors mediating hypothermia. Conceivably, CGP7930, but not rac-BHFF, acts as an allosteric agonist at these latter receptors. Taken together, the results provide further evidence of pharmacologically distinct GABAB receptor subtypes, possibly allowing for a more selective therapeutic interference with the GABAB system. PMID:20628000

  8. GABAB(1) receptor subunit isoforms differentially regulate stress resilience.

    PubMed

    O'Leary, Olivia F; Felice, Daniela; Galimberti, Stefano; Savignac, Hélène M; Bravo, Javier A; Crowley, Tadhg; El Yacoubi, Malika; Vaugeois, Jean-Marie; Gassmann, Martin; Bettler, Bernhard; Dinan, Timothy G; Cryan, John F

    2014-10-21

    Stressful life events increase the susceptibility to developing psychiatric disorders such as depression; however, many individuals are resilient to such negative effects of stress. Determining the neurobiology underlying this resilience is instrumental to the development of novel and more effective treatments for stress-related psychiatric disorders. GABAB receptors are emerging therapeutic targets for the treatment of stress-related disorders such as depression. These receptors are predominantly expressed as heterodimers of a GABAB(2) subunit with either a GABAB(1a) or a GABAB(1b) subunit. Here we show that mice lacking the GABAB(1b) receptor isoform are more resilient to both early-life stress and chronic psychosocial stress in adulthood, whereas mice lacking GABAB(1a) receptors are more susceptible to stress-induced anhedonia and social avoidance compared with wild-type mice. In addition, increased hippocampal expression of the GABAB(1b) receptor subunit is associated with a depression-like phenotype in the helpless H/Rouen genetic mouse model of depression. Stress resilience in GABAB(1b)(-/-) mice is coupled with increased proliferation and survival of newly born cells in the adult ventral hippocampus and increased stress-induced c-Fos activation in the hippocampus following early-life stress. Taken together, the data suggest that GABAB(1) receptor subunit isoforms differentially regulate the deleterious effects of stress and, thus, may be important therapeutic targets for the treatment of depression. PMID:25288769

  9. Postnatal alterations in GABAB receptor tone produce sensorimotor gating deficits and protein level differences in adulthood.

    PubMed

    Bolton, Monica M; Heaney, Chelcie F; Murtishaw, Andrew S; Sabbagh, Jonathan J; Magcalas, Christy M; Kinney, Jefferson W

    2015-04-01

    The GABA transmitter system plays a vital role in modulating synaptic formation and activity during development. The GABAB receptor subtype in particular has been implicated in cell migration, promotion of neuronal differentiation, neurite outgrowth, and synapse formation but it's role in development is not well characterized. In order to investigate the effects of brief alterations in GABAB signaling in development, we administered to rats the GABAB agonist baclofen (2.0mg/kg) or antagonist phaclofen (0.3mg/kg) on postnatal days 7, 9, and 12, and evaluated sensorimotor gating in adulthood. We also examined tissue for changes in multiple proteins associated with GABAB receptor function and proteins associated with synapse formation. Our data indicate that early postnatal alterations to GABAB receptor-mediated signaling produced sex differences in sensorimotor gating in adulthood. Additionally, we found differences in GABAB receptor subunits and kalirin protein levels in the brain versus saline treated controls. Our data demonstrate that a subtle alteration in GABAB receptor function in early postnatal life induces changes that persist into adulthood. PMID:25314921

  10. Mouse hippocampal GABAB1 but not GABAB2 subunit-containing receptor complex levels are paralleling retrieval in the multiple-T-maze

    PubMed Central

    Falsafi, Soheil K.; Ghafari, Maryam; Miklósi, András G.; Engidawork, Ephrem; Gröger, Marion; Höger, Harald; Lubec, Gert

    2015-01-01

    GABAB receptors are heterodimeric G-protein coupled receptors known to be involved in learning and memory. Although a role for GABAB receptors in cognitive processes is evident, there is no information on hippocampal GABAB receptor complexes in a multiple T maze (MTM) task, a robust paradigm for evaluation of spatial learning. Trained or untrained (yoked control) C57BL/6J male mice (n = 10/group) were subjected to the MTM task and sacrificed 6 h following their performance. Hippocampi were taken, membrane proteins extracted and run on blue native PAGE followed by immunoblotting with specific antibodies against GABAB1, GABAB1a, and GABAB2. Immunoprecipitation with subsequent mass spectrometric identification of co-precipitates was carried out to show if GABAB1 and GABAB2 as well as other interacting proteins co-precipitate. An antibody shift assay (ASA) and a proximity ligation assay (PLA) were also used to see if the two GABAB subunits are present in the receptor complex. Single bands were observed on Western blots, each representing GABAB1, GABAB1a, or GABAB2 at an apparent molecular weight of approximately 100 kDa. Subsequently, densitometric analysis revealed that levels of GABAB1 and GABAB1a but not GABAB2- containing receptor complexes were significantly higher in trained than untrained groups. Immunoprecipitation followed by mass spectrometric studies confirmed the presence of GABAB1, GABAB2, calcium calmodulin kinases I and II, GluA1 and GluA2 as constituents of the complex. ASA and PLA also showed the presence of the two subunits of GABAB receptor within the complex. It is shown that increased levels of GABAB1 subunit-containing complexes are paralleling performance in a land maze. PMID:26539091

  11. Discriminative Stimulus Effects of the GABAB Receptor-Positive Modulator rac-BHFF: Comparison with GABAB Receptor Agonists and Drugs of Abuse

    PubMed Central

    Cheng, Kejun; Rice, Kenner C.

    2013-01-01

    GABAB receptor-positive modulators are thought to have advantages as potential medications for anxiety, depression, and drug addiction. They may have fewer side effects than GABAB receptor agonists, because selective enhancement of activated receptors could have effects different from nonselective activation of all receptors. To examine this, pigeons were trained to discriminate the GABAB receptor-positive modulator (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF) from its vehicle. The discriminative stimulus effects of rac-BHFF were not mimicked by the GABAB receptor agonists baclofen and γ-hydroxybutyrate (GHB), not by diazepam, and not by alcohol, cocaine, and nicotine, whose self-administration has been reported to be attenuated by GABAB receptor-positive modulators. The discriminative stimulus effects of rac-BHFF were not antagonized by the GABAB receptor antagonist 3-aminopropyl (diethoxymethyl)phosphinic acid (CGP35348) but were attenuated by the less efficacious GABAB receptor-positive modulator 2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethylpropyl)phenol (CGP7930), suggesting the possibility that rac-BHFF produces its discriminative stimulus effects by directly activating GABAB2 subunits of GABAB receptors. At a dose 10-fold lower than the training dose, rac-BHFF enhanced the discriminative stimulus effects of baclofen, but not of GHB. This study provides evidence that the effects of GABAB receptor-positive modulators are not identical to those of GABAB receptor agonists. In addition, the results suggest that positive modulation of GABAB receptors does not produce discriminative stimulus effects similar to those of benzodiazepines, alcohol, cocaine, and nicotine. Finally, the finding that rac-BHFF enhanced effects of baclofen but not of GHB is consistent with converging evidence that the populations of GABAB receptors mediating the effects of baclofen and GHB are not identical. PMID:23275067

  12. CGP7930: a positive allosteric modulator of the GABAB receptor.

    PubMed

    Adams, C L; Lawrence, A J

    2007-01-01

    CGP7930 (3-(3',5'-Di-tert-butyl-4'-hydroxy)phenyl-2,2-dimethylpropanol) is a positive allosteric modulator of the metabotropic GABAB receptor. CGP7930 has been found to modulate the GABAB receptor in the open, or high affinity, state increasing agonist affinity for the receptor and signal transduction efficacy following agonist stimulation. The GABAB heteromeric subunit B2, involved in signal transduction but not ligand binding, seems to be the site of action of CGP7930 and similar allosteric modulators. When administered alone in naïve animals, CGP7930 acts as an anxiolytic in rodents without other overt behavioral effects and has also been demonstrated to reduce self-administration of nicotine, cocaine, or alcohol in rodents, suggesting that "fine tuning" of the GABAB receptor by positive allosteric modulators may be able to regulate abuse of these drugs. Baclofen, the GABAB agonist, is currently finding use in treating addiction and various other disorders, but this can result in off-target effects and tolerance. CGP7930 when co-administered with baclofen enhances its potency, which could in theory minimize deleterious effects. Further study of CGP7930 is required, but this compound, and others like it, holds potential in a clinical setting. PMID:17894647

  13. Behavioral Effects of γ-Hydroxybutyrate, Its Precursor γ-Butyrolactone, and GABAB Receptor Agonists: Time Course and Differential Antagonism by the GABAB Receptor Antagonist 3-Aminopropyl(diethoxymethyl)phosphinic Acid (CGP35348)

    PubMed Central

    Koek, Wouter; Mercer, Susan L.; Coop, Andrew; France, Charles P.

    2009-01-01

    γ-Hydroxybutyrate (GHB) is used therapeutically and recreationally. The mechanism by which GHB produces its therapeutic and recreational effects is not entirely clear, although GABAB receptors seem to play an important role. This role could be complex, because there are indications that different GABAB receptor mechanisms mediate the effects of GHB and the prototypical GABAB receptor agonist baclofen. To further explore possible differences in underlying GABAB receptor mechanisms, the present study examined the effects of GHB and baclofen on operant responding and their antagonism by the GABAB receptor antagonist 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348). Pigeons were trained to peck a key for access to food during response periods that started at different times after the beginning of the session. In these pigeons, GHB, its precursor γ-butyrolactone (GBL), and the GABAB receptor agonists baclofen and 3-aminopropyl(methyl)phosphinic acid hydrochloride (SKF97541) decreased the rate of responding in a dose- and time-dependent manner. CGP35348 shifted the dose-response curve of each agonist to the right, but the magnitude of the shift differed among the agonists. Schild analysis yielded a pA2 value of CGP35348 to antagonize GHB and GBL [i.e., 3.9 (3.7–4.2)] that was different (P = 0.0011) from the pA2 value to antagonize baclofen and SKF97541 [i.e., 4.5 (4.4–4.7)]. This finding is further evidence that the GABAB receptor mechanisms mediating the effects of GHB and prototypical GABAB receptor agonists are not identical. A better understanding of the similarities and differences between these mechanisms, and their involvement in the therapeutic effects of GHB and baclofen, could lead to more effective medications with fewer adverse effects. PMID:19564487

  14. Swimming behavior regulation by GABAB receptors in Paramecium.

    PubMed

    Ramoino, Paola; Fronte, Paola; Beltrame, Francesco; Diaspro, Alberto; Fato, Marco; Raiteri, Luca; Stigliani, Sara; Usai, Cesare

    2003-12-10

    In Paramecium, internal Ca(2+) concentration increase coupled to membrane depolarization induces a reversal in the direction of ciliary beating and, consequently, a reversal in swimming direction. The ciliary reversal (CR) duration is correlated to Ca(2+) influx, and the addition of drugs that block the Ca(2+) current leads to a reduction in the backward swimming duration. In this study we have examined the possible function of GABA(B) receptors in P. primaurelia swimming control. The presence of GABA(B) immunoanalogue in Paramecium was evidenced using SDS-PAGE, Western blotting, and confocal laser scanning microscopy. By applying the specific GABA(B) receptor agonist baclofen, a dose-dependent inhibition of the membrane depolarization-induced CR duration was observed. This inhibition was antagonized by phaclofen, persisted when K(+) channel blockers were applied, and disappeared after treatment with nifedipine and verapamil. Moreover, the action of baclofen on depolarization-induced CR was suppressed by treatment with pertussis toxin. Therefore, these experiments suggest that baclofen modulates CR by a G protein (G(0) or G(1)) mediated inhibition of dihydropyridine-sensible calcium channels. Finally, synthesis and release of GABA in the environment by Paramecium have been demonstrated by HPLC. Possible correlations between GABA(B) receptor activation and the regulation of intracellular Ca(2+) levels are discussed. PMID:14644161

  15. Role of heteromer formation in GABAB receptor function.

    PubMed

    Kuner, R; Köhr, G; Grünewald, S; Eisenhardt, G; Bach, A; Kornau, H C

    1999-01-01

    Recently, GBR1, a seven-transmembrane domain protein with high affinity for gamma-aminobutyric acid (GABA)B receptor antagonists, was identified. Here, a GBR1-related protein, GBR2, was shown to be coexpressed with GBR1 in many brain regions and to interact with it through a short domain in the carboxyl-terminal cytoplasmic tail. Heterologously expressed GBR2 mediated inhibition of adenylyl cyclase; however, inwardly rectifying potassium channels were activated by GABAB receptor agonists only upon coexpression with GBR1 and GBR2. Thus, the interaction of these receptors appears to be crucial for important physiological effects of GABA and provides a mechanism in receptor signaling pathways that involve a heterotrimeric GTP-binding protein. PMID:9872744

  16. Inhibition of spontaneous EPSCs and IPSCs by presynaptic GABAB receptors on rat supraoptic magnocellular neurons.

    PubMed Central

    Kabashima, N; Shibuya, I; Ibrahim, N; Ueta, Y; Yamashita, H

    1997-01-01

    1. The function of presynaptic GABA receptors in the regulation of transmitter release in supraoptic nucleus (SON) magnocellular neurons was investigated by recording spontaneous postsynaptic currents from rat magnocellular SON neurons in a slice preparation (150 microns thick, 1.8 mm in diameter) using the whole-cell patch-clamp technique. 2. Both the spontaneous EPSCs and IPSCs were TTX resistant. The EPSCs were abolished by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), whereas the IPSCs were abolished by picrotoxin, suggesting that the EPSCs and IPSCs are synaptic inputs from glutamatergic and GABAergic neurons, respectively. 3. The selective GABAB agonist, baclofen, reduced the frequency of both the EPSCs and IPSCs without affecting the amplitude. The time constant of the decay phase of both the EPSCs and IPSCs remained unchanged after baclofen application. 4. The reduction of the frequency of the synaptic currents by baclofen was dose dependent (10 nM to 100 microM) and the EC50 values were 5.8 and 8.5 microM for the EPSCs and IPSCs, respectively. 5. The effect of baclofen (10 microM) was antagonized by the selective GABAB antagonist, 2-hydroxy-saclofen (2OH-saclofen), at 300 microM. 6. When given alone, 2OH-saclofen (100 microM) increased the frequency of both the EPSCs and IPSCs without affecting their amplitude, suggesting that endogenously released GABA in the slice acts on presynaptic GABAB receptors. 7. The GABAA agonist, muscimol, reduced the frequency of EPSCs, and picrotoxin increased the frequency of the EPSCs, suggesting that GABAA receptors also participate in the presynaptic inhibition of glutamate release. 8. Taken together, these data suggest that GABAB receptors are present on the presynaptic terminals of both GABA and glutamate neurons in the SON, and that these presynaptic GABAB receptors play an important role in the regulation of the neuronal activity in SON magnocellular neurons. Images Figure 1 PMID:9350623

  17. Activation but not blockade of GABAB receptors during early-life alters anxiety in adulthood in BALB/c mice.

    PubMed

    Sweeney, Fabian F; O'Leary, Olivia F; Cryan, John F

    2014-06-01

    Although the underlying pathophysiology of anxiety disorders is unknown it is clear that a combination of genetic and environmental factors in early life predispose to disease risk. Preclinical research increasingly suggests an important role for the GABAB receptor in modulating anxiety behaviour, with GABAB receptor deficient mice having increased anxiety behaviour. Previous studies have highlighted critical windows during development where adult anxiety behaviour is primed. However, little is known regarding the role played by the GABAB receptors in the developmental processes that underlie adult anxiety behaviour. To this end, we treated male BALB/c mouse pups with the either the selective GABAB receptor agonist, R-baclofen (2 mg/kg, s.c), the GABAB receptor antagonist CGP 52432 (10 mg/kg and 30 mg/kg) or vehicle from postnatal days (P) 14-28. The anxiety behaviour of these mice was then assessed in adulthood (P62 onwards) in a battery of behavioural tests comprising; the stress induced hyperthermia (SIH) test, defensive marble burying (DMB), elevated-plus maze (EPM) and the forced swim test (FST). Postnatal R-baclofen treatment resulted in increased anxiety-like behaviour in the EPM as shown by approach-avoidance and ethological measures. Other behavioural measures were not significantly altered. Interestingly, blockade of GABAB receptors with CGP52432 in early life caused no alterations in emotional behaviour. These data suggest that during early life GABAB receptor signalling can play a functional role in programing anxiety behaviour in adulthood. The underlying neurodevelopmental processes underlying these effects remain to be discovered. PMID:24050962

  18. Role of GABA(B) receptors in learning and memory and neurological disorders.

    PubMed

    Heaney, Chelcie F; Kinney, Jefferson W

    2016-04-01

    Although it is evident from the literature that altered GABAB receptor function does affect behavior, these results often do not correspond well. These differences could be due to the task protocol, animal strain, ligand concentration, or timing of administration utilized. Because several clinical populations exhibit learning and memory deficits in addition to altered markers of GABA and the GABAB receptor, it is important to determine whether altered GABAB receptor function is capable of contributing to the deficits. The aim of this review is to examine the effect of altered GABAB receptor function on synaptic plasticity as demonstrated by in vitro data, as well as the effects on performance in learning and memory tasks. Finally, data regarding altered GABA and GABAB receptor markers within clinical populations will be reviewed. Together, the data agree that proper functioning of GABAB receptors is crucial for numerous learning and memory tasks and that targeting this system via pharmaceuticals may benefit several clinical populations. PMID:26814961

  19. GABAB Receptor-Positive Modulators: Brain Region-Dependent Effects

    PubMed Central

    Advani, Tushar; Burke, Teresa F.; Cheng, Kejun; Rice, Kenner C.; Koek, Wouter

    2012-01-01

    This study examined the positive modulatory properties of 2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930) and (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF) at γ-aminobutyric acid B (GABAB) receptors in different brain regions. Using quantitative autoradiography, we measured GABAB receptor-stimulated binding of guanosine 5′-O-(3-[35S]thiotriphosphate) ([35S]GTPγS) to G proteins in medial prefrontal cortex (mPFC), hippocampus, and cerebellum. CGP7930 and rac-BHFF enhanced baclofen-stimulated [35S]GTPγS binding similarly in mPFC and hippocampus, but were more effective in cerebellum. CGP7930 (100 μM) increased [35S]GTPγS binding stimulated by baclofen (30 μM) from 29 to 241% above basal in mPFC and from 13 to 1530% above basal in cerebellum. Likewise, rac-BHFF (10 μM) increased baclofen-stimulated [35S]GTPγS binding more in cerebellum (from 13 to 1778% above basal) than in mPFC (from 29 to 514% above basal). rac-BHFF (10 μM) in combination with γ-hydroxybutyrate (20 mM) increased [35S]GTPγS binding in cerebellum but not in mPFC. rac-BHFF also enhanced the effects of 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348). Consistent with its partial agonist properties, CGP35348 stimulated [35S]GTPγS binding in mPFC when given alone (to 18% above basal), but less extensively than baclofen (140% above basal), and antagonized baclofen when given together. CGP35348 (1 mM) in combination with rac-BHFF (100 μM) produced an increase in [35S]GTPγS binding that was larger in cerebellum (from 61 to 1260% above basal) than in mPFC (from 18 to 118% above basal). Taken together, the results show that GABAB receptor-positive modulators enhance [35S]GTPγS binding stimulated by GABAB receptor agonists in a brain region-dependent manner. This regionally selective enhancement is further evidence of pharmacologically distinct GABAB receptor populations, possibly allowing for more selective therapeutic targeting

  20. GABAB Receptor Constituents Revealed by Tandem Affinity Purification from Transgenic Mice*

    PubMed Central

    Bartoi, Tudor; Rigbolt, Kristoffer T. G.; Du, Dan; Köhr, Georg; Blagoev, Blagoy; Kornau, Hans-Christian

    2010-01-01

    GABAB receptors function as heterodimeric G-protein-coupled receptors for the neurotransmitter γ-aminobutyric acid (GABA). Receptor subtypes, based on isoforms of the ligand-binding subunit GABAB1, are thought to involve a differential set of associated proteins. Here, we describe two mouse lines that allow a straightforward biochemical isolation of GABAB receptors. The transgenic mice express GABAB1 isoforms that contain sequences for a two-step affinity purification, in addition to their endogenous subunit repertoire. Comparative analyses of purified samples from the transgenic mice and wild-type control animals revealed two novel components of the GABAB1 complex. One of the identified proteins, potassium channel tetramerization domain-containing protein 12, associates with heterodimeric GABAB receptors via the GABAB2 subunit. In transfected hippocampal neurons, potassium channel tetramerization domain-containing protein 12 augmented axonal surface targeting of GABAB2. The mice equipped with tags on GABAB1 facilitate validation and identification of native binding partners of GABAB receptors, providing insight into the molecular mechanisms of synaptic modulation. PMID:20406808

  1. GABAB receptor constituents revealed by tandem affinity purification from transgenic mice.

    PubMed

    Bartoi, Tudor; Rigbolt, Kristoffer T G; Du, Dan; Köhr, Georg; Blagoev, Blagoy; Kornau, Hans-Christian

    2010-07-01

    GABA(B) receptors function as heterodimeric G-protein-coupled receptors for the neurotransmitter gamma-aminobutyric acid (GABA). Receptor subtypes, based on isoforms of the ligand-binding subunit GABA(B1), are thought to involve a differential set of associated proteins. Here, we describe two mouse lines that allow a straightforward biochemical isolation of GABA(B) receptors. The transgenic mice express GABA(B1) isoforms that contain sequences for a two-step affinity purification, in addition to their endogenous subunit repertoire. Comparative analyses of purified samples from the transgenic mice and wild-type control animals revealed two novel components of the GABA(B1) complex. One of the identified proteins, potassium channel tetramerization domain-containing protein 12, associates with heterodimeric GABA(B) receptors via the GABA(B2) subunit. In transfected hippocampal neurons, potassium channel tetramerization domain-containing protein 12 augmented axonal surface targeting of GABA(B2). The mice equipped with tags on GABA(B1) facilitate validation and identification of native binding partners of GABA(B) receptors, providing insight into the molecular mechanisms of synaptic modulation. PMID:20406808

  2. Discriminative stimulus effects of the GABAB receptor-positive modulator rac-BHFF: comparison with GABAB receptor agonists and drugs of abuse.

    PubMed

    Koek, Wouter; Cheng, Kejun; Rice, Kenner C

    2013-03-01

    GABA(B) receptor-positive modulators are thought to have advantages as potential medications for anxiety, depression, and drug addiction. They may have fewer side effects than GABA(B) receptor agonists, because selective enhancement of activated receptors could have effects different from nonselective activation of all receptors. To examine this, pigeons were trained to discriminate the GABA(B) receptor-positive modulator (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF) from its vehicle. The discriminative stimulus effects of rac-BHFF were not mimicked by the GABA(B) receptor agonists baclofen and γ-hydroxybutyrate (GHB), not by diazepam, and not by alcohol, cocaine, and nicotine, whose self-administration has been reported to be attenuated by GABA(B) receptor-positive modulators. The discriminative stimulus effects of rac-BHFF were not antagonized by the GABA(B) receptor antagonist 3-aminopropyl (diethoxymethyl)phosphinic acid (CGP35348) but were attenuated by the less efficacious GABA(B) receptor-positive modulator 2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethylpropyl)phenol (CGP7930), suggesting the possibility that rac-BHFF produces its discriminative stimulus effects by directly activating GABA(B2) subunits of GABA(B) receptors. At a dose 10-fold lower than the training dose, rac-BHFF enhanced the discriminative stimulus effects of baclofen, but not of GHB. This study provides evidence that the effects of GABA(B) receptor-positive modulators are not identical to those of GABA(B) receptor agonists. In addition, the results suggest that positive modulation of GABA(B) receptors does not produce discriminative stimulus effects similar to those of benzodiazepines, alcohol, cocaine, and nicotine. Finally, the finding that rac-BHFF enhanced effects of baclofen but not of GHB is consistent with converging evidence that the populations of GABA(B) receptors mediating the effects of baclofen and GHB are not identical. PMID:23275067

  3. Presynaptic Excitation via GABAB Receptors in Habenula Cholinergic Neurons Regulates Fear Memory Expression.

    PubMed

    Zhang, Juen; Tan, Lubin; Ren, Yuqi; Liang, Jingwen; Lin, Rui; Feng, Qiru; Zhou, Jingfeng; Hu, Fei; Ren, Jing; Wei, Chao; Yu, Tao; Zhuang, Yinghua; Bettler, Bernhard; Wang, Fengchao; Luo, Minmin

    2016-07-28

    Fear behaviors are regulated by adaptive mechanisms that dampen their expression in the absence of danger. By studying circuits and the molecular mechanisms underlying this adaptive response, we show that cholinergic neurons of the medial habenula reduce fear memory expression through GABAB presynaptic excitation. Ablating these neurons or inactivating their GABAB receptors impairs fear extinction in mice, whereas activating the neurons or their axonal GABAB receptors reduces conditioned fear. Although considered exclusively inhibitory, here, GABAB mediates excitation by amplifying presynaptic Ca(2+) entry through Cav2.3 channels and potentiating co-release of glutamate, acetylcholine, and neurokinin B to excite interpeduncular neurons. Activating the receptors for these neurotransmitters or enhancing neurotransmission with a phosphodiesterase inhibitor reduces fear responses of both wild-type and GABAB mutant mice. We identify the role of an extra-amygdalar circuit and presynaptic GABAB receptors in fear control, suggesting that boosting neurotransmission in this pathway might ameliorate some fear disorders. PMID:27426949

  4. GABA(B) receptor subunit 1 binds to proteins affected in 22q11 deletion syndrome.

    PubMed

    Zunner, Dagmar; Deschermeier, Christina; Kornau, Hans-Christian

    2010-03-01

    GABA(B) receptors mediate slow inhibitory effects of the neurotransmitter gamma-aminobutyric acid (GABA) on synaptic transmission in the central nervous system. They function as heterodimeric G-protein-coupled receptors composed of the seven-transmembrane domain proteins GABA(B1) and GABA(B2), which are linked through a coiled-coil interaction. The ligand-binding subunit GABA(B1) is at first retained in the endoplasmic reticulum and is transported to the cell surface only upon assembly with GABA(B2). Here, we report that GABA(B1), via the coiled-coil domain, can also bind to soluble proteins of unknown function, that are affected in 22q11 deletion/DiGeorge syndrome and are therefore referred to as DiGeorge critical region 6 (DGCR6). In transfected neurons the GABA(B1)-DGCR6 association resulted in a redistribution of both proteins into intracellular clusters. Furthermore, the C-terminus of GABA(B2) interfered with the novel interaction, consistent with heterodimer formation overriding transient DGCR6-binding to GABA(B1). Thus, sequential coiled-coil interactions may direct GABA(B1) into functional receptors. PMID:20036641

  5. The role of GABAB receptors in human reinforcement learning.

    PubMed

    Ort, Andres; Kometer, Michael; Rohde, Judith; Seifritz, Erich; Vollenweider, Franz X

    2014-10-01

    Behavioral evidence from human studies suggests that the γ-aminobutyric acid type B receptor (GABAB receptor) agonist baclofen modulates reinforcement learning and reduces craving in patients with addiction spectrum disorders. However, in contrast to the well established role of dopamine in reinforcement learning, the mechanisms by which the GABAB receptor influences reinforcement learning in humans remain completely unknown. To further elucidate this issue, a cross-over, double-blind, placebo-controlled study was performed in healthy human subjects (N=15) to test the effects of baclofen (20 and 50mg p.o.) on probabilistic reinforcement learning. Outcomes were the feedback-induced P2 component of the event-related potential, the feedback-related negativity, and the P300 component of the event-related potential. Baclofen produced a reduction of P2 amplitude over the course of the experiment, but did not modulate the feedback-related negativity. Furthermore, there was a trend towards increased learning after baclofen administration relative to placebo over the course of the experiment. The present results extend previous theories of reinforcement learning, which focus on the importance of mesolimbic dopamine signaling, and indicate that stimulation of cortical GABAB receptors in a fronto-parietal network leads to better attentional allocation in reinforcement learning. This observation is a first step in our understanding of how baclofen may improve reinforcement learning in healthy subjects. Further studies with bigger sample sizes are needed to corroborate this conclusion and furthermore, test this effect in patients with addiction spectrum disorder. PMID:25194227

  6. Presynaptic GABAB Receptors Regulate Hippocampal Synapses during Associative Learning in Behaving Mice.

    PubMed

    Jurado-Parras, M Teresa; Delgado-García, José M; Sánchez-Campusano, Raudel; Gassmann, Martin; Bettler, Bernhard; Gruart, Agnès

    2016-01-01

    GABAB receptors are the G-protein-coupled receptors for GABA, the main inhibitory neurotransmitter in the central nervous system. Pharmacological activation of GABAB receptors regulates neurotransmission and neuronal excitability at pre- and postsynaptic sites. Electrophysiological activation of GABAB receptors in brain slices generally requires strong stimulus intensities. This raises the question as to whether behavioral stimuli are strong enough to activate GABAB receptors. Here we show that GABAB1a-/- mice, which constitutively lack presynaptic GABAB receptors at glutamatergic synapses, are impaired in their ability to acquire an operant learning task. In vivo recordings during the operant conditioning reveal a deficit in learning-dependent increases in synaptic strength at CA3-CA1 synapses. Moreover, GABAB1a-/- mice fail to synchronize neuronal activity in the CA1 area during the acquisition process. Our results support that activation of presynaptic hippocampal GABAB receptors is important for acquisition of a learning task and for learning-associated synaptic changes and network dynamics. PMID:26848590

  7. Presynaptic GABAB Receptors Regulate Hippocampal Synapses during Associative Learning in Behaving Mice

    PubMed Central

    Jurado-Parras, M. Teresa; Delgado-García, José M.; Sánchez-Campusano, Raudel; Gassmann, Martin; Bettler, Bernhard; Gruart, Agnès

    2016-01-01

    GABAB receptors are the G-protein-coupled receptors for GABA, the main inhibitory neurotransmitter in the central nervous system. Pharmacological activation of GABAB receptors regulates neurotransmission and neuronal excitability at pre- and postsynaptic sites. Electrophysiological activation of GABAB receptors in brain slices generally requires strong stimulus intensities. This raises the question as to whether behavioral stimuli are strong enough to activate GABAB receptors. Here we show that GABAB1a-/- mice, which constitutively lack presynaptic GABAB receptors at glutamatergic synapses, are impaired in their ability to acquire an operant learning task. In vivo recordings during the operant conditioning reveal a deficit in learning-dependent increases in synaptic strength at CA3-CA1 synapses. Moreover, GABAB1a-/- mice fail to synchronize neuronal activity in the CA1 area during the acquisition process. Our results support that activation of presynaptic hippocampal GABAB receptors is important for acquisition of a learning task and for learning-associated synaptic changes and network dynamics. PMID:26848590

  8. Cockroach GABAB receptor subtypes: molecular characterization, pharmacological properties and tissue distribution.

    PubMed

    Blankenburg, S; Balfanz, S; Hayashi, Y; Shigenobu, S; Miura, T; Baumann, O; Baumann, A; Blenau, W

    2015-01-01

    γ-aminobutyric acid (GABA) is the predominant inhibitory neurotransmitter in the central nervous system (CNS). Its effects are mediated by either ionotropic GABAA receptors or metabotropic GABAB receptors. GABAB receptors regulate, via Gi/o G-proteins, ion channels, and adenylyl cyclases. In humans, GABAB receptor subtypes are involved in the etiology of neurologic and psychiatric disorders. In arthropods, however, these members of the G-protein-coupled receptor family are only inadequately characterized. Interestingly, physiological data have revealed important functions of GABAB receptors in the American cockroach, Periplaneta americana. We have cloned cDNAs coding for putative GABAB receptor subtypes 1 and 2 of P. americana (PeaGB1 and PeaGB2). When both receptor proteins are co-expressed in mammalian cells, activation of the receptor heteromer with GABA leads to a dose-dependent decrease in cAMP production. The pharmacological profile differs from that of mammalian and Drosophila GABAB receptors. Western blot analyses with polyclonal antibodies have revealed the expression of PeaGB1 and PeaGB2 in the CNS of the American cockroach. In addition to the widespread distribution in the brain, PeaGB1 is expressed in salivary glands and male accessory glands. Notably, PeaGB1-like immunoreactivity has been detected in the GABAergic salivary neuron 2, suggesting that GABAB receptors act as autoreceptors in this neuron. PMID:25242738

  9. Alterations in cortical GABAB receptors in neonatal rats exposed to hypoxic stress: role of glucose, oxygen, and epinephrine resuscitation.

    PubMed

    Anju, T R; Abraham, Pretty Mary; Antony, Sherin; Paulose, C S

    2010-10-01

    Hypoxia in neonates can cause permanent brain damage by gene and receptor level alterations mediated through changes in neurotransmitters. The present study evaluated GABA(B) receptor alterations, gene expression changes in glutamate decarboxylase and hypoxia-inducible factor 1A in the cerebral cortex of hypoxic neonatal rats and the resuscitation groups with glucose, oxygen, and epinephrine. Under hypoxic stress, a significant decrease in total GABA and GABA(B) receptors, GABA(B) and GAD gene expression was observed in the cerebral cortex, which accounts for the respiratory inhibition. Hypoxia-inducible factor 1A was upregulated under hypoxia to maintain body homeostasis. Hypoxic rats supplemented with glucose alone and with oxygen showed a reversal of the receptor alterations and changes in GAD and HIF-1A to near control. Being a source of immediate energy, glucose can reduce the ATP-depletion-induced changes in GABA and oxygenation, which helps in encountering hypoxia. Resuscitation with oxygen alone and epinephrine was less effective in reversing the receptor alterations. Thus, our study suggests that reduction in the GABA(B) receptors functional regulation during hypoxia plays an important role in cortical damage. Resuscitation with glucose alone and glucose and oxygen to hypoxic neonatal rats helps in protecting the brain from severe hypoxic damage. PMID:20473556

  10. Regulation of muscarinic acetylcholine receptor-mediated synaptic responses by GABAB receptors in the rat hippocampus

    PubMed Central

    Morton, Robin A; Manuel, Nick A; Bulters, Diederick O; Cobb, Stuart R; Davies, Ceri H

    2001-01-01

    Both GABAB and muscarinic acetylcholine receptors (mAChRs) influence hippocampal-dependent mnemonic processing. Here the possibility of a direct interaction between GABAB receptors and mAChR-mediated synaptic responses has been studied using intracellular recording in rat hippocampal slices. The GABAB receptor agonist(−)-baclofen (5–10 μm) depressed an atropine-sensitive slow EPSP (EPSPM) and occluded the GABAB-receptor-mediated IPSP (IPSPB) which preceded it. These inhibitory effects were accompanied by postsynaptic hyperpolarization (9 ± 2 mV) and a reduction in cell input resistance (12 ± 3 %). The selective GABAB receptor antagonist CGP 55845A (1 μm) fully reversed the depressant effects of (−)-baclofen (5–10 μm) such that in the combined presence of (−)-baclofen and CGP 55845A the EPSPM was 134 ± 21 % of control. (−)-Baclofen (5–10 μm) caused a small (28 ± 11 %) inhibition of carbachol-induced (3.0 μm) postsynaptic depolarizations and increases in input resistance. CGP 55845A (1 μm) alone caused an increase in the amplitude of the EPSPM (253 ± 74 % of control) and blocked the IPSPB that preceded it. In contrast, the selective GABA uptake inhibitor NNC 05–0711 (10 μm) increased the amplitude of the IPSPB by 141 ± 38 % and depressed the amplitude of the EPSPM by 58 ± 10 %. This inhibition was abolished by CGP 55845A (1 μm). Taken together these data provide good evidence that synaptically released GABA activates GABAB receptors that inhibit mAChR-mediated EPSPs in hippocampal CA1 pyramidal neurones. The mechanism of inhibition may involve both pre- and postsynaptic elements. PMID:11559773

  11. Modular composition and dynamics of native GABAB receptors identified by high-resolution proteomics.

    PubMed

    Schwenk, Jochen; Pérez-Garci, Enrique; Schneider, Andy; Kollewe, Astrid; Gauthier-Kemper, Anne; Fritzius, Thorsten; Raveh, Adi; Dinamarca, Margarita C; Hanuschkin, Alexander; Bildl, Wolfgang; Klingauf, Jürgen; Gassmann, Martin; Schulte, Uwe; Bettler, Bernhard; Fakler, Bernd

    2016-02-01

    GABAB receptors, the most abundant inhibitory G protein-coupled receptors in the mammalian brain, display pronounced diversity in functional properties, cellular signaling and subcellular distribution. We used high-resolution functional proteomics to identify the building blocks of these receptors in the rodent brain. Our analyses revealed that native GABAB receptors are macromolecular complexes with defined architecture, but marked diversity in subunit composition: the receptor core is assembled from GABAB1a/b, GABAB2, four KCTD proteins and a distinct set of G-protein subunits, whereas the receptor's periphery is mostly formed by transmembrane proteins of different classes. In particular, the periphery-forming constituents include signaling effectors, such as Cav2 and HCN channels, and the proteins AJAP1 and amyloid-β A4, both of which tightly associate with the sushi domains of GABAB1a. Our results unravel the molecular diversity of GABAB receptors and their postnatal assembly dynamics and provide a roadmap for studying the cellular signaling of this inhibitory neurotransmitter receptor. PMID:26691831

  12. The effects of agonists of ionotropic GABA(A) and metabotropic GABA(B) receptors on learning.

    PubMed

    Zyablitseva, Evgeniya A; Kositsyn, Nikolay S; Shul'gina, Galina I

    2009-05-01

    The research described here investigates the role played by inhibitory processes in the discriminations made by the nervous system of humans and animals between familiar and unfamiliar and significant and nonsignificant events. This research compared the effects of two inhibitory mediators of gamma-aminobutyric acid (GABA): 1) phenibut, a nonselective agonist of ionotropic GABA(A) and metabotropic GABA(B) receptors and 2) gaboxadol a selective agonist of ionotropic GABA(A) receptors on the process of developing active defensive and inhibitory conditioned reflexes in alert non-immobilized rabbits. It was found that phenibut, but not gaboxadol, accelerates the development of defensive reflexes at an early stage of conditioning. Both phenibut and gaboxadol facilitate the development of conditioned inhibition, but the effect of gaboxadol occurs at later stages of conditioning and is less stable than that of phenibut. The earlier and more stable effects of phenibut, as compared to gaboxadol, on storage in memory of the inhibitory significance of a stimulus may occur because GABA(B) receptors play the dominant role in the development of internal inhibition during an early stage of conditioning. On the other hand this may occur because the participation of both GABA(A) and GABA(B) receptors are essential to the process. We discuss the polyfunctionality of GABA receptors as a function of their structure and the positions of the relevant neurons in the brain as this factor can affect regulation of various types of psychological processes. PMID:19476215

  13. Marlin-1 and conventional kinesin link GABAB receptors to the cytoskeleton and regulate receptor transport.

    PubMed

    Vidal, René L; Ramírez, Omar A; Sandoval, Lisette; Koenig-Robert, Roger; Härtel, Steffen; Couve, Andrés

    2007-07-01

    The cytoskeleton and cytoskeletal motors play a fundamental role in neurotransmitter receptor trafficking, but proteins that link GABA(B) receptors (GABA(B)Rs) to the cytoskeleton have not been described. We recently identified Marlin-1, a protein that interacts with GABA(B)R1. Here, we explore the association of GABA(B)Rs and Marlin-1 to the cytoskeleton using a combination of biochemistry, microscopy and live cell imaging. Our results indicate that Marlin-1 is associated to microtubules and the molecular motor kinesin-I. We demonstrate that a fraction of Marlin-1 is mobile in dendrites of cultured hippocampal neurons and that mobility is microtubule-dependent. We also show that GABA(B)Rs interact robustly with kinesin-I and that intracellular membranes containing GABA(B)Rs are sensitive to treatments that disrupt a protein complex containing Marlin-1, kinesin-I and tubulin. Finally, we report that a kinesin-I mutant severely impairs receptor transport. We conclude that Marlin-1 and kinesin-1 link GABA(B)Rs to the tubulin cytoskeleton in neurons. PMID:17532644

  14. A negative allosteric modulator modulates GABAB-receptor signalling through GB2 subunits.

    PubMed

    Sun, Bing; Chen, Linhai; Liu, Lei; Xia, Zhixiong; Pin, Jean-Philippe; Nan, Fajun; Liu, Jianfeng

    2016-03-15

    An γ-aminobutyric acid type B (GABAB)-receptor mediates slow and prolonged synaptic inhibition in the central nervous system, which represents an interesting target for the treatment of various diseases and disorders of the central nervous system. To date, only one activator of the GABAB-receptor, baclofen, is on the market for the treatment of spasticity. Inhibitors of the GABAB-receptor, such as antagonists, show anti-absence seizure activity and pro-cognitive properties. In a search for allosteric compounds of the GABAB-receptor, although several positive allosteric modulators have been developed, it is only recently that the first negative allosteric modulator (NAM), CLH304a (also named Compound 14), has been reported. In the present study, we provide further information on the mechanism of action of CLH304a, and also show the possibility of designing more NAMs, such as CLH391 and CLH393, based on the structure of CLH304a. First we show that CLH304a inhibits native GABAB-receptor activity in cultured cerebellar granular neurons. We then show that CLH304a has inverse agonist properties and non-competitively inhibits the effect of agonists, indicating that it binds at a different site to GABA. The GABAB-receptor is a mandatory heterodimer made of GB1 subunits, in which agonists bind, and GB2 subunits, which activate G-proteins. By using various combinations made up of wild-type and/or mutated GB1 and GB2 subunits, we show that CLH304a acts on the heptahelical domain of GB2 subunits. These data revealed the possibility of designing innovative NAMs acting in the heptahelical domain of the GB2 subunits, offering novel possibilities for therapeutic intervention based on GABAB-receptor inhibition. PMID:26772870

  15. Binding characteristics of gamma-hydroxybutyric acid as a weak but selective GABAB receptor agonist.

    PubMed

    Mathivet, P; Bernasconi, R; De Barry, J; Marescaux, C; Bittiger, H

    1997-02-19

    The aim of this study was to reexamine the concept that gamma-hydroxybutyric acid (GHB) is a weak but selective agonist at gamma-aminobutyric acidB (GABAB) receptors, using binding experiments with several radioligands. Ki values of GHB were similar (approximately equal to 100 microM) in three agonist radioligand assays for GABAB receptors, [3H]baclofen (beta-para-chlorophenyl-gamma-aminobutyric acid), [3H]CGP 27492 (3-aminopropyl-phosphinic acid) and [3H]GABA, in the presence of the GABAA receptor agonist isoguvacine with rat cortical, cerebellar and hippocampal membranes. In competition experiments between GHB and the GABAB receptor antagonist, [3H]CGP 54626 (3-N [1-{(S)-3,4-dichlorophenyl}-ethylamino]-2-(S)-hydroxypropyl cyclo-hexylmethyl phosphinic acid), the IC50 values were significantly increased with 300 microM of 5'-guanyl-imidodiphosphate (Gpp(NH)p), which suggested that guanine nucleotide binding proteins (G-proteins) modulate GHB binding on GABAB receptors. The inhibition by GHB of [3H]CGP 27492 binding in cortical membranes was not altered in the presence of 0.3 or 3 mM of the two GHB dehydrogenase inhibitors, valproate and ethosuximide. Thus, GHB is not reconverted into GABA by GHB dehydrogenase. Taken together, the results of this study demonstrated that GHB is an endogenous weak but selective agonist at GABAB receptors. PMID:9083788

  16. Experimental absence seizures: potential role of gamma-hydroxybutyric acid and GABAB receptors.

    PubMed

    Bernasconi, R; Lauber, J; Marescaux, C; Vergnes, M; Martin, P; Rubio, V; Leonhardt, T; Reymann, N; Bittiger, H

    1992-01-01

    We have investigated whether the pathogenesis of spontaneous generalized non-convulsive seizures in rats with genetic absence epilepsy is due to an increase in the brain levels of gamma-hydroxybutyric acid (GHB) or in the rate of its synthesis. Concentrations of GHB or of its precursor gamma-butyrolactone (GBL) were measured with a new GC/MS technique which allows the simultaneous assessment of GHB and GBL. The rate of GHB synthesis was estimated from the increase in GHB levels after inhibition of its catabolism with valproate. The results of this study do not indicate significant differences in GHB or GBL levels, or in their rates of synthesis in rats showing spike-and-wave discharges (SWD) as compared to rats without SWD. Binding data indicate that GHB, but not GBL, has a selective, although weak affinity for GABAB receptors (IC50 = 150 microM). Similar IC50 values were observed in membranes prepared from rats showing SWD and from control rats. The average GHB brain levels of 2.12 +/- 0.23 nmol/g measured in the cortex and of 4.28 +/- 0.90 nmol/g in the thalamus are much lower than the concentrations necessary to occupy a major part of the GABAB receptors. It is unlikely that local accumulations of GHB reach concentrations 30-70-fold higher than the average brain levels. After injection of 3.5 mmol/kg GBL, a dose sufficient to induce SWD, brain concentrations reach 240 +/- 31 nmol/g (Snead, 1991) and GHB could thus stimulate the GABAB receptor. Like the selective and potent GABAB receptor agonist R(-)-baclofen, GHB causes a dose-related decrease in cerebellar cGMP. This decrease and the increase in SWD caused by R(-)-baclofen were completely blocked by the selective and potent GABAB receptor antagonist CGP 35348, whereas only the increase in the duration of SWD induced by GHB was totally antagonized by CGP 35348. The decrease in cerebellar cGMP levels elicited by GHB was only partially antagonized by CGP 35348. These findings suggest that all effects of R

  17. Spinal GABA-B receptor modulates neutrophil recruitment to the knee joint in zymosan-induced arthritis.

    PubMed

    Bassi, Gabriel S; do C Malvar, David; Cunha, Thiago M; Cunha, Fernando Q; Kanashiro, Alexandre

    2016-08-01

    Recent studies have demonstrated that the central nervous system controls inflammatory responses by activating complex efferent neuroimmune pathways. The present study was designed to evaluate the role that central gamma-aminobutyric acid type B (GABA-B) receptor plays in neutrophil migration in a murine model of zymosan-induced arthritis by using different pharmacological tools. We observed that intrathecal administration of baclofen, a selective GABA-B agonist, exacerbated the inflammatory response in the knee after zymosan administration characterized by an increase in the neutrophil recruitment and knee joint edema, whereas saclofen, a GABA-B antagonist, exerted the opposite effect. Intrathecal pretreatment of the animals with SB203580 (an inhibitor of p38 mitogen-activated protein kinase) blocked the pro-inflammatory effect of baclofen. On the other hand, systemic administration of guanethidine, a sympatholytic drug that inhibits catecholamine release, and nadolol, a beta-adrenergic receptor antagonist, reversed the effect of saclofen. Moreover, saclofen suppressed the release of the pro-inflammatory cytokines into the knee joint (ELISA) and pain-related behaviors (open field test). Since the anti-inflammatory effect of saclofen depends on the sympathetic nervous system integrity, we observed that isoproterenol, a beta-adrenergic receptor agonist, mimics the central GABA-B blockade decreasing knee joint neutrophil recruitment. Together, these results demonstrate that the pharmacological manipulation of spinal GABAergic transmission aids control of neutrophil migration to the inflamed joint by modulating the activation of the knee joint-innervating sympathetic terminal fibers through a mechanism dependent on peripheral beta-adrenergic receptors and central components, such as p38 MAPK. PMID:27106212

  18. Effects of repeated cocaine on medial prefrontal cortical GABAB receptor modulation of neurotransmission in the mesocorticolimbic dopamine system.

    PubMed

    Jayaram, Prathiba; Steketee, Jeffery D

    2004-08-01

    Increased excitatory output from medial prefrontal cortex is an important component in the development of cocaine sensitization. Activation of GABAergic systems in the prefrontal cortex can decrease glutamatergic activity. A recent study suggested that sensitization might be associated with a decrease in GABAB receptor responsiveness in the medial prefrontal cortex. Therefore, the present study examined whether repeated exposure to cocaine-modified neurochemical changes in the mesocorticolimbic dopamine system induced by infusion of baclofen into the medial prefrontal cortex. In vivo microdialysis studies were conducted to monitor dopamine, glutamate and GABA levels in the medial prefrontal cortex and glutamate levels in the ipsilateral nucleus accumbens and ventral tegmental area during the infusion of baclofen into medial prefrontal cortex. Baclofen minimally affected glutamate levels in the medial prefrontal cortex, nucleus accumbens or ventral tegmental area of control animals, but dose-dependently increased glutamate levels in each of these regions in animals sensitized to cocaine. This effect was not the result of changes in GABAB receptor-mediated modulation of dopamine or GABA in the medial prefrontal cortex. The data suggest that alterations in GABAB receptor modulation of medial prefrontal cortical excitatory output may play an important role in the development of sensitization to cocaine. PMID:15287889

  19. [GABAB receptor as therapeutic target for drug addiction: from baclofen to positive allosteric modulators].

    PubMed

    Agabio, Roberta; Colombo, Giancarlo

    2015-01-01

    The present paper summarizes experimental and clinical data indicating the therapeutic potential of the GABAB receptor agonist, baclofen, in the treatment of alcohol use disorder (AUD) and substance use disorder (SUD). Multiple preclinical studies have demonstrated the ability of baclofen to suppress alcohol drinking (including binge- and relapse-like drinking), oral alcohol self-administration, and intravenous self-administration of cocaine, nicotine, amphetamine, methamphetamine, morphine, and heroin in rodents. Some randomized, controlled trials (RCTs) and case reports support the efficacy of baclofen in suppressing alcohol consumption, craving for alcohol, and alcohol withdrawal symptomatology in alcohol-dependent patients. Data from RCTs and open studies investigating baclofen efficacy on SUD are currently less conclusive. Interest in testing high doses of baclofen in AUD and SUD treatment has recently emerged. Preclinical research has extended the anti-addictive properties of baclofen to positive allosteric modulators of the GABAB receptor (GABAB PAMs). In light of their more favourable side effect profile (compared to baclofen), GABAB PAMs may represent a major step forward in a GABAB receptor-based pharmacotherapy of AUD and SUD. PMID:26093587

  20. Developing oligodendrocytes express functional GABA(B) receptors that stimulate cell proliferation and migration.

    PubMed

    Luyt, Karen; Slade, Timothy P; Dorward, Jienchi J; Durant, Claire F; Wu, Yue; Shigemoto, Ryuichi; Mundell, Stuart J; Váradi, Anikó; Molnár, Elek

    2007-02-01

    GABA(B) receptors (GABA(B)Rs) are involved in early events during neuronal development. The presence of GABA(B)Rs in developing oligodendrocytes has not been established. Using immunofluorescent co-localization, we have identified GABA(B)R proteins in O4 marker-positive oligodendrocyte precursor cells (OPCs) in 4-day-old mouse brain periventricular white matter. In culture, OPCs, differentiated oligodendrocytes (DOs) and type 2 astrocytes (ASTs) express both the GABA(B1abcdf) and GABA(B2) subunits of the GABA(B)R. Using semiquantitative PCR analysis with GABA(B)R isoform-selective primers we found that the expression level of GABA(B1abd) was substantially higher in OPCs or ASTs than in DOs. In contrast, the GABA(B2) isoform showed a similar level of expression in OPCs and DOs, and a significantly higher level in ASTs. This indicates that the expression of GABA(B1) and GABA(B2) subunits are under independent control during oligodendroglial development. Activation of GABA(B)Rs using the selective agonist baclofen demonstrated that these receptors are functionally active and negatively coupled to adenylyl cyclase. Manipulation of GABA(B)R activity had no effect on OPC migration in a conventional agarose drop assay, whereas baclofen significantly increased OPC migration in a more sensitive transwell microchamber-based assay. Exposure of cultured OPCs to baclofen increased their proliferation, providing evidence for a functional role of GABA(B)Rs in oligodendrocyte development. The presence of GABA(B)Rs in developing oligodendrocytes provides a new mechanism for neuronal-glial interactions during development and may offer a novel target for promoting remyelination following white matter injury. PMID:17144904

  1. Structure and functional interaction of the extracellular domain of human GABAB receptor GBR2

    PubMed Central

    Geng, Yong; Xiong, Dazhi; Mosyak, Lidia; Malito, David L.; Kniazeff, Julie; Chen, Yan; Burmakina, Svetlana; Quick, Matthias; Bush, Martin; Javitch, Jonathan A.; Pin, Jean-Philippe; Fan, Qing R.

    2012-01-01

    Inhibitory neurotransmission is mediated primarily by GABA. Metabotropic GABAB receptor is a G protein coupled receptor central to mammalian brain function. Malfunction of GABAB receptor has been implicated in a number of neurological disorders. GABAB receptor functions as a heterodimeric assembly of GBR1 and GBR2 subunits, where GBR1 is responsible for ligand-binding and GBR2 is responsible for G protein coupling. Here we demonstrate that the GBR2 ectodomain directly interacts with the GBR1 ectodomain to increase agonist affinity by selectively stabilizing the agonist-bound conformation of GBR1. We present the crystal structure of the GBR2 ectodomain, which reveals a polar heterodimeric interface. We also identify specific heterodimer contacts from both subunits, and GBR1 residues involved in ligand recognition. Lastly, our structural and functional data indicate that the GBR2 ectodomain adopts a constitutively open conformation, suggesting a structural asymmetry in the active state of GABAB receptor that is unique to the GABAergic system. PMID:22660477

  2. Effect of GABA(B) receptor agonist SKF97541 on cortical and hippocampal epileptic afterdischarges.

    PubMed

    Fábera, P; Mareš, P

    2014-01-01

    Activation of GABA(B) receptors leads to longer inhibitory postsynaptic potentials than activation of GABA(A) receptors. Therefore GABA(B) receptors may be a target for anticonvulsant therapy. The present study examined possible effects of GABA(B) receptor agonist SKF97541 on cortical and hippocampal epileptic afterdischarges (ADs). Epileptic ADs elicited by electrical stimulation of sensorimotor cortex or dorsal hippocampus were studied in adult male Wistar rats. Stimulation series were applied 6 times with 10- or 20-min interval. Either interval was efficient for reliable elicitation of cortical ADs but stimulation at 10-min intervals did not reliably elicit hippocampal ADs, many stimulations were without effect. SKF97541 in dose 1 mg/kg significantly prolonged cortical ADs. Duration of hippocampal ADs was not significantly changed by either dose of SKF97541 in spite of a marked myorelaxant effect of the higher dose. Our present data demonstrated that neither cortical nor hippocampal ADs in adult rats were suppressed by GABA(B) receptor agonist SKF97541. Proconvulsant effect on cortical ADs indicates a different role in these two brain structures. In addition, duration of refractory period for electrically-induced ADs in these two structures in adult rats is different. PMID:24702499

  3. Diminished Presynaptic GABAB Receptor Function in the Neocortex of a Genetic Model of Absence Epilepsy

    PubMed Central

    Inaba, Yugi; D’Antuono, Margherita; Bertazzoni, Giuliano; Biagini, Giuseppe; Avoli, Massimo

    2016-01-01

    Changes in GABAB receptor subunit expression have been recently reported in the neocortex of epileptic WAG/Rij rats that are genetically prone to experience absence seizures. These alterations may lead to hyperexcitability by down-regulating the function of presynaptic GABAB receptors in neocortical networks as suggested by a reduction in paired-pulse depression. Here, we tested further this hypothesis by analyzing the effects induced by the GABAB receptor agonist baclofen (0.1–10 μM) on the inhibitory events recorded in vitro from neocortical slices obtained from epileptic (>180 day-old) WAG/Rij and age-matched, non-epileptic control (NEC) rats. We found that higher doses of baclofen were required to depress pharmacologically isolated, stimulus-induced IPSPs generated by WAG/Rij neurons as compared to NEC. We also obtained similar evidence by comparing the effects of baclofen on the rate of occurrence of synchronous GABAergic events recorded by WAG/Rij and NEC neocortical slices treated with 4-aminopyridine + glutamatergic receptor antagonists. In conclusion, these data highlight a decreased function of presynaptic GABAB receptors in the WAG/Rij rat neocortex. We propose that this alteration may contribute to neocortical hyperexcitability and thus to absence seizures. PMID:19176980

  4. Opposite Effects of KCTD Subunit Domains on GABAB Receptor-mediated Desensitization*

    PubMed Central

    Seddik, Riad; Jungblut, Stefan P.; Silander, Olin K.; Rajalu, Mathieu; Fritzius, Thorsten; Besseyrias, Valérie; Jacquier, Valérie; Fakler, Bernd; Gassmann, Martin; Bettler, Bernhard

    2012-01-01

    GABAB receptors assemble from principle and auxiliary subunits. The principle subunits GABAB1 and GABAB2 form functional heteromeric GABAB(1,2) receptors that associate with homotetramers of auxiliary KCTD8, -12, -12b, or -16 (named after their K+ channel tetramerization domain) subunits. These auxiliary subunits constitute receptor subtypes with distinct functional properties. KCTD12 and -12b generate desensitizing receptor responses while KCTD8 and -16 generate largely non-desensitizing receptor responses. The structural elements of the KCTDs underlying these differences in desensitization are unknown. KCTDs are modular proteins comprising a T1 tetramerization domain, which binds to GABAB2, and a H1 homology domain. KCTD8 and -16 contain an additional C-terminal H2 homology domain that is not sequence-related to the H1 domains. No functions are known for the H1 and H2 domains. Here we addressed which domains and sequence motifs in KCTD proteins regulate desensitization of the receptor response. We found that the H1 domains in KCTD12 and -12b mediate desensitization through a particular sequence motif, T/NFLEQ, which is not present in the H1 domains of KCTD8 and -16. In addition, the H2 domains in KCTD8 and -16 inhibit desensitization when expressed C-terminal to the H1 domains but not when expressed as a separate protein in trans. Intriguingly, the inhibitory effect of the H2 domain is sequence-independent, suggesting that the H2 domain sterically hinders desensitization by the H1 domain. Evolutionary analysis supports that KCTD12 and -12b evolved desensitizing properties by liberating their H1 domains from antagonistic H2 domains and acquisition of the T/NFLEQ motif. PMID:23035119

  5. Role of GABAB Receptor and L-Arg in GABA-Induced Vasorelaxation in Non-diabetic and Streptozotocin-Induced Diabetic Rat Vessels

    PubMed Central

    Kharazmi, Fatemah; Soltani, Nepton; Rezaei, Sana; Keshavarz, Mansoor; Farsi, Leila

    2015-01-01

    Background: Hypertension is considered an independent risk factor for cardiovascular mortality in diabetic patients. The present study was designed to determine the role of gamma amino butyric acid B (GABAB) receptor and L-arginine (L-Arg) in GABA-induced vasorelaxation in normal and streptozotocin-induced diabetic rat vessels. Methods: Diabetes was induced by a single i.p. injection of streptozotocin (STZ, 60 mg/kg). Eight weeks later, superior mesenteric arteries of all groups were isolated and perfused according to the McGregor method. Results: Baseline perfusion pressure of STZ diabetic rats was significantly higher than non-diabetic rats in both intact and denuded endothelium. In the presence of faclofen, a selective GABAB receptor blocker, GABA-induced relaxation in intact and denuded endothelium mesenteric beds of STZ diabetic rats was suppressed, but this response in non-diabetic rats was not suppressed. Our results showed that in the presence of L-Arg, a nitric oxide precursor, GABA induced vasorelaxation in both diabetic and non-diabetic vessels. Conclusion: From the results of this study, it may be concluded that the vasorelaxatory effect of GABA in diabetic vessel is mediated by the GABAB receptor and nitric oxide, but it seems that in non-diabetic vessel GABAB receptor does not play any role in GABA-induced vasorelaxation, but nitric oxide induced GABA relaxation in non-diabetic vessel. PMID:25864813

  6. Inhibition of mechanosensitivity in visceral primary afferents by GABAB receptors involves calcium and potassium channels.

    PubMed

    Page, A J; O'Donnell, T A; Blackshaw, L A

    2006-01-01

    GABA(B) receptors inhibit mechanosensitivity of visceral afferents. This is associated with reduced triggering of events that lead to gastro-esophageal reflux, with important therapeutic consequences. In other neuronal systems, GABA(B) receptor activation may be linked via G-proteins to reduced N-type Ca(2+) channel opening, increased inward rectifier K(+) channel opening, plus effects on a number of intracellular messengers. Here we aimed to determine the role of Ca(2+) and K(+) channels in the inhibition of vagal afferent mechanoreceptor function by the GABA(B) receptor agonist baclofen. The responses of three types of ferret gastro-esophageal vagal afferents (mucosal, tension and tension mucosal receptors) to graded mechanical stimuli were investigated in vitro. The effects of baclofen (200 microM) alone on these responses were quantified, and the effects of baclofen in the presence of the G-protein-coupled inward rectifier potassium channel blocker Rb(+) (4.7 mM) and/or the N-type calcium channel blocker omega-conotoxin GVIA (0.1 microM). Baclofen inhibition of mucosal receptor mechanosensitivity was abolished by both blockers. Its inhibitory effect on tension mucosal receptors was partly reduced by both. The inhibitory effect of baclofen on tension receptors was unaffected. The data indicate that the inhibitory action of GABA(B) receptors is mediated via different pathways in mucosal, tension and tension mucosal receptors via mechanisms involving both N-type Ca(2+) channels and inwardly rectifying K(+) channels and others. PMID:16289839

  7. Resequencing of the auxiliary GABAB receptor subunit gene KCTD12 in chronic tinnitus

    PubMed Central

    Sand, P. G.; Langguth, B.; Itzhacki, J.; Bauer, A.; Geis, S.; Cárdenas-Conejo, Z. E.; Pimentel, V.; Kleinjung, T.

    2012-01-01

    Tinnitus is a common and often incapacitating hearing disorder marked by the perception of phantom sounds. Susceptibility factors remain largely unknown but GABAB receptor signaling has long been implicated in the response to treatment and, putatively, in the etiology of the disorder. We hypothesized that variation in KCTD12, the gene encoding an auxiliary subunit of GABAB receptors, could help to predict the risk of developing tinnitus. Ninety-five Caucasian outpatients with a diagnosis of chronic tinnitus were systematically screened for mutations in the KCTD12 open reading frame and the adjacent 3′ untranslated region by Sanger sequencing. Allele frequencies were determined for 14 known variants of which three (rs73237446, rs34544607, and rs41287030) were polymorphic. When allele frequencies were compared to data from a large reference population of European ancestry, rs34544607 was associated with tinnitus (p = 0.04). However, KCTD12 genotype did not predict tinnitus severity (p = 0.52) and the association with rs34544607 was weakened after screening 50 additional cases (p = 0.07). Pending replication in a larger cohort, KCTD12 may act as a risk modifier in chronic tinnitus. Issues that are yet to be addressed include the effects of neighboring variants, e.g., in the KCTD12 gene regulatory region, plus interactions with variants of GABAB1 and GABAB2. PMID:22654739

  8. CGP 36,742, an orally active GABAB receptor antagonist, facilitates memory in a social recognition test in rats.

    PubMed

    Mondadori, C; Moebius, H J; Zingg, M

    1996-05-01

    CGP 36,742, an orally active GABAB receptor antagonist, improves the retention performance of rats in a social recognition test. This effect is detectable over a very wide range of doses (0.03 to 300 mg/kg, p.o.). Considering its binding (32 mumol affinity for the GABAB site) the surprisingly potent activity of CGP 36,742 makes it appear quite possible that the effect is mediated by an as yet unknown receptor subtype. PMID:8762176

  9. Association of Rgs7/Gβ5 complexes with Girk channels and GABAB receptors in hippocampal CA1 pyramidal neurons.

    PubMed

    Fajardo-Serrano, Ana; Wydeven, Nicole; Young, Daniele; Watanabe, Masahiko; Shigemoto, Ryuichi; Martemyanov, Kirill A; Wickman, Kevin; Luján, Rafael

    2013-12-01

    In the hippocampus, signaling through G protein-coupled receptors is modulated by Regulators of G protein signaling (Rgs) proteins, which act to stimulate the rate of GTP hydrolysis, and consequently, G protein inactivation. The R7-Rgs subfamily selectively deactivates the G(i/o)-class of Gα subunits that mediate the action of several GPCRs. Here, we used co-immunoprecipitation, electrophysiology and immunoelectron microscopy techniques to investigate the formation of macromolecular complexes and spatial relationship of Rgs7/Gβ5 complexes and its prototypical signaling partners, the GABAB receptor and Girk channel. Co-expression of recombinant GABAB receptors and Girk channels in combination with co-immunoprecipitation experiments established that the Rgs7/Gβ5 forms complexes with GABAB receptors or Girk channels. Using electrophysiological experiments, we found that GABAB -Girk current deactivation kinetics was markedly faster in cells coexpressing Rgs7/Gβ5. At the electron microscopic level, immunolabeling for Rgs7 and Gβ5 proteins was found primarily in the dendritic layers of the hippocampus and showed similar distribution patterns. Immunoreactivity was mostly localized along the extrasynaptic plasma membrane of dendritic shafts and spines of pyramidal cells and, to a lesser extent, to that of presynaptic terminals. Quantitative analysis of immunogold particles for Rgs7 and Gβ5 revealed an enrichment of the two proteins around excitatory synapses on dendritic spines, virtually identical to that of Girk2 and GABAB1 . These data support the existence of macromolecular complexes composed of GABAB receptor-G protein-Rgs7-Girk channels in which Rgs7 and Gβ5 proteins may preferentialy modulate GABAB receptor signaling through the deactivation of Girk channels on dendritic spines. In contrast, Rgs7 and Girk2 were associated but mainly segregated from GABAB1 in dendritic shafts, where Rgs7/Gβ5 signaling complexes might modulate Girk-dependent signaling via a

  10. Association of Rgs7/Gβ5 complexes with Girk channels and GABAB receptors in hippocampal CA1 pyramidal neurons

    PubMed Central

    Fajardo-Serrano, Ana; Wydeven, Nicole; Young, Daniele; Watanabe, Masahiko; Shigemoto, Ryuichi; Martemyanov, Kirill A.; Wickman, Kevin; Luján, Rafael

    2013-01-01

    In the hippocampus, signalling through G protein-coupled receptors is modulated by Regulators of G protein Signalling (Rgs) proteins, which act to stimulate the rate of GTP hydrolysis, and consequently, G protein inactivation. The R7-Rgs subfamily selectively deactivates the Gi/o-class of Gα subunits that mediate the action of several GPCRs. Here, we used co-immunoprecipitation, electrophysiology and immunoelectron microscopy techniques to investigate the formation of macromolecular complexes and spatial relationship of Rgs7/Gβ5 complexes and its prototypical signalling partners, the GABAB receptor and Girk channel. Co-expression of recombinant GABAB receptors and Girk channels in combination with co-immunoprecipitation experiments established that the Rgs7/Gβ5 forms complexes with GABAB receptors or Girk channels. Using electrophysiological experiments, we found that GABAB-Girk current deactivation kinetics was markedly faster in cells co-expressing Rgs7/Gβ5. At the electron microscopic level, immunolabelling for Rgs7 and Gβ5 proteins was found primarily in the dendritic layers of the hippocampus and showed similar distribution patterns. Immunoreactivity was mostly localized along the extrasynaptic plasma membrane of dendritic shafts and spines of pyramidal cells and, to a lesser extent, to that of presynaptic terminals. Quantitative analysis of immunogold particles for Rgs7 and Gβ5 revealed an enrichment of the two proteins around excitatory synapses on dendritic spines, virtually identical to that of Girk2 and GABAB1. These data support the existence of macromolecular complexes composed of GABAB receptor-G protein-Rgs7-Girk channels, in which Rgs7 and Gβ5 proteins may preferentially modulate GABAB receptor signalling through the deactivation of Girk channels on dendritic spines. In contrast, Rgs7 and Girk2 were associated but mainly segregated from GABAB1 in dendritic shafts, where Rgs7/Gβ5 signalling complexes might modulate Girk-dependent signalling

  11. Sodium salicylate reduces the level of GABAB receptors in the rat's inferior colliculus.

    PubMed

    Butt, S; Ashraf, F; Porter, L A; Zhang, H

    2016-03-01

    Previous studies have indicated that sodium salicylate (SS) can cause hearing abnormalities through affecting the central auditory system. In order to understand central effects of the drug, we examined how a single intraperitoneal injection of the drug changed the level of subunits of the type-B γ-aminobutyric acid receptor (GABAB receptor) in the rat's inferior colliculus (IC). Immunohistochemical and western blotting experiments were conducted three hours following a drug injection, as previous studies indicated that a tinnitus-like behavior could be reliably induced in rats within this time period. Results revealed that both subunits of the receptor, GABABR1 and GABABR2, reduced their level over the entire area of the IC. Such a reduction was observed in both cell body and neuropil regions. In contrast, no changes were observed in other brain structures such as the cerebellum. Thus, a coincidence existed between a structure-specific reduction in the level of GABAB receptor subunits in the IC and the presence of a tinnitus-like behavior. This coincidence likely suggests that a reduction in the level of GABAB receptor subunits was involved in the generation of a tinnitus-like behavior and/or used by the nervous system to restore normal hearing following application of SS. PMID:26705739

  12. Expression of GABAB receptors in magnocellular neurosecretory cells of male, virgin female and lactating rats.

    PubMed

    Richards, D S; Villalba, R M; Alvarez, F J; Stern, J E

    2005-07-01

    GABA is one of the key neurotransmitters that regulate the firing activity of neurones in the supraoptic (SON) and paraventricular (PVN) nuclei. In the present study, we used immunohistochemical techniques to study the distribution and subcellular localisation of metabotropic GABA(B) receptors in magnocellular neurones in the SON and PVN. Robust GABA(B) receptor immunoreactivity (GABA(B)R; both subunit 1 and subunit 2 of the heterodimer), was observed in the SON and PVN. At the light microcope level, GABA(B)R immonoreactivity displayed a clustered pattern localised both intracytoplasmically and at the plasma membrane. Densitometry analysis indicated that GABA(B)R immunoreactivity was significantly more intense in vasopressin cells than in oxytocin cells, both in male, virgin female and lactating rats, and was denser in males than in virgin females. Light and electron microscope studies indicated that cytoplasmic GABA(B)R was localised in various organelles, including the Golgi, early endosomes and lysosomes, suggesting the cycling of the receptor within the endocytic and trafficking pathways. Some smaller clusters at the level of the cell plasma membrane were apposed to glutamic acid decarboxylase 67 immunoreactive boutons, and appeared to be colocalised with gephyrin, a constituent protein of the postsynaptic density at inhibitory synapses. The presence of GABA(B)R immunoreactivity at synaptic and extrasynaptic sites was supported by electron microscopy. These results provide anatomical evidence for the expression of postsynaptic GABA(B) receptors in magnocellular neurosecretory cells. PMID:15946159

  13. Gamma-hydroxybutyrate (GHB) induces cognitive deficits and affects GABAB receptors and IGF-1 receptors in male rats.

    PubMed

    Johansson, Jenny; Grönbladh, Alfhild; Hallberg, Mathias

    2014-08-01

    In recent years, the abuse of the club drug gamma-hydroxybutyrate (GHB) has become increasingly popular among adolescents. The drug induces euphoria but can also result in sedation, anaesthesia as well as short-term amnesia. In addition, the abuse of GHB causes cognitive impairments and the mechanism by which GHB induces these impairments is not clarified. The present study investigates the impact of GHB treatment on spatial learning and memory using a water maze (WM) test in rats. Furthermore, the behavioural data is combined with an autoradiographic analysis of the GABAB and the IGF-1 receptor systems. The results demonstrate that the animals administered with GHB display an impaired performance in the WM test as compared to controls. In addition, significant alterations in GABAB and IGF-1 receptor density as well as GABAB receptor functionality, were observed in several brain regions associated with cognitive functions e.g. hippocampus. To conclude, our findings suggest that GHB treatment can affect spatial learning and memory, and that this outcome at least to some extent is likely to involve both GABAB and IGF-1 receptors. PMID:24786330

  14. Evidence of a pathogenic role for CD8+ T cells in anti-GABAB receptor limbic encephalitis

    PubMed Central

    Golombeck, Kristin S.; Bönte, Kathrin; Mönig, Constanze; van Loo, Karen M.; Hartwig, Marvin; Schwindt, Wolfram; Widman, Guido; Lindenau, Matthias; Becker, Albert J.; Glatzel, Markus; Elger, Christian E.; Wiendl, Heinz; Meuth, Sven G.; Lohmann, Hubertus; Gross, Catharina C.

    2016-01-01

    Objectives: To characterize the cellular autoimmune response in patients with γ-aminobutyric acid (GABA)B receptor antibody–associated limbic encephalitis (GABAB-R LE). Methods: Patients underwent MRI, extensive neuropsychological assessment, and multiparameter flow cytometry of peripheral blood and CSF. Results: We identified a series of 3 cases of nonparaneoplastic GABAB-R LE and one case of paraneoplastic GABAB-R LE associated with small cell lung cancer. All patients exhibited temporal lobe epilepsy, neuropsychological deficits, and MRI findings typical of LE. Absolute numbers of CD19+ B cells, CD138+ CD19+ plasma cells, CD4+ T cells, activated HLADR+ CD4+ T cells, as well as CD8+ T cells and HLADR+ CD8+ T cells did not differ in peripheral blood but were elevated in CSF of patients with GABAB-R LE compared to controls. Augmented absolute numbers of CD138+ CD19+ plasma cells and activated HLADR+ CD8+ T cells in CSF corresponded to higher overall neuropsychological and memory deficits in patients with GABAB-R LE. A histologic specimen of one patient following selective amygdalohippocampectomy revealed perivascular infiltrates of CD138+ plasma cells and CD4+ T cells, whereas cytotoxic CD8+ T cells were detected within the brain parenchyma in close contact to neurons. Conclusion: Our data suggest a pathogenic role for CD8+ T cells in addition to the established role of plasma cell–derived autoantibodies in GABAB-R LE. PMID:27213174

  15. Human brain somatostatin release from isolated cortical nerve endings and its modulation through GABAB receptors.

    PubMed Central

    Bonanno, G.; Gemignani, A.; Schmid, G.; Severi, P.; Cavazzani, P.; Raiteri, M.

    1996-01-01

    1. The release of somatostatin-like immunoreactivity (SRIF-LI) in the human brain was studied in synaptosomal preparations from fresh neocortical specimens obtained from patients undergoing neurosurgery to remove deeply sited tumours. 2. The basal outflow of SRIF-LI from superfused synaptosomes was increased about 3 fold during exposure to a depolarizing medium containing 15 mM KCl. The K(+)-evoked overflow of SRIF-LI was almost totally dependent on the presence of Ca2+ in the superfusion medium. 3. The GABAB receptor agonist, (-)-baclofen (0.3 - 100 microM), inhibited the overflow of SRIF-LI in a concentration-dependent manner (EC50 = 1.84 +/- 0.20 microM; maximal effect: about 50%). The novel GABAB receptor ligand, 3-aminopropyl(difluoromethyl)phosphinic acid (CGP 47656) mimicked (-)-baclofen in inhibiting the SRIF-LI overflow (EC50 = 3.06 +/- 0.52 microM; maximal effect: about 50%), whereas the GABAA receptor agonist, muscimol, was ineffective up to 100 microM. 4. The inhibition by 10 microM (-)-baclofen of the K(+)-evoked SRIF-LI overflow was concentration-dependently prevented by two selective GABAB receptor antagonists, 3-amino-propyl (diethoxymethyl)-phosphinic acid (CGP 35348) (IC50 = 24.40 +/- 2.52 microM) and [3-[[(3,4-dichlorophenyl) methyl]amino]propyl] (diethoxymethyl) phosphinic acid (CGP 52432) (IC50 = 0.06 +/- 0.005 microM). 5. The inhibition of SRIF-LI overflow caused by 10 microM CGP 47656 was abolished by 1 microM CGP 52432. 6. When human synaptosomes were labelled with [3H]-GABA and depolarized in superfusion with 15 mM KCl, the inhibition by 10 microM (-)-baclofen of the depolarization-evoked [3H]-GABA overflow was largely prevented by 10 microM CGP 47656 which therefore behaved as an autoreceptor antagonist. 7. In conclusion: (a) the characteristics of SRIF-LI release from synaptosomal preparations of human neocortex are compatible with a neuronal origin; (b) the nerve terminals releasing the neuropeptide possess inhibitory receptors of the

  16. Prolonged activation of NMDA receptors promotes dephosphorylation and alters postendocytic sorting of GABAB receptors

    PubMed Central

    Terunuma, Miho; Vargas, Karina J.; Wilkins, Megan E.; Ramírez, Omar A.; Jaureguiberry-Bravo, Matías; Pangalos, Menelas N.; Smart, Trevor G.; Moss, Stephen J.; Couve, Andrés

    2010-01-01

    Slow and persistent synaptic inhibition is mediated by metabotropic GABAB receptors (GABABRs). GABABRs are responsible for the modulation of neurotransmitter release from presynaptic terminals and for hyperpolarization at postsynaptic sites. Postsynaptic GABABRs are predominantly found on dendritic spines, adjacent to excitatory synapses, but the control of their plasma membrane availability is still controversial. Here, we explore the role of glutamate receptor activation in regulating the function and surface availability of GABABRs in central neurons. We demonstrate that prolonged activation of NMDA receptors (NMDA-Rs) leads to endocytosis, a diversion from a recycling route, and subsequent lysosomal degradation of GABABRs. These sorting events are paralleled by a reduction in GABABR-dependent activation of inwardly rectifying K+ channel currents. Postendocytic sorting is critically dependent on phosphorylation of serine 783 (S783) within the GABABR2 subunit, an established substrate of AMP-dependent protein kinase (AMPK). NMDA-R activation leads to a rapid increase in phosphorylation of S783, followed by a slower dephosphorylation, which results from the activity of AMPK and protein phosphatase 2A, respectively. Agonist activation of GABABRs counters the effects of NMDA. Thus, NMDA-R activation alters the phosphorylation state of S783 and acts as a molecular switch to decrease the abundance of GABABRs at the neuronal plasma membrane. Such a mechanism may be of significance during synaptic plasticity or pathological conditions, such as ischemia or epilepsy, which lead to prolonged activation of glutamate receptors. PMID:20643948

  17. Presynaptic GABAB receptors reduce transmission at parabrachial synapses in the lateral central amygdala by inhibiting N-type calcium channels

    PubMed Central

    Delaney, A.J.; Crane, J.W.

    2016-01-01

    The nocioceptive information carried by neurons of the pontine parabrachial nucleus to neurons of the lateral division of the central amydala (CeA-L) is thought to contribute to the affective components of pain and is required for the formation of conditioned-fear memories. Importantly, excitatory transmission between parabrachial axon terminals and CeA-L neurons can be inhibited by a number of presynaptic receptors linked to Gi/o-type G-proteins, including α2-adrenoceptors and GABAB receptors. While the intracellular signalling pathway responsible for α2-adrenoceptor inhibition of synaptic transmission at this synapse is known, the mechanism by which GABAB receptors inhibits transmission has not been determined. The present study demonstrates that activation of presynaptic GABAB receptors reduces excitatory transmission between parabrachial axon terminals and CeA-L neurons by inhibiting N-type calcium channels. While the involvement of Gβγ subunits in mediating the inhibitory effects of GABAB receptors on N-type calcium channels is unclear, this inhibition does not involve Gβγ-independent activation of pp60C-src tyrosine kinase. The results of this study further enhance our understanding of the modulation of the excitatory input from parabrachial axon terminals to CeA-L neurons and indicate that presynaptic GABAB receptors at this synapse could be valuable therapeutic targets for the treatment of fear- and pain-related disorders. PMID:26755335

  18. Presynaptic GABAB receptors reduce transmission at parabrachial synapses in the lateral central amygdala by inhibiting N-type calcium channels.

    PubMed

    Delaney, A J; Crane, J W

    2016-01-01

    The nocioceptive information carried by neurons of the pontine parabrachial nucleus to neurons of the lateral division of the central amydala (CeA-L) is thought to contribute to the affective components of pain and is required for the formation of conditioned-fear memories. Importantly, excitatory transmission between parabrachial axon terminals and CeA-L neurons can be inhibited by a number of presynaptic receptors linked to Gi/o-type G-proteins, including α2-adrenoceptors and GABAB receptors. While the intracellular signalling pathway responsible for α2-adrenoceptor inhibition of synaptic transmission at this synapse is known, the mechanism by which GABAB receptors inhibits transmission has not been determined. The present study demonstrates that activation of presynaptic GABAB receptors reduces excitatory transmission between parabrachial axon terminals and CeA-L neurons by inhibiting N-type calcium channels. While the involvement of Gβγ subunits in mediating the inhibitory effects of GABAB receptors on N-type calcium channels is unclear, this inhibition does not involve Gβγ-independent activation of pp60C-src tyrosine kinase. The results of this study further enhance our understanding of the modulation of the excitatory input from parabrachial axon terminals to CeA-L neurons and indicate that presynaptic GABAB receptors at this synapse could be valuable therapeutic targets for the treatment of fear- and pain-related disorders. PMID:26755335

  19. The interactive role of CB(1) and GABA(B) receptors in hippocampal synaptic plasticity in rats.

    PubMed

    Nazari, Masoumeh; Komaki, Alireza; Karamian, Ruhollah; Shahidi, Siamak; Sarihi, Abdolrahman; Asadbegi, Masoumeh

    2016-01-01

    Long-term potentiation (LTP) of synaptic transmission is a cellular process underlying learning and memory. Cannabinoids are known to be powerful modulators of this kind of synaptic plasticity. Changes in GABAergic inhibition have also been shown to affect synaptic plasticity in the hippocampus. GABA receptor type B (GABAB) and cannabinoid receptor type 1 (CB1) exhibit overlapping anatomical localization in some brain areas including the hippocampus. CB1 and GABAB are also localized to the same cells and share a common signaling pathway in some brain areas. In this study, we examined the hippocampal effects of co-administrating AM251 and CGP55845, which are CB1 and GABAB antagonists, respectively, on LTP induction in the dentate gyrus (DG) of rats. LTP in the hippocampal area was induced by high-frequency stimulation (HFS) of the perforant path. Our results showed that HFS coupled with administration of the CB1 antagonist increased both the population spike (PS) amplitude and field excitatory post-synaptic potential (fEPSP). Conversely, the GABAB antagonist decreased these parameters along with decreased LTP induction. We also demonstrated that the co-administration of CB1 and GABAB antagonists had different effects on the PS amplitude and fEPSP slope. It is likely that GABAB receptor antagonists modulate cannabinoid outputs that cause a decrease in synaptic plastisity, while in the simultaneous consumption of two antagonists, CB1 antagonists can alter the release of GABA which in turn results in enhancement of LTP induction. These findings suggest that there are functional interactions between the CB1 and GABAB receptor in the hippocampus. PMID:26611204

  20. Suppression of ATP-induced excitability in rat small-diameter trigeminal ganglion neurons by activation of GABAB receptor.

    PubMed

    Takeda, Mamoru; Ikeda, Mizuho; Takahashi, Masayuki; Kanazawa, Takuya; Nasu, Masanori; Matsumoto, Shigeji

    2013-09-01

    The aim of the present study was to investigate whether a GABAB receptor agonist could modulate ATP-activated neuronal excitability of nociceptive TRG neurons using perforated whole-cell patch-clamp and immunohistochemical techniques. Immunohistochemical analysis revealed that 86% of P2X3 receptor-immunoreactive, small-diameter TRG neurons co-expressed GABAB receptor. Under voltage-clamp conditions (Vh=-60mV), application of ATP activated the inward current in acutely isolated rat TRG neurons in a dose-dependent manner (10-50 μM) and this current could be blocked by pyridoxal-phosphate-6-azophenyl-27,47-disulfonic acid (PPADS) (10 μM), a selective P2 purinoreceptor antagonist. The peak amplitude of ATP-activated currents was significantly inhibited after application of GABAB receptor agonist, baclofen (10-50 μM), in a concentration-dependent and reversible manner. The baclofen-induced inhibition of ATP-activated current was abolished by co-application of 3-amino-2 (4-chlorophenyl)-2hydroxypropysufonic acid) saclofen, a GABAB receptor antagonist (50 μM). Under current-clamp conditions, application of 20 μM ATP significantly depolarized the membrane potential resulting in increased mean action potential frequencies, and these ATP-induced effects were significantly inhibited by baclofen and these effects were antagonized by co-application of saclofen. Together, the results suggested that GABAB receptor activation could inhibit the ATP-induced excitability of small-diameter TRG neurons activated through the P2X3 receptor. Thus, the interaction between P2X3 and GABAB receptors of small-diameter TRG neuronal cell bodies is a potential therapeutic target for the treatment of trigeminal nociception. PMID:24004472

  1. Evaluation of peripheral versus central effects of GABAB receptor activation using a novel, positive allosteric modulator of the GABAB receptor ADX71943, a pharmacological tool compound with a fully peripheral activity profile

    PubMed Central

    Kalinichev, M; Donovan-Rodriguez, T; Girard, F; Riguet, E; Rouillier, M; Bournique, B; Haddouk, H; Mutel, V; Poli, S

    2014-01-01

    Background and Purpose The GABAB receptor agonist, baclofen, has shown promising effects in patients suffering from pain, post-traumatic stress disorder, alcoholism, overactive bladder and gastroesophageal reflux disease. However, baclofen's short duration of action and side effects limit its wider use. Here we characterized a novel, GABAB receptor positive allosteric modulator (PAM) ADX71943. Experimental Approach In vitro, ADX71943 was assessed for pharmacological activity and selectivity using recombinant and native GABAB receptors. In vivo ADX71943 was assessed in the acetic acid-induced writhing (AAW) test in mice and formalin tests (FTs) in mice and rats. Marble burying (MB) and elevated plus maze (EPM) tests, rotarod, spontaneous locomotor activity (sLMA) and body temperature (BT) tests in mice and rats were used to investigate centrally-mediated effects. Key Results In vitro, in the presence of GABA, ADX71943 increased the potency and efficacy of agonists and showed selectivity at the GABAB receptor. ADX71943 reduced pain-associated behaviours in AAW; an effect blocked by GABAB receptor antagonist CGP63360. ADX71943 reduced pain in the FT in mice and rats, but was inactive in the MB and EPM despite reaching high concentrations in plasma. ADX71943 had no effect on BT, rotarod and sLMA. Conclusions and Implications ADX71943 showed consistent and target-related efficacy in tests of disorders that have a significant peripheral component (acute and chronic pain), while having no effect in those associated with centrally-mediated anxiety-like reactivity and side effects. Thus, ADX71943 is a useful pharmacological tool for delineation of peripherally- versus centrally-mediated effects of GABAB receptor activation. PMID:24923436

  2. The positive allosteric GABAB receptor modulator rac-BHFF enhances baclofen-mediated analgesia in neuropathic mice.

    PubMed

    Zemoura, Khaled; Ralvenius, William T; Malherbe, Pari; Benke, Dietmar

    2016-09-01

    Neuropathic pain is associated with impaired inhibitory control of spinal dorsal horn neurons, which are involved in processing pain signals. The metabotropic GABAB receptor is an important component of the inhibitory system and is highly expressed in primary nociceptors and intrinsic dorsal horn neurons to control their excitability. Activation of GABAB receptors with the orthosteric agonist baclofen effectively reliefs neuropathic pain but is associated with severe side effects that prevent its widespread application. The recently developed positive allosteric GABAB receptor modulators lack most of these side effects and are therefore promising drugs for the treatment of pain. Here we tested the high affinity positive allosteric modulator rac-BHFF for its ability to relief neuropathic pain induced by chronic constriction of the sciatic nerve in mice. rac-BHFF significantly increased the paw withdrawal threshold to mechanical stimulation in healthy mice, indicating an endogenous GABABergic tone regulating the sensitivity to mechanical stimuli. Surprisingly, rac-BHFF displayed no analgesic activity in neuropathic mice although GABAB receptor expression was not affected in the dorsal horn as shown by quantitative receptor autoradiography. However, activation of spinal GABAB receptors by intrathecal injection of baclofen reduced hyperalgesia and its analgesic effect was considerably potentiated by co-application of rac-BHFF. These results indicate that under conditions of neuropathic pain the GABAergic tone is too low to provide a basis for allosteric modulation of GABAB receptors. However, allosteric modulators would be well suited as an add-on to reduce the dose of baclofen required to achieve analgesia. PMID:27108932

  3. GABAB receptor-mediated contractile effects resistant to tetrodotoxin in isolated cat ileum.

    PubMed

    Pencheva, N; Venkova, K; Radomirov, R

    1990-06-21

    The effects of gamma-aminobutyric acid (GABA) and GABAergic drugs were studied on longitudinal strips from cat terminal ileum prepared after removing the myenteric plexus. GABA and baclofen exerted concentration-dependent contractile effects. Muscimol was ineffective, and bicuculline did not antagonize the effect of GABA. The complete elimination of the neural input to the smooth muscle cells by tetrodotoxin failed to prevent the action of GABA and baclofen. Pharmacological analyses of the effects indicated the existence of GABAB receptors on the smooth muscle cells in the longitudinal layer of cat terminal ileum. PMID:2169425

  4. Adaptation in sound localization: from GABA(B) receptor-mediated synaptic modulation to perception.

    PubMed

    Stange, Annette; Myoga, Michael H; Lingner, Andrea; Ford, Marc C; Alexandrova, Olga; Felmy, Felix; Pecka, Michael; Siveke, Ida; Grothe, Benedikt

    2013-12-01

    Across all sensory modalities, the effect of context-dependent neural adaptation can be observed at every level, from receptors to perception. Nonetheless, it has long been assumed that the processing of interaural time differences, which is the primary cue for sound localization, is nonadaptive, as its outputs are mapped directly onto a hard-wired representation of space. Here we present evidence derived from in vitro and in vivo experiments in gerbils indicating that the coincidence-detector neurons in the medial superior olive modulate their sensitivity to interaural time differences through a rapid, GABA(B) receptor-mediated feedback mechanism. We show that this mechanism provides a gain control in the form of output normalization, which influences the neuronal population code of auditory space. Furthermore, psychophysical tests showed that the paradigm used to evoke neuronal GABA(B) receptor-mediated adaptation causes the perceptual shift in sound localization in humans that was expected on the basis of our physiological results in gerbils. PMID:24141311

  5. GABAergic Afferents activate both GABAA and GABAB receptors in mouse substantia nigra dopaminergic neurons in vivo

    PubMed Central

    Brazhnik, Elena; Shah, Fulva; Tepper, James M.

    2008-01-01

    Most in vivo electrophysiological studies of substantia nigra have employed rats. With the recent proliferation of the use of mice for in vitro neurophysiological studies due to the availability of various genetically modified strains to identify the roles of various channels and proteins in neuronal function, it is crucial to obtain data on in vivo responses in mice to verify that the in vitro results reflect functioning of systems comparable to those that have been well studied in rat. Inhibitory responses of rat nigral dopaminergic neurons by stimulation of afferents from striatum, globus pallidus or pars reticulata have been shown to be mediated predominantly or exclusively by GABAA receptors. This is puzzling given the substantial expression of GABAB receptors and the ubiquitous appearance of GABAB synaptic responses in rat dopaminergic neurons in vitro. In the present study we studied electrically evoked GABAergic inhibition in nigral dopaminergic neurons in C57BL/6J mice. Stimulation of the three major GABAergic inputs elicited stronger and longer lasting inhibitory responses than those seen in rats. The early inhibition was GABAA mediated, whereas the later component, absent in rats, was GABAB mediated and selectively enhanced by GABA uptake inhibition. Striatal-evoked inhibition exhibited a slower onset and a weaker initial component compared to inhibition from globus pallidus or substantia nigra pars reticulata. These results are discussed with respect to differences in the size and neuronal density of the rat and mouse brain, and the different sites of synaptic contact of the synapses from the three GABAergic afferents. PMID:18842898

  6. GABAB receptor modulation of serotonin neurons in the dorsal raphé nucleus and escalation of aggression in mice

    PubMed Central

    Takahashi, Aki; Shimamoto, Akiko; Boyson, Christopher O.; DeBold, Joseph F.; Miczek, Klaus A.

    2010-01-01

    The serotonin (5-HT) system in the brain has been studied more than any other neurotransmitter for its role in the neurobiological basis of aggression. However, which mechanisms modulate the 5-HT system to promote escalated aggression is not clear. We here explore the role of GABAergic modulation in the raphé nuclei, from where most 5-HT in the forebrain originates, on escalated aggression in male mice. Pharmacological activation of GABAB, but not GABAA, receptors in the dorsal raphé nucleus (DRN) escalated aggressive behaviors. In contrast, GABA agonists did not escalate aggressive behaviors after microinjection into the median raphé nucleus (MRN). The aggression-heightening effect of the GABAB agonist baclofen depended on the activation of 5-HT neurons in the DRN because it was blocked by co-administration of the 5-HT1A agonist 8-OH-DPAT, which acts on autoreceptors and inhibits 5-HT neural activity. In vivo microdialysis showed that GABAB activation in the DRN increased extracellular 5-HT level in the medial prefrontal cortex (mPFC). This may be due to an indirect action via presynaptic GABAB receptors. The presynaptic GABAB receptors suppress Ca2+ channel activity and inhibit neurotransmission, and the co-administration of N-type Ca2+ channel blocker facilitated the effect of baclofen. These findings suggest that the indirect disinhibition of 5-HT neuron activity by presynaptic GABAB receptors on non-5-HT neurons in the DRN is one of the neurobiological mechanisms of escalated aggression. PMID:20810897

  7. GABAB receptor deficiency causes failure of neuronal homeostasis in hippocampal networks.

    PubMed

    Vertkin, Irena; Styr, Boaz; Slomowitz, Edden; Ofir, Nir; Shapira, Ilana; Berner, David; Fedorova, Tatiana; Laviv, Tal; Barak-Broner, Noa; Greitzer-Antes, Dafna; Gassmann, Martin; Bettler, Bernhard; Lotan, Ilana; Slutsky, Inna

    2015-06-23

    Stabilization of neuronal activity by homeostatic control systems is fundamental for proper functioning of neural circuits. Failure in neuronal homeostasis has been hypothesized to underlie common pathophysiological mechanisms in a variety of brain disorders. However, the key molecules regulating homeostasis in central mammalian neural circuits remain obscure. Here, we show that selective inactivation of GABAB, but not GABA(A), receptors impairs firing rate homeostasis by disrupting synaptic homeostatic plasticity in hippocampal networks. Pharmacological GABA(B) receptor (GABA(B)R) blockade or genetic deletion of the GB(1a) receptor subunit disrupts homeostatic regulation of synaptic vesicle release. GABA(B)Rs mediate adaptive presynaptic enhancement to neuronal inactivity by two principle mechanisms: First, neuronal silencing promotes syntaxin-1 switch from a closed to an open conformation to accelerate soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly, and second, it boosts spike-evoked presynaptic calcium flux. In both cases, neuronal inactivity removes tonic block imposed by the presynaptic, GB(1a)-containing receptors on syntaxin-1 opening and calcium entry to enhance probability of vesicle fusion. We identified the GB(1a) intracellular domain essential for the presynaptic homeostatic response by tuning intermolecular interactions among the receptor, syntaxin-1, and the Ca(V)2.2 channel. The presynaptic adaptations were accompanied by scaling of excitatory quantal amplitude via the postsynaptic, GB(1b)-containing receptors. Thus, GABA(B)Rs sense chronic perturbations in GABA levels and transduce it to homeostatic changes in synaptic strength. Our results reveal a novel role for GABA(B)R as a key regulator of population firing stability and propose that disruption of homeostatic synaptic plasticity may underlie seizure's persistence in the absence of functional GABA(B)Rs. PMID:26056260

  8. GABAB receptor deficiency causes failure of neuronal homeostasis in hippocampal networks

    PubMed Central

    Vertkin, Irena; Styr, Boaz; Slomowitz, Edden; Ofir, Nir; Shapira, Ilana; Berner, David; Fedorova, Tatiana; Laviv, Tal; Barak-Broner, Noa; Greitzer-Antes, Dafna; Gassmann, Martin; Bettler, Bernhard; Lotan, Ilana; Slutsky, Inna

    2015-01-01

    Stabilization of neuronal activity by homeostatic control systems is fundamental for proper functioning of neural circuits. Failure in neuronal homeostasis has been hypothesized to underlie common pathophysiological mechanisms in a variety of brain disorders. However, the key molecules regulating homeostasis in central mammalian neural circuits remain obscure. Here, we show that selective inactivation of GABAB, but not GABAA, receptors impairs firing rate homeostasis by disrupting synaptic homeostatic plasticity in hippocampal networks. Pharmacological GABAB receptor (GABABR) blockade or genetic deletion of the GB1a receptor subunit disrupts homeostatic regulation of synaptic vesicle release. GABABRs mediate adaptive presynaptic enhancement to neuronal inactivity by two principle mechanisms: First, neuronal silencing promotes syntaxin-1 switch from a closed to an open conformation to accelerate soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly, and second, it boosts spike-evoked presynaptic calcium flux. In both cases, neuronal inactivity removes tonic block imposed by the presynaptic, GB1a-containing receptors on syntaxin-1 opening and calcium entry to enhance probability of vesicle fusion. We identified the GB1a intracellular domain essential for the presynaptic homeostatic response by tuning intermolecular interactions among the receptor, syntaxin-1, and the CaV2.2 channel. The presynaptic adaptations were accompanied by scaling of excitatory quantal amplitude via the postsynaptic, GB1b-containing receptors. Thus, GABABRs sense chronic perturbations in GABA levels and transduce it to homeostatic changes in synaptic strength. Our results reveal a novel role for GABABR as a key regulator of population firing stability and propose that disruption of homeostatic synaptic plasticity may underlie seizure's persistence in the absence of functional GABABRs. PMID:26056260

  9. Presynaptic GABAB Receptors Regulate Experience-Dependent Development of Inhibitory Short-Term Plasticity

    PubMed Central

    Kotak, Vibhakar C.; Sanes, Dan H.

    2010-01-01

    Short-term changes in synaptic gain support information processing throughout the CNS, yet we know little about the developmental regulation of such plasticity. Here we report that auditory experience is necessary for the normal maturation of synaptic inhibitory short-term plasticity (iSTP) in the auditory cortex, and that presynaptic GABAB receptors regulate this development. Moderate or severe hearing loss was induced in gerbils, and iSTP was characterized by measuring inhibitory synaptic current amplitudes in response to repetitive stimuli. We reveal a profound developmental shift of iSTP from depressing to facilitating after the onset of hearing. Even moderate hearing loss prevented this shift. This iSTP change was mediated by a specific class of inhibitory interneurons, the low-threshold spiking cells. Further, using paired recordings, we reveal that presynaptic GABAB receptors at interneuron-pyramidal connections regulate iSTP in an experience-dependent manner. This novel synaptic mechanism may support the emergence of mature temporal processing in the auditory cortex. PMID:20164356

  10. The role of GABAB receptors in the vestibular oculomotor system in mice.

    PubMed

    Shimizu, Naoki; Wood, Scott; Kushiro, Keisuke; Perachio, Adrian; Makishima, Tomoko

    2016-04-01

    Systemic administration of a gamma-amino butyric acid type B (GABAB) receptor agonist, baclofen, affects various physiological and psychological processes. To date, the effects on oculomotor system have been well characterized in primates, however those in mice have not been explored. In this study, we investigated the effects of baclofen focusing on vestibular-related eye movements. Two rotational paradigms, i.e. sinusoidal rotation and counter rotation were employed to stimulate semicircular canals and otolith organs in the inner ear. Experimental conditions (dosage, routes and onset of recording) were determined based on the prior studies exploring the behavioral effects of baclofen in mice. With an increase in dosage, both canal and otolith induced ocular responses were gradually affected. There was a clear distinction in the drug sensitivity showing that eye movements derived from direct vestibulo-ocular reflex pathways were relatively unaltered, while the responses through higher-order neural networks in the vestibular system were substantially decreased. These findings were consistent with those observed in primates suggesting a well-conserved role of GABAB receptors in the oculomotor system across frontal-eyed and lateral-eyed animals. We showed here a previously unrecognized effect of baclofen on the vestibular oculomotor function in mice. When interpreting general animal performance under the drug, the potential contribution of altered balance system should be taken into consideration. PMID:26778789

  11. LACK OF FUNCTIONAL GABAB RECEPTORS ALTERS Kiss1, Gnrh1 AND Gad1 mRNA EXPRESSION IN THE MEDIAL BASAL HYPOTHALAMUS AT POSTNATAL DAY 4

    PubMed Central

    Di Giorgio, Noelia P.; Catalano, Paolo N.; López, Paula V.; González, Betina; Semaan, Sheila J.; López, Gabriela C.; Kauffman, Alexander S.; Rulli, Susana B.; Somoza, Gustavo M.; Bettler, Bernhard; Libertun, Carlos; Lux-Lantos, Victoria A.

    2013-01-01

    Background/Aims Adult mice lacking functional GABAB receptors (GABAB1KO) show altered Gnrh1 and Gad1 expressions in the preoptic area-anterior hypothalamus (POA-AH) and females display disruption of cyclicity and fertility. Here we addressed whether sexual differentiation of the brain and the proper wiring of the GnRH and kisspeptin systems were already disturbed in postnatal day 4 (PND4) GABAB1KO mice. Methods PND4 wild type (WT) and GABAB1KO mice of both sexes were sacrificed; tissues were collected to determine mRNA expression (qPCR), amino acids (HPLC), and hormones (RIA and/or IHC). Results GnRH neuron number (IHC) did not differ among groups in olfactory bulbs or OVLT-POA. Gnrh1 mRNA (qPCR) in POA-AH was similar among groups. Gnrh1 mRNA in medial basal hypothalamus (MBH) was similar in WTs but was increased in GABAB1KO females compared to GABAB1KO males. Hypothalamic GnRH (RIA) was sexually different in WTs (males > females) but this sex difference was lost in GABAB1KOs; the same pattern was observed when analyzing only the MBH, but not in the POA-AH. Arcuate nucleus Kiss1 mRNA (micropunch-qPCR) was higher in WT females than in WT males and GABAB1KO females. Gad1 mRNA in MBH was increased in GABAB1KO females compared to GABAB1KO males. Serum LH and gonadal estradiol content were also increased in GABAB1KOs. Conclusion We demonstrate that GABABRs participate in the sexual differentiation of the ARC/MBH, because sex differences in several reproductive genes, such as Gad1, Kiss1 and Gnrh1, are critically disturbed in GABAB1KO mice at PND4, probably altering the organization and development of neural circuits governing the reproductive axis. PMID:24080944

  12. The GABA(B) receptor positive modulator BHF177 attenuated anxiety, but not conditioned fear, in rats.

    PubMed

    Li, Xia; Kaczanowska, Katarzyna; Finn, M G; Markou, Athina; Risbrough, Victoria B

    2015-10-01

    GABAB (γ-aminobutyric acid B) receptors may be a therapeutic target for anxiety disorders. Here we characterized the effects of the GABAB receptor positive allosteric modulator (PAM) BHF177 on conditioned and unconditioned physiological responses to threat in the light-enhanced startle (LES), stress-induced hyperthermia, and fear-potentiated startle (FPS) procedures in rats. The effects of BHF177 on LES were compared with those of the GABAB receptor agonists baclofen and CGP44532, and the positive control buspirone, a 5-HT1A receptor partial agonist with anxiolytic activity in humans. Baclofen (0.4, 0.9 and 1.25 mg/kg) and CGP44532 (0.065, 0.125 and 0.25 mg/kg) administration had significant sedative, but not anxiolytic, activity reflected in overall decrease in the startle response in the LES tests. BHF177 (10, 20 and 40 mg/kg) had no effect on LES, nor did it produce an overall sedative effect. Interesting, however, when rats were grouped by high and low LES responses, BHF177 had anxiolytic-like effects only on LES in high, but not low, LES responding rats. BHF177 also blocked stress-induced hyperthermia, but had no effect on conditioned fear responses in the FPS test. Buspirone (1 and 3 mg/kg) had an anxiolytic-like profile in both LES and FPS tests. These results indicate that BHF177 may specifically attenuate unconditioned anxiety in individuals that exhibit a high anxiety state, and has fewer sedative effects than direct agonists. Thus, BHF177 or other GABAB receptor PAMs may be promising compounds for alleviating increased anxiety seen in various psychiatric disorders with a superior side-effect profile compared to GABAB receptor agonists. PMID:26002628

  13. Presynaptic GABAB Autoreceptor Regulation of Nicotinic Acetylcholine Receptor Mediated [3H]-GABA Release from Mouse Synaptosomes

    PubMed Central

    McClure-Begley, Tristan D.; Grady, Sharon R.; Marks, Michael J.; Collins, Allan C.; Stitzel, Jerry A.

    2014-01-01

    Activation of nicotinic acetylcholine receptors (nAChRs) can elicit neurotransmitter release from presynaptic nerve terminals. Mechanisms contributing to cell-and-terminal specific regulation of nAChR-mediated neurotransmitter exocytosis are not fully understood. The experiments discussed here examine how activation of GABAB auto- and hetero-receptors suppress nAChR-mediated release of [3H]-GABA and [3H]-dopamine (3H-DA) from mouse striatal synaptosomes. Activation of presynaptic GABAB receptors with (R)-baclofen decreased both [3H]-GABA and [3H]-DA release evoked by potassium depolarization. However, when nAChRs were activated with ACh to evoke neurotransmitter release, (R)-baclofen had no effect on [3H]-DA release, but potently inhibited ACh-evoked [3H]-GABA release. Inhibition of nAChR-evoked [3H]-GABA release by (R)-baclofen was time sensitive and the effect was lost after prolonged exposure to the GABAB agonist. The early inhibitory effect of GABA activation on ACh-evoked [3H]-GABA release was partially attenuated by antagonists of the phosphatase, calcineurin. Furthermore, antagonists of protein kinase C (PKC) prevented the time-dependent loss of the inhibitory (R)-baclofen effect on [3H]-GABA release. These results suggest that α4β2*-nAChRs present on GABAergic nerve terminals in the striatum are subject to functional regulation by GABAB autoreceptors that is apparently cell-type specific, since it is absent from DAergic striatal nerve terminals. In addition, the functional modulation of α4β2*-type nAChRs on striatal GABAergic nerve terminals by GABAB autoreceptor activation is time-sensitive and appears to involve opposing actions of calcineurin and PKC. PMID:24953818

  14. Embryonic GABA(B) receptor blockade alters cell migration, adult hypothalamic structure, and anxiety- and depression-like behaviors sex specifically in mice.

    PubMed

    Stratton, Matthew S; Staros, Michelle; Budefeld, Tomaz; Searcy, Brian T; Nash, Connor; Eitel, Chad; Carbone, David; Handa, Robert J; Majdic, Gregor; Tobet, Stuart A

    2014-01-01

    Neurons of the paraventricular nucleus of the hypothalamus (PVN) regulate the hypothalamic- pituitary-adrenal (HPA) axis and the autonomic nervous system. Females lacking functional GABA(B) receptors because of a genetic disruption of the R1 subunit have altered cellular characteristics in and around the PVN at birth. The genetic disruption precluded appropriate assessments of physiology or behavior in adulthood. The current study was conducted to test the long term impact of a temporally restricting pharmacological blockade of the GABA(B) receptor to a 7-day critical period (E11-E17) during embryonic development. Experiments tested the role of GABA(B) receptor signaling in fetal development of the PVN and later adult capacities for adult stress related behaviors and physiology. In organotypic slices containing fetal PVN, there was a female specific, 52% increase in cell movement speeds with GABA(B) receptor antagonist treatment that was consistent with a sex-dependent lateral displacement of cells in vivo following 7 days of fetal exposure to GABA(B) receptor antagonist. Anxiety-like and depression-like behaviors, open-field activity, and HPA mediated responses to restraint stress were measured in adult offspring of mothers treated with GABA(B) receptor antagonist. Embryonic exposure to GABA(B) receptor antagonist resulted in reduced HPA axis activation following restraint stress and reduced depression-like behaviors. There was also increased anxiety-like behavior selectively in females and hyperactivity in males. A sex dependent response to disruptions of GABA(B) receptor signaling was identified for PVN formation and key aspects of physiology and behavior. These changes correspond to sex specific prevalence in similar human disorders, namely anxiety disorders and hyperactivity. PMID:25162235

  15. Embryonic GABAB Receptor Blockade Alters Cell Migration, Adult Hypothalamic Structure, and Anxiety- and Depression-Like Behaviors Sex Specifically in Mice

    PubMed Central

    Stratton, Matthew S.; Staros, Michelle; Budefeld, Tomaz; Searcy, Brian T.; Nash, Connor; Eitel, Chad; Carbone, David; Handa, Robert J.; Majdic, Gregor; Tobet, Stuart A.

    2014-01-01

    Neurons of the paraventricular nucleus of the hypothalamus (PVN) regulate the hypothalamic- pituitary-adrenal (HPA) axis and the autonomic nervous system. Females lacking functional GABAB receptors because of a genetic disruption of the R1 subunit have altered cellular characteristics in and around the PVN at birth. The genetic disruption precluded appropriate assessments of physiology or behavior in adulthood. The current study was conducted to test the long term impact of a temporally restricting pharmacological blockade of the GABAB receptor to a 7-day critical period (E11–E17) during embryonic development. Experiments tested the role of GABAB receptor signaling in fetal development of the PVN and later adult capacities for adult stress related behaviors and physiology. In organotypic slices containing fetal PVN, there was a female specific, 52% increase in cell movement speeds with GABAB receptor antagonist treatment that was consistent with a sex-dependent lateral displacement of cells in vivo following 7 days of fetal exposure to GABAB receptor antagonist. Anxiety-like and depression-like behaviors, open-field activity, and HPA mediated responses to restraint stress were measured in adult offspring of mothers treated with GABAB receptor antagonist. Embryonic exposure to GABAB receptor antagonist resulted in reduced HPA axis activation following restraint stress and reduced depression-like behaviors. There was also increased anxiety-like behavior selectively in females and hyperactivity in males. A sex dependent response to disruptions of GABAB receptor signaling was identified for PVN formation and key aspects of physiology and behavior. These changes correspond to sex specific prevalence in similar human disorders, namely anxiety disorders and hyperactivity. PMID:25162235

  16. Effects of the GABAB Receptor-Positive Modulators CGP7930 and rac-BHFF in Baclofen- and γ-Hydroxybutyrate-Discriminating Pigeons

    PubMed Central

    France, Charles P.; Cheng, Kejun; Rice, Kenner C.

    2012-01-01

    In vivo effects of GABAB receptor-positive modulators suggest them to have therapeutic potential to treat central nervous system disorders such as anxiety and drug abuse. Although these effects are thought to be mediated by positive modulation of GABAB receptors, such modulation has been examined primarily in vitro. This study further examined the in vivo properties of the GABAB receptor-positive modulators 2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethylpropyl) phenol (CGP7930) and (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF). In pigeons discriminating baclofen from saline, γ-hydroxybutyrate (GHB) produced 100% baclofen-appropriate responding, and the GABAB antagonist 3-aminopropyl(dimethoxymethyl) phosphinic acid (CGP35348) blocked the effects of both drugs. CGP7930 and rac-BHFF produced at most 41 and 74% baclofen-appropriate responding, respectively, and enhanced the discriminative stimulus effects of baclofen, but not of GHB. In pigeons discriminating GHB from saline, CGP7930 and rac-BHFF produced at most 1 and 49% GHB-appropriate responding, respectively, and enhanced the effects of baclofen, but not of GHB. Enhancement of the discriminative stimulus effects of baclofen by rac-BHFF and CGP7930 is further evidence of their effectiveness as GABAB receptor-positive modulators in vivo. Furthermore, lack of complete substitution of the positive modulators rac-BHFF and CGP7930 for baclofen and GHB suggests that their discriminative stimulus effects differ from those of GABAB receptor agonists. Finally, together with converging evidence that the GABAB receptor populations mediating the effects of baclofen and GHB are not identical, the present findings suggest that these populations differ in their susceptibility to positive modulatory effects. Such differences could allow for more selective therapeutic targeting of the GABAB system. PMID:22319197

  17. Effects of the GABAB receptor-positive modulators CGP7930 and rac-BHFF in baclofen- and γ-hydroxybutyrate-discriminating pigeons.

    PubMed

    Koek, Wouter; France, Charles P; Cheng, Kejun; Rice, Kenner C

    2012-05-01

    In vivo effects of GABA(B) receptor-positive modulators suggest them to have therapeutic potential to treat central nervous system disorders such as anxiety and drug abuse. Although these effects are thought to be mediated by positive modulation of GABA(B) receptors, such modulation has been examined primarily in vitro. This study further examined the in vivo properties of the GABA(B) receptor-positive modulators 2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethylpropyl) phenol (CGP7930) and (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF). In pigeons discriminating baclofen from saline, γ-hydroxybutyrate (GHB) produced 100% baclofen-appropriate responding, and the GABA(B) antagonist 3-aminopropyl(dimethoxymethyl) phosphinic acid (CGP35348) blocked the effects of both drugs. CGP7930 and rac-BHFF produced at most 41 and 74% baclofen-appropriate responding, respectively, and enhanced the discriminative stimulus effects of baclofen, but not of GHB. In pigeons discriminating GHB from saline, CGP7930 and rac-BHFF produced at most 1 and 49% GHB-appropriate responding, respectively, and enhanced the effects of baclofen, but not of GHB. Enhancement of the discriminative stimulus effects of baclofen by rac-BHFF and CGP7930 is further evidence of their effectiveness as GABA(B) receptor-positive modulators in vivo. Furthermore, lack of complete substitution of the positive modulators rac-BHFF and CGP7930 for baclofen and GHB suggests that their discriminative stimulus effects differ from those of GABA(B) receptor agonists. Finally, together with converging evidence that the GABA(B) receptor populations mediating the effects of baclofen and GHB are not identical, the present findings suggest that these populations differ in their susceptibility to positive modulatory effects. Such differences could allow for more selective therapeutic targeting of the GABA(B) system. PMID:22319197

  18. Transport along the dendritic endoplasmic reticulum mediates the trafficking of GABAB receptors

    PubMed Central

    Valenzuela, José I.; Jaureguiberry-Bravo, Matías; Salas, Daniela A.; Ramírez, Omar A.; Cornejo, Víctor H.; Lu, Hsiangmin E.; Blanpied, Thomas A.; Couve, Andrés

    2014-01-01

    ABSTRACT In neurons, secretory organelles within the cell body are complemented by the dendritic endoplasmic reticulum (ER) and Golgi outposts (GOPs), whose role in neurotransmitter receptor trafficking is poorly understood. γ-aminobutyric acid (GABA) type B metabotropic receptors (GABABRs) regulate the efficacy of synaptic transmission throughout the brain. Their plasma membrane availability is controlled by mechanisms involving an ER retention motif and assembly-dependent ER export. Thus, they constitute an ideal molecular model to study ER trafficking, but the extent to which the dendritic ER participates in GABABR biosynthesis has not been thoroughly explored. Here, we show that GABAB1 localizes preferentially to the ER in dendrites and moves long distances within this compartment. Not only diffusion but also microtubule and dynein-dependent mechanisms control dendritic ER transport. GABABRs insert throughout the somatodendritic plasma membrane but dendritic post-ER carriers containing GABABRs do not fuse selectively with GOPs. This study furthers our understanding of the spatial selectivity of neurotransmitter receptors for dendritic organelles. PMID:24895402

  19. Modulation of non-adrenergic, non-cholinergic neural bronchoconstriction in guinea-pig airways via GABAB-receptors.

    PubMed

    Belvisi, M G; Ichinose, M; Barnes, P J

    1989-08-01

    via an action at GABAB receptors and that GABA might play a role in the regulation of neurogenic responses in the airways. PMID:2477104

  20. GABAA and GABAB receptor-mediated effects in guinea-pig ileum.

    PubMed

    Giotti, A; Luzzi, S; Spagnesi, S; Zilletti, L

    1983-03-01

    -pig ileum: a bicuculline-sensitive GABA(A) receptor, which elicits contraction through an excitatory action on cholinergic post-ganglionic neurones; and a bicuculline-insensitive GABA(B) receptor which causes relaxation through an inhibitory presynaptic action on cholinergic post-ganglionic neurones. We confirm that GABA, homotaurine and muscimol are GABA(A) agonists, while GABA and (-)-baclofen are GABA(B) agonists. PMID:6301600

  1. The GABAB receptor agonist, baclofen, contributes to three distinct varieties of amnesia in the human brain - A detailed case report.

    PubMed

    Zeman, Adam; Hoefeijzers, Serge; Milton, Fraser; Dewar, Michaela; Carr, Melanie; Streatfield, Claire

    2016-01-01

    We describe a patient in whom long-term, therapeutic infusion of the selective gamma-amino-butyric acid type B (GABAB) receptor agonist, baclofen, into the cerebrospinal fluid (CSF) gave rise to three distinct varieties of memory impairment: i) repeated, short periods of severe global amnesia, ii) accelerated long-term forgetting (ALF), evident over intervals of days and iii) a loss of established autobiographical memories. This pattern of impairment has been reported in patients with temporal lobe epilepsy (TLE), in particular the subtype of Transient Epileptic Amnesia (TEA). The amnesic episodes and accelerated forgetting remitted on withdrawal of baclofen, while the autobiographical amnesia (AbA) persisted. This exceptional case highlights the occurrence of 'non-standard' forms of human amnesia, reflecting the biological complexity of memory processes. It suggests a role for GABAB signalling in the modulation of human memory over multiple time-scales and hints at its involvement in 'epileptic amnesia'. PMID:26599496

  2. Effects of GABA(B) receptor agents on cocaine priming, discrete contextual cue and food induced relapses.

    PubMed

    Filip, Małgorzata; Frankowska, Małgorzata

    2007-10-01

    In the present study we investigated the effects of the GABA(B) receptor antagonist (2S)-(+)-5,5-dimethyl-2-morpholineacetic acid (SCH 50911), the agonists baclofen and 3-aminopropyl(methyl)phosphinic acid (SKF 97541), and the allosteric positive modulator 3,5-bis(1,1-dimethylethyl)-4-hydroxy-beta,beta-dimethylbenzenepropanol (CGP 7930) on cocaine seeking behavior. The effects of the above drugs on the reinstatement of responding induced by natural reinforcer (food) were also studied. Male Wistar rats were trained to self-administer either cocaine (0.5 mg/kg/infusion) or food (sweet milk) and responding on the reinforcer-paired lever was extinguished. Reinstatement of responding was induced by a noncontingent presentation of the self-administered reinforcer (10 mg/kg cocaine, i.p.), a discrete contextual cue, or a contingent presentation of food. SCH 50911 (3-10 mg/kg) dose-dependently attenuated responding on the previously cocaine-paired lever during both reinstatement conditions, with slightly greater efficacy at reducing conditioned cue reinstatement. At the same time, it failed to alter reinstatement of food-seeking behavior. Baclofen (1.25-5 mg/kg) and SKF 97541 (0.03-0.3 mg/kg) attenuated cocaine- or food-seeking behavior; the effect of the drug appeared more effective for cocaine-seeking than food-seeking. CGP 7930 (10-30 mg/kg) reduced cocaine seeking without affecting food-induced reinstatement on reward seeking. Our results indicate that tonic activation of GABA(B) receptors is required for cocaine seeking behavior in rats. Moreover, the GABA(B) receptor antagonist SCH 50911 was effective in reducing relapse to cocaine at doses that failed to alter reinstatement of food-seeking behavior (present study), basal locomotor activity, cocaine and food self-administration (Filip et al., submitted for publication), suggesting its selective effects on motivated drug-seeking behavior. The potent inhibitory responses on cocaine seeking behavior were also seen

  3. Positive Modulation of GABAB Receptors Decreased Nicotine Self-administration and Counteracted Nicotine-induced Enhancement of Brain Reward Function in Rats

    PubMed Central

    Paterson, Neil E.; Vlachou, Styliani; Guery, Sebastien; Kaupmann, Klemens; Froestl, Wolfgang; Markou, Athina

    2008-01-01

    Acute administration of γ-aminobutyric acid (GABA)-B receptor agonists decreases nicotine, cocaine, ethanol, and heroin self-administration, and also decreases food-maintained responding and suppresses locomotor activity at high doses. GABAB receptor positive modulators may represent potentially improved therapeutic compounds because of their fewer side-effects than receptor agonists. The present study investigated the effects of administration of the GABAB receptor positive modulators 2,6-Di-tert-butyl-4-(3-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930) and N-[(1R,2R,4S)-bicyclo[2.2.1]hept-2-yl]-2-methyl-5-[4-(trifluoromethyl)phenyl]-4-pyrimidinamine (BHF177), and co-administration of the GABAB receptor positive modulator N,N'-dicyclopentyl-2-methylsulfanyl-5-nitro-pyrimidine-4,6-diamine (GS39783) with the GABAB receptor agonist (3-amino-2[S]-hydroxypropyl)-methylphosphinic acid (CGP44532) on nicotine- and food-maintained responding under fixed-ratio 5 (FR5) and progressive-ratio schedules of reinforcement. Furthermore, the effects of BHF177 and CGP44532 on nicotine-induced enhancement of brain reward function were evaluated. The results indicated that administration of CGP7930 decreased nicotine self-administration under an FR5 schedule. Administration of either GS39783 or CGP44532 selectively decreased nicotine self-administration, while co-administration of these compounds had additive effects. BHF177 administration selectively decreased nicotine-, but not food-, maintained responding under FR5 and progressive-ratio schedules. The nicotine-induced enhancement of brain reward function was blocked by BHF177 or CGP44532, although the highest doses of both compounds, particularly CGP44532, decreased brain reward function when administered alone, suggesting an additive, rather than interactive, effect. Overall, the present results indicate that GABAB receptor positive modulators, similarly to GABAB receptor agonists, attenuated the reinforcing and reward

  4. GABAB receptor-mediated activation of astrocytes by gamma-hydroxybutyric acid

    PubMed Central

    Gould, Timothy; Chen, Lixin; Emri, Zsuzsa; Pirttimaki, Tiina; Errington, Adam C.; Crunelli, Vincenzo; Parri, H. Rheinallt

    2014-01-01

    The gamma-aminobutyric acid (GABA) metabolite gamma-hydroxybutyric acid (GHB) shows a variety of behavioural effects when administered to animals and humans, including reward/addiction properties and absence seizures. At the cellular level, these actions of GHB are mediated by activation of neuronal GABAB receptors (GABABRs) where it acts as a weak agonist. Because astrocytes respond to endogenous and exogenously applied GABA by activation of both GABAA and GABABRs, here we investigated the action of GHB on astrocytes on the ventral tegmental area (VTA) and the ventrobasal (VB) thalamic nucleus, two brain areas involved in the reward and proepileptic action of GHB, respectively, and compared it with that of the potent GABABR agonist baclofen. We found that GHB and baclofen elicited dose-dependent (ED50: 1.6 mM and 1.3 µM, respectively) transient increases in intracellular Ca2+ in VTA and VB astrocytes of young mice and rats, which were accounted for by activation of their GABABRs and mediated by Ca2+ release from intracellular store release. In contrast, prolonged GHB and baclofen exposure caused a reduction in spontaneous astrocyte activity and glutamate release from VTA astrocytes. These findings have key (patho)physiological implications for our understanding of the addictive and proepileptic actions of GHB. PMID:25225100

  5. Characterization of (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one as a positive allosteric modulator of GABAB receptors

    PubMed Central

    Malherbe, P; Masciadri, R; Norcross, R D; Knoflach, F; Kratzeisen, C; Zenner, M-T; Kolb, Y; Marcuz, A; Huwyler, J; Nakagawa, T; Porter, R H P; Thomas, A W; Wettstein, J G; Sleight, A J; Spooren, W; Prinssen, E P

    2008-01-01

    Background and purpose: As baclofen is active in patients with anxiety disorders, GABAB receptors have been implicated in the modulation of anxiety. To avoid the side effects of baclofen, allosteric enhancers of GABAB receptors have been studied to provide an alternative therapeutic avenue for modulation of GABAB receptors. The aim of this study was to characterize derivatives of (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF) as enhancers of GABAB receptors. Experimental approach: Enhancing properties of rac-BHFF were assessed in the Chinese hamster ovary (CHO)-Gα16-hGABAB(1a,2a) cells by Fluorometric Imaging Plate Reader and GTPγ[35S]-binding assays, and in rat hippocampal slices by population spike (PS) recordings. In vivo activities of rac-BHFF were assessed using the loss of righting reflex (LRR) and stress-induced hyperthermia (SIH) models. Key results: In GTPγ[35S]-binding assays, 0.3 μM rac-BHFF or its pure enantiomer (+)-BHFF shifted the GABA concentration–response curve to the left, an effect that resulted in a large increase in both GABA potency (by 15.3- and 87.3-fold) and efficacy (149% and 181%), respectively. In hippocampal slices, rac-BHFF enhanced baclofen-induced inhibition of PS of CA1 pyramidal cells. In an in vivo mechanism-based model in mice, rac-BHFF increased dose-dependently the LRR induced by baclofen with a minimum effective dose of 3 mg kg−1 p.o. rac-BHFF (100 mg kg−1 p.o.) tested alone had no effect on LRR nor on spontaneous locomotor activity, but exhibited anxiolytic-like activity in the SIH model in mice. Conclusions and implications: rac-BHFF derivatives may serve as valuable pharmacological tools to elucidate the pathophysiological roles played by GABAB receptors in the central and peripheral nervous systems. PMID:18536733

  6. GABAB and group I metabotropic glutamate receptors in the striatopallidal complex in primates

    PubMed Central

    SMITH, YOLAND; CHARARA, ALI; HANSON, JESSE E.; PAQUET, MARYSE; LEVEY, ALLAN I.

    2000-01-01

    Glutamate and GABA neurotransmission is mediated through various types of ionotropic and metabotropic receptors. In this review, we summarise some of our recent findings on the subcellular and subsynaptic localisation of GABAB and group I metabotropic glutamate receptors in the striatopallidal complex of monkeys. Polyclonal antibodies that specifically recognise GABABR1, mGluR1a and mGluR5 receptor subtypes were used for immunoperoxidase and pre-embedding immunogold techniques at the light and electron microscope levels. Both subtypes of group I mGluRs were expressed postsynaptically in striatal projection neurons and interneurons where they aggregate perisynaptically at asymmetric glutamatergic synapses and symmetric dopaminergic synaptic junctions. Moreover, they are also strongly expressed in the main body of symmetric synapses established by putative intrastriatal GABAergic terminals. In the globus pallidus, both receptor subtypes are found postsynaptically in the core of striatopallidal GABAergic synapses and perisynaptically at subthalamopallidal glutamatergic synapses. Finally, extrasynaptic labelling was commonly seen in the globus pallidus and the striatum. Moderate to intense GABABR1 immunoreactivity was observed in the striatopallidal complex. At the electron microscope level, GABABR1 immunostaining was commonly found in neuronal cell bodies and dendrites. Many striatal dendritic spines also displayed GABABR1 immunoreactivity. Moreover, GABABR1-immunoreactive axons and axon terminals were frequently encountered. In the striatum, GABABR1-immunoreactive boutons resembled terminals of cortical origin, while in the globus pallidus, subthalamic-like terminals were labelled. Pre-embedding immunogold data showed that postsynaptic GABABR1 receptors are concentrated at extrasynaptic sites on dendrites, spines and somata in the striatopallidal complex, perisynaptically at asymmetric synapses and in the main body of symmetric striatopallidal synapses in the GPe and

  7. Altered emotionality and neuronal excitability in mice lacking KCTD12, an auxiliary subunit of GABAB receptors associated with mood disorders

    PubMed Central

    Cathomas, F; Stegen, M; Sigrist, H; Schmid, L; Seifritz, E; Gassmann, M; Bettler, B; Pryce, C R

    2015-01-01

    Gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the brain, is fundamental to brain function and implicated in the pathophysiology of several neuropsychiatric disorders. GABA activates G-protein-coupled GABAB receptors comprising principal GABAB1 and GABAB2 subunits as well as auxiliary KCTD8, 12, 12b and 16 subunits. The KCTD12 gene has been associated with bipolar disorder, major depressive disorder and schizophrenia. Here we compare Kctd12 null mutant (Kctd12−/−) and heterozygous (Kctd12+/−) with wild-type (WT) littermate mice to determine whether lack of or reduced KCTD12 expression leads to phenotypes that, extrapolating to human, could constitute endophenotypes for neuropsychiatric disorders with which KCTD12 is associated. Kctd12−/− mice exhibited increased fear learning but not increased memory of a discrete auditory-conditioned stimulus. Kctd12+/− mice showed increased activity during the inactive (light) phase of the circadian cycle relative to WT and Kctd12−/− mice. Electrophysiological recordings from hippocampal slices, a region of high Kctd12 expression, revealed an increased intrinsic excitability of pyramidal neurons in Kctd12−/− and Kctd12+/− mice. This is the first direct evidence for involvement of KCTD12 in determining phenotypes of emotionality, behavioral activity and neuronal excitability. This study provides empirical support for the polymorphism and expression evidence that KCTD12 confers risk for and is associated with neuropsychiatric disorders. PMID:25689571

  8. Subcellular compartment-specific molecular diversity of pre- and postsynaptic GABAB-activated GIRK channels in Purkinje cells

    PubMed Central

    Fernández-Alacid, Laura; Aguado, Carolina; Ciruela, Francisco; Martín, Ricardo; Colón, José; Cabañero, María José; Gassmann, Martin; Watanabe, Masahiko; Shigemoto, Ryuichi; Wickman, Kevin; Bettler, Bernhard; Sánchez-Prieto, José; Luján, Rafael

    2009-01-01

    Activation of G protein-gated inwardly-rectifying K+ (GIRK or Kir3) channels by metabotropic gamma-aminobutyric acid (B) (GABAB) receptors is an essential signalling pathway controlling neuronal excitability and synaptic transmission in the brain. To investigate the relationship between GIRK channel subunits and GABAB receptors in cerebellar Purkinje cells at post- and pre-synaptic sites, we used biochemical, functional and immunohistochemical techniques. Co-immunoprecipitation analysis demonstrated that GIRK subunits are co-assembled with GABAB receptors in the cerebellum. Immunoelectron microscopy showed that the subunit composition of GIRK channels in Purkinje cell spines is compartment-dependent. Thus, at extrasynaptic sites GIRK channels are formed by GIRK1/GIRK2/GIRK3, postsynaptic densities contain GIRK2/GIRK3 and dendritic shafts contain GIRK1/GIRK3. The postsynaptic association of GIRK subunits with GABAB receptors in Purkinje cells is supported by the subcellular regulation of the ion channel and the receptor in mutant mice. At presynaptic sites, GIRK channels localized to parallel fibre terminals are formed by GIRK1/GIRK2/GIRK3 and co-localize with GABAB receptors. Consistent with this morphological evidence we demonstrate their functional interaction at axon terminals in the cerebellum by showing that GIRK channels play a role in the inhibition of glutamate release by GABAB receptors. The association of GIRK channels and GABAB receptors with excitatory synapses at both post- and presynaptic sites indicates their intimate involvement in the modulation of glutamatergic neurotransmission in the cerebellum. PMID:19558451

  9. Characterization of the antiabsence effects of SCH 50911, a GABA-B receptor antagonist, in the lethargic mouse, gamma-hydroxybutyrate, and pentylenetetrazole models.

    PubMed

    Hosford, D A; Wang, Y; Liu, C C; Snead, O C

    1995-09-01

    Recent studies have shown that gamma-aminobutyric acidB (GABAB) receptor antagonists suppress absence seizures in animal models. (+)-5,5-Dimethyl-2-morpholineacetic acid, hydrochloride (SCH 50911) is a new GABAB antagonist that is structurally dissimilar to previously studied GABAB antagonists such as 3-aminopropyl-diethoxymethyl-phosphinic acid (CGP 35348), 3-aminopropyl-n-butyl-phosphinic acid (CGP 36742) or 3-aminopropyl-cyclohexylmethyl-phosphinic acid (CGP 46381). In this study we measured the antiabsence effects of SCH 50911 in three animal models: the lethargic (lh/lh) mutant mouse, which has spontaneous absence seizures; and two rat models in which absence seizures were induced by administration of either gamma-hydroxybutyrate or pentylenetetrazole. SCH 50911 abolished seizures in all three models in a dose-dependent fashion (ID100 = 8-170 mumol/kg). In each model SCH 50911 was more potent (ID50 = 2-22 mumol/kg) than the following antiabsence compounds: the GABAB antagonist CGP 35348 (ID50 = 210-890 mumol/kg); ethosuximide (ID50 < or = 142-1240 mumol/kg); trimethadione (ID50 = 520-1100 mumol/kg); and valproic acid (ID50 = 900-2360 mumol/kg). SCH 50911 was equipotent with the GABAB antagonist CGP 46381 (ID50 = 20 mumol/kg) in the lh/lh mouse model. These findings suggest that antiabsence activity may be a defining feature of GABAB receptor antagonists and provide a rationale for pursuing clinical trials of GABAB receptor antagonists in human patients with absence seizures. PMID:7562514

  10. GABAA and GABAB receptor-mediated effects on the spontaneous activity of the longitudinal layer in cat terminal ileum.

    PubMed

    Pencheva, N; Radomirov, R; Venkova, K

    1991-01-01

    1. GABA and GABAergic agonists-muscimol and (+/-)baclofen changed the spontaneous mechanical activity in isolated cat terminal ileum. 2. GABA at doses ranging from 5 microM to 2 mM produced concentration-dependent biphasic responses consisting of a transient relaxation followed by contractions with a tonic and a phasic components. 3. The GABA-induced relaxation was sensitive to bicuculline and picrotoxinin and was mimicked by muscimol, while the GABA-induced contractions were insensitive to bicuculline and picrotoxinin and were mimicked by (+/-)baclofen. Specific cross desensitization occurred between GABA and muscimol or GABA and (+/-)baclofen. 4. The bicuculline-sensitive relaxation induced by GABA and muscimol was abolished by atropine or tetrodotoxin (TTX), while the bicuculline-insensitive contractions induced by GABA and (+/-)baclofen were not antagonized by atropine or TTX, though they were slightly suppressed. 5. The GABA effects in the longitudinal layer of cat terminal ileum were mediated by the following receptors: -GABAA prejunctional receptors whose activation causes relaxation, probably through an inhibitory action on cholinergic neurons; -GABAB prejunctional receptors whose activation cause contractions; -GABAB postjunctional receptors located on the smooth muscle membrane whose activation induces tonic and phasic contractions. PMID:1646745

  11. [The pharmacological differences between kynurenine- and korazol-induced seizures (the participation of GABA-B receptors and dopamine)].

    PubMed

    Lapin, I P

    1998-01-01

    In experiments of male SHR (nonbred) and C57B1/6 mice [correction of rats] bicucullin intensified corasole-induced convulsions but had no effect on kynurenine convulsions, removed the anticonvulsive effect of phenibut against kynurenine and did not affect the anticonvulsive effect of diazepam against corasole. Phenibut and baclofen reduced the anticonvulsive effect of diazepam against corasole and caffeine. Haloperidol increased kynurenine-induced convulsions and had no effect on those caused by corasole. Dopamine removed the effect of haloperidol. Haloperidol and 6-oxydopamine weakened the sedative effect of phenibut. Blockade of GAMAB-receptors and weakening of dopaminergic activity are important in the mechanisms of kynurenine convulsions, and blockage of GABAA-receptors unrelated to it is important in the mechanisms of corasole convulsions. A functional antagonism in anticonvulsive activity may exist between these receptors. Bicucullin may probably have an effect both on GABAA- and GABAB-receptors. PMID:9621167

  12. GABAB Receptor Agonist R-Baclofen Reverses Social Deficits and Reduces Repetitive Behavior in Two Mouse Models of Autism.

    PubMed

    Silverman, J L; Pride, M C; Hayes, J E; Puhger, K R; Butler-Struben, H M; Baker, S; Crawley, J N

    2015-08-01

    Autism spectrum disorder (ASD) is diagnosed by two core behavioral criteria, unusual reciprocal social interactions and communication, and stereotyped, repetitive behaviors with restricted interests. Excitatory/inhibitory imbalance is a prominent hypothesis for the etiology of autism. The selective GABAB receptor agonist R-baclofen previously reversed social deficits and reduced repetitive behaviors in a mouse model of Fragile X syndrome, and Arbaclofen improved some clinical symptoms in some Fragile X and ASD patients. To evaluate R-baclofen in a broader range of mouse models of ASD, we tested both the R-baclofen enantiomer and the less potent S-baclofen enantiomer in two inbred strains of mice that display low sociability and/or high repetitive or stereotyped behaviors. R-baclofen treatment reversed social approach deficits in BTBR T+ Itpr3tf/J (BTBR), reduced repetitive self-grooming and high marble burying scores in BTBR, and reduced stereotyped jumping in C58/J (C58), at nonsedating doses. S-baclofen produced minimal effects at the same doses. These findings encourage investigations of R-baclofen in other preclinical model systems. Additional clinical studies may be warranted to further evaluate the hypothesis that the GABAB receptor represents a promising pharmacological target for treating appropriately stratified subsets of individuals with ASD. PMID:25754761

  13. GABAB receptors as a common target for hypothermia and spike and wave seizures: intersecting mechanisms of thermoregulation and absence epilepsy.

    PubMed

    Ostojić, Z S; Ilić, T V; Vesković, S M; Andjus, P R

    2013-05-15

    In the current study the link among the γ-hydroxybutyrate (GHB)/pentylenetetrazole (PTZ)-induced absence-like seizures and concomitant decreases in the core temperature, as well as electroencephalographic (EEG) activity during rewarming from deep hypothermia produced by a drug-free protocol were investigated. During the rewarming period after deep cooling, most Wistar rats suffered from bilaterally synchronous spike and waves with no or mild behavioral correlates. Spike and wave seizures were temperature-dependent and were initially registered when body temperature (Tb) reached 25-27°C, but mostly during the mild hypothermia of 0.3-1.3°C (Tb of 36.3-37.3°C). In chemical absence models, spike and wave discharges were also closely accompanied by mild systemic hypothermia, as both PTZ- and GHB-induced temperature decreases ranged from about 1-1.4°C respectively, together with EEG markers of absence activity. Thus, throughout the different experimental designs, the occurrence of spike and wave discharges was always related to a mild (0.3-1.4°C) decrease of Tb. Benzodiazepine diazepam as the GABAA-positive allosteric modulator and CGP 62349 as the selective antagonist of GABAB receptors were used to determine if their well-known anticonvulsant properties also affect hypothermia elicited by these drugs. Finally, during the course of spontaneous rewarming from deep hypothermia, another selective GABAB-blocking agent, CGP 35348, was used to elucidate if GABAB inhibitory system could be critically implicated in the generation of hypothermia-dependent spike and waves. Diazepam prevented both the PTZ-induced hypothermia and electrographic absence seizures, but these two beneficial effects did not occur in the GHB model. Even though diazepam delayed GHB-induced maximal temperature decrease, the GHB effects remained highly significant. The GABAB antagonist CGP 62349 completely prevented hypothermia as well as absence seizures in both chemical models. Likewise, spike and

  14. Different in vitro and in vivo profiles of substituted 3-aminopropylphosphinate and 3-aminopropyl(methyl)phosphinate GABAB receptor agonists as inhibitors of transient lower oesophageal sphincter relaxation

    PubMed Central

    Lehmann, A; Antonsson, M; Aurell-Holmberg, A; Blackshaw, LA; Brändén, L; Elebring, T; Jensen, J; Kärrberg, L; Mattsson, JP; Nilsson, K; Oja, SS; Saransaari, P; von Unge, S

    2012-01-01

    BACKGROUND AND PURPOSE Gastro-oesophageal reflux is predominantly caused by transient lower oesophageal sphincter relaxation (TLOSR) and GABAB receptor stimulation inhibits TLOSR. Lesogaberan produces fewer CNS side effects than baclofen, which has been attributed to its affinity for the GABA transporter (GAT), the action of which limits stimulation of central GABAB receptors. To understand the structure–activity relationship for analogues of lesogaberan (3-aminopropylphosphinic acids), and corresponding 3-aminopropyl(methyl)phosphinic acids, we have compared representatives of these classes in different in vitro and in vivo models. EXPERIMENTAL APPROACH The compounds were characterized in terms of GABAB agonism in vitro. Binding to GATs and cellular uptake was done using rat brain membranes and slices respectively. TLOSR was measured in dogs, and CNS side effects were evaluated as hypothermia in mice and rats. KEY RESULTS 3-Aminopropylphosphinic acids inhibited TLOSR with a superior therapeutic index compared to 3-aminopropyl(methyl)phosphinic acids. This difference was most likely due to differential GAT-mediated uptake into brain cells of the former but not latter. In agreement, 3-aminopropyl(methyl)phosphinic acids were much more potent in producing hypothermia in rats even when administered i.c.v. CONCLUSIONS AND IMPLICATIONS An enhanced therapeutic window for 3-aminopropylphosphinic acids compared with 3-aminopropyl(methyl)phosphinic acids with respect to inhibition of TLOSR was observed and is probably mechanistically linked to neural cell uptake of the former but not latter group of compounds. These findings offer a platform for discovery of new GABAB receptor agonists for the treatment of reflux disease and other conditions where selective peripheral GABAB receptor agonism may afford therapeutic effects. PMID:21950457

  15. Effects of GABA agonists on body temperature regulation in GABAB(1)−/− mice

    PubMed Central

    Quéva, Christophe; Bremner-Danielsen, Marianne; Edlund, Anders; Jonas Ekstrand, A; Elg, Susanne; Erickson, Sven; Johansson, Thore; Lehmann, Anders; Mattsson, Jan P

    2003-01-01

    Activation of GABAB receptors evokes hypothermia in wildtype (GABAB(1)+/+) but not in GABAB receptor knockout (GABAB(1)−/−) mice. The aim of the present study was to determine the hypothermic and behavioural effects of the putative GABAB receptor agonist γ-hydroxybutyrate (GHB), and of the GABAA receptor agonist muscimol. In addition, basal body temperature was determined in GABAB(1)+/+, GABAB(1)+/− and GABAB(1)−/− mice. GABAB(1)−/− mice were generated by homologous recombination in embryonic stem cells. Correct gene targeting was assessed by Southern blotting, PCR and Western blotting. GABAB receptor-binding sites were quantified with radioligand binding. Measurement of body temperature was done using subcutaneous temperature-sensitive chips, and behavioural changes after drug administration were scored according to a semiquantitative scale. GABAB(1)−/− mice had a short lifespan, probably caused by generalised seizure activity. No histopathological or blood chemistry changes were seen, but the expression of GABAB(2) receptor protein was below the detection limit in brains from GABAB(1)−/− mice, in the absence of changes in mRNA levels. GABAB receptor-binding sites were absent in brain membranes from GABAB(1)−/− mice. GABAB(1)−/− mice were hypothermic by approximately 1°C compared to GABAB(1)+/+ and GABAB(1)+/− mice. Injection of baclofen (9.6 mg kg−1) produced a large reduction in body temperature and behavioural effects in GABAB(1)+/+ and in GABAB(1)+/− mice, but GABAB(1)−/− mice were unaffected. The same pattern was seen after administration of GHB (400 mg kg−1). The GABAA receptor agonist muscimol (2 mg kg−1), on the other hand, produced a more pronounced hypothermia in GABAB(1)−/−mice. In GABAB(1)+/+ and GABAB(1)+/− mice, muscimol induced sedation and reduced locomotor activity. However, when given to GABAB(1)−/− mice, muscimol triggered periods of intense jumping and wild running. It is concluded that

  16. Blockade of presynaptic 4-aminopyridine-sensitive potassium channels increases initial neurotransmitter release probability, reinstates synaptic transmission altered by GABAB receptor activation in rat midbrain periaqueductal gray.

    PubMed

    Li, Guangying; Liu, Zhi-Liang; Zhang, Wei-Ning; Yang, Kun

    2016-01-01

    The activation of γ-aminobutyric acid receptor subtype B (GABAB) receptors in the midbrain ventrolateral periaqueductal gray (vlPAG) induces both postsynaptic and presynaptic inhibition. Whereas the postsynaptic inhibition is mediated by G protein-coupled inwardly rectifying K channels, the presynaptic inhibition of neurotransmitter release is primarily mediated by voltage-gated calcium channels. Using whole-cell recordings from acute rat PAG slices, we report here that the bath application of 4-aminopyridine, a voltage-gated K channel blocker, increases the initial GABA and glutamate release probability (P) and reinstates P depressed by presynaptic GABAB receptor activation at inhibitory and excitatory synapses, respectively. However, Ba, which blocks G protein-coupled inwardly rectifying K channels, does not produce similar effects. Our data suggest that the blockade of presynaptic 4-aminopyridine-sensitive K channels in vlPAG facilitates neurotransmitter release and reinstates synaptic transmission that has been altered by presynaptic GABAB receptor activation. Because vlPAG is involved in the descending pain control system, the present results may have potential therapeutic applications. PMID:26575285

  17. New effects of GABAB receptor allosteric modulator rac-BHFF on ambient GABA, uptake/release, Em and synaptic vesicle acidification in nerve terminals.

    PubMed

    Pozdnyakova, N; Dudarenko, M; Borisova, T

    2015-09-24

    Positive allosteric modulators of GABAB receptors have great therapeutic potential for medications of anxiety, depression, etc. The effects of recently discovered modulator rac-BHFF on the key characteristics of GABAergic neurotransmission were investigated in cortical and hippocampal presynaptic nerve terminals of rats (synaptosomes). The ambient level of [(3)H]GABA that is a balance between release and uptake of the neurotransmitter increased significantly in the presence of rac-BHFF (at concentrations 10-30μM). The initial velocity of synaptosomal [(3)H]GABA uptake was suppressed by the modulator. In the presence of GABA transporter blocker NO-711, it was shown that rac-BHFF increased tonic release of [(3)H]GABA from synaptosomes (at concentrations 3-30μM). Rac-BHFF within the concentration range of 0.3-30μM did not enhance inhibiting effect of (±)-baclofen on depolarization-induced exocytotic release of [(3)H]GABA. Rac-BHFF (0.3-30μM) caused dose-dependent depolarization of the plasma membrane and dissipation of the proton gradient of synaptic vesicles in synaptosomes that was shown in the absence/presence of GABAB receptor antagonist saclofen using fluorescent dyes rhodamine 6G and acridine orange, respectively, and so, the above effects of rac-BHFF were not associated with the modulation of presynaptic GABAB receptors. Therefore, drug development strategy of positive allosteric modulation of GABAB receptors is to eliminate the above side effects of rac-BHFF in presynapse, and vice versa, these new properties of rac-BHFF may be exploited appropriately. PMID:26197223

  18. Reducing effect of saikosaponin A, an active ingredient of Bupleurum falcatum, on alcohol self-administration in rats: Possible involvement of the GABAB receptor.

    PubMed

    Maccioni, Paola; Lorrai, Irene; Carai, Mauro A M; Riva, Antonella; Morazzoni, Paolo; Mugnaini, Claudia; Corelli, Federico; Gessa, Gian Luigi; Colombo, Giancarlo

    2016-05-16

    Recent studies demonstrated that treatment with saikosaponin A (SSA) - an active ingredient of the medicinal herb, Bupleurum falcatum L. - selectively suppressed, likely via a GABAB receptor-mediated mechanism, intravenous self-administration of morphine and cocaine in rats [Yoon et al., 2012; 2013]. The present study was designed to investigate whether the capacity of SSA to suppress morphine and cocaine self-administration extends to oral alcohol self-administration. To this end, selectively bred Sardinian alcohol-preferring (sP) rats were trained to lever-respond on a Fixed Ratio (FR) 4 (FR4) schedule of reinforcement for alcohol (15%, v/v) in daily 30-min sessions. Once responding had stabilized, rats were tested under the FR4 (measure of alcohol reinforcing properties) and Progressive Ratio (PR; measure of alcohol motivational properties) schedules of reinforcement. The possible involvement of the GABAB receptor system was investigated testing the effect of (a) pretreatment with the GABAB receptor antagonist, SCH50911, and (b) combined treatment with the positive allosteric modulator of the GABAB receptor, GS39783. Treatment with SSA (0, 0.25, 0.5, and 1mg/kg, i.p.) markedly reduced lever-responding for alcohol, amount of self-administered alcohol, and breakpoint for alcohol (defined as the lowest response requirement not achieved in the PR experiment). Pretreatment with 2mg/kg SCH50911 (i.p.) resulted in a partial blockade of the reducing effect of 0.5mg/kg SSA on lever-responding for alcohol and amount of self-administered alcohol. Combination of per se ineffective doses of GS39783 (5mg/kg, i.g.) and SSA (0.1mg/kg, i.p.) reduced lever-responding for alcohol and amount of self-administered alcohol. These results (a) extend to alcohol self-administration the capacity of SSA to suppress morphine and cocaine self-administration in rats and (b) suggest that the GABAB receptor system is likely part of the neural substrate underlying the reducing effect of SSA on

  19. GABAB receptor-mediated, layer-specific synaptic plasticity reorganizes gamma-frequency neocortical response to stimulation.

    PubMed

    Ainsworth, Matthew; Lee, Shane; Kaiser, Marcus; Simonotto, Jennifer; Kopell, Nancy J; Whittington, Miles A

    2016-05-10

    Repeated presentations of sensory stimuli generate transient gamma-frequency (30-80 Hz) responses in neocortex that show plasticity in a task-dependent manner. Complex relationships between individual neuronal outputs and the mean, local field potential (population activity) accompany these changes, but little is known about the underlying mechanisms responsible. Here we show that transient stimulation of input layer 4 sufficient to generate gamma oscillations induced two different, lamina-specific plastic processes that correlated with lamina-specific changes in responses to further, repeated stimulation: Unit rates and recruitment showed overall enhancement in supragranular layers and suppression in infragranular layers associated with excitatory or inhibitory synaptic potentiation onto principal cells, respectively. Both synaptic processes were critically dependent on activation of GABAB receptors and, together, appeared to temporally segregate the cortical representation. These data suggest that adaptation to repetitive sensory input dramatically alters the spatiotemporal properties of the neocortical response in a manner that may both refine and minimize cortical output simultaneously. PMID:27118845

  20. GABAB receptor-mediated, layer-specific synaptic plasticity reorganizes gamma-frequency neocortical response to stimulation

    PubMed Central

    Ainsworth, Matthew; Lee, Shane; Kaiser, Marcus; Simonotto, Jennifer; Kopell, Nancy J.

    2016-01-01

    Repeated presentations of sensory stimuli generate transient gamma-frequency (30–80 Hz) responses in neocortex that show plasticity in a task-dependent manner. Complex relationships between individual neuronal outputs and the mean, local field potential (population activity) accompany these changes, but little is known about the underlying mechanisms responsible. Here we show that transient stimulation of input layer 4 sufficient to generate gamma oscillations induced two different, lamina-specific plastic processes that correlated with lamina-specific changes in responses to further, repeated stimulation: Unit rates and recruitment showed overall enhancement in supragranular layers and suppression in infragranular layers associated with excitatory or inhibitory synaptic potentiation onto principal cells, respectively. Both synaptic processes were critically dependent on activation of GABAB receptors and, together, appeared to temporally segregate the cortical representation. These data suggest that adaptation to repetitive sensory input dramatically alters the spatiotemporal properties of the neocortical response in a manner that may both refine and minimize cortical output simultaneously. PMID:27118845

  1. Modulation of TLR3/TLR4 inflammatory signaling by the GABAB receptor agonist baclofen in glia and immune cells: relevance to therapeutic effects in multiple sclerosis

    PubMed Central

    Crowley, Tadhg; Fitzpatrick, John-Mark; Kuijper, Teun; Cryan, John F.; O’Toole, Orna; O’Leary, Olivia F.; Downer, Eric J.

    2015-01-01

    The GABAB receptor agonist, baclofen, is used to treat muscle tightness and cramping caused by spasticity in a number of disorders including multiple sclerosis (MS), but its precise mechanism of action is unknown. Neuroinflammation drives the central pathology in MS and is mediated by both immunoreactive glial cells and invading lymphocytes. Furthermore, a body of data indicates that the Toll-like receptor (TLR) family of innate immune receptors is implicated in MS progression. In the present study we investigated whether modulation of GABAB receptors using baclofen can exert anti-inflammatory effects by targeting TLR3 and(or) TLR4-induced inflammatory signaling in murine glial cells and human peripheral blood mononuclear cells (PBMCs) isolated from healthy control individuals and patients with the relapse-remitting (RR) form of MS. TLR3 and TLR4 stimulation promoted the nuclear sequestration of NF-κB and pro-inflammatory cytokine expression in murine glia, while TLR4, but not TLR3, promoted pro-inflammatory cytokine expression in PBMCs isolated from both healthy donors and RR-MS patients. Importantly, this effect was exacerbated in RR-MS patient immune cells. We present further evidence that baclofen dose-dependently attenuated TLR3- and TLR4-induced inflammatory signaling in primary glial cells. Pre-exposure of PBMCs isolated from healthy donors to baclofen attenuated TLR4-induced TNF-α expression, but did not affect TLR4-induced TNF-α expression in RR-MS patient PBMCs. Interestingly, mRNA expression of the GABAB receptor was reduced in PBMCs from RR-MS donors when compared to healthy controls, an effect that might contribute to the differential sensitivity to baclofen seen in healthy and RR-MS patient cells. Overall these findings indicate that baclofen differentially regulates TLR3 and TLR4 signaling in glia and immune cells, and offers insight on the role of baclofen in the treatment of neuroinflammatory disease states including MS. PMID:26283920

  2. Attenuation of the stimulant response to ethanol is associated with enhanced ataxia for a GABAA, but not a GABAB, receptor agonist

    PubMed Central

    Holstein, Sarah E.; Dobbs, Lauren; Phillips, Tamara J.

    2008-01-01

    Background The γ-aminobutyric acid (GABA) system is implicated in the neurobiological actions of ethanol, and pharmacological agents that increase the activity of this system have been proposed as potential treatments for alcohol use disorders. As ethanol has its own GABA mimetic properties, it is critical to determine the mechanism by which GABAergic drugs may reduce the response to ethanol (i.e. via an inhibition or an accentuation of the neurobiological effects of ethanol). Methods In the present study, we examined the ability of three different types of GABAergic compounds, the GABA reuptake inhibitor NO-711, the GABAA receptor agonist muscimol, and the GABAB receptor agonist baclofen, to attenuate the locomotor stimulant response to ethanol in FAST mice, which were selectively bred for extreme sensitivity to ethanol-induced locomotor stimulation. In order to determine whether these compounds produced a specific reduction in stimulation, their effects on ethanol-induced motor incoordination were also examined. Results NO-711, muscimol, and baclofen were all found to potently attenuate the locomotor stimulant response to ethanol in FAST mice. However, both NO-711 and muscimol produced a marked increase in ethanol-induced ataxia, whereas baclofen did not accentuate this response. Conclusions These results suggest that pharmacological agents that increase extracellular concentrations of GABA and GABAA receptor activity may attenuate the stimulant effects of ethanol by accentuating its intoxicating and sedative properties. However, selective activation of the GABAB receptor appears to produce a specific attenuation of ethanol-induced stimulation, suggesting that GABAB receptor agonists may hold greater promise as potential pharmacotherapies for alcohol use disorders. PMID:18945218

  3. Inhibition of presynaptic calcium transients in cortical inputs to the dorsolateral striatum by metabotropic GABAB and mGlu2/3 receptors

    PubMed Central

    Kupferschmidt, David A; Lovinger, David M

    2015-01-01

    Cortical inputs to the dorsolateral striatum (DLS) are dynamically regulated during skill learning and habit formation, and are dysregulated in disorders characterized by impaired action control. Therefore, a mechanistic investigation of the processes regulating corticostriatal transmission is key to understanding DLS-associated circuit function, behaviour and pathology. Presynaptic GABAB and group II metabotropic glutamate (mGlu2/3) receptors exert marked inhibitory control over corticostriatal glutamate release in the DLS, yet the signalling pathways through which they do so are unclear. We developed a novel approach using the genetically encoded calcium (Ca2+) indicator GCaMP6 to assess presynaptic Ca2+ in corticostriatal projections to the DLS. Using simultaneous photometric presynaptic Ca2+ and striatal field potential recordings, we report that relative to P/Q-type Ca2+ channels, N-type channels preferentially contributed to evoked presynaptic Ca2+ influx in motor cortex projections to, and excitatory transmission in, the DLS. Activation of GABAB or mGlu2/3 receptors inhibited both evoked presynaptic Ca2+ transients and striatal field potentials. mGlu2/3 receptor-mediated depression did not require functional N-type Ca2+ channels, but was attenuated by blockade of P/Q-type channels. These findings reveal presynaptic mechanisms of inhibitory modulation of corticostriatal function that probably contribute to the selection and shaping of behavioural repertoires. Key points Plastic changes at cortical inputs to the dorsolateral striatum (DLS) underlie skill learning and habit formation, so characterizing the mechanisms by which these inputs are regulated is important for understanding the neural basis of action control. We developed a novel approach using the genetically encoded calcium (Ca2+) indicator GCaMP6 and brain slice photometry to assess evoked presynaptic Ca2+ transients in cortical inputs to the DLS and study their regulation by GABAB and mGlu2

  4. Regulator of G protein signaling 6 (RGS6) protein ensures coordination of motor movement by modulating GABAB receptor signaling.

    PubMed

    Maity, Biswanath; Stewart, Adele; Yang, Jianqi; Loo, Lipin; Sheff, David; Shepherd, Andrew J; Mohapatra, Durga P; Fisher, Rory A

    2012-02-10

    γ-Aminobutyric acid (GABA) release from inhibitory interneurons located within the cerebellar cortex limits the extent of neuronal excitation in part through activation of metabotropic GABA(B) receptors. Stimulation of these receptors triggers a number of downstream signaling events, including activation of GIRK channels by the Gβγ dimer resulting in membrane hyperpolarization and inhibition of neurotransmitter release from presynaptic sites. Here, we identify RGS6, a member of the R7 subfamily of RGS proteins, as a key regulator of GABA(B)R signaling in cerebellum. RGS6 is enriched in the granule cell layer of the cerebellum along with neuronal GIRK channel subunits 1 and 2 where RGS6 forms a complex with known binding partners Gβ(5) and R7BP. Mice lacking RGS6 exhibit abnormal gait and ataxia characterized by impaired rotarod performance improved by treatment with a GABA(B)R antagonist. RGS6(-/-) mice administered baclofen also showed exaggerated motor coordination deficits compared with their wild-type counterparts. Isolated cerebellar neurons natively expressed RGS6, GABA(B)R, and GIRK channel subunits, and cerebellar granule neurons from RGS6(-/-) mice showed a significant delay in the deactivation kinetics of baclofen-induced GIRK channel currents. These results establish RGS6 as a key component of GABA(B)R signaling and represent the first demonstration of an essential role for modulatory actions of RGS proteins in adult cerebellum. Dysregulation of RGS6 expression in human patients could potentially contribute to loss of motor coordination and, thus, pharmacological manipulation of RGS6 levels might represent a viable means to treat patients with ataxias of cerebellar origin. PMID:22179605

  5. Regulator of G Protein Signaling 6 (RGS6) Protein Ensures Coordination of Motor Movement by Modulating GABAB Receptor Signaling*

    PubMed Central

    Maity, Biswanath; Stewart, Adele; Yang, Jianqi; Loo, Lipin; Sheff, David; Shepherd, Andrew J.; Mohapatra, Durga P.; Fisher, Rory A.

    2012-01-01

    γ-Aminobutyric acid (GABA) release from inhibitory interneurons located within the cerebellar cortex limits the extent of neuronal excitation in part through activation of metabotropic GABAB receptors. Stimulation of these receptors triggers a number of downstream signaling events, including activation of GIRK channels by the Gβγ dimer resulting in membrane hyperpolarization and inhibition of neurotransmitter release from presynaptic sites. Here, we identify RGS6, a member of the R7 subfamily of RGS proteins, as a key regulator of GABABR signaling in cerebellum. RGS6 is enriched in the granule cell layer of the cerebellum along with neuronal GIRK channel subunits 1 and 2 where RGS6 forms a complex with known binding partners Gβ5 and R7BP. Mice lacking RGS6 exhibit abnormal gait and ataxia characterized by impaired rotarod performance improved by treatment with a GABABR antagonist. RGS6−/− mice administered baclofen also showed exaggerated motor coordination deficits compared with their wild-type counterparts. Isolated cerebellar neurons natively expressed RGS6, GABABR, and GIRK channel subunits, and cerebellar granule neurons from RGS6−/− mice showed a significant delay in the deactivation kinetics of baclofen-induced GIRK channel currents. These results establish RGS6 as a key component of GABABR signaling and represent the first demonstration of an essential role for modulatory actions of RGS proteins in adult cerebellum. Dysregulation of RGS6 expression in human patients could potentially contribute to loss of motor coordination and, thus, pharmacological manipulation of RGS6 levels might represent a viable means to treat patients with ataxias of cerebellar origin. PMID:22179605

  6. GABAB receptors inhibit low-voltage activated and high-voltage activated Ca(2+) channels in sensory neurons via distinct mechanisms.

    PubMed

    Huang, Dongyang; Huang, Sha; Peers, Chris; Du, Xiaona; Zhang, Hailin; Gamper, Nikita

    2015-09-18

    Growing evidence suggests that mammalian peripheral somatosensory neurons express functional receptors for gamma-aminobutyric acid, GABAA and GABAB. Moreover, local release of GABA by pain-sensing (nociceptive) nerve fibres has also been suggested. Yet, the functional significance of GABA receptor triggering in nociceptive neurons is not fully understood. Here we used patch-clamp recordings from small-diameter cultured DRG neurons to investigate effects of GABAB receptor agonist baclofen on voltage-gated Ca(2+) currents. We found that baclofen inhibited both low-voltage activated (LVA, T-type) and high-voltage activated (HVA) Ca(2+) currents in a proportion of DRG neurons by 22% and 32% respectively; both effects were sensitive to Gi/o inhibitor pertussis toxin. Inhibitory effect of baclofen on both current types was about twice less efficacious as compared to that of the μ-opioid receptor agonist DAMGO. Surprisingly, only HVA but not LVA current modulation by baclofen was partially prevented by G protein inhibitor GDP-β-S. In contrast, only LVA but not HVA current modulation was reversed by the application of a reducing agent dithiothreitol (DTT). Inhibition of T-type Ca(2+) current by baclofen and the recovery of such inhibition by DTT were successfully reconstituted in the expression system. Our data suggest that inhibition of LVA current in DRG neurons by baclofen is partially mediated by an unconventional signaling pathway that involves a redox mechanism. These findings reinforce the idea of targeting peripheral GABA receptors for pain relief. PMID:26239659

  7. Bidirectional enantioselective effects of the GABAB receptor agonist baclofen in two mouse models of excessive ethanol consumption

    PubMed Central

    Kasten, Chelsea R.; Blasingame, Shelby N.; Boehm, Stephen L.

    2014-01-01

    The GABAB receptor agonist baclofen has been studied extensively in preclinical models of alcohol use disorders, yet results on its efficacy have been uncertain. Racemic baclofen, which is used clinically, can be broken down into separate enantiomers of the drug. Baclofen has been shown to produce enantioselective effects in behavioral assays including those modeling reflexive and sexual behavior. The current studies sought to characterize the enantioselective effects of baclofen in two separate models of ethanol consumption. The first was a Drinking-in-the-Dark procedure that provides “binge-like” ethanol access to mice by restricting access to a two hour period, three hours into the dark cycle. The second was a two-bottle choice procedure that utilized selectively bred High Alcohol Preferring 1 (HAP1) mice to model chronic ethanol access. HAP1 mice are selectively bred to consume pharmacologically relevant amounts of ethanol in a 24-hour two-bottle choice paradigm. The results showed that baclofen yields enantioselective effects on ethanol intake in both models, and that these effects are bidirectional. Total ethanol intake was decreased by R(+)- baclofen, while total intake was increased by S(-)-baclofen in the binge-like and chronic drinking models. Whereas overall binge-like saccharin intake was significantly reduced by R(+)- baclofen, chronic intake was not significantly altered. S(-)- baclofen did not significantly alter saccharin intake. Neither enantiomer significantly affected locomotion during binge-like reinforcer consumption. Collectively, these results demonstrate that baclofen produces enantioselective effects on ethanol consumption. More importantly, the modulation of consumption is bidirectional. The opposing enantioselective effects may explain some of the variance seen in published baclofen literature. PMID:25557834

  8. Differential effects of K+ channel blockers on antinociception induced by alpha 2-adrenoceptor, GABAB and kappa-opioid receptor agonists.

    PubMed Central

    Ocaña, M.; Baeyens, J. M.

    1993-01-01

    1. The effects of several K+ channel blockers (sulphonylureas, 4-aminopyridine and tetraethylammonium) on the antinociception induced by clonidine, baclofen and U50,488H were evaluated by use of a tail flick test in mice. 2. Clonidine (0.125-2 mg kg-1, s.c.) induced a dose-dependent antinociceptive effect. The ATP-dependent K+ (KATP) channel blocker gliquidone (4-8 micrograms/mouse, i.c.v.) produced a dose-dependent displacement to the right of the clonidine dose-response line, but neither 4-aminopyridine (4-AP) (25-250 ng/mouse, i.c.v.) nor tetraethylammonium (TEA) (10-20 micrograms/mouse, i.c.v.) significantly modified clonidine-induced antinociception. 3. The order of potency of sulphonylureas in antagonizing clonidine-induced antinociception was gliquidone > glipizide > glibenclamide > tolbutamide, which is the same order of potency as these drugs block KATP channels in neurones of the CNS. 4. Baclofen (2-16 mg kg-1, s.c.) also induced a dose-dependent antinociceptive effect. Both 4-AP (2.5-25 ng/mouse, i.c.v.) and TEA (10-20 micrograms/mouse, i.c.v.) dose-dependently antagonized baclofen antinociception, producing a displacement to the right of the baclofen dose-response line. However, gliquidone (8-16 micrograms/mouse, i.c.v.) did not significantly modify the baclofen effect. 5. None of the K+ channel blockers tested (gliquidone, 8-16 micrograms/mouse; 4-AP, 25-250 ng/mouse and TEA, 10-20 micrograms/mouse, i.c.v.), significantly modified the antinociception induced by U50,488H (8 mg kg-1, s.c.). 6. These results suggest that the opening of K+ channels is involved in the antinociceptive effect of alpha 2 and GABAB, but not kappa-opioid, receptor agonists.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7905339

  9. Visual experience prevents dysregulation of GABAB receptor-dependent short-term depression in adult superior colliculus

    PubMed Central

    Balmer, Timothy S.

    2015-01-01

    Progressive loss of plasticity during development prevents refined circuits from regressing to an immature state and is thought to depend on maturation of GABAergic inhibition. For example, a gradual reduction in size of visual receptive fields (RFs) occurs in the superior colliculus (SC) during development. Maintenance of the refined state throughout adulthood requires early light exposure. Here we investigate the potential role of changes in long- or short-term plasticity in experience-dependent maintenance of refined RFs. Using an acute SC slice preparation, we found that long-term plasticity was not affected by visual deprivation, indicating that it does not underlie deprivation-induced RF enlargement. In contrast, visual deprivation altered short-term plasticity in an unexpected way. Specifically, GABAB receptor (GABABR)-mediated paired pulse depression was increased in slices from dark-reared animals. This increase was mimicked by GABAAR blockade in slices from normally reared animals, suggesting that experience-dependent maintenance of GABAAR function prevents an increase in probability of neurotransmitter release. GABABR-mediated short-term depression in response to strong stimulation (such as occurs during vision) was reduced in slices from dark-reared animals. This change was mimicked in slices from normal animals by reducing GABA release. These results are consistent with the hypothesis that early visual experience maintains GABAergic inhibition and prevents later deprivation-induced alterations of short-term depression in SC. Identifying how plasticity is restricted in mature circuits could guide therapies to enhance recovery of function in adults. PMID:25568162

  10. Bidirectional enantioselective effects of the GABAB receptor agonist baclofen in two mouse models of excessive ethanol consumption.

    PubMed

    Kasten, Chelsea R; Blasingame, Shelby N; Boehm, Stephen L

    2015-02-01

    The GABAB receptor agonist baclofen has been studied extensively in preclinical models of alcohol-use disorders, yet results on its efficacy have been uncertain. Racemic baclofen, which is used clinically, can be broken down into separate enantiomers of the drug. Baclofen has been shown to produce enantioselective effects in behavioral assays, including those modeling reflexive and sexual behavior. The current studies sought to characterize the enantioselective effects of baclofen in two separate models of ethanol consumption. The first was a Drinking-in-the-Dark procedure that provides "binge-like" ethanol access to mice by restricting access to a 2-h period, 3 h into the dark cycle. The second was a two-bottle choice procedure that utilized selectively bred High Alcohol Preferring 1 (HAP1) mice to model chronic ethanol access. HAP1 mice are selectively bred to consume pharmacologically relevant amounts of ethanol in a 24-h two-bottle choice paradigm. The results showed that baclofen yields enantioselective effects on ethanol intake in both models, and that these effects are bidirectional. Total ethanol intake was decreased by R(+)-baclofen, while total intake was increased by S(-)-baclofen in the binge-like and chronic drinking models. Whereas overall binge-like saccharin intake was significantly reduced by R(+)-baclofen, chronic intake was not significantly altered. S(-)-baclofen did not significantly alter saccharin intake. Neither enantiomer significantly affected locomotion during binge-like reinforcer consumption. Collectively, these results demonstrate that baclofen produces enantioselective effects on ethanol consumption. More importantly, the modulation of consumption is bidirectional. The opposing enantioselective effects may explain some of the variance seen in published baclofen literature. PMID:25557834

  11. Endoplasmic Reticulum Sorting and Kinesin-1 Command the Targeting of Axonal GABAB Receptors

    PubMed Central

    Valdés, Viviana; Valenzuela, José Ignacio; Salas, Daniela A.; Jaureguiberry-Bravo, Matías; Otero, Carolina; Thiede, Christina; Schmidt, Christoph F.; Couve, Andrés

    2012-01-01

    In neuronal cells the intracellular trafficking machinery controls the availability of neurotransmitter receptors at the plasma membrane, which is a critical determinant of synaptic strength. Metabotropic γ amino-butyric acid (GABA) type B receptors (GABABRs) are neurotransmitter receptors that modulate synaptic transmission by mediating the slow and prolonged responses to GABA. GABABRs are obligatory heteromers constituted by two subunits, GABABR1 and GABABR2. GABABR1a and GABABR1b are the most abundant subunit variants. GABABR1b is located in the somatodendritic domain whereas GABABR1a is additionally targeted to the axon. Sushi domains located at the N-terminus of GABABR1a constitute the only difference between both variants and are necessary and sufficient for axonal targeting. The precise targeting machinery and the organelles involved in sorting and transport have not been described. Here we demonstrate that GABABRs require the Golgi apparatus for plasma membrane delivery but that axonal sorting and targeting of GABABR1a operate in a pre-Golgi compartment. In the axon GABABR1a subunits are enriched in the endoplasmic reticulum (ER), and their dynamic behavior and colocalization with other secretory organelles like the ER-to-Golgi intermediate compartment (ERGIC) suggest that they employ a local secretory route. The transport of axonal GABABR1a is microtubule-dependent and kinesin-1, a molecular motor of the kinesin family, determines axonal localization. Considering that progression of GABABRs through the secretory pathway is regulated by an ER retention motif our data contribute to understand the role of the axonal ER in non-canonical sorting and targeting of neurotransmitter receptors. PMID:22952914

  12. ADX71441, a novel, potent and selective positive allosteric modulator of the GABAB receptor, shows efficacy in rodent models of overactive bladder

    PubMed Central

    Kalinichev, M; Palea, S; Haddouk, H; Royer-Urios, I; Guilloteau, V; Lluel, P; Schneider, M; Saporito, M; Poli, S

    2014-01-01

    Background and Purpose The GABAB receptor agonist baclofen reduces urethral resistance and detrusor overactivity in patients with spasticity. However, baclofen's side effects limit its use for the treatment of overactive bladder (OAB). Here, we tested a novel GABAB positive allosteric modulator (PAM) ADX71441 in models of OAB in mice and guinea pigs. Experimental Approach Mice were left untreated or given (p.o.) vehicle (1= CMC), ADX71441 (1, 3, 10 mg kg−1) or oxybutynin (100 mg kg−1; Experiment 1) or vehicle (1= CMC), baclofen (1, 3, 6 mg kg−1) or oxybutynin (Experiment 2). Treated mice were then overhydrated with water, challenged with furosemide, before being placed into micturition chambers and monitored for urinary parameters. In anaesthetized guinea pigs, intravesical infusion of acetic acid was used to induce OAB and the effects of ADX71441 (1, 3 mg kg−1) or baclofen (1 mg kg−1), administered i.v., on cystometric parameters were monitored. Key Results In mice, 10 mg kg−1 ADX71441 increased urinary latencies, reduced the number of urinary events and the total and average urinary volumes. In guinea pigs, ADX71441 (1 and 3 mg kg−1) increased the intercontraction interval (ICI) and bladder capacity (BC), and reduced micturition frequency (MF) compared to vehicle. At 3 mg kg−1 ADX71441 completely inhibited the micturition reflex and induced overflow incontinence in five out of 10 animals. Baclofen slightly increased ICI and BC and reduced MF. Conclusion and Implications Our findings demonstrate, for the first time, that a GABAB PAM has potential as a novel approach for the treatment of OAB. PMID:24224799

  13. Thymoquinone and vitamin C attenuates pentylenetetrazole-induced seizures via activation of GABAB1 receptor in adult rats cortex and hippocampus.

    PubMed

    Ullah, Ikram; Badshah, Haroon; Naseer, Muhammad Imran; Lee, Hae Young; Kim, Myeong Ok

    2015-03-01

    Epilepsy is a common neurological disorder that leads to neuronal excitability and provoke various forms of cellular reorganization in the brain. In this study, we investigate the anti-convulsant and neuroprotective effects of thymoquinone (TQ) and vitamin C against pentylenetetrazole (PTZ)-induced generalized seizures. Epileptic seizures were induced in adult rats using systemic intraperitoneal injections of PTZ (50 mg/kg) for 7 days. Animals pretreated with either TQ or vitamin C or in combination attenuated PTZ-induced seizures and mortality in rats as well neurodegeneration in the cells. Compared to PTZ, TQ and vitamin C significantly prolonged the onset of seizures (p > 0.05) as well decrease the high-grade seizures. Analysis of electroencephalogram (EEG) recordings revealed that TQ or vitamin C supplementation significantly reduced polyspike and epileptiform discharges. Epileptic seizures caused a decline in expression of gamma-aminobutyric acid B1 receptor (GABAB1R) (p > 0.05), unchanged expression of protein kinase A (PKA), decreased calcium/calmodulin-dependent protein kinase II (CaMKII) (p > 0.05) and inhibit the phosphorylation of cAMP response element-binding protein (CREB) (p > 0.05) in cortex and hippocampus, respectively, compared with control. Changes in expression of GABAB1R, CaMKII and CREB by PTZ were reversed by TQ and vitamin C supplementation. Moreover, PTZ significantly increased Bax, decreased Bcl-2 expression and finally the activation of caspase-3. TQ and vitamin C pretreatment reversed all these deleterious effects induced by PTZ. TQ and vitamin C showed anticonvulsant effects via activation of GABAB1R/CaMKII/CREB pathway and suggest a potential therapeutic role in epilepsy. PMID:25429759

  14. Cloning and characterization of GABAA α subunits and GABAB subunits in Xenopus laevis during development

    PubMed Central

    Kaeser, Gwendolyn E.; Rabe, Brian A.; Saha, Margaret S.

    2011-01-01

    Gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the adult nervous system, acts via two classes of receptors, the ionotropic GABAA and metabotropic GABAB receptors. During the development of the nervous system GABA acts in a depolarizing, excitatory manner and plays an important role in various neural developmental processes including cell proliferation, migration, synapse formation and activity-dependent differentiation. Here we describe the spatial and temporal expression patterns of the GABAA and GABAB receptors during early development of Xenopus laevis. Using in situ hybridization and qRT-PCR, GABAA α2 was detected as a maternal mRNA. All other α-subunits were first detected by tailbud through hatching stages. Expression of the various subunits was seen in the brain, spinal cord, cranial ganglia, olfactory epithelium, pineal, and pituitary gland. Each receptor subunit showed a distinctive, unique expression pattern suggesting these receptors have specific functions and are regulated in a precise spatial and temporal manner. PMID:21384470

  15. The GABAB receptor antagonist CGP 36,742 and the nootropic oxiracetam facilitate the formation of long-term memory.

    PubMed

    Mondadori, C; Möbius, H J; Borkowski, J

    1996-05-01

    The memory-enhancing effects of a single treatment with the GABAB antagonist CGP 36,742 (10 mg/kg) or the nootropic agent oxiracetam (100 mg/kg) given immediately after a learning experience ('post-trial') remain detectable for at least 4 months thereafter. This indicates that in all probability these substances facilitate the formation of the long-term memory trace. PMID:8762175

  16. A novel GABAergic action mediated by functional coupling between GABAB-like receptor and two different high-conductance K+ channels in cricket Kenyon cells.

    PubMed

    Nakamura, Atsunao; Yoshino, Masami

    2013-04-01

    The γ-aminobutyric acid type B (GABA(B)) receptor has been shown to attenuate high-voltage-activated Ca(2+) currents and enhance voltage-dependent or inwardly rectifying K(+) currents in a variety of neurons. In this study, we report a novel coupling of GABA(B)-like receptor with two different high-conductance K(+) channels, Na(+)-activated K(+) (K(Na)) channel and Ca(2+)-activated K(+) (K(Ca)) channel, in Kenyon cells isolated from the mushroom body of the cricket brain. Single-channel activities of K(Na) and K(Ca) channels in response to bath applications of GABA and the GABA(B)-specific agonist SKF97541 were recorded with the cell-attached patch configuration. The open probability (P(o)) of both K(Na) and K(Ca) channels was found to be increased by bath application of GABA, and this increase in Po was antagonized by coapplication of the GABAB antagonist CGP54626, suggesting that GABA(B)-like receptors mediate these actions. Similarly, GABA(B)-specific agonist SKF97541 increased the Po of both K(Na) and K(Ca) channels. Perforated-patch recordings using β-escin further revealed that SKF97541 increased the amplitude of the outward currents elicited by step depolarizations. Under current-clamp conditions, SKF97541 decreased the firing frequency of spontaneous action potential (AP) and changed the AP waveform. The amplitude and duration of AP were decreased, whereas the afterhyperpolarization of AP was increased. Resting membrane potential, however, was not significantly altered by SKF97541. Taken together, these results suggest that GABA(B)-like receptor is functionally coupled with both K(Na) and K(Ca) channels and this coupling mechanism may serve to prevent AP formation and limit excitatory synaptic input. PMID:23303861

  17. Involvement of PKC and PKA in the enhancement of L-type calcium current by GABAB receptor activation in neonatal hippocampus

    PubMed Central

    Bray, Jennifer G.; Mynlieff, Michelle

    2011-01-01

    In the early neonatal period activation of GABAB receptors attenuates calcium current through N-type calcium channels while enhancing current through L-type calcium channels in rat hippocampal neurons. The attenuation of N-type calcium current has been previously demonstrated to occur through direct interactions of the βγ subunits of Gi/o G-proteins, but the signal transduction pathway for the enhancement of L-type calcium channels in mammalian neurons remains unknown. In the present study, calcium currents were elicited in acute cultures from postnatal day 6–8 rat hippocampi in the presence of various modulators of protein kinase A (PKA) and protein kinase C (PKC) pathways. Overnight treatment with an inhibitor of Gi/o (pertussis toxin, 200 ng/ml) abolished the attenuation of calcium current by the GABAB agonist, baclofen (10 μM) with no effect on the enhancement of calcium current. These data indicate that while the attenuation of N-type calcium current is mediated by the Gi/o subtype of G-protein, the enhancement of L-type calcium current requires activation of a different G-protein. The enhancement of the sustained component of calcium current by baclofen was blocked by PKC inhibitors, GF-109203X (500 nM), chelerythrine chloride (5 μM), and PKC fragment 19–36 (2 μM) and mimicked by the PKC activator phorbol-12-myristate-13-acetate (1 μM). The enhancement of the sustained component of calcium current was blocked by PKA inhibitors H-89 (1 μM) and PKA fragment 6–22 (500 nM) but not Rp-cAMPS (30 μM) and it was not mimicked by the PKA activator, 8-Br-cAMP (500 μM – 1 mM). The data suggest that activation of PKC alone is sufficient to enhance L-type calcium current but that PKA may also be involved in the GABAB receptor mediated effect. PMID:21277353

  18. General, kappa, delta and mu opioid receptor antagonists mediate feeding elicited by the GABA-B agonist baclofen in the ventral tegmental area and nucleus accumbens shell in rats: reciprocal and regional interactions.

    PubMed

    Miner, Patricia; Shimonova, Lyudmila; Khaimov, Arthur; Borukhova, Yaffa; Ilyayeva, Ester; Ranaldi, Robert; Bodnar, Richard J

    2012-03-14

    Food intake is significantly increased following administration of agonists of GABA and opioid receptors into the nucleus accumbens shell (NACs) and ventral tegmental area (VTA). GABA-A or GABA-B receptor antagonist pretreatment within the VTA or NACs differentially affects mu-opioid agonist-induced feeding elicited from the same site. Correspondingly, general or selective opioid receptor antagonist pretreatment within the VTA or NACs differentially affects GABA agonist-induced feeding elicited from the same site. Regional interactions have been evaluated in feeding studies by administering antagonists in one site prior to agonist administration in a second site. Thus, opioid antagonist-opioid agonist and GABA antagonist-GABA agonist feeding interactions have been identified between the VTA and NACs. However, pretreatment with GABA-A or GABA-B receptor antagonists in the VTA failed to affect mu opioid agonist-induced feeding elicited from the NACs, and correspondingly, these antagonists administered in the NACs failed to affect mu opioid-induced feeding elicited from the VTA. To evaluate whether regional and reciprocal VTA and NACs feeding interactions occur for opioid receptor modulation of GABA agonist-mediated feeding, the present study examined whether feeding elicited by the GABA-B agonist, baclofen microinjected into the NACs was dose-dependently blocked by pretreatment with general (naltrexone: NTX), mu (beta-funaltrexamine: BFNA), kappa (nor-binaltorphamine: NBNI) or delta (naltrindole: NTI) opioid antagonists in the VTA, and correspondingly, whether VTA baclofen-induced feeding was dose-dependently blocked by NACs pretreatment with NTX, BFNA, NBNI or NTI in rats. Bilateral pairs of cannulae aimed at the VTA and NACs were stereotaxically implanted in rats, and their food intakes were assessed following vehicle and baclofen (200 ng) in each site. Baclofen produced similar magnitudes of increased food intake following VTA and NACs treatment. Baclofen

  19. GABAB receptor-mediated tonic inhibition regulates the spontaneous firing of locus coeruleus neurons in developing rats and in citalopram-treated rats

    PubMed Central

    Wang, Han-Ying; Kuo, Zhao-Chen; Fu, Yu-Show; Chen, Ruei-Feng; Min, Ming-Yuan; Yang, Hsiu-Wen

    2015-01-01

    Noradrenaline (NA)-releasing neurons in the locus coeruleus (LC) provide NA to the forebrain. Their activity is believed to be a key factor regulating the wakefulness/arousal level of the brain. In this study, we found that the activity of NA-releasing neurons in the LC (LC neurons) was subject to γ-aminobutyric acid (GABA) tonic inhibition through GABAB receptors (GABABRs), but not GABAA receptors. The intensity of GABABR tonic inhibition was found to depend on ambient GABA levels, as it was dramatically increased by blockade of GABA reuptake. It also varied with the function of GABABRs. The GABABR activity on LC neurons was found to increase with postnatal age up to postnatal days 8–10, resulting in increased tonic inhibition. Interestingly, there was no significant difference in the spontaneous activity of LC neurons at different postnatal ages unless GABABR tonic inhibition was blocked. These results show that, during postnatal development, there is a continuous increase in GABABR tonic inhibition that maintains the activity of LC neurons at a proper level. In male, but not female, rats, chronic perinatal treatment with citalopram, a selective serotonin reuptake inhibitor, reduced GABABR activity and tonic inhibition, which might result in the significantly higher spontaneous activity of LC neurons seen in these animals. In conclusion, our results show that GABABR-mediated tonic inhibition has a direct impact on the spontaneous activity of LC neurons and that the extent of the effect varies with ambient GABA levels and functionality of GABABR signalling. PMID:25556794

  20. [The influence of the GABA-B receptor antagonists 2-hydoxysaclofen and faclofen on the sedative effect of fenibut and baclofen].

    PubMed

    Lapin, I P

    1995-01-01

    Pretreatment of NIH-Swiss mice with HYS (8 mg/kg) is shown to reduce the inhibiting effect (namely, the reduction of the locomotion rate and the number of horizontal movements) of PHE (80 mg/kg) and do not affect the action of an equipotent dose (4 mg/kg) of BAC. BAC induced shortening of the locomotion period is reduced by HYS. HYS appeared to be inactive with respect to inhibiting effect of PHE. PHE and BAC shortening of the distance covered was insensitive to HYS administration. HYS reduces decrease in the rate and duration of rearings induced by PHE. PHA (8 mg/kg) do not change the sedative effect of PHE and BAC on locomotion, attenuated the PHE-induced inhibition of rearings and increase the effect of BAC. It is suggested that GABA-B receptors affect the inhibitory action of PHE rather strong than that of BAC and differ in the inhibition of horizontal and vertical components of the locomotor activity of mice. PMID:8704585

  1. G(o) transduces GABAB-receptor modulation of N-type calcium channels in cultured dorsal root ganglion neurons.

    PubMed

    Menon-Johansson, A S; Berrow, N; Dolphin, A C

    1993-11-01

    High-voltage-activated (HVA) calcium channel currents (IBa) were recorded from acutely replated cultured dorsal root ganglion (DRG) neurons. IBa was irreversibly inhibited by 56.9 +/- 2.7% by 1 microM omega-conotoxin-GVIA (omega-CTx-GVIA), whereas the 1,4-dihydropyridine antagonist nicardipine was ineffective. The selective gamma-aminobutyric acidB (GABAB) agonist, (-)-baclofen (50 microM), inhibited the HVA IBa by 30.7 +/- 5.4%. Prior application of omega-CTx-GVIA completely occluded inhibition of the HVA IBa by (-)-baclofen, indicating that in this preparation (-)-baclofen inhibits N-type current. To investigate which G protein subtype was involved, cells were replated in the presence of anti-G protein antisera. Under these conditions the antibodies were shown to enter the cells through transient pores created during the replating procedure. Replating DRGs in the presence of anti-G(o) antiserum, raised against the C-terminal decapeptide of the G alpha o subunit, reduced (-)-baclofen inhibition of the HVA IBa, whereas replating DRGs in the presence of the anti-Gi antiserum did not. Using anti-G alpha o antisera (1:2000) and confocal laser microscopy, G alpha o localisation was investigated in both unreplated and replated neurons. G alpha o immunoreactivity was observed at the plasma membrane, neurites, attachment plaques and perinuclear region, and was particularly pronounced at points of cell-to-cell contact. The plasma membrane G alpha o immunoreactivity was completely blocked by preincubation with the immunising G alpha o undecapeptide (1 microgram.ml-1) for 1 h at 37 degrees C. A similar treatment also blocked recognition of G alpha o in brain membranes on immunoblots.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8309795

  2. Noise-induced hearing loss is correlated with alterations in the expression of GABAB receptors and PKC gamma in the murine cochlear nucleus complex

    PubMed Central

    Kou, Zhen-Zhen; Qu, Juan; Zhang, Dong-Liang; Li, Hui; Li, Yun-Qing

    2013-01-01

    Noise overexposure may induce permanent noise-induced hearing loss (NIHL). The cochlear nucleus complex (CNC) is the entry point for sensory information in the central auditory system. Impairments in gamma-aminobutyric acid (GABA)—mediated synaptic transmission in the CNC have been implicated in the pathogenesis of auditory disorders. However, the role of protein kinase C (PKC) signaling pathway in GABAergic inhibition in the CNC in NIHL remains elusive. Thus, we investigated the alterations of glutamic acid decarboxylase 67 (GAD67, the chemical marker for GABA-containing neurons), PKC γ subunit (PKCγ) and GABAB receptor (GABABR) expression in the CNC using transgenic GAD67-green fluorescent protein (GFP) knock-in mice, BALB/c mice and C57 mice. Immunohistochemical results indicate that the GFP-labeled GABAergic neurons were distributed in the molecular layer (ML) and fusiform cell layer (FCL) of the dorsal cochlear nucleus (DCN). We found that 69.91% of the GFP-positive neurons in the DCN were immunopositive for both PKCγ and GABABR1. The GAD67-positive terminals made contacts with PKCγ/GABABR1 colocalized neurons. Then we measured the changes of auditory thresholds in mice after noise exposure for 2 weeks, and detected the GAD67, PKCγ, and GABABR expression at mRNA and protein levels in the CNC. With noise over-exposure, there was a reduction in GABABR accompanied by an increase in PKCγ expression, but no significant change in GAD67 expression. In summary, our results demonstrate that alterations in the expression of PKCγ and GABABRs may be involved in impairments in GABAergic inhibition within the CNC and the development of NIHL. PMID:23908607

  3. GABAB Encephalitis: A Fifty-Two-Year-Old Man with Seizures, Dysautonomia, and Acute Heart Failure

    PubMed Central

    Loftspring, Matthew C.; Landsness, Eric; Wooliscroft, Lindsey; Rudock, Robert; Jo, Sally; Patel, Kevin R.

    2015-01-01

    Autoantibodies to the γ-aminobutyric acid receptor, subtype B (GABAB), are a known cause of limbic encephalitis. The spectrum of clinical manifestations attributable to this antibody is not well defined at the present time. Here we present a case of GABAB encephalitis presenting with encephalopathy, status epilepticus, dysautonomia, and acute heart failure. To our knowledge, heart failure and dysautonomia have not yet been reported with this syndrome. PMID:26609456

  4. Structure-Activity Studies of Cysteine-Rich α-Conotoxins that Inhibit High-Voltage-Activated Calcium Channels via GABA(B) Receptor Activation Reveal a Minimal Functional Motif.

    PubMed

    Carstens, Bodil B; Berecki, Géza; Daniel, James T; Lee, Han Siean; Jackson, Kathryn A V; Tae, Han-Shen; Sadeghi, Mahsa; Castro, Joel; O'Donnell, Tracy; Deiteren, Annemie; Brierley, Stuart M; Craik, David J; Adams, David J; Clark, Richard J

    2016-04-01

    α-Conotoxins are disulfide-rich peptides that target nicotinic acetylcholine receptors. Recently we identified several α-conotoxins that also modulate voltage-gated calcium channels by acting as G protein-coupled GABA(B) receptor (GABA(B)R) agonists. These α-conotoxins are promising drug leads for the treatment of chronic pain. To elucidate the diversity of α-conotoxins that act through this mechanism, we synthesized and characterized a set of peptides with homology to α-conotoxins known to inhibit high voltage-activated calcium channels via GABA(B)R activation. Remarkably, all disulfide isomers of the active α-conotoxins Pu1.2 and Pn1.2, and the previously studied Vc1.1 showed similar levels of biological activity. Structure determination by NMR spectroscopy helped us identify a simplified biologically active eight residue peptide motif containing a single disulfide bond that is an excellent lead molecule for developing a new generation of analgesic peptide drugs. PMID:26948522

  5. Upregulation of genes related to bone formation by γ-amino butyric acid and γ-oryzanol in germinated brown rice is via the activation of GABAB-receptors and reduction of serum IL-6 in rats

    PubMed Central

    Muhammad, Sani Ismaila; Maznah, Ismail; Mahmud, Rozi; Zuki, Abu Bakar Zakaria; Imam, Mustapha Umar

    2013-01-01

    -treated groups. Conclusion GABA and ORZ from GBR stimulates osteoblastogenesis by upregulation of bone formation genes, possibly via the activation of GABAB receptors and by inhibiting the activity of inflammatory cytokines and reactive oxygen species. Therefore, it could be used effectively in the management of osteoporosis. PMID:24098073

  6. L-baclofen-sensitive GABAB binding sites in the medial vestibular nucleus localized by immunocytochemistry

    NASA Technical Reports Server (NTRS)

    Holstein, G. R.; Martinelli, G. P.; Cohen, B.

    1992-01-01

    L-Baclofen-sensitive GABAB binding sites in the medial vestibular nucleus (MVN) were identified immunocytochemically and visualized ultrastructurally in L-baclofen-preinjected rats and monkeys, using a mouse monoclonal antibody with specificity for the p-chlorophenyl moiety of baclofen. Saline-preinjected animals showed no immunostain. In drug-injected animals, there was evidence for both pre- and postsynaptic GABAergic inhibition in MVN mediated by GABAB receptors. These neural elements could be utilized in control of velocity storage in the vestibulo-ocular reflex.

  7. Play.

    ERIC Educational Resources Information Center

    Rogers, Fred; Sharapan, Hedda

    1993-01-01

    Contends that, in childhood, work and play seem to come together. Says that for young children their play is their work, and the more adults encourage children to play, the more they emphasize important lifelong resource. Examines some uses of children's play, making and building, artwork, dramatic play, monsters and superheroes, gun play, and…

  8. gamma-Hydroxybutyrate conversion into GABA induces displacement of GABAB binding that is blocked by valproate and ethosuximide.

    PubMed

    Hechler, V; Ratomponirina, C; Maitre, M

    1997-05-01

    gamma-Hydroxybutyrate (GHB) has been reported to be a ligand for GABAB receptor(s), although with low or very low affinity (IC50 = 150-796 microM). In addition, several reports argue for a role of GHB via GABAB receptors in both in vivo and in vitro electro-physiological experiments. In the present study, we demonstrate that the inhibition of GHB's conversion into GABA by rat brain membranes blocks the ability of GHB to interfere with GABAB binding. In particular, the inhibition of GHB dehydrogenase by valproate or ethosuximide and the blockade of GABA-T by aminooxyacetic acid induce the disappearance of the GABA-like effect of GHB at GABAB, but also at GABAA, receptors. This finding could explain the misinterpretation of in vitro or in vivo experiments where GHB possesses a GABA-like effect. But in addition, it is postulated that the normal metabolism of GHB in brain induces GABAB mechanisms that could be blocked by the administration of valproate or ethosuximide. PMID:9152382

  9. Rapid antidepressants stimulate the decoupling of GABAB receptors from GIRK/Kir3 channels through increased protein stability of 14-3-3η

    PubMed Central

    Workman, E R; Haddick, P C G; Bush, K; Dilly, G A; Niere, F; Zemelman, B V; Raab-Graham, K F

    2015-01-01

    A single injection of N-methyl-D-aspartate receptor (NMDAR) antagonists produces a rapid antidepressant response. Lasting changes in the synapse structure and composition underlie the effectiveness of these drugs. We recently discovered that rapid antidepressants cause a shift in the γ-aminobutyric acid receptor (GABABR) signaling pathway, such that GABABR activation shifts from opening inwardly rectifiying potassium channels (Kir/GIRK) to increasing resting dendritic calcium signal and mammalian Target of Rapamycin activity. However, little is known about the molecular and biochemical mechanisms that initiate this shift. Herein, we show that GABABR signaling to Kir3 (GIRK) channels decreases with NMDAR blockade. Blocking NMDAR signaling stabilizes the adaptor protein 14-3-3η, which decouples GABABR signaling from Kir3 and is required for the rapid antidepressant efficacy. Consistent with these results, we find that key proteins involved in GABABR signaling bidirectionally change in a depression model and with rapid antidepressants. In socially defeated rodents, a model for depression, GABABR and 14-3-3η levels decrease in the hippocampus. The NMDAR antagonists AP5 and Ro-25-6981, acting as rapid antidepressants, increase GABABR and 14-3-3η expression and decrease Kir3.2. Taken together, these data suggest that the shift in GABABR function requires a loss of GABABR-Kir3 channel activity mediated by 14-3-3η. Our findings support a central role for 14-3-3η in the efficacy of rapid antidepressants and define a critical molecular mechanism for activity-dependent alterations in GABABR signaling. PMID:25560757

  10. Electrophysiological study of SR 42641, a novel aminopyridazine derivative of GABA: antagonist properties and receptor selectivity of GABAA versus GABAB responses.

    PubMed Central

    Desarmenien, M.; Desaulles, E.; Feltz, P.; Hamann, M.

    1987-01-01

    A new arylamino-pyridazine gamma-aminobutyric acid (GABA) derivative, SR 42641, has been tested for its ability to antagonize the actions of GABA on mammalian sensory neurones. SR 42641 and bicuculline reversibly decreased GABAA-induced depolarizations and currents recorded intracellularly from dorsal root ganglion neurons (DRG). Dose-response curves were shifted to the right in a parallel fashion. KB values (determined under voltage clamp conditions) were respectively 0.12 +/- 0.05 and 0.38 +/- 0.08 microM. Similar values were obtained with current clamp recording conditions. The study of the GABA-induced Cl- current under voltage-clamp conditions did not show any voltage-dependency of the antagonist effect of SR 42641. In nodose ganglion neurones, SR 42641 (0.4-4.5 microM) did not alter the (-)-baclofen-induced shortening of the calcium component of action potentials. At concentrations higher than 10 microM, SR 42641 itself prolonged calcium-dependent action potentials. Patch-clamp recordings from DRG cultured neurones indicated that SR 42641 did not affect the calcium current responsible for sustained calcium entry into cells. We conclude that SR 42641 is a potent competitive GABA antagonist, specific for the GABAA receptor. It does not act at the level of the chloride ionophore. PMID:2435350

  11. Globus pallidus neurons dynamically regulate the activity pattern of subthalamic nucleus neurons through the frequency-dependent activation of postsynaptic GABAA and GABAB receptors.

    PubMed

    Hallworth, Nicholas E; Bevan, Mark D

    2005-07-01

    Reciprocally connected GABAergic neurons of the globus pallidus (GP) and glutamatergic neurons of the subthalamic nucleus (STN) are a putative generator of pathological rhythmic burst firing in Parkinson's disease (PD). Burst firing of STN neurons may be driven by rebound depolarization after barrages of GABA(A) receptor (GABA(A)R)-mediated IPSPs arising from pallidal fibers. To determine the conditions under which pallidosubthalamic transmission activates these and other postsynaptic GABARs, a parasagittal mouse brain slice preparation was developed in which pallidosubthalamic connections were preserved. Intact connectivity was first confirmed through the injection of a neuronal tracer into the GP. Voltage-clamp and gramicidin-based perforated-patch current-clamp recordings were then used to study the relative influences of GABA(A)R- and GABA(B)R-mediated pallidosubthalamic transmission on STN neurons. Spontaneous phasic, but not tonic, activation of postsynaptic GABA(A)Rs reduced the frequency and disrupted the rhythmicity of autonomous firing in STN neurons. However, postsynaptic GABA(B)Rs were only sufficiently activated to impact STN firing when pallidosubthalamic transmission was elevated or pallidal fibers were synchronously activated by electrical stimulation. In a subset of neurons, rebound burst depolarizations followed high-frequency, synchronous stimulation of pallidosubthalamic fibers. Although GABA(B)R-mediated hyperpolarization was itself sufficient to generate rebound bursts, coincident activation of postsynaptic GABA(A)Rs produced longer and more intense burst firing. These findings elucidate a novel route through which burst activity can be generated in the STN, and suggest that GABARs on STN neurons could act in a synergistic manner to generate abnormal burst activity in PD. PMID:16000620

  12. GABAB agonism promotes sleep and reduces cataplexy in murine narcolepsy.

    PubMed

    Black, Sarah Wurts; Morairty, Stephen R; Chen, Tsui-Ming; Leung, Andrew K; Wisor, Jonathan P; Yamanaka, Akihiro; Kilduff, Thomas S

    2014-05-01

    γ-Hydroxybutyrate (GHB) is an approved therapeutic for the excessive sleepiness and sudden loss of muscle tone (cataplexy) characteristic of narcolepsy. The mechanism of action for these therapeutic effects is hypothesized to be GABAB receptor dependent. We evaluated the effects of chronic administration of GHB and the GABAB agonist R-baclofen (R-BAC) on arousal state and cataplexy in two models of narcolepsy: orexin/ataxin-3 (Atax) and orexin/tTA; TetO diphtheria toxin mice (DTA). Mice were implanted for EEG/EMG monitoring and dosed with GHB (150 mg/kg), R-BAC (2.8 mg/kg), or vehicle (VEH) bid for 15 d-a treatment paradigm designed to model the twice nightly GHB dosing regimen used by human narcoleptics. In both models, R-BAC increased NREM sleep time, intensity, and consolidation during the light period; wake bout duration increased and cataplexy decreased during the subsequent dark period. GHB did not increase NREM sleep consolidation or duration, although NREM delta power increased in the first hour after dosing. Cataplexy decreased from baseline in 57 and 86% of mice after GHB and R-BAC, respectively, whereas cataplexy increased in 79% of the mice after VEH. At the doses tested, R-BAC suppressed cataplexy to a greater extent than GHB. These results suggest utility of R-BAC-based therapeutics for narcolepsy. PMID:24806675

  13. GABAB Agonism Promotes Sleep and Reduces Cataplexy in Murine Narcolepsy

    PubMed Central

    Black, Sarah Wurts; Morairty, Stephen R.; Chen, Tsui-Ming; Leung, Andrew K.; Wisor, Jonathan P.

    2014-01-01

    γ-Hydroxybutyrate (GHB) is an approved therapeutic for the excessive sleepiness and sudden loss of muscle tone (cataplexy) characteristic of narcolepsy. The mechanism of action for these therapeutic effects is hypothesized to be GABAB receptor dependent. We evaluated the effects of chronic administration of GHB and the GABAB agonist R-baclofen (R-BAC) on arousal state and cataplexy in two models of narcolepsy: orexin/ataxin-3 (Atax) and orexin/tTA; TetO diphtheria toxin mice (DTA). Mice were implanted for EEG/EMG monitoring and dosed with GHB (150 mg/kg), R-BAC (2.8 mg/kg), or vehicle (VEH) bid for 15 d–a treatment paradigm designed to model the twice nightly GHB dosing regimen used by human narcoleptics. In both models, R-BAC increased NREM sleep time, intensity, and consolidation during the light period; wake bout duration increased and cataplexy decreased during the subsequent dark period. GHB did not increase NREM sleep consolidation or duration, although NREM delta power increased in the first hour after dosing. Cataplexy decreased from baseline in 57 and 86% of mice after GHB and R-BAC, respectively, whereas cataplexy increased in 79% of the mice after VEH. At the doses tested, R-BAC suppressed cataplexy to a greater extent than GHB. These results suggest utility of R-BAC-based therapeutics for narcolepsy. PMID:24806675

  14. Play

    NASA Astrophysics Data System (ADS)

    Harteveld, Casper

    Designing a game with a serious purpose involves considering the worlds of Reality and Meaning yet it is undeniably impossible to create a game without a third world, one that is specifically concerned with what makes a game a game: the play elements. This third world, the world of people like designers and artists, and disciplines as computer science and game design, I call the world of Play and this level is devoted to it. The level starts off with some of the misperceptions people have of play. Unlike some may think, we play all the time, even when we grow old—this was also very noticeable in designing the game Levee Patroller as the team exhibited very playful behavior at many occasions. From there, I go into the aspects that characterize this world. The first concerns the goal of the game. This relates to the objectives people have to achieve within the game. This is constituted by the second aspect: the gameplay. Taking actions and facing challenges is subsequently constituted by a gameworld, which concerns the third aspect. And all of it is not possible without the fourth and final aspect, the type of technology that creates and facilitates the game. The four aspects together make up a “game concept” and from this world such a concept can be judged on the basis of three closely interrelated criteria: engagement, immersion, and fun.

  15. Antitussive effects of GABAB agonists in the cat and guinea-pig.

    PubMed Central

    Bolser, D. C.; Aziz, S. M.; DeGennaro, F. C.; Kreutner, W.; Egan, R. W.; Siegel, M. I.; Chapman, R. W.

    1993-01-01

    1. GABAB agonists inhibit neuronal processes which are important in the pathogenesis of airway disease, such as bronchospasm. Cough is a prominent symptom of pulmonary disease, but the effects of GABAB agonists on this airway reflex are unknown. Experiments were conducted to determine the antitussive effect of GABAB receptor agonists in comparison to the known antitussive agents, codeine and dextromethorphan. 2. Unanaesthetized guinea-pigs were exposed to aerosols of 0.3 mM capsaicin to elicit coughing, which was detected with a microphone and counted. Cough also was produced in anaesthetized cats by mechanical stimulation of the intrathoracic trachea and was recorded from electromyograms of respiratory muscle activity. 3. In guinea-pigs, the GABAB agonists baclofen and 3-aminopropyl-phosphinic acid (3-APPi) produced dose-dependent inhibition of capsaicin-induced cough when administered by subcutaneous or inhaled routes. The potencies of baclofen and 3-APPi compared favourably with codeine and dextromethorphan. 4. The GABAB antagonist, CGP 35348 (0.3- 30 mg kg-1, s.c.) inhibited the antitussive effect of baclofen (3.0 mg kg-1, s.c.). However, CGP 35348 (10 mg kg-1, s.c.) had no effect on the antitussive activity of codeine (30 mg kg-1, s.c.). The antitussive effect of baclofen was not influenced by the GABAA antagonist, bicuculline (3 mg kg-1, s.c.) or naloxone (0.3 mg kg-1, s.c.). 5. In the cat, baclofen (0.3-3.0 mg kg-1, i.v.) decreased mechanically-induced cough in a dose-dependent manner. In this model, baclofen (ED50 = 0.63 mg kg-1) was less potent than either codeine or dextromethorphan.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8220912

  16. Contribution of NMDA, GABAA and GABAB receptors and l-arginine-NO-cGMP, MEK1/2 and CaMK-II pathways in the antidepressant-like effect of 7-fluoro-1,3-diphenylisoquinoline-1-amine in mice.

    PubMed

    Pesarico, Ana Paula; Stangherlin, Eluza Curte; Rosa, Suzan Gonçalves; Mantovani, Anderson C; Zeni, Gilson; Nogueira, Cristina Wayne

    2016-07-01

    It has been reported that the antidepressant-like effect of 7-fluoro-1,3-diphenylisoquinoline-1-amine (FDPI) may result from the modulation of brain monoaminergic systems. However, the mechanisms of FDPI action are not fully understood. The aim of this study was to investigate the contribution of N-methyl-d-aspartate (NMDA) and gamma-aminobutyric acid (GABA) systems as well as l-arginine-nitric oxide-(NO)-cyclic guanosine monophosphate-(cGMP), mitogen-activated protein/extracellular signal-regulated kinase (MEK1/2) and Ca(2+)/calmodulin-dependent protein kinase II (CaMK-II) signaling pathways in the antidepressant-like effect of FDPI in the mouse forced swimming test (FST). The levels of NO and uptake of [(3)H]glutamate and [(3)H]GABA were determined in prefrontal cortices of Swiss mice. Pretreatments with NMDA (0.1 pmol/site, i.c.v., a NMDA receptor agonist), bicuculline (1mg/kg, i.p., a GABAA receptor antagonist), phaclofen (2mg/kg, i.p., a GABAB receptor antagonist) and l-arginine (750mg/kg, i.p., a NO precursor), KN-62 (1μg/site, a CaMK-II inhibitor), U0126 (5μg/site, a MEK1/2 inhibitor) and PD09058 (5μg/site, a MEK1/2 inhibitor) blocked the antidepressant-like effect of FDPI, at a dose of 1mg/kg, in the FST. ODQ (30 pmol/site, i.c.v., a soluble guanylate cyclase (sGC) inhibitor) in combination with a sub-effective dose of FDPI (0.1mg/kg, i.g.) reduced the immobility time in the FST. The administration of FDPI (50mg/kg) to mice increased the glutamate uptake and reduced NO levels in the prefrontal cortex of mice. The results suggest a contribution of NMDA, GABAA and GABAB receptors and l-arginine-NO-cGMP pathway in the antidepressant-like action of FDPI in mice, and this effect is related to CaMK-II and MEK 1/2 activation. PMID:27112660

  17. Rescue of GABAB and GIRK function in the lateral habenula by protein phosphatase 2A inhibition ameliorates depression-like phenotypes in mice.

    PubMed

    Lecca, Salvatore; Pelosi, Assunta; Tchenio, Anna; Moutkine, Imane; Lujan, Rafael; Hervé, Denis; Mameli, Manuel

    2016-03-01

    The lateral habenula (LHb) encodes aversive signals, and its aberrant activity contributes to depression-like symptoms. However, a limited understanding of the cellular mechanisms underlying LHb hyperactivity has precluded the development of pharmacological strategies to ameliorate depression-like phenotypes. Here we report that an aversive experience in mice, such as foot-shock exposure (FsE), induces LHb neuronal hyperactivity and depression-like symptoms. This occurs along with increased protein phosphatase 2A (PP2A) activity, a known regulator of GABAB receptor (GABABR) and G protein-gated inwardly rectifying potassium (GIRK) channel surface expression. Accordingly, FsE triggers GABAB1 and GIRK2 internalization, leading to rapid and persistent weakening of GABAB-activated GIRK-mediated (GABAB-GIRK) currents. Pharmacological inhibition of PP2A restores both GABAB-GIRK function and neuronal excitability. As a consequence, PP2A inhibition ameliorates depression-like symptoms after FsE and in a learned-helplessness model of depression. Thus, GABAB-GIRK plasticity in the LHb represents a cellular substrate for aversive experience. Furthermore, its reversal by PP2A inhibition may provide a novel therapeutic approach to alleviate symptoms of depression in disorders that are characterized by LHb hyperactivity. PMID:26808347

  18. Nerve Regenerative Effects of GABA-B Ligands in a Model of Neuropathic Pain

    PubMed Central

    Cavalli, Erica; Pajardi, Giorgio

    2014-01-01

    Neuropathic pain arises as a direct consequence of a lesion or disease affecting the peripheral somatosensory system. It may be associated with allodynia and increased pain sensitivity. Few studies correlated neuropathic pain with nerve morphology and myelin proteins expression. Our aim was to test if neuropathic pain is related to nerve degeneration, speculating whether the modulation of peripheral GABA-B receptors may promote nerve regeneration and decrease neuropathic pain. We used the partial sciatic ligation- (PSL-) induced neuropathic model. The biochemical, morphological, and behavioural outcomes of sciatic nerve were analysed following GABA-B ligands treatments. Simultaneous 7-days coadministration of baclofen (10 mg/kg) and CGP56433 (3 mg/kg) alters tactile hypersensitivity. Concomitantly, specific changes of peripheral nerve morphology, nerve structure, and myelin proteins (P0 and PMP22) expression were observed. Nerve macrophage recruitment decreased and step coordination was improved. The PSL-induced changes in nociception correlate with altered nerve morphology and myelin protein expression. Peripheral synergic effects, via GABA-B receptor activation, promote nerve regeneration and likely ameliorate neuropathic pain. PMID:25165701

  19. Acute kidney injury: what part do toll-like receptors play?

    PubMed Central

    Vallés, Patricia G; Lorenzo, Andrea Gil; Bocanegra, Victoria; Vallés, Roberto

    2014-01-01

    The innate immune system plays an important role as a first response to tissue injury. This first response is carried out via germline-encoded receptors. Toll-like receptors (TLRs) are the first identified and best studied family of pattern recognition receptors. TLRs are expressed on a variety of cell types, including epithelial cells, endothelia, dendritic cells, monocytes/macrophages, and B- and T-cells. TLRs initiate innate immune responses and concurrently shape the subsequent adaptive immune response. They are sensors of both pathogens, through the exogenous pathogen-associated molecular patterns (PAMPs), and tissue injury, through the endogenous danger-associated molecular patterns (DAMPs). TLR signaling is critical in defending against invading microorganisms; however, sustained receptor activation is also implicated in the pathogenesis of inflammatory diseases. Ischemic kidney injury involves early TLR-driven immunopathology, and the resolution of inflammation is needed for rapid regeneration of injured tubule cells. Notably, the activation of TLRs also has been implicated in epithelial repair. This review focuses on the role of TLRs and their endogenous ligands within the inflammatory response of acute kidney injury. PMID:24971030

  20. GABAA receptors in the dorsal raphé nucleus of mice: escalation of aggression after alcohol consumption

    PubMed Central

    Takahashi, Aki; Kwa, Carolyn; DeBold, Joseph F.

    2010-01-01

    Rationale The dorsal raphé nucleus (DRN), the origin for serotonin (5-HT) in forebrain areas, has been implicated in the neural control of escalated aggression. Gamma aminobutyric acid type-A (GABAA) and type-B (GABAB) receptors are expressed in the DRN and modulate 5-HT neuronal activity, and both play a role in the behavioral effect of alcohol. Objective The purpose of this study is to examine the interaction between drugs acting on GABA receptors in the DRN and alcohol in their effects on aggressive behaviors. Method Male CFW mice, housed with a female, were trained to self-administer ethanol (1.0 g/kg) or water via an operant conditioning panel in their home cage. Immediately after they drank either ethanol or water, the animals were microinfused with a GABAergic drug into the DRN, and their aggressive behaviors were assessed 10 min later. Muscimol (0.006 nmol), a GABAA receptor agonist, escalated alcohol-heightened aggression but had no effect in the absence of ethanol. This effect of muscimol was prominent in the animals that showed alcohol-heightened aggression, but not the animals that reduced or did not change aggressive behavior after ethanol infusion compared to water. On the other hand, the GABAB agonist baclofen (0.06 nmol) increased aggressive behavior similarly in both water and ethanol conditions. Antagonists of the GABAA and GABAB receptors, bicuculline (0.006 nmol) and phaclofen (0.3 nmol) respectively, did not suppress heightened-aggressive behavior induced by ethanol self-administration. Conclusion GABAA receptors in the DRN are one of the neurobiological targets of alcohol-heightened aggression. Activation of the GABAB receptors in the DRN also produced escalated aggression, but that is independent of the effect of alcohol. PMID:20589493

  1. Arabidopsis abscisic acid receptors play an important role in disease resistance.

    PubMed

    Lim, Chae Woo; Lee, Sung Chul

    2015-06-01

    Stomata are natural pores of plants and constitute the entry points for water during transpiration. However, they also facilitate the ingress of potentially harmful bacterial pathogens. The phytohormone abscisic acid (ABA) plays a pivotal role in protecting plants against biotic stress, by regulating stomatal closure. In the present study, we investigated the mechanism whereby ABA influences plant defense responses to Pseudomonas syringae pv. tomato (Pst) DC3000, which is a virulent bacterial pathogen of Arabidopsis, at the pre-invasive stage. We found that overexpression of two ABA receptors, namely, RCAR4/PYL10-OX and RCAR5/PYL11-OX (hereafter referred to as RCARs), resulted in ABA-hypersensitive phenotypes being exhibited during the seed germination and seedling growth stages. Sensitivity to ABA enhanced the resistance of RCAR4-OX and RCAR5-OX plants to Pst DC3000, through promoting stomatal closure leading to the development of resistance to this bacterial pathogen. Protein phosphatase HAB1 is an important component that is responsible for ABA signaling and which interacts with ABA receptors. We found that hab1 mutants exhibited enhanced resistance to Pst DC3000; moreover, similar to RCAR4-OX and RCAR5-OX plants, this enhanced resistance was correlated with stomatal closure. Taken together, our findings demonstrate that alteration of RCAR4- or RCAR5-HAB1 mediated ABA signaling influences resistance to bacterial pathogens via stomatal regulation. PMID:25969135

  2. Toll-like receptor 4 plays a central role in cardiac dysfunction during trauma hemorrhage shock

    PubMed Central

    Zhang, Xia; Lu, Chen; Gao, Ming; Cao, Xinyun; Ha, Tuanzhu; Kalbfleisch, John H.; Williams, David L.; Li, Chuanfu; Kao, Race L.

    2014-01-01

    Cardiac dysfunction is a major consequence that contributes to the high mortality of trauma-hemorrhage (TH) patients. Recent evidence suggests that innate immune and inflammatory responses mediated by Toll-like receptors (TLRs) play a critical role in the pathophysiologic mechanisms of acute organ dysfunction during TH. This study investigated the role of TLR4 in cardiac dysfunction following TH. TLR4 deficient (TLR4−/−, n=7/group) and age-matched wild type (WT, n=8/group) mice were subjected to TH that was induced by soft tissue injury and blood withdrawal from the jugular vein to a mean arterial pressure of 35 ± 5 mm Hg. Cardiac function and mean arterial pressure were measured with a Millar system before, during and after blood withdrawal. Sham surgical operated mice served as control (WT, n=9/group; TLR4−/−, n=10/group). Cardiac function in WT mice was significantly reduced following TH. However cardiac function was well preserved in TLR4−/− mice. Administration of a TLR4 antagonist (3mg/kg) to WT mice also significantly attenuated TH-induced cardiac dysfunction. Western blot showed that either TLR4−/− or TLR4 antagonist markedly attenuated TH-induced decreases in the levels of phosphorylated-Akt in myocardium. In addition, inhibition of TLR4 attenuated TH-induced myocardial NF-κB binding activity as well as lung MPO activity and TNFα production. The data indicate that TLR4 plays a central role in TH-induced cardiac dysfunction. TLR4 deficiency or TLR4 inhibition attenuated cardiac dysfunction following TH which may involve activation of the PI3K/Akt signaling and decrease of NF-κB binding activity. TLR4 antagonism may be a new and novel approach for the treatment and management of cardiac dysfunction in TH patients. PMID:24569510

  3. GPR55, a G-protein coupled receptor for lysophosphatidylinositol, plays a role in motor coordination.

    PubMed

    Wu, Chia-Shan; Chen, Hongmei; Sun, Hao; Zhu, Jie; Jew, Chris P; Wager-Miller, James; Straiker, Alex; Spencer, Corinne; Bradshaw, Heather; Mackie, Ken; Lu, Hui-Chen

    2013-01-01

    The G-protein coupled receptor 55 (GPR55) is activated by lysophosphatidylinositols and some cannabinoids. Recent studies found prominent roles for GPR55 in neuropathic/inflammatory pain, cancer and bone physiology. However, little is known about the role of GPR55 in CNS development and function. To address this question, we performed a detailed characterization of GPR55 knockout mice using molecular, anatomical, electrophysiological, and behavioral assays. Quantitative PCR studies found that GPR55 mRNA was expressed (in order of decreasing abundance) in the striatum, hippocampus, forebrain, cortex, and cerebellum. GPR55 deficiency did not affect the concentrations of endocannabinoids and related lipids or mRNA levels for several components of the endocannabinoid system in the hippocampus. Normal synaptic transmission and short-term as well as long-term synaptic plasticity were found in GPR55 knockout CA1 pyramidal neurons. Deleting GPR55 function did not affect behavioral assays assessing muscle strength, gross motor skills, sensory-motor integration, motor learning, anxiety or depressive behaviors. In addition, GPR55 null mutant mice exhibited normal contextual and auditory-cue conditioned fear learning and memory in a Pavlovian conditioned fear test. In contrast, when presented with tasks requiring more challenging motor responses, GPR55 knockout mice showed impaired movement coordination. Taken together, these results suggest that GPR55 plays a role in motor coordination, but does not strongly regulate CNS development, gross motor movement or several types of learned behavior. PMID:23565223

  4. Unbalanced upregulation of ryanodine receptor 2 plays a particular role in early development of daunorubicin cardiomyopathy

    PubMed Central

    Kucerova, Dana; Doka, Gabriel; Kruzliak, Peter; Turcekova, Katarina; Kmecova, Jana; Brnoliakova, Zuzana; Kyselovic, Jan; Kirchhefer, Uwe; Müller, Frank U; Krenek, Peter; Boknik, Peter; Klimas, Jan

    2015-01-01

    Calcium release channel on the sarcoplasmic reticulum of cardiomyocytes (ryanodine receptor type 2, RyR2) plays a critical role in the regulation of calcium and was identified as a crucial factor for development of chronic anthracycline cardiomyopathy. Its early stages are less well described although these determine the later development. Hence, we tested the effect of repeated, short-term anthracycline (daunorubicin) administration on cardiac performance, cardiomyocyte function and accompanied changes in calcium regulating proteins expression. Ten-twelve weeks old male Wistar rats were administered with 6 doses of daunorubicin (DAU, 3 mg/kg, i.p., every 48 h), controls (CON) received vehicle. Left ventricular function (left ventricular pressure, LVP; rate of pressure development, +dP/dt and decline, -dP/dt) was measured using left ventricular catheterization under tribromethanol anaesthesia (15 ml/kg b.w.). Cell shortening was measured in enzymatically isolated cardiomyocytes. The expressions of RyR2 and associated intracellular calcium regulating proteins, cytoskeletal proteins (alpha-actinin, alpha-tubul in) as well as oxidative stress regulating enzymes (gp91phox, MnSOD) were detected in ventricular tissue samples using immunoblotting. mRNA expressions of cardiac damage markers (Nppa and Nppb, atrial and brain natriuretic peptides; Myh6, Myh7 and Myh7b, myosin heavy chain alpha and beta) were detected using RT-PCR. Thiobarbituric acid reactive substances concentration was measured to estimate oxidative stress. DAU rats exhibited significantly depressed left ventricular features (LVP by 14%, +dP/dt by 36% and -dP/dt by 30%; for all P<0.05), in line with concomitant increase in Nppa and Nppb gene expressions (3.23- and 2.18-fold, for both P<0.05), and a 4.34-fold increase in Myh7 (P<0.05). Controversially, we observed increased cell shortening of isolated cardiac cells by 31% (p<0.05). DAU administration was associated with a twofold upregulation of RyR2 (P<0

  5. Importance of the gamma-aminobutyric acid(B) receptor C-termini for G-protein coupling.

    PubMed

    Grünewald, Sylvia; Schupp, Bettina J; Ikeda, Stephen R; Kuner, Rohini; Steigerwald, Frank; Kornau, Hans-Christian; Köhr, Georg

    2002-05-01

    Functional gamma-aminobutyric acid(B) (GABA(B)) receptors assemble from two subunits, GABA(B(1)) and GABA(B(2).) This heteromerization, which involves a C-terminal coiled-coil interaction, ensures efficient surface trafficking and agonist-dependent G-protein activation. In the present study, we took a closer look at the implications of the intracellular C termini of GABA(B(1)) and GABA(B(2)) for G-protein coupling. We generated a series of C-terminal mutants of GABA(B(1)) and GABA(B(2)) and tested them for physical interaction, surface trafficking, coupling to adenylyl cyclase, and G-protein-gated inwardly rectifying potassium channels in human embryonic kidney (HEK) 293 cells as well as on endogenous calcium channels in sympathetic neurons of the superior cervical ganglion (SCG). We found that the C-terminal interaction contributes only partly to the heterodimeric assembly of the subunits, indicating the presence of an additional interaction site. The described endoplasmic reticulum retention signal within the C terminus of GABA(B(1)) functioned only in the context of specific amino acids, which constitute part of the GABA(B(1)) coiled-coil sequence. This finding may provide a link between the retention signal and its shielding by the coiled coil of GABA(B(2).) In HEK293 cells, we observed that the two well-known GABA(B) receptor antagonists [S-(R*,R*)]-[3-[[1-(3,4-dichlorophenyl)ethyl]amino]-2-hydroxypropyl](cyclohexylmethyl) phosphinic acid (CGP54626) and (+)-(2S)-5,5-dimethyl-2-morpholineacetic acid (SCH50911) CGP54626 and SCH50911 function as inverse agonists. The C termini of GABA(B(1)) and GABA(B(2)) strongly influenced agonist-independent G-protein coupling, although they were not necessary for agonist-dependent G-protein coupling. The C-terminal GABA(B) receptor mutants described here demonstrate that the active receptor conformation is stabilized by the coiled-coil interaction. Thus, the C-terminal conformation of the GABA(B) receptor may determine its

  6. Sodium salicylate potentiates the GABAB-GIRK pathway to suppress rebound depolarization in neurons of the rat's medial geniculate body.

    PubMed

    Wang, Xin-Xing; Jin, Yan; Luo, Bin; Sun, Jing-Wu; Zhang, Jinsheng; Wang, Ming; Chen, Lin

    2016-02-01

    Rebound depolarization (RD) is a voltage response to the offset from pre-hyperpolarization of neuronal membrane potential, which manifests a particular form of the postsynaptic membrane potential response to inhibitory presynaptic inputs. We previously demonstrated that sodium salicylate (NaSal), a tinnitus inducer, can drastically suppress the RD in neurons of rat medial geniculate body (MGB) (Su et al, 2012; PLoS ONE 7, e46969). The purpose of the present study was to investigate the underlying cellular mechanism by using whole-cell patch-clamp recordings in rat MGB slices. NaSal (1.4 mM) had no effects on the current mediated by T-type Ca(2+) channels, indicating that it does not target these channels to suppress the RD. Instead, NaSal was shown to hyperpolarize the resting membrane potential to suppress the RD. NaSal had no effects on the current mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, indicating that it does not target these channels to hyperpolarize the resting membrane potential. NaSal induced an outward leak current that could be abolished by CGP55845, a GABAB receptor blocker, or respectively by Ba(2+) and Tertiapin-Q, blockers for G-protein-gated inwardly rectifying potassium (GIRK) channels, indicating that NaSal potentiates the GABAB-GIRK pathway to hyperpolarize the resting membrane potential. Our study demonstrates that NaSal targets GABAB receptors to alter functional behaviors of MGB neurons, which may be implicated in NaSal-induced tinnitus. PMID:26688177

  7. The amide linker in nonpeptide neurotensin receptor ligands plays a key role in calcium signaling at the neurotensin receptor type 2.

    PubMed

    Thomas, James B; Giddings, Angela M; Olepu, Srinivas; Wiethe, Robert W; Warner, Keith R; Sarret, Philippe; Longpre, Jean-Michel; Runyon, Scott P; Gilmour, Brian P

    2015-01-01

    Compounds acting via the GPCR neurotensin receptor type 2 (NTS2) display analgesia in relevant preclinical models. The amide bond in nonpeptide NTS1 antagonists plays a central role in receptor recognition and molecular conformation. Using NTS2 FLIPR and binding assays, we found that it is also a key molecular structure for binding and calcium mobilization at NTS2. We found that reversed amides display a shift from agonist to antagonist activity and provided examples of the first competitive nonpeptide antagonists observed in the NTS2 FLIPR assay. These compounds will be valuable tools for determining the role of calcium signaling in vitro to NTS2 mediated analgesia. PMID:25881832

  8. Integrin Receptors Play a Key Role in the Regulation of Hepatic CYP3A.

    PubMed

    Jonsson-Schmunk, Kristina; Wonganan, Piynauch; Choi, Jin Huk; Callahan, Shellie M; Croyle, Maria A

    2016-05-01

    Landmark studies describing the effect of microbial infection on the expression and activity of hepatic CYP3A used bacterial lipopolysaccharide as a model antigen. Our efforts to determine whether these findings were translatable to viral infections led us to observations suggesting that engagement of integrin receptors is key in the initiation of processes responsible for changes in hepatic CYP3A4 during infection and inflammation. Studies outlined in this article were designed to evaluate whether engagement of integrins, receptors commonly used by a variety of microbes to enter cellular targets, is vital in the regulation of CYP3A in the presence and absence of virus infection. Mice infected with a recombinant adenovirus (AdlacZ) experienced a 70% reduction in hepatic CYP3A catalytic activity. Infection with a mutant virus with integrin-binding arginine-glycine-aspartic acid (RGD) sequences deleted from the penton base protein of the virus capsid (AdΔRGD) did not alter CYP3A activity. CYP3A mRNA and protein levels in AdlacZ-treated animals were also suppressed, whereas those of mice given AdΔRGD were not significantly different from uninfected control mice. Silencing of the integrinβ-subunit reverted adenovirus-mediated CYP3A4 suppression in vitro. Silencing of theα-subunit did not. Suppression of integrin subunits had a profound effect on nuclear receptors pregnane X receptor and constitutive androstane receptor, whereas retinoid X receptorαwas largely unaffected. To our knowledge, this is the first time that extracellular receptors, like integrins, have been indicated in the regulation of CYP3A. This finding has several implications owing to the important role of integrins in normal physiologic process and in many disease states. PMID:26868618

  9. Chemokines and their receptors play important roles in the development of hepatocellular carcinoma

    PubMed Central

    Liang, Chun-Min; Chen, Long; Hu, Heng; Ma, Hui-Ying; Gao, Ling-Ling; Qin, Jie; Zhong, Cui-Ping

    2015-01-01

    The chemokine system consists of four different subclasses with over 50 chemokines and 19 receptors. Their functions in the immune system have been well elucidated and research during the last decades unveils their new roles in hepatocellular carcinoma (HCC). The chemokines and their receptors in the microenvironment influence the development of HCC by several aspects including: inflammation, effects on immune cells, angiogenesis, and direct effects on HCC cells. Regarding these aspects, pre-clinical research by targeting the chemokine system has yielded promising data, and these findings bring us new clues in the chemokine-based therapies for HCC. PMID:26052384

  10. Marlin-1, a novel RNA-binding protein associates with GABA receptors.

    PubMed

    Couve, Andrés; Restituito, Sophie; Brandon, Julia M; Charles, Kelly J; Bawagan, Hinayana; Freeman, Katie B; Pangalos, Menelas N; Calver, Andrew R; Moss, Stephen J

    2004-04-01

    GABA(B) receptors are heterodimeric G protein-coupled receptors that mediate slow synaptic inhibition in the central nervous system. Whereas heterodimerization between GABA(B) receptor GABA(B)R1 and GABA(B)R2 subunits is essential for functional expression, how neurons coordinate the assembly of these critical receptors remains to be established. Here we have identified Marlin-1, a novel GABA(B) receptor-binding protein that associates specifically with the GABA(B)R1 subunit in yeast, tissue culture cells, and neurons. Marlin-1 is expressed in the brain and exhibits a granular distribution in cultured hippocampal neurons. Marlin-1 binds different RNA species including the 3'-untranslated regions of both the GABA(B)R1 and GABA(B)R2 mRNAs in vitro and also associates with RNA in cultured neurons. Inhibition of Marlin-1 expression via small RNA interference technology results in enhanced intracellular levels of the GABA(B)R2 receptor subunit without affecting the level of GABA(B)R1. Together our results suggest that Marlin-1 functions to regulate the cellular levels of GABA(B) R2 subunits, which may have significant effects on the production of functional GABA(B) receptor heterodimers. Therefore, our observations provide an added level of regulation for the control of GABA(B) receptor expression and for the efficacy of inhibitory synaptic transmission. PMID:14718537

  11. Host kinin B1 receptor plays a protective role against melanoma progression

    PubMed Central

    Maria, Andrea G.; Dillenburg-Pilla, Patrícia; Reis, Rosana I.; Floriano, Elaine M.; Tefé-Silva, Cristiane; Ramos, Simone G.; Pesquero, João B.; Nahmias, Clara; Costa-Neto, Claudio M.

    2016-01-01

    Melanoma is a very aggressive tumor that arises from melanocytes. Late stage and widely spread diseases do not respond to standard therapeutic approaches. The kallikrein-kinin system (KKS) participates in biological processes such as vasodilatation, pain and inflammatory response. However, the role of KKS in tumor formation and progression is not completely understood. The role of the host kinin B1 receptor in melanoma development was evaluated using a syngeneic melanoma model. Primary tumors and metastasis were respectively induced by injecting B16F10 melanoma cells, which are derived from C57BL/6 mice, subcutaneously or in the tail vein in wild type C57BL/6 and B1 receptor knockout mice (B1−/−). Tumors developed in B1−/− mice presented unfavorable prognostic factors such as increased incidence of ulceration, higher levels of IL-10, higher activation of proliferative pathways such as ERK1/2 and Akt, and increased mitotic index. Furthermore, in the metastasis model, B1−/− mice developed larger metastatic colonies in the lung and lower CD8+immune effector cells when compared with WT animals. Altogether, our results provide evidences that B1−/− animals developed primary tumors with multiple features associated with poor prognosis and unfavorable metastatic onset, indicating that the B1 receptor may contribute to improve the host response against melanoma progression. PMID:26898917

  12. Two dopamine receptors play different roles in phase change of the migratory locust

    PubMed Central

    Guo, Xiaojiao; Ma, Zongyuan; Kang, Le

    2015-01-01

    The migratory locust, Locusta migratoria, shows remarkable phenotypic plasticity at behavioral, physiological, and morphological levels in response to fluctuation in population density. Our previous studies demonstrated that dopamine (DA) and the genes in the dopamine metabolic pathway mediate phase change in Locusta. However, the functions of different dopamine receptors in modulating locust phase change have not been fully explored. In the present study, DA concentration in the brain increased during crowding and decreased during isolation. The expression level of dopamine receptor 1 (Dop1) increased from 1 to 4 h of crowding, but remained unchanged during isolation. Injection of Dop1 agonist SKF38393 into the brains of solitary locusts promoted gregarization, induced conspecific attraction-response and increased locomotion. RNAi knockdown of Dop1 and injection of antagonist SCH23390 in gregarious locusts induced solitary behavior, promoted the shift to repulsion-response and reduced locomotion. By contrast, the expression level of dopamine receptor 2 (Dop2) gradually increased during isolation, but remained stable during crowding. During the isolation of gregarious locusts, injection of Dop2 antagonist S(–)-sulpiride or RNAi knockdown of Dop2 inhibited solitarization, maintained conspecific attraction-response and increased locomotion; by comparison, the isolated controls displayed conspecific repulsion-response and weaker motility. Activation of Dop2 in solitary locusts through injection of agonist, R(-)-TNPA, did not affect their behavioral state. Thus, DA-Dop1 signaling in the brain of Locusta induced the gregariousness, whereas DA-Dop2 signaling mediated the solitariness. Our study demonstrated that Dop1 and Dop2 modulated locust phase change in two different directions. Further investigation of Locusta Dop1 and Dop2 functions in modulating phase change will improve our understanding of the molecular mechanism underlying phenotypic plasticity in locusts

  13. Liver X Receptors (LXRs) Alpha and Beta Play Distinct Roles in the Mouse Epididymis.

    PubMed

    Whitfield, Marjorie; Ouvrier, Aurélia; Cadet, Rémi; Damon-Soubeyrand, Christelle; Guiton, Rachel; Janny, Laurent; Kocer, Ayhan; Marceau, Geoffroy; Pons-Rejraji, Hanae; Trousson, Amalia; Drevet, Joël R; Saez, Fabrice

    2016-03-01

    After its production in the testis, a spermatozoon has to undergo posttesticular maturation steps to become fully motile and fertile. The first step is epididymal maturation, during which immature spermatozoa are transformed into biochemically mature cells ready to proceed to the next step, capacitation, a physiological process occurring in the female genital tract. The biochemical transformations include modification of sperm lipid composition during epididymal transit, with significant changes in fatty acids, phospholipids, and sterols between the caput and the cauda epididymal spermatozoa. Although quantitative aspects of these changes are well documented for several mammalian species, molecular mechanisms governing these steps are poorly understood. Transgenic male mice invalidated for the two liver X receptors (LXRalpha and LXRbeta, nuclear oxysterol receptors regulating cholesterol and lipid metabolism) become sterile when aging, showing an epididymal phenotype. We used single-knockout-model mice to characterize the role of each LXR isoform during sperm maturation in the epididymis. We show here that although a certain redundancy exists in the functions of the two LXR isoforms, some physiological processes are more under the influence of only one of them. In both cases, aging males showed slight subfertility, associated with dyslipidemia, emphasizing the importance of lipid metabolism in relation with male fertility. PMID:26792941

  14. Endoperoxide 4 receptors play a role in evoking the exercise pressor reflex in rats with simulated peripheral artery disease.

    PubMed

    Yamauchi, Katsuya; Kim, Joyce S; Stone, Audrey J; Ruiz-Velasco, Victor; Kaufman, Marc P

    2013-06-01

    Ligating the femoral artery for 72 h in decerebrated rats exaggerates the exercise pressor reflex. The sensory arm of this reflex is comprised of group III and IV afferents, which can be either sensitized or stimulated by PGE2. In vitro studies showed that endoperoxide (EP) 3 and 4 receptors were responsible for the PGE2-induced sensitization of rat dorsal root ganglion cells. This in vitro finding prompted us to test the hypothesis that blockade of EP3 and/or EP4 receptors attenuated the exaggerated exercise pressor reflex in rats with ligated femoral arteries. We measured the cardiovascular responses to static hindlimb contraction or tendon stretch before and after femoral arterial injection of L798106 (an EP3 antagonist) or L161982 (an EP4 antagonist). The pressor and cardioaccelerator responses to either contraction or tendon stretch were not attenuated by L798106 in either the ligated or freely perfused rats. Likewise in five rats whose hindlimb muscles were freely perfused, the pressor and cardioaccelerator responses to either contraction or tendon stretch were not attenuated by L161982. In the six ligated rats, however, the pressor response to contraction was attenuated by L161982, averaging 37 ± 3 mmHg before, 18 ± 2 mmHg afterward (P < 0.05). Western blotting analysis revealed that ligation of the femoral artery for 72 h increased the EP4 receptor protein in the L4 and L5 dorsal root ganglia over their freely perfused counterparts by 24% (P < 0.05). We conclude that EP4 receptors, but not EP3 receptors, play an important role in the exaggerated exercise pressor reflex found in rats with ligated femoral arteries. PMID:23568893

  15. CHASE domain-containing receptors play an essential role in the cytokinin response of the moss Physcomitrella patens

    PubMed Central

    von Schwartzenberg, Klaus; Lindner, Ann-Cathrin; Gruhn, Njuscha; Šimura, Jan; Novák, Ondřej; Strnad, Miroslav; Gonneau, Martine; Nogué, Fabien; Heyl, Alexander

    2016-01-01

    While the molecular basis for cytokinin action is quite well understood in flowering plants, little is known about the cytokinin signal transduction in early diverging land plants. The genome of the bryophyte Physcomitrella patens (Hedw.) B.S. encodes three classical cytokinin receptors, the CHASE domain-containing histidine kinases, CHK1, CHK2, and CHK3. In a complementation assay with protoplasts of receptor-deficient Arabidopsis thaliana as well as in cytokinin binding assays, we found evidence that CHK1 and CHK2 receptors can function in cytokinin perception. Using gene targeting, we generated a collection of CHK knockout mutants comprising single (Δchk1, Δchk2, Δchk3), double (Δchk1,2, Δchk1,3, Δchk2,3), and triple (Δchk1,2,3) mutants. Mutants were characterized for their cytokinin response and differentiation capacities. While the wild type did not grow on high doses of cytokinin (1 µM benzyladenine), the Δchk1,2,3 mutant exhibited normal protonema growth. Bud induction assays showed that all three cytokinin receptors contribute to the triggering of budding, albeit to different extents. Furthermore, while the triple mutant showed no response in this bioassay, the remaining mutants displayed budding responses in a diverse manner to different types and concentrations of cytokinins. Determination of cytokinin levels in mutants showed no drastic changes for any of the cytokinins; thus, in contrast to Arabidopsis, revealing only small impacts of cytokinin signaling on homeostasis. In summary, our study provides a first insight into the molecular action of cytokinin in an early diverging land plant and demonstrates that CHK receptors play an essential role in bud induction and gametophore development. PMID:26596764

  16. Eukaryotic Initiation Factor 5A Plays an Essential Role in Luteinizing Hormone Receptor Regulation

    PubMed Central

    Menon, Bindu; Gulappa, Thippeswamy

    2014-01-01

    Down-regulation of LH receptor (LHR) in the ovary by its ligand is mediated by a specific RNA-binding protein, designated LH receptor mRNA–binding protein (LRBP), through translational suppression and mRNA degradation. Using yeast 2-hybrid screens, we previously identified eukaryotic initiation factor 5A (eIF5A) as one of the proteins that interacts with LRBP during LHR mRNA down-regulation. The present study examined the role of eIF5A and its hypusination in the context of LHR mRNA down-regulation. The association of eIF5A with LRBP or LHR mRNA was determined using immunoprecipitation and RNA immunoprecipitation assays. The results showed that the association of eIF5A with the LHR mRNA-LRBP complex increased significantly during down-regulation. Furthermore, gel fractionation and the hypusination activity assay both showed increased hypusination of eIF5A during LHR mRNA down-regulation. Abolishment of hypusination by pretreatment with the chemical inhibitor GC7 prevented the association of eIF5A with LHR mRNA and LRBP. Inhibition of hypusination also reduced the extent of ligand-induced down-regulation of LHR mRNA as well as the expression of functional LHRs assessed by real-time PCR and 125I-human chorionic gonadotropin (hCG) binding assays, respectively. The loss of human chorionic gonadotropin–mediated downstream signaling during LHR down-regulation was also restored by inhibition of hypusination of eIF5A. Thus, the present study, for the first time, reveals the crucial role of eIF5A and its hypusination in the regulation of LHR expression in the ovary. PMID:25216047

  17. GABAB-mediated modulation of ionic conductances in type I hair cells isolated from guinea-pig semicircular canals.

    PubMed

    Lapeyre, P N; Kolston, P J; Ashmore, J F

    1993-04-23

    Mammalian vestibular type I hair cells (VIHCs) are innervated by an afferent synaptic calyx which contains vesicles and is immunoreactive for GABA. We describe here the effects of GABA on electrophysiological properties and on cytosolic free-calcium levels ([Ca2+]i) of VIHCs isolated from guinea-pig ampullae. Whole-cell tight-seal macroscopic currents recorded from VIHCs showed that 100 microM GABA induced a decrease in the outward currents elicited by depolarizing membrane potentials. These are known to comprise potassium calcium-dependent currents. This effect was mimicked by baclofen, a GABAB agonist, and was not affected by picrotoxin, a GABAA antagonist. GABA also induced an increase in the inward current elicited at hyperpolarized membrane potentials in 50% of the tested cells. Single channel recording in cell-attached patches revealed that externally applied GABA produced a decrease and an increase in the open probability of 170 pS and 45 pS and of 15 pS channels, respectively. In imaging experiments using the dye Fura-2 to measure [Ca2+]i, the only reversible modulation of [Ca2+]i observed in response to GABA application was a decrease. These results demonstrate a modulation of calcium and potassium conductances by GABA, via GABAB receptors, in guinea-pig VIHCs. PMID:7685230

  18. Ischemia-like Oxygen and Glucose Deprivation Mediates Down-regulation of Cell Surface γ-Aminobutyric AcidB Receptors via the Endoplasmic Reticulum (ER) Stress-induced Transcription Factor CCAAT/Enhancer-binding Protein (C/EBP)-homologous Protein (CHOP)*

    PubMed Central

    Maier, Patrick J.; Zemoura, Khaled; Acuña, Mario A.; Yévenes, Gonzalo E.; Zeilhofer, Hanns Ulrich; Benke, Dietmar

    2014-01-01

    Cerebral ischemia frequently leads to long-term disability and death. Excitotoxicity is believed to be the main cause for ischemia-induced neuronal death. Although a role of glutamate receptors in this process has been firmly established, the contribution of metabotropic GABAB receptors, which control excitatory neurotransmission, is less clear. A prominent characteristic of ischemic insults is endoplasmic reticulum (ER) stress associated with the up-regulation of the transcription factor CCAAT/enhancer-binding protein-homologous protein (CHOP). After inducing ER stress in cultured cortical neurons by sustained Ca2+ release from intracellular stores or by a brief episode of oxygen and glucose deprivation (in vitro model of cerebral ischemia), we observed an increased expression of CHOP accompanied by a strong reduction of cell surface GABAB receptors. Our results indicate that down-regulation of cell surface GABAB receptors is caused by the interaction of the receptors with CHOP in the ER. Binding of CHOP prevented heterodimerization of the receptor subunits GABAB1 and GABAB2 and subsequent forward trafficking of the receptors to the cell surface. The reduced level of cell surface receptors diminished GABAB receptor signaling and, thus, neuronal inhibition. These findings indicate that ischemia-mediated up-regulation of CHOP down-regulates cell surface GABAB receptors by preventing their trafficking from the ER to the plasma membrane. This mechanism leads to diminished neuronal inhibition and may contribute to excitotoxicity in cerebral ischemia. PMID:24668805

  19. Orphan nuclear receptor oestrogen-related receptor γ (ERRγ) plays a key role in hepatic cannabinoid receptor type 1-mediated induction of CYP7A1 gene expression.

    PubMed

    Zhang, Yaochen; Kim, Don-Kyu; Lee, Ji-Min; Park, Seung Bum; Jeong, Won-Il; Kim, Seong Heon; Lee, In-Kyu; Lee, Chul-Ho; Chiang, John Y L; Choi, Hueng-Sik

    2015-09-01

    Bile acids are primarily synthesized from cholesterol in the liver and have important roles in dietary lipid absorption and cholesterol homoeostasis. Detailed roles of the orphan nuclear receptors regulating cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid synthesis, have not yet been fully elucidated. In the present study, we report that oestrogen-related receptor γ (ERRγ) is a novel transcriptional regulator of CYP7A1 expression. Activation of cannabinoid receptor type 1 (CB1 receptor) signalling induced ERRγ-mediated transcription of the CYP7A1 gene. Overexpression of ERRγ increased CYP7A1 expression in vitro and in vivo, whereas knockdown of ERRγ attenuated CYP7A1 expression. Deletion analysis of the CYP7A1 gene promoter and a ChIP assay revealed an ERRγ-binding site on the CYP7A1 gene promoter. Small heterodimer partner (SHP) inhibited the transcriptional activity of ERRγ and thus regulated CYP7A1 expression. Overexpression of ERRγ led to increased bile acid levels, whereas an inverse agonist of ERRγ, GSK5182, reduced CYP7A1 expression and bile acid synthesis. Finally, GSK5182 significantly reduced hepatic CB1 receptor-mediated induction of CYP7A1 expression and bile acid synthesis in alcohol-treated mice. These results provide the molecular mechanism linking ERRγ and bile acid metabolism. PMID:26348907

  20. Structural, signalling and regulatory properties of the group I metabotropic glutamate receptors: prototypic family C G-protein-coupled receptors.

    PubMed Central

    Hermans, E; Challiss, R A

    2001-01-01

    In 1991 a new type of G-protein-coupled receptor (GPCR) was cloned, the type 1a metabotropic glutamate (mGlu) receptor, which, despite possessing the defining seven-transmembrane topology of the GPCR superfamily, bore little resemblance to the growing number of other cloned GPCRs. Subsequent studies have shown that there are eight mammalian mGlu receptors that, together with the calcium-sensing receptor, the GABA(B) receptor (where GABA is gamma-aminobutyric acid) and a subset of pheromone, olfactory and taste receptors, make up GPCR family C. Currently available data suggest that family C GPCRs share a number of structural, biochemical and regulatory characteristics, which differ markedly from those of the other GPCR families, most notably the rhodopsin/family A GPCRs that have been most widely studied to date. This review will focus on the group I mGlu receptors (mGlu1 and mGlu5). This subgroup of receptors is widely and differentially expressed in neuronal and glial cells within the brain, and receptor activation has been implicated in the control of an array of key signalling events, including roles in the adaptative changes needed for long-term depression or potentiation of neuronal synaptic connectivity. In addition to playing critical physiological roles within the brain, the mGlu receptors are also currently the focus of considerable attention because of their potential as drug targets for the treatment of a variety of neurological and psychiatric disorders. PMID:11672421

  1. Adenosine A2A receptor plays an important role in radiation-induced dermal injury.

    PubMed

    Perez-Aso, Miguel; Mediero, Aránzazu; Low, Yee Cheng; Levine, Jamie; Cronstein, Bruce N

    2016-01-01

    Ionizing radiation is a common therapeutic modality and following irradiation dermal changes, including fibrosis and atrophy, may lead to permanent changes. We have previously demonstrated that occupancy of A2A receptor (A2AR) stimulates collagen production, so we determined whether blockade or deletion of A2AR could prevent radiation-induced fibrosis. After targeted irradiation (40 Gy) of the skin of wild-type (WT) or A2AR knockout (A2ARKO) mice, the A2AR antagonist ZM241385 was applied daily for 28 d. In irradiated WT mice treated with the A2AR antagonist, there was a marked reduction in collagen content and skin thickness, and ZM241385 treatment reduced the number of myofibroblasts and angiogenesis. After irradiation, there is an increase in loosely packed collagen fibrils, which is significantly diminished by ZM241385. Irradiation also induced an increase in epidermal thickness, prevented by ZM241385, by increasing the number of proliferating keratinocytes. Similarly, in A2ARKO mice, the changes in collagen alignment, skin thickness, myofibroblast content, angiogenesis, and epidermal hyperplasia were markedly reduced following irradiation. Radiation-induced changes in the dermis and epidermis were accompanied by an infiltrate of T cells, which was prevented in both ZM241385-treated and A2ARKO mice. Radiation therapy is administered to a significant number of patients with cancer, and radiation reactions may limit this therapeutic modality. Our findings suggest that topical application of an A2AR antagonist prevents radiation dermatitis and may be useful in the prevention or amelioration of radiation changes in the skin. PMID:26415936

  2. Role of post-translational modifications on structure, function and pharmacology of class C G protein-coupled receptors.

    PubMed

    Nørskov-Lauritsen, Lenea; Bräuner-Osborne, Hans

    2015-09-15

    G protein-coupled receptors are divided into three classes (A, B and C) based on homology of their seven transmembrane domains. Class C is the smallest class with 22 human receptor subtypes including eight metabotropic glutamate (mGlu1-8) receptors, two GABAB receptors (GABAB1 and GABAB2), three taste receptors (T1R1-3), one calcium-sensing (CaS) receptor, one GPCR, class C, group 6, subtype A (GPRC6) receptor, and seven orphan receptors. G protein-coupled receptors undergo a number of post-translational modifications, which regulate their structure, function and/or pharmacology. Here, we review the existence of post-translational modifications in class C G protein-coupled receptors and their regulatory roles, with particular focus on glycosylation, phosphorylation, ubiquitination, SUMOylation, disulphide bonding and lipidation. PMID:25981296

  3. Calcium-Sensing Receptors of Human Neural Cells Play Crucial Roles in Alzheimer's Disease

    PubMed Central

    Chiarini, Anna; Armato, Ubaldo; Liu, Daisong; Dal Prà, Ilaria

    2016-01-01

    In aged subjects, late-onset Alzheimer's disease (LOAD) starts in the lateral entorhinal allocortex where a failure of clearance mechanisms triggers an accumulation of neurotoxic amyloid-β42 oligomers (Aβ42-os). In neurons and astrocytes, Aβ42-os enhance the transcription of Aβ precursor protein (APP) and β-secretase/BACE1 genes. Thus, by acting together with γ-secretase, the surpluses of APP and BACE1 amplify the endogenous production of Aβ42-os which pile up, damage mitochondria, and are oversecreted. At the plasmalemma, exogenous Aβ42-os bind neurons' and astrocytes' calcium-sensing receptors (CaSRs) activating a set of intracellular signaling pathways which upkeep Aβ42-os intracellular accumulation and oversecretion by hindering Aβ42-os proteolysis. In addition, Aβ42-os accumulating in the extracellular milieu spread and reach mounting numbers of adjacent and remoter teams of neurons and astrocytes which in turn are recruited, again via Aβ42-os•CaSR-governed mechanisms, to produce and release additional Aβ42-os amounts. This relentless self-sustaining mechanism drives AD progression toward upper cortical areas. Later on accumulating Aβ42-os elicit the advent of hyperphosphorylated (p)-Tau oligomers which acting together with Aβ42-os and other glial neurotoxins cooperatively destroy wider and wider cognition-related cortical areas. In parallel, Aβ42-os•CaSR signals also elicit an excess production and secretion of nitric oxide and vascular endothelial growth factor-A from astrocytes, of Aβ42-os and myelin basic protein from oligodendrocytes, and of proinflammatory cytokines, nitric oxide and (likely) Aβ42-os from microglia. Activated astrocytes and microglia survive the toxic onslaught, whereas neurons and oligodendrocytes increasingly die. However, we have shown that highly selective allosteric CaSR antagonists (calcilytics), like NPS 2143 and NPS 89626, efficiently suppress all the neurotoxic effects Aβ42-os•CaSR signaling drives in

  4. Yes and Lyn play a role in nuclear translocation of the epidermal growth factor receptor.

    PubMed

    Iida, M; Brand, T M; Campbell, D A; Li, C; Wheeler, D L

    2013-02-01

    The epidermal growth factor receptor (EGFR) is a central regulator of tumor progression in human cancers. Cetuximab is an anti-EGFR antibody that has been approved for use in oncology. Previously we investigated mechanisms of resistance to cetuximab using a model derived from the non-small cell lung cancer line NCI-H226. We demonstrated that cetuximab-resistant clones (Ctx(R)) had increased nuclear localization of the EGFR. This process was mediated by Src family kinases (SFKs), and nuclear EGFR had a role in resistance to cetuximab. To better understand SFK-mediated nuclear translocation of EGFR, we investigated which SFK member(s) controlled this process as well as the EGFR tyrosine residues that are involved. Analyses of mRNA and protein expression indicated upregulation of the SFK members Yes (v-Yes-1 yamaguchi sarcoma viral oncogene) and Lyn (v-yes-1 Yamaguchi sarcoma viral-related oncogene homolog) in all Ctx(R) clones. Further, immunoprecipitation analysis revealed that EGFR interacts with Yes and Lyn in Ctx(R) clones, but not in cetuximab-sensitive (Ctx(S)) parental cells. Using RNAi interference, we found that knockdown of either Yes or Lyn led to loss of EGFR translocation to the nucleus. Conversely, overexpression of Yes or Lyn in low nuclear EGFR-expressing Ctx(S) parental cells led to increased nuclear EGFR. Chromatin immunoprecipitation (ChIP) assays confirmed nuclear EGFR complexes associated with the promoter of the known EGFR target genes B-Myb and iNOS. Further, all Ctx(R) clones exhibited upregulation of B-Myb and iNOS at the mRNA and protein levels. siRNAs directed at Yes or Lyn led to decreased binding of EGFR complexes to the B-Myb and iNOS promoters based on ChIP analyses. SFKs have been shown to phosphorylate EGFR on tyrosines 845 and 1101 (Y845 and Y1101), and mutation of Y1101, but not Y845, impaired nuclear entry of the EGFR. Taken together, our findings demonstrate that Yes and Lyn phosphorylate EGFR at Y1101, which influences EGFR

  5. [GABA-Receptors in Modulation of Fear Memory Extinction].

    PubMed

    Dubrovina, N I

    2016-01-01

    GABA is the major inhibitory neurotransmitter in the central nervous system determining the efficacy of neuronal interaction. GABA-receptors play a key role in different aspects of fear memory--acquisition and consolidation, retention, reconsolidation and extinction. Extinction is an important behavioural phenomenon which allows organism to adapt its behavior to a changing environment. Extinction of fear memory is a form of new inhibitory learning which interferes with expression of the initial acquired fear conditioning. Resistance to extinction is symptom of depression and posttraumatic stress disorder. The aim of the present review was to summarize own and literary data about GABAergic modulation of fear extinction and pharmacological correction of extinction impairment at influences on GABA(A)- and GABA(B)- receptors. PMID:27538279

  6. Thyroid Hormone Receptor α Plays an Essential Role in Male Skeletal Muscle Myoblast Proliferation, Differentiation, and Response to Injury.

    PubMed

    Milanesi, Anna; Lee, Jang-Won; Kim, Nam-Ho; Liu, Yan-Yun; Yang, An; Sedrakyan, Sargis; Kahng, Andrew; Cervantes, Vanessa; Tripuraneni, Nikita; Cheng, Sheue-yann; Perin, Laura; Brent, Gregory A

    2016-01-01

    Thyroid hormone plays an essential role in myogenesis, the process required for skeletal muscle development and repair, although the mechanisms have not been established. Skeletal muscle develops from the fusion of precursor myoblasts into myofibers. We have used the C2C12 skeletal muscle myoblast cell line, primary myoblasts, and mouse models of resistance to thyroid hormone (RTH) α and β, to determine the role of thyroid hormone in the regulation of myoblast differentiation. T3, which activates thyroid hormone receptor (TR) α and β, increased myoblast differentiation whereas GC1, a selective TRβ agonist, was minimally effective. Genetic approaches confirmed that TRα plays an important role in normal myoblast proliferation and differentiation and acts through the Wnt/β-catenin signaling pathway. Myoblasts with TRα knockdown, or derived from RTH-TRα PV (a frame-shift mutation) mice, displayed reduced proliferation and myogenic differentiation. Moreover, skeletal muscle from the TRα1PV mutant mouse had impaired in vivo regeneration after injury. RTH-TRβ PV mutant mouse model skeletal muscle and derived primary myoblasts did not have altered proliferation, myogenic differentiation, or response to injury when compared with control. In conclusion, TRα plays an essential role in myoblast homeostasis and provides a potential therapeutic target to enhance skeletal muscle regeneration. PMID:26451739

  7. Integrin receptors play a role in the internalin B-dependent entry of Listeria monocytogenes into host cells.

    PubMed

    Auriemma, Clementina; Viscardi, Maurizio; Tafuri, Simona; Pavone, Luigi Michele; Capuano, Federico; Rinaldi, Laura; Della Morte, Rossella; Iovane, Giuseppe; Staiano, Norma

    2010-09-01

    Listeria monocytogenes enters non-phagocytic cells by binding its surface proteins inlA (internalin) and inlB to the host's E-cadherin and Met, respectively. The two internalins play either separate or cooperative roles in the colonization of infected tissues. Here, we studied bacterial uptake into HeLa cells using an L. monocytogenes mutant strain (DeltainlA) carrying a deletion in the gene coding for inlA. The DeltainlA mutant strain showed the capability to invade HeLa cells. The monoclonal anti-beta(3)- and anti-beta(1)-integrin subunit antibodies prevented bacterial uptake into the cells, while the anti-beta(2)- and anti-beta(4)-integrin subunit antibodies failed to affect L. monocytogenes entry into HeLa cells. Three structurally distinct disintegrins (kistrin, echistatin and flavoridin) also inhibited bacterial uptake, showing different potencies correlated to their selective affinity for the beta(3)- and beta(1)-integrin subunits. In addition to inducing Met phosphorylation, infection of cells by the L. monocytogenes DeltainlA mutant strain promoted the tyrosine phosphorylation of the focal adhesion-associated proteins FAK and paxillin. Our findings provide the first evidence that beta(3)- and beta(1)-integrin receptors play a role in the inlB-dependent internalization of L. monocytogenes into host cells. PMID:20526749

  8. Mitochondrial respiratory chain is involved in insulin-stimulated hydrogen peroxide production and plays an integral role in insulin receptor autophosphorylation in neurons

    PubMed Central

    Storozhevykh, Tatiana P; Senilova, Yana E; Persiyantseva, Nadezhda A; Pinelis, Vsevolod G; Pomytkin, Igor A

    2007-01-01

    Background Accumulated evidence suggests that hydrogen peroxide (H2O2) generated in cells during insulin stimulation plays an integral role in insulin receptor signal transduction. The role of insulin-induced H2O2 in neuronal insulin receptor activation and the origin of insulin-induced H2O2 in neurons remain unclear. The aim of the present study is to test the following hypotheses (1) whether insulin-induced H2O2 is required for insulin receptor autophosphorylation in neurons, and (2) whether mitochondrial respiratory chain is involved in insulin-stimulated H2O2 production, thus playing an integral role in insulin receptor autophosphorylation in neurons. Results Insulin stimulation elicited rapid insulin receptor autophosphorylation accompanied by an increase in H2O2 release from cultured cerebellar granule neurons (CGN). N-acetylcysteine (NAC), a H2O2 scavenger, inhibited both insulin-stimulated H2O2 release and insulin-stimulated autophosphorylation of insulin receptor. Inhibitors of respiratory chain-mediated H2O2 production, malonate and carbonyl cyanide-4-(trifluoromethoxy)-phenylhydrazone (FCCP), inhibited both insulin-stimulated H2O2 release from neurons and insulin-stimulated autophosphorylation of insulin receptor. Dicholine salt of succinic acid, a respiratory substrate, significantly enhanced the effect of suboptimal insulin concentration on the insulin receptor autophosphorylation in CGN. Conclusion Results of the present study suggest that insulin-induced H2O2 is required for the enhancement of insulin receptor autophosphorylation in neurons. The mitochondrial respiratory chain is involved in insulin-stimulated H2O2 production, thus playing an integral role in the insulin receptor autophosphorylation in neurons. PMID:17919343

  9. ZFAT plays critical roles in peripheral T cell homeostasis and its T cell receptor-mediated response

    SciTech Connect

    Doi, Keiko; Fujimoto, Takahiro; Okamura, Tadashi; Ogawa, Masahiro; Tanaka, Yoko; Mototani, Yasumasa; Goto, Motohito; Ota, Takeharu; Matsuzaki, Hiroshi; Kuroki, Masahide; Tsunoda, Toshiyuki; Sasazuki, Takehiko; Shirasawa, Senji

    2012-08-17

    Highlights: Black-Right-Pointing-Pointer We generated Cd4-Cre-mediated T cell-specific Zfat-deficient mice. Black-Right-Pointing-Pointer Zfat-deficiency leads to reduction in the number of the peripheral T cells. Black-Right-Pointing-Pointer Impaired T cell receptor-mediated response in Zfat-deficient peripheral T cells. Black-Right-Pointing-Pointer Decreased expression of IL-7R{alpha}, IL-2R{alpha} and IL-2 in Zfat-deficient peripheral T cells. Black-Right-Pointing-Pointer Zfat plays critical roles in peripheral T cell homeostasis. -- Abstract: ZFAT, originally identified as a candidate susceptibility gene for autoimmune thyroid disease, has been reported to be involved in apoptosis, development and primitive hematopoiesis. Zfat is highly expressed in T- and B-cells in the lymphoid tissues, however, its physiological function in the immune system remains totally unknown. Here, we generated the T cell-specific Zfat-deficient mice and demonstrated that Zfat-deficiency leads to a remarkable reduction in the number of the peripheral T cells. Intriguingly, a reduced expression of IL-7R{alpha} and the impaired responsiveness to IL-7 for the survival were observed in the Zfat-deficient T cells. Furthermore, a severe defect in proliferation and increased apoptosis in the Zfat-deficient T cells following T cell receptor (TCR) stimulation was observed with a reduced IL-2R{alpha} expression as well as a reduced IL-2 production. Thus, our findings reveal that Zfat is a critical regulator in peripheral T cell homeostasis and its TCR-mediated response.

  10. Epidermal growth factor receptor plays a role in the regulation of liver and plasma lipid levels in adult male mice

    PubMed Central

    Zhang, Xiuqi; Garcia, Oscar A.; Wang, Rebecca F.; Stevenson, Mary C.; Threadgill, David W.; Russell, William E.

    2014-01-01

    Dsk5 mice have a gain of function in the epidermal growth factor receptor (EGFR), caused by a point mutation in the kinase domain. We analyzed the effect of this mutation on liver size, histology, and composition. We found that the livers of 12-wk-old male Dsk5 heterozygotes (+/Dsk5) were 62% heavier compared with those of wild-type controls (+/+). The livers of the +/Dsk5 mice compared with +/+ mice had larger hepatocytes with prominent, polyploid nuclei and showed modestly increased cell proliferation indices in both hepatocytes and nonparenchymal cells. An analysis of total protein, DNA, and RNA (expressed relative to liver weight) revealed no differences between the mutant and wild-type mice. However, the livers of the +/Dsk5 mice had more cholesterol but less phospholipid and fatty acid. Circulating cholesterol levels were twice as high in adult male +/Dsk5 mice but not in postweaned young male or female mice. The elevated total plasma cholesterol resulted mainly from an increase in low-density lipoprotein (LDL). The +/Dsk5 adult mouse liver expressed markedly reduced protein levels of LDL receptor, no change in proprotein convertase subtilisin/kexin type 9, and a markedly increased fatty acid synthase and 3-hydroxy-3-methyl-glutaryl-CoA reductase. Increased expression of transcription factors associated with enhanced cholesterol synthesis was also observed. Together, these findings suggest that the EGFR may play a regulatory role in hepatocyte proliferation and lipid metabolism in adult male mice, explaining why elevated levels of EGF or EGF-like peptides have been positively correlated to increased cholesterol levels in human studies. PMID:24407590

  11. Peroxisome proliferator-activated receptor alpha plays a crucial role in behavioral repetition and cognitive flexibility in mice

    PubMed Central

    D'Agostino, Giuseppe; Cristiano, Claudia; Lyons, David J.; Citraro, Rita; Russo, Emilio; Avagliano, Carmen; Russo, Roberto; Raso, Giuseppina Mattace; Meli, Rosaria; De Sarro, Giovambattista; Heisler, Lora K.; Calignano, Antonio

    2015-01-01

    Background/objectives Nuclear peroxisome proliferator activated receptor-α (PPAR-α) plays a fundamental role in the regulation of lipid homeostasis and is the target of medications used to treat dyslipidemia. However, little is known about the role of PPAR-α in mouse behavior. Methods To investigate the function of Ppar-α in cognitive functions, a behavioral phenotype analysis of mice with a targeted genetic disruption of Ppar-α was performed in combination with neuroanatomical, biochemical and pharmacological manipulations. The therapeutic exploitability of PPAR-α was probed in mice using a pharmacological model of psychosis and a genetic model (BTBR T + tf/J) exhibiting a high rate of repetitive behavior. Results An unexpected role for brain Ppar-α in the regulation of cognitive behavior in mice was revealed. Specifically, we observed that Ppar-α genetic perturbation promotes rewiring of cortical and hippocampal regions and a behavioral phenotype of cognitive inflexibility, perseveration and blunted responses to psychomimetic drugs. Furthermore, we demonstrate that the antipsychotic and autism spectrum disorder (ASD) medication risperidone ameliorates the behavioral profile of Ppar-α deficient mice. Importantly, we reveal that pharmacological PPAR-α agonist treatment in mice improves behavior in a pharmacological model of ketamine-induced behavioral dysinhibition and repetitive behavior in BTBR T + tf/J mice. Conclusion Our data indicate that Ppar-α is required for normal cognitive function and that pharmacological stimulation of PPAR-α improves cognitive function in pharmacological and genetic models of impaired cognitive function in mice. These results thereby reveal an unforeseen therapeutic application for a class of drugs currently in human use. PMID:26137440

  12. Platelet-Activating Factor Receptor Plays a Role in Lung Injury and Death Caused by Influenza A in Mice

    PubMed Central

    Garcia, Cristiana C.; Russo, Remo C.; Guabiraba, Rodrigo; Fagundes, Caio T.; Polidoro, Rafael B.; Tavares, Luciana P.; Salgado, Ana Paula C.; Cassali, Geovanni D.; Sousa, Lirlândia P.; Machado, Alexandre V.; Teixeira, Mauro M.

    2010-01-01

    Influenza A virus causes annual epidemics which affect millions of people worldwide. A recent Influenza pandemic brought new awareness over the health impact of the disease. It is thought that a severe inflammatory response against the virus contributes to disease severity and death. Therefore, modulating the effects of inflammatory mediators may represent a new therapy against Influenza infection. Platelet activating factor (PAF) receptor (PAFR) deficient mice were used to evaluate the role of the gene in a model of experimental infection with Influenza A/WSN/33 H1N1 or a reassortant Influenza A H3N1 subtype. The following parameters were evaluated: lethality, cell recruitment to the airways, lung pathology, viral titers and cytokine levels in lungs. The PAFR antagonist PCA4248 was also used after the onset of flu symptoms. Absence or antagonism of PAFR caused significant protection against flu-associated lethality and lung injury. Protection was correlated with decreased neutrophil recruitment, lung edema, vascular permeability and injury. There was no increase of viral load and greater recruitment of NK1.1+ cells. Antibody responses were similar in WT and PAFR-deficient mice and animals were protected from re-infection. Influenza infection induces the enzyme that synthesizes PAF, lyso-PAF acetyltransferase, an effect linked to activation of TLR7/8. Therefore, it is suggested that PAFR is a disease-associated gene and plays an important role in driving neutrophil influx and lung damage after infection of mice with two subtypes of Influenza A. Further studies should investigate whether targeting PAFR may be useful to reduce lung pathology associated with Influenza A virus infection in humans. PMID:21079759

  13. GABAB-mediated rescue of altered excitatory–inhibitory balance, gamma synchrony and behavioral deficits following constitutive NMDAR-hypofunction

    PubMed Central

    Gandal, M J; Sisti, J; Klook, K; Ortinski, P I; Leitman, V; Liang, Y; Thieu, T; Anderson, R; Pierce, R C; Jonak, G; Gur, R E; Carlson, G; Siegel, S J

    2012-01-01

    Reduced N-methyl-D-aspartate-receptor (NMDAR) signaling has been associated with schizophrenia, autism and intellectual disability. NMDAR-hypofunction is thought to contribute to social, cognitive and gamma (30–80 Hz) oscillatory abnormalities, phenotypes common to these disorders. However, circuit-level mechanisms underlying such deficits remain unclear. This study investigated the relationship between gamma synchrony, excitatory–inhibitory (E/I) signaling, and behavioral phenotypes in NMDA-NR1neo−/− mice, which have constitutively reduced expression of the obligate NR1 subunit to model disrupted developmental NMDAR function. Constitutive NMDAR-hypofunction caused a loss of E/I balance, with an increase in intrinsic pyramidal cell excitability and a selective disruption of parvalbumin-expressing interneurons. Disrupted E/I coupling was associated with deficits in auditory-evoked gamma signal-to-noise ratio (SNR). Gamma-band abnormalities predicted deficits in spatial working memory and social preference, linking cellular changes in E/I signaling to target behaviors. The GABAB-receptor agonist baclofen improved E/I balance, gamma-SNR and broadly reversed behavioral deficits. These data demonstrate a clinically relevant, highly translatable neural-activity-based biomarker for preclinical screening and therapeutic development across a broad range of disorders that share common endophenotypes and disrupted NMDA-receptor signaling. PMID:22806213

  14. Conserved Glycine Residues in the Cytoplasmic Domain of the Aspartate Receptor Play Essential Roles in Kinase Coupling and On–Off Switching†

    PubMed Central

    Coleman, Matthew D.; Bass, Randal B.; Mehan, Ryan S.; Falke, Joseph J.

    2010-01-01

    The aspartate receptor of the bacterial chemotaxis pathway serves as a scaffold for the formation of a multiprotein signaling complex containing the receptor and the cytoplasmic pathway components. Within this complex, the receptor regulates the autophosphorylation activity of histidine kinase CheA, thereby controlling the signals sent to the flagellar motor and the receptor adaptation system. The receptor cytoplasmic domain, which controls the on–off switching of CheA, possesses 14 glycine residues that are highly conserved in related receptors. In principle, these conserved glycines could be required for static turns, bends, or close packing in the cytoplasmic domain, or they could be required for conformational dynamics during receptor on–off switching. To determine which glycines are essential and to probe their functional roles, we have substituted each conserved glycine with both alanine and cysteine, and then measured the effects on receptor function in vivo and in vitro. The results reveal a subset of six glycines which are required for receptor function during cellular chemotaxis. Two of these essential glycines (G388 and G391) are located at a hairpin turn at the distal end of the folded cytoplasmic domain, where they are required for the tertiary fold of the signaling subdomain and for CheA kinase activation. Three other essential glycines (G338, G339, and G437) are located at the border between the adaptation and signaling subdomains, where they play key roles in CheA kinase activation and on–off switching. These three glycines form a ring around the four-helix bundle that comprises the receptor cytoplasmic domain, yielding a novel architectural feature termed a bundle hinge. The final essential glycine (G455) is located in the adaptation subdomain where it is required for on–off switching. Overall, the findings confirm that six of the 14 conserved cytoplasmic glycines are essential for receptor function because they enable helix turns and bends

  15. Repeated cocaine weakens GABAB-Girk signaling in Layer 5/6 pyramidal neurons in the prelimbic cortex

    PubMed Central

    Hearing, Matthew; Kotecki, Lydia; de Velasco, Ezequiel Marron Fernandez; Fajardo-Serrano, Ana; Luján, Rafael; Wickman, Kevin

    2013-01-01

    Summary Repeated cocaine exposure triggers adaptations in Layer 5/6 glutamatergic neurons in the medial prefrontal cortex (mPFC) that promote behavioral sensitization and drug-seeking behavior. While suppression of metabotropic inhibitory signaling has been implicated in these behaviors, underlying mechanisms are unknown. Here, we show that Girk/KIR3 channels mediate most of the GABAB receptor (GABABR)-dependent inhibition of Layer 5/6 pyramidal neurons in the mPFC and that repeated cocaine suppresses this pathway. This adaptation was selective for GABABR-dependent Girk signaling in Layer 5/6 pyramidal neurons of the prelimbic cortex (PrLC) and involved a D1/5 dopamine receptor- and phosphorylation-dependent internalization of GABABR and Girk channels. Persistent suppression of Girk signaling in Layer 5/6 of the dorsal mPFC enhanced cocaine-induced locomotor activity and occluded behavioral sensitization. Thus, the cocaine-induced suppression of GABABR-Girk signaling in Layer 5/6 pyramidal neurons of the prelimbic cortex appears to represent an early adaptation critical for promoting addiction-related behavior. PMID:24094109

  16. The Arabidopsis F-box E3 ligase RIFP1 plays a negative role in abscisic acid signalling by facilitating ABA receptor RCAR3 degradation.

    PubMed

    Li, Ying; Zhang, Liang; Li, Dekuan; Liu, Zhibin; Wang, Jianmei; Li, Xufeng; Yang, Yi

    2016-03-01

    The phytohormone abscisic acid (ABA) plays a vital role in plant growth and development. The function of ABA is mediated by a group of newly discovered ABA receptors, named PYRABACTIN RESISTANCE 1/PYR-LIKE/REGULATORY COMPONENTS OF ABA RECEPTORs (PYR1/PYLs/RCARs). Here, we report that an Arabidopsis thaliana F-box protein RCAR3 INTERACTING F-BOX PROTEIN 1 (RIFP1) interacts with ABA receptor (RCAR3) and SCF E3 ligase complex subunits Arabidopsis SKP1-LIKE PROTEINs (ASKs) in vitro and in vivo. The rifp1 mutant plants displayed increased ABA-mediated inhibition of seed germination and water loss of detached leaves, while the overexpression of RIFP1 in Arabidopsis led to plants being insensitive to ABA. Meanwhile, the rifp1 mutant plants showed greater tolerance to water deficit. In addition, the RCAR3 protein level was more stable in the rifp1 mutant plants than in the wild-type plants, indicating that RIFP1 facilitates the proteasome degradation of RCAR3. Accordingly, the loss of RIFP1 increased the transcript levels of several ABA-responsive genes. Taken together, these data indicate that RIFP1 plays a negative role in the RCAR3-mediated ABA signalling pathway and likely functions as an adaptor subunit of the SCF ubiquitin ligase complex to regulate ABA receptor RCAR3 stability. PMID:26386272

  17. A LysM receptor-like kinase plays a critical role in chitin signaling and fungal resistance in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chitin, a polymer of N-acetyl-D-glucosamine, is found in fungal cell walls, but not in plants. Plant cells are capable of perceiving chitin fragments (chitooligosaccharides) to trigger plant defense. We identified a LysM receptor-like protein (AtLysM RLK1) that is required for the perception of chit...

  18. GENES, IN ADDITION TO TOLL-LIKE RECEPTOR 2, PLAY A ROLE IN ANTIBACTERIAL DEFENSE TO STREPTOCOCCAL PNEUMONIA

    EPA Science Inventory

    Streptococcus infection in human populations continues to be a major cause of morbidity and mortality. To evaluate the effect of genetic background and toll-like receptor 2 (TLR2) on antibacterial defense to streptococcal infection, eight genetically diverse strains of mic...

  19. A LysM Receptor-like Kinase Plays a Critical Role in Chitin Signaling and Fungal Resistance in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chitin, a polymer of N-acetyl-D-glucosamine, is found in fungal cell walls, but not in plants. Plant cells are capable of perceiving chitin fragments (chitooligosaccharides) to trigger plant defense. We identified a LysM receptor-like protein (AtLysM RLK1) that is required for the perception of chit...

  20. Differential expression of metabotropic glutamate and GABA receptors at neocortical glutamatergic and GABAergic axon terminals

    PubMed Central

    Bragina, Luca; Bonifacino, Tiziana; Bassi, Silvia; Milanese, Marco; Bonanno, Giambattista; Conti, Fiorenzo

    2015-01-01

    Metabotropic glutamate (Glu) receptors (mGluRs) and GABAB receptors are highly expressed at presynaptic sites. To verify the possibility that the two classes of metabotropic receptors contribute to axon terminals heterogeneity, we studied the localization of mGluR1α, mGluR5, mGluR2/3, mGluR7, and GABAB1 in VGLUT1-, VGLUT2-, and VGAT- positive terminals in the cerebral cortex of adult rats. VGLUT1-positive puncta expressed mGluR1α (∼5%), mGluR5 (∼6%), mGluR2/3 (∼22%), mGluR7 (∼17%), and GABAB1 (∼40%); VGLUT2-positive terminals expressed mGluR1α (∼10%), mGluR5 (∼11%), mGluR2/3 (∼20%), mGluR7 (∼28%), and GABAB1 (∼25%); whereas VGAT-positive puncta expressed mGluR1α (∼27%), mGluR5 (∼24%), mGluR2/3 (∼38%), mGluR7 (∼31%), and GABAB1 (∼19%). Control experiments ruled out the possibility that postsynaptic mGluRs and GABAB1 might have significantly biased our results. We also performed functional assays in synaptosomal preparations, and showed that all agonists modify Glu and GABA levels, which return to baseline upon exposure to antagonists. Overall, these findings indicate that mGluR1α, mGluR5, mGluR2/3, mGluR7, and GABAB1 expression differ significantly between glutamatergic and GABAergic axon terminals, and that the robust expression of heteroreceptors may contribute to the homeostatic regulation of the balance between excitation and inhibition. PMID:26388733

  1. Association of adverse childhood experiences, age of menarche, and adult reproductive behavior: does the androgen receptor gene play a role?

    PubMed

    Jorm, Anthony F; Christensen, Helen; Rodgers, Bryan; Jacomb, Patricia A; Easteal, Simon

    2004-02-15

    Previous research has reported associations between adverse childhood experiences, early menarche, and early sexual activity. One hypothesis to account for these findings is that an X-linked androgen receptor GGC-repeat polymorphism predisposes fathers to behaviors which include family abandonment and their daughters to earlier menarche and sexual activity and less stable relationships. Retrospective data relevant to this theory were examined from a community survey involving 3,702 women in the age groups 20-24, 40-44, and 60-64 years, and another involving 908 women aged 18-79 years. Earlier age of menarche was found to be associated with adverse childhood experiences and earlier sexual activity. However, the androgen receptor gene polymorphism was unrelated to adverse fathering behavior or to marital breakdown. PMID:14755454

  2. Tuning and playing a motor rhythm: how metabotropic glutamate receptors orchestrate generation of motor patterns in the mammalian central nervous system.

    PubMed

    Nistri, Andrea; Ostroumov, Konstantin; Sharifullina, Elina; Taccola, Giuliano

    2006-04-15

    Repeated motor activities like locomotion, mastication and respiration need rhythmic discharges of functionally connected neurons termed central pattern generators (CPGs) that cyclically activate motoneurons even in the absence of descending commands from higher centres. For motor pattern generation, CPGs require integration of multiple processes including activation of ion channels and transmitter receptors at strategic locations within motor networks. One emerging mechanism is activation of glutamate metabotropic receptors (mGluRs) belonging to group I, while group II and III mGluRs appear to play an inhibitory function on sensory inputs. Group I mGluRs generate neuronal membrane depolarization with input resistance increase and rapid fluctuations in intracellular Ca(2+), leading to enhanced excitability and rhythmicity. While synchronicity is probably due to modulation of inhibitory synaptic transmission, these oscillations occurring in coincidence with strong afferent stimuli or application of excitatory agents can trigger locomotor-like patterns. Hence, mGluR-sensitive spinal oscillators play a role in accessory networks for locomotor CPG activation. In brainstem networks supplying tongue muscle motoneurons, group I receptors facilitate excitatory synaptic inputs and evoke synchronous oscillations which stabilize motoneuron firing at regular, low frequency necessary for rhythmic tongue contractions. In this case, synchronicity depends on the strong electrical coupling amongst motoneurons rather than inhibitory transmission, while cyclic activation of K(ATP) conductances sets its periodicity. Activation of mGluRs is therefore a powerful strategy to trigger and recruit patterned discharges of motoneurons. PMID:16469790

  3. Regional Fos-expression induced by γ-hydroxybutyrate (GHB): comparison with γ-butyrolactone (GBL) and effects of co-administration of the GABAB antagonist SCH 50911 and putative GHB antagonist NCS-382.

    PubMed

    van Nieuwenhuijzen, P S; McGregor, I S; Chebib, M; Hunt, G E

    2014-09-26

    γ-Hydroxybutyrate (GHB) has a complex array of neural actions that include effects on its own high-affinity GHB receptor, the release of neuroactive steroids, and agonist actions at GABAA and GABAB receptors. We previously reported partial overlap in the c-Fos expression patterns produced by GHB and the GABAB agonist, baclofen in rats. The present study extends these earlier findings by examining the extent to which GHB Fos expression and behavioral sedation are prevented by (2S)-(+)-5,5-dimethyl-2-morpholineacetic acid (SCH 50911), a GABAB antagonist, and NCS-382, a putative antagonist at the high-affinity GHB receptor. We also compare Fos expression caused by GHB and its precursor γ-butyrolactone (GBL), which is a pro-drug for GHB but lacks the high sodium content of the parent GHB molecule. Both GHB (1,000 mg/kg) and GBL (600 mg/kg) induced rapid sedation in rats that lasted over 90 min and caused similar Fos expression patterns, albeit with GBL causing greater activation of the nucleus accumbens (core and shell) and dentate gyrus (granular layer). Pretreatment with SCH 50911 (100mg/kg) partly reversed the sedative effects of GHB and significantly reduced GHB-induced Fos expression in only four regions: the tenia tecta, lateral habenula, dorsal raphe and laterodorsal tegmental nucleus. NCS-382 (50mg/kg) had no effect on GHB-induced sedation or Fos expression. When given alone, both NCS-382 and SCH 50911 increased Fos expression in the bed nucleus of the stria terminalis, central amygdala, parasubthalamic nucleus and nucleus of the solitary tract. SCH 50911 alone affected the Islands of Calleja and the medial, central and paraventricular thalamic nuclei. Overall, this study shows a surprising lack of reversal of GHB-induced Fos expression by two relevant antagonists, both of which have marked intrinsic actions. This may reflect the limited doses tested but also suggests that GHB Fos expression reflects mechanisms independent of GHB and GABAB receptors. PMID

  4. Insulin Receptor Signaling in the GnRH Neuron Plays a Role in the Abnormal GnRH Pulsatility of Obese Female Mice

    PubMed Central

    DiVall, Sara A.; Herrera, Danny; Sklar, Bonnie; Wu, Sheng; Wondisford, Fredric; Radovick, Sally; Wolfe, Andrew

    2015-01-01

    Infertility associated with obesity is characterized by abnormal hormone release from reproductive tissues in the hypothalamus, pituitary, and ovary. These tissues maintain insulin sensitivity upon peripheral insulin resistance. Insulin receptor signaling may play a role in the dysregulation of gonadotropin-releasing hormone (GnRH) secretion in obesity, but the interdependence of hormone secretion in the reproductive axis and the multi-hormone and tissue dysfunction in obesity hinders investigations of putative contributing factors to the disrupted GnRH secretion. To determine the role of GnRH insulin receptor signaling in the dysregulation of GnRH secretion in obesity, we created murine models of diet-induced obesity (DIO) with and without intact insulin signaling in the GnRH neuron. Obese control female mice were infertile with higher luteinizing hormone levels and higher GnRH pulse amplitude and total pulsatile secretion compared to lean control mice. In contrast, DIO mice with a GnRH specific knockout of insulin receptor had improved fertility, luteinizing hormone levels approaching lean mice, and GnRH pulse amplitude and total secretion similar to lean mice. Pituitary responsiveness was similar between genotypes. These results suggest that in the obese state, insulin receptor signaling in GnRH neurons increases GnRH pulsatile secretion and consequent LH secretion, contributing to reproductive dysfunction. PMID:25780937

  5. Human neutrophil Fcγ receptors initiate and play specialized nonredundant roles in antibody-mediated inflammatory diseases

    PubMed Central

    Tsuboi, Naotake; Asano, Kenichi; Lauterbach, Michael; Mayadas, Tanya N.

    2008-01-01

    Summary Antibody-antigen complex mediated inflammation is integral to the pathogenesis of many autoimmune diseases. Mice deficient in the γ-chain of Fc-receptors are protected in IgG-mediated glomerulonephritis and the Arthus reaction and FcR-bearing mast cells and macrophages have been assigned primary roles in these processes. Here we demonstrate that neutrophil selective transgenic expression of the two uniquely human activating FcγRs, FcγRIIA and FcγRIIIB was sufficient to restore susceptibility to progressive anti-glomerular basement membrane (GBM) nephritis and the cutaneous Reverse Passive Arthus (RPA) reaction in γ-chain deficient mice. Both FcγRIIA and FcγRIIIB mediated robust neutrophil accumulation in tissues suggesting direct roles for these human receptors in IC-induced neutrophil recruitment, while FcγRIIA alone mediated organ injury. In an acute model of anti-GBM nephritis, both FcγRIIIB and FcγRIIA promoted initial neutrophil recruitment to glomerular immune-complexes (ICs) accessible to circulating cells, while FcγRIIA further sustained accumulation. In a model of soluble ICs deposited strictly within the post-capillary venules of the cremaster muscle, FcγRIIIB was solely responsible for converting initial selectin-dependent tethers to slow rolling and adhesion. However, in the cremaster RPA reaction, dependent on vascular and tissue accumulation of soluble ICs, FcγRIIA predominated in neutrophil recruitment that was dependent on G-protein coupled receptor activation. Thus, human FcγRs on neutrophils serve as the primary molecular links between ICs and immunological disease with FcγRIIA promoting tissue injury, and FcγRIIIB and FcγRIIA displaying specialized context-dependent functions in IC-induced neutrophil recruitment. PMID:18538590

  6. The ABA receptor PYL9 together with PYL8 plays an important role in regulating lateral root growth.

    PubMed

    Xing, Lu; Zhao, Yang; Gao, Jinghui; Xiang, Chengbin; Zhu, Jian-Kang

    2016-01-01

    Abscisic acid is a phytohormone regulating plant growth, development and stress responses. PYR1/PYL/RCAR proteins are ABA receptors that function by inhibiting PP2Cs to activate SnRK2s, resulting in phosphorylation of ABFs and other effectors of ABA response pathways. Exogenous ABA induces growth quiescence of lateral roots, which is prolonged by knockout of the ABA receptor PYL8. Among the 14 members of PYR1/PYL/RCAR protein family, PYL9 is a close relative of PYL8. Here we show that knockout of both PYL9 and PYL8 resulted in a longer ABA-induced quiescence on lateral root growth and a reduced sensitivity to ABA on primary root growth and lateral root formation compared to knockout of PYL8 alone. Induced overexpression of PYL9 promoted the lateral root elongation in the presence of ABA. The prolonged quiescent phase of the pyl8-1pyl9 double mutant was reversed by exogenous IAA. PYL9 may regulate auxin-responsive genes in vivo through direct interaction with MYB77 and MYB44. Thus, PYL9 and PYL8 are both responsible for recovery of lateral root from ABA inhibition via MYB transcription factors. PMID:27256015

  7. The ABA receptor PYL9 together with PYL8 plays an important role in regulating lateral root growth

    PubMed Central

    Xing, Lu; Zhao, Yang; Gao, Jinghui; Xiang, Chengbin; Zhu, Jian-Kang

    2016-01-01

    Abscisic acid is a phytohormone regulating plant growth, development and stress responses. PYR1/PYL/RCAR proteins are ABA receptors that function by inhibiting PP2Cs to activate SnRK2s, resulting in phosphorylation of ABFs and other effectors of ABA response pathways. Exogenous ABA induces growth quiescence of lateral roots, which is prolonged by knockout of the ABA receptor PYL8. Among the 14 members of PYR1/PYL/RCAR protein family, PYL9 is a close relative of PYL8. Here we show that knockout of both PYL9 and PYL8 resulted in a longer ABA-induced quiescence on lateral root growth and a reduced sensitivity to ABA on primary root growth and lateral root formation compared to knockout of PYL8 alone. Induced overexpression of PYL9 promoted the lateral root elongation in the presence of ABA. The prolonged quiescent phase of the pyl8-1pyl9 double mutant was reversed by exogenous IAA. PYL9 may regulate auxin-responsive genes in vivo through direct interaction with MYB77 and MYB44. Thus, PYL9 and PYL8 are both responsible for recovery of lateral root from ABA inhibition via MYB transcription factors. PMID:27256015

  8. G Protein-Coupled Receptor Signaling and Sphingosine-1-Phosphate Play a Phylogenetically Conserved Role in Endocrine Pancreas Morphogenesis ▿

    PubMed Central

    Serafimidis, Ioannis; Heximer, Scott; Beis, Dimitris; Gavalas, Anthony

    2011-01-01

    During development pancreatic endocrine cells migrate in a coordinated fashion. This migration is necessary to form fully functional islets, but the mechanisms involved remain unknown. Therapeutic strategies to restore β-cell mass and islet functionality by reprogramming endogenous exocrine cells would be strengthened from simultaneous treatments that enhance endocrine cell clustering. We found that endocrine progenitors respond to and regulate G protein-coupled receptor (GPCR) signaling in order to cluster in islets. Rgs4, a dedicated regulator of GPCR signaling, was specifically expressed in early epithelial endocrine progenitors of both zebrafish and mouse, and its expression in the mouse endocrine progenitors was strictly dependent upon Ngn3, the key specification gene of the endocrine lineage. Rgs4 loss of function resulted in defects in islet cell aggregation. By genetically inactivating Gαi-mediated GPCR signaling in endocrine progenitors, we established its role in islet cell aggregation in both mouse and zebrafish. Finally, we identified sphingosine-1-phosphate (S1P) as a ligand mediating islet cell aggregation in both species acting through distinct but closely related receptors. PMID:21911471

  9. Toll-Like Receptor 3 (TLR3) Plays a Major Role in the Formation of Rabies Virus Negri Bodies

    PubMed Central

    Ménager, Pauline; Roux, Pascal; Mégret, Françoise; Bourgeois, Jean-Pierre; Le Sourd, Anne-Marie; Danckaert, Anne; Lafage, Mireille; Préhaud, Christophe; Lafon, Monique

    2009-01-01

    Human neurons express the innate immune response receptor, Toll-like receptor 3 (TLR3). TLR3 levels are increased in pathological conditions such as brain virus infection. Here, we further investigated the production, cellular localisation, and function of neuronal TLR3 during neuronotropic rabies virus (RABV) infection in human neuronal cells. Following RABV infection, TLR3 is not only present in endosomes, as observed in the absence of infection, but also in detergent-resistant perinuclear inclusion bodies. As well as TLR3, these inclusion bodies contain the viral genome and viral proteins (N and P, but not G). The size and composition of inclusion bodies and the absence of a surrounding membrane, as shown by electron microscopy, suggest they correspond to the previously described Negri Bodies (NBs). NBs are not formed in the absence of TLR3, and TLR3−/− mice—in which brain tissue was less severely infected—had a better survival rate than WT mice. These observations demonstrate that TLR3 is a major molecule involved in the spatial arrangement of RABV–induced NBs and viral replication. This study shows how viruses can exploit cellular proteins and compartmentalisation for their own benefit. PMID:19247444

  10. Molecular basis for amino acid sensing by family C G-protein-coupled receptors

    PubMed Central

    Wellendorph, P; Bräuner-Osborne, H

    2009-01-01

    Family C of human G-protein-coupled receptors (GPCRs) is constituted by eight metabotropic glutamate receptors, two γ-aminobutyric acid type B (GABAB1–2) subunits forming the heterodimeric GABAB receptor, the calcium-sensing receptor, three taste1 receptors (T1R1–3), a promiscuous L-α-amino acid receptor G-protein-coupled receptor family C, group 6, subtype A (GPRC6A) and seven orphan receptors. Aside from the orphan receptors, the family C GPCRs are dimeric receptors characterized by a large extracellular Venus flytrap domain which bind the endogenous agonists. Except from the GABAB1–2 and T1R2–3 receptor, all receptors are either activated or positively modulated by amino acids. In this review, we outline mutational, biophysical and structural studies which have elucidated the interaction of the amino acids with the Venus flytrap domains, molecular mechanisms of receptor selectivity and the initial steps in receptor activation. PMID:19298394

  11. Gender Effect in Experimental Models of Human Medulloblastoma: Does the Estrogen Receptor β Signaling Play a Role?

    PubMed Central

    Ciucci, Alessandra; Meco, Daniela; De Stefano, Ilaria; Travaglia, Daniele; Zannoni, Gian Franco; Scambia, Giovanni; Riccardi, Riccardo; Saran, Anna

    2014-01-01

    Background The male-to-female sex ratio for medulloblastoma (MB) is approximately 1.5∶1, female gender being also a favorable prognostic factor. This study aimed at evaluating the impact of gender on MB tumorigenesis. Methods In vitro activity of 17β-estradiol (E2), DPN [2,3-bis(4-hydroxyphenyl)-propionitrile, a selective estrogen receptor β (ERβ)-agonist], PPT [4,4′,4″-(4-Propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol, a selective ERα-agonist] or DHT (5 alpha-dihydrotestosterone) was evaluated in three human MB cell lines. D283 Med cells were transplanted into athymic mice. Results A significant expression of ERβ, with little or no ERα, and low AR (androgen receptor) was found in MB cell lines. The compounds tested did not affect cell proliferation. In vivo, we observed a significantly lower growth of D283 Med in nude female mice compared to males. At microscopic examination, tumors from females showed a shift towards differentiation, as evaluated by lower nestin, and higher NSE (neuron-specific enolase) and GFAP (glial fibrillary acidic protein) expression compared to males. Tumors from females also showed lower Ki67 and p53 expression. The wild-type ERβ protein (ERβ1) was lost in male tumors, while it was a permanent feature in females, and a strong negative correlation was found between Ki67 and ERβ1 expression. Conversely, tumor levels of ERβ2 and ERβ5 did not significantly differ between genders. Increased levels of cyclin-dependent kinase inhibitor p21 were observed in females, suggesting that estrogen may decrease tumor growth through blocking cell cycle progression. An inhibition of the insulin-like growth factor I (IGF-I) signaling was also evident in females. Conclusion We provides mechanistic evidence supporting the idea that ERβ1 signaling may have pro-differentiation and tumor suppressive function in medulloblastomas. PMID:25000562

  12. Sigma-2 Receptors Play a Role in Cellular Metabolism: Stimulation of Glycolytic Hallmarks by CM764 in Human SK-N-SH Neuroblastoma.

    PubMed

    Nicholson, Hilary; Mesangeau, Christophe; McCurdy, Christopher R; Bowen, Wayne D

    2016-02-01

    Sigma-2 receptors are attractive antineoplastic targets due to their ability to induce apoptosis and their upregulation in rapidly proliferating cancer cells compared with healthy tissue. However, this role is inconsistent with overexpression in cancer, which is typically associated with upregulation of prosurvival factors. Here, we report a novel metabolic regulatory function for sigma-2 receptors. CM764 [6-acetyl-3-(4-(4-(2-amino-4-fluorophenyl)piperazin-1-yl)butyl)benzo[d]oxazol-2(3H)-one] binds with Ki values of 86.6 ± 2.8 and 3.5 ± 0.9 nM at the sigma-1 and sigma-2 receptors, respectively. CM764 increased reduction of MTT [3-[4,5 dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide] in human SK-N-SH neuroblastoma compared with untreated cells, an effect not due to proliferation. This effect was attenuated by five different sigma antagonists, including CM572 [3-(4-(4-(4-fluorophenyl)piperazin-1-yl)butyl)-6-isothiocyanatobenzo[d]oxazol-2(3H)-one], which has no significant affinity for sigma-1 receptors. This effect was also observed in MG-63 osteosarcoma and HEK293T cells, indicating that this function is not exclusive to neuroblastoma or to cancer cells. CM764 produced an immediate, robust, and transient increase in cytosolic calcium, consistent with sigma-2 receptor activation. Additionally, we observed an increase in the total NAD(+)/NADH level and the ATP level in CM764-treated SK-N-SH cells compared with untreated cells. After only 4 hours of treatment, basal levels of reactive oxygen species were reduced by 90% in cells treated with CM764 over untreated cells, and HIF1α and VEGF levels were increased after 3-24 hours of treatment. These data indicate that sigma-2 receptors may play a role in induction of glycolysis, representing a possible prosurvival function for the sigma-2 receptor that is consistent with its upregulation in cancer cells compared with healthy tissue. PMID:26574517

  13. The Nuclear Orphan Receptor COUP-TFII Plays an Essential Role in Adipogenesis, Glucose Homeostasis, and Energy Metabolism

    PubMed Central

    Li, Luoping; Xie, Xin; Qin, Jun; Jeha, George S.; Saha, Pradip K.; Yan, Jun; Haueter, Claire Menoza; Chan, Lawrence; Tsai, Sophia Y.; Tsai, Ming-Jer.

    2009-01-01

    Summary Adipose tissue development and function play a central role in the pathogenesis and pathophysiology of metabolic syndromes. Here we show that Chicken Ovalbumin Upstream Promoter Transcription Factor II (COUP-TFII) plays a pivotal role in adipogenesis and energy homeostasis. COUP-TFII is expressed in the early stages of white adipocyte (WAT) development. COUP-TFII heterozygous mice (COUP-TFII+/-) have much less WAT than wild type mice (COUP-TFII+/+). COUP-TFII+/- mice display a decreased expression of key regulators for WAT development. Knock down COUP-TFII in 3T3-L1 cells resulted in an increased expression of Wnt10b, while chromatin immunoprecipitation analysis revealed that Wnt10b is a direct target of COUP-TFII. Moreover, COUP-TFII+/− mice have increased mitochondrial biogenesis in WAT, and COUP-TFII+/− mice have improved glucose homeostasis and increased energy expenditure. Thus, COUP-TFII regulates adipogenesis by regulating the key molecules in adipocyte development, and can serve as a new target for regulating energy metabolism. PMID:19117548

  14. Toll-Like Receptor 6 Plays an Important Role in Host Innate Resistance to Brucella abortus Infection in Mice

    PubMed Central

    de Almeida, Leonardo A.; Macedo, Gilson C.; Marinho, Fábio A. V.; Gomes, Marco T. R.; Corsetti, Patrícia P.; Silva, Aristóbolo M.; Cassataro, Juliana; Giambartolomei, Guillermo H.

    2013-01-01

    Brucella abortus is recognized by several Toll-like receptor (TLR)-associated pathways triggering proinflammatory responses that affect both the nature and intensity of the immune response. Previously, we demonstrated that B. abortus-mediated dendritic cell (DC) maturation and control of infection are dependent on the adaptor molecule MyD88. However, the involvement of all TLRs in response to B. abortus infection is not completely understood. Therefore, we decided to evaluate the requirement for TLR6 in host resistance to B. abortus. Here, we demonstrated that TLR6 is an important component for triggering an innate immune response against B. abortus. An in vitro luciferase assay indicated that TLR6 cooperates with TLR2 to sense Brucella and further activates NF-κB signaling. However, in vivo analysis showed that TLR6, not TLR2, is required for the efficient control of B. abortus infection. Additionally, B. abortus-infected dendritic cells require TLR6 to induce tumor necrosis factor alpha (TNF-α) and interleukin-12 (IL-12). Furthermore, our findings demonstrated that the mitogen-activated protein kinase (MAPK) signaling pathway is impaired in TLR2, TLR6, and TLR2/6 knockout (KO) DCs when infected with B. abortus, which may account for the lower proinflammatory cytokine production observed in TLR6 KO mouse dendritic cells. In summary, the results presented here indicate that TLR6 is required to trigger innate immune responses against B. abortus in vivo and is required for the full activation of DCs to induce robust proinflammatory cytokine production. PMID:23460520

  15. Nod-Like Receptor Protein-3 Inflammasome Plays an Important Role during Early Stages of Wound Healing

    PubMed Central

    Weinheimer-Haus, Eileen M.; Mirza, Rita E.; Koh, Timothy J.

    2015-01-01

    The Nod-like receptor protein (NLRP)-3 inflammasome/IL-1β pathway is involved in the pathogenesis of various inflammatory skin diseases, but its biological role in wound healing remains to be elucidated. Since inflammation is typically thought to impede healing, we hypothesized that loss of NLRP-3 activity would result in a downregulated inflammatory response and accelerated wound healing. NLRP-3 null mice, caspase-1 null mice and C57Bl/6 wild type control mice (WT) received four 8 mm excisional cutaneous wounds; inflammation and healing were assessed during the early stage of wound healing. Consistent with our hypothesis, wounds from NLRP-3 null and caspase-1 null mice contained lower levels of the pro-inflammatory cytokines IL-1β and TNF-α compared to WT mice and had reduced neutrophil and macrophage accumulation. Contrary to our hypothesis, re-epithelialization, granulation tissue formation, and angiogenesis were delayed in NLRP-3 null mice and caspase-1 null mice compared to WT mice, indicating that NLRP-3 signaling is important for early events in wound healing. Topical treatment of excisional wounds with recombinant IL-1β partially restored granulation tissue formation in wounds of NLRP-3 null mice, confirming the importance of NLRP-3-dependent IL-1β production during early wound healing. Despite the improvement in healing, angiogenesis and levels of the pro-angiogenic growth factor VEGF were further reduced in IL-1β treated wounds, suggesting that IL-1β has a negative effect on angiogenesis and that NLRP-3 promotes angiogenesis in an IL-1β-independent manner. These findings indicate that the NLRP-3 inflammasome contributes to the early inflammatory phase following skin wounding and is important for efficient healing. PMID:25793779

  16. Behavioral Analyses of GHB: Receptor Mechanisms

    PubMed Central

    Carter, Lawrence P.; Koek, Wouter; France, Charles P.

    2009-01-01

    GHB is used therapeutically and recreationally, although the precise mechanism of action responsible for its different behavioral effects is not entirely clear. The purpose of this review is to summarize how behavioral procedures, especially drug discrimination procedures, have been used to study the mechanism of action of GHB. More specifically, we will review several different drug discrimination procedures and discuss how they have been used to qualitatively and quantitatively study different components of the complex mechanism of action of GHB. A growing number of studies have provided evidence that the behavioral effects of GHB are mediated predominantly by GABAB receptors. However, there is also evidence that the mechanisms mediating the effects of GHB and the prototypical GABAB receptor agonist baclofen are not identical, and that other mechanisms such as GHB receptors and subtypes of GABAA and GABAB receptors might contribute to the effects of GHB. These findings are consistent with the different behavioral profile, abuse liability, and therapeutic indications of GHB and baclofen. A better understanding of the similarities and differences between GHB and baclofen, as well as the pharmacological mechanisms of action underlying the recreational and therapeutic effects of GHB, could lead to more effective medications with fewer adverse effects. PMID:19010351

  17. Do HLA genes play a prominent role in determining T cell receptor V{alpha} segment usage in humans?

    SciTech Connect

    Gulwani-Akolkar, B.; Shi, B.; Akolkar, P.N.

    1995-04-15

    Previous studies in humans have demonstrated that HLA genes can profoundly influence the TCR V{beta} repertoire. To similarly assess the influence of HLA genes on the TCR V{alpha} segment repertoire, the V{alpha} repertoires of 12 individuals from three unrelated families were determined by quantitative PCR. Each family contained at least one pair of HLA-identical and -nonidentical siblings. Repertoire analysis was performed on purified CD4{sup +} and CD8{sup +} cells by using V{alpha}-specific primers. We were unable to demonstrate more similar V{alpha} repertoires between HLA-identical siblings than between HLA-nonidentical siblings. In contrast, when a similar analysis was performed on the same individuals for the V{beta} repertoire, HLA-identical siblings were found to have significantly more similar repertoires than HLA-nonidentical siblings. Furthermore, both the V{alpha} and V{beta} repertoires of monozygotic twins showed striking similarity. Despite our inability to shown an influence of HLA genes on the V{alpha} repertoire, we did observe a very strong skewing in terms of preferential expression on CD4{sup +} or CD8{sup +} cells of several V{alpha} segments, notably TCRAV1, -2, -5, -6, -7, -11, -12, and -13. These studies suggest that HLA genes play less of a role in determining V{alpha} segment usage than V{beta}. Nevertheless, the pronounced skewing of V{alpha} segment expression in the CD4{sup +} or CD8{sup +} populations suggests some role for HLA genes in determining the V{alpha} TCR repertoire. Furthermore, the striking similarity of V{alpha} repertoires of identical twins suggests a major role for non-HLA genes in determining the V{alpha} repertoire. 35 refs., 8 figs., 3 tabs.

  18. The Ron Receptor Tyrosine Kinase Regulates Macrophage Heterogeneity and Plays a Protective Role in Diet-Induced Obesity, Atherosclerosis, and Hepatosteatosis.

    PubMed

    Yu, Shan; Allen, Joselyn N; Dey, Adwitia; Zhang, Limin; Balandaram, Gayathri; Kennett, Mary J; Xia, Mingcan; Xiong, Na; Peters, Jeffrey M; Patterson, Andrew; Hankey-Giblin, Pamela A

    2016-07-01

    Obesity is a chronic inflammatory disease mediated in large part by the activation of inflammatory macrophages. This chronic inflammation underlies a whole host of diseases including atherosclerosis, hepatic steatosis, insulin resistance, type 2 diabetes, and cancer, among others. Macrophages are generally classified as either inflammatory or alternatively activated. Some tissue-resident macrophages are derived from yolk sac erythromyeloid progenitors and fetal liver progenitors that seed tissues during embryogenesis and have the ability to repopulate through local proliferation. These macrophages tend to be anti-inflammatory in nature and are generally involved in tissue remodeling, repair, and homeostasis. Alternatively, during chronic inflammation induced by obesity, bone marrow monocyte-derived macrophages are recruited to inflamed tissues, where they produce proinflammatory cytokines and exacerbate inflammation. The extent to which these two populations of macrophages are plastic in their phenotype remains controversial. We have demonstrated previously that the Ron receptor tyrosine kinase is expressed on tissue-resident macrophages, where it limits inflammatory macrophage activation and promotes a repair phenotype. In this study, we demonstrate that Ron is expressed in a subpopulation of macrophages during chronic inflammation induced by obesity that exhibit a repair phenotype as determined by the expression of arginase 1. In addition, we demonstrate that the Ron receptor plays a protective role in the progression of diet-induced obesity, hepatosteatosis, and atherosclerosis. These results suggest that altering macrophage heterogeneity in vivo could have the potential to alleviate obesity-associated diseases. PMID:27233965

  19. Endocytic trafficking towards the vacuole plays a key role in the auxin receptor SCF(TIR)-independent mechanism of lateral root formation in A. thaliana.

    PubMed

    Pérez-Henríquez, Patricio; Raikhel, Natasha V; Norambuena, Lorena

    2012-11-01

    Plants' developmental plasticity plays a pivotal role in responding to environmental conditions. One of the most plastic plant organs is the root system. Different environmental stimuli such as nutrients and water deficiency may induce lateral root formation to compensate for a low level of water and/or nutrients. It has been shown that the hormone auxin tunes lateral root development and components for its signaling pathway have been identified. Using chemical biology, we discovered an Arabidopsis thaliana lateral root formation mechanism that is independent of the auxin receptor SCF(TIR). The bioactive compound Sortin2 increased lateral root occurrence by acting upstream from the morphological marker of lateral root primordium formation, the mitotic activity. The compound did not display auxin activity. At the cellular level, Sortin2 accelerated endosomal trafficking, resulting in increased trafficking of plasma membrane recycling proteins to the vacuole. Sortin2 affected Late endosome/PVC/MVB trafficking and morphology. Combining Sortin2 with well-known drugs showed that endocytic trafficking of Late E/PVC/MVB towards the vacuole is pivotal for Sortin2-induced SCF(TIR)-independent lateral root initiation. Our results revealed a distinctive role for endosomal trafficking in the promotion of lateral root formation via a process that does not rely on the auxin receptor complex SCF(TIR). PMID:22848095

  20. Identification and characterization of GABA(A) receptor autoantibodies in autoimmune encephalitis.

    PubMed

    Ohkawa, Toshika; Satake, Shin'Ichiro; Yokoi, Norihiko; Miyazaki, Yu; Ohshita, Tomohiko; Sobue, Gen; Takashima, Hiroshi; Watanabe, Osamu; Fukata, Yuko; Fukata, Masaki

    2014-06-11

    Autoimmune forms of encephalitis have been associated with autoantibodies against synaptic cell surface antigens such as NMDA- and AMPA-type glutamate receptors, GABA(B) receptor, and LGI1. However, it remains unclear how many synaptic autoantigens are yet to be defined. Using immunoproteomics, we identified autoantibodies against the GABA(A) receptor in human sera from two patients diagnosed with encephalitis who presented with cognitive impairment and multifocal brain MRI abnormalities. Both patients had antibodies directed against the extracellular epitope of the β3 subunit of the GABA(A) receptor. The β3-subunit-containing GABA(A) receptor was a major target of the patients' serum antibodies in rat hippocampal neurons because the serum reactivity to the neuronal surface was greatly decreased by 80% when the β3 subunit was knocked down. Our developed multiplex ELISA testing showed that both patients had similar levels of GABA(A) receptor antibodies, one patient also had a low level of LGI1 antibodies, and the other also had CASPR2 antibodies. Application of the patients' serum at the time of symptom presentation of encephalitis to rat hippocampal neuron cultures specifically decreased both synaptic and surface GABA(A) receptors. Furthermore, treatment of neurons with the patients' serum selectively reduced miniature IPSC amplitude and frequency without affecting miniature EPSCs. These results strongly suggest that the patients' GABA(A) receptor antibodies play a central role in the patients' symptoms. Therefore, this study establishes anti-GABA(A) receptor encephalitis and expands the pathogenic roles of GABA(A) receptor autoantibodies. PMID:24920620

  1. Outdoor Play and Play Equipment.

    ERIC Educational Resources Information Center

    Naylor, Heather

    1985-01-01

    Discusses aspects of the play environment and its effect on children's play behavior. Indoor and outdoor play spaces are considered along with factors affecting the use of outdoor environments for play. Children's preferences for different outdoor play environments and for various play structures are explored. Guides for choosing play equipment…

  2. Scavenger Receptor Class A Plays a Central Role in Mediating Mortality and the Development of the Pro-Inflammatory Phenotype in Polymicrobial Sepsis

    PubMed Central

    Ozment, Tammy R.; Ha, Tuanzhu; Breuel, Kevin F.; Ford, Tiffany R.; Ferguson, Donald A.; Kalbfleisch, John; Schweitzer, John B.; Kelley, Jim L.; Li, Chuanfu; Williams, David L.

    2012-01-01

    Sepsis is a frequent complication in critical illness. The mechanisms that are involved in initiation and propagation of the disease are not well understood. Scavenger receptor A (SRA) is a membrane receptor that binds multiple polyanions such as oxidized LDL and endotoxin. Recent studies suggest that SRA acts as a pattern recognition receptor in the innate immune response. The goal of the present study was to determine the role of SRA in polymicrobial sepsis. SRA deficient (SRA−/−) and C57BL/6JB/6J (WT) male mice were subjected to cecal ligation and puncture (CLP) to induce polymicrobial sepsis. NFκB activity, myeloperoxidase activity, and co-association of SRA with toll like receptor (TLR) 4 and TLR2 was analyzed in the lungs. Spleens were analyzed for apoptosis. Serum cytokines and chemokines were assayed. Blood and peritoneal fluid were cultured for aerobic and anaerobic bacterial burdens. Long term survival was significantly increased in SRA−/− septic mice (53.6% vs. 3.6%, p<0.05) when compared to WT mice. NFκB activity was 45.5% lower in the lungs of SRA−/− septic mice versus WT septic mice (p<0.05). Serum levels of interleukin (IL)-5, IL-6, IL-10 and monocyte chemoattractant protein −1 were significantly lower in septic SRA−/− mice when compared to septic WT mice (p<0.05). We found that SRA immuno-precipitated with TLR4, but not TLR2, in the lungs of WT septic mice. We also found that septic SRA−/− mice had lower bacterial burdens than WT septic mice. SRA deficiency had no effect on pulmonary neutrophil infiltration or splenocyte apoptosis during sepsis. We conclude that SRA plays a pivotal, and previously unknown, role in mediating the pathophysiology of sepsis/septic shock in a murine model of polymicrobial sepsis. Mechanistically, SRA interacts with TLR4 to enhance the development of the pro-inflammatory phenotype and mediate the morbidity and mortality of sepsis/septic shock. PMID:23071440

  3. Phosphorylation of Tyr-610 in the Receptor Kinase BAK1 Plays a Role in Brassinosteroid Signaling and Basal Defense Gene Expression

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BAK1 is a leucine-rich repeat receptor-like kinase (LRR-RLK) that functions as a co-receptor with the brassinosteroid (BR) receptor BRI1 and the flagellin receptor FLS2, and also functions as a negative regulator of programmed cell death. BAK1 has been shown to autophosphorylate on numerous serine/t...

  4. Playful Gaming.

    ERIC Educational Resources Information Center

    Makedon, Alexander

    A philosophical analysis of play and games is undertaken in this paper. Playful gaming, which is shown to be a synthesis of play and games, is utilized as a category for undertaking the examination of play and games. The significance of playful gaming to education is demonstrated through analyses of Plato's, Dewey's, Sartre's, and Marcuse's…

  5. New Play.

    ERIC Educational Resources Information Center

    Lersten, Kenneth C.

    There have been many theories and hypotheses about play, one of which is the equation of play with "transcendence." Play may have the ingredients to allow us to transcend and, for a moment, remythologize life. There have been recent authors who have given play the status of theology, indicating that play contains elements also found in religion.…

  6. Plectin regulates the signaling and trafficking of the HIV-1 co-receptor CXCR4 and plays a role in HIV-1 infection

    SciTech Connect

    Ding Yun; Zhang Li; Goodwin, J. Shawn; Wang Ziqing; Liu Bingdong; Zhang Jingwu; Fan Guohuang

    2008-02-01

    The CXC chemokine CXCL12 and its cognate receptor CXCR4 play an important role in inflammation, human immunodeficiency virus (HIV) infection and cancer metastasis. The signal transduction and intracellular trafficking of CXCR4 are involved in these functions, but the underlying mechanisms remain incompletely understood. In the present study, we demonstrated that the CXCR4 formed a complex with the cytolinker protein plectin in a ligand-dependent manner in HEK293 cells stably expressing CXCR4. The glutathione-S-transferase (GST)-CXCR4 C-terminal fusion proteins co-precipitated with the full-length and the N-terminal fragments of plectin isoform 1 but not with the N-terminal deletion mutants of plectin isoform 1, thereby suggesting an interaction between the N-terminus of plectin and the C-terminus of CXCR4. This interaction was confirmed by confocal microscopic reconstructions showing co-distribution of these two proteins in the internal vesicles after ligand-induced internalization of CXCR4 in HEK293 cells stably expressing CXCR4. Knockdown of plectin with RNA interference (RNAi) significantly inhibited ligand-dependent CXCR4 internalization and attenuated CXCR4-mediated intracellular calcium mobilization and activation of extracellular signal regulated kinase 1/2 (ERK1/2). CXCL12-induced chemotaxis of HEK293 cells stably expressing CXCR4 and of Jurkat T cells was inhibited by the plectin RNAi. Moreover, CXCR4 tropic HIV-1 infection in MAGI (HeLa-CD4-LTR-Gal) cells was inhibited by the RNAi of plectin. Thus, plectin appears to interact with CXCR4 and plays an important role in CXCR4 signaling and trafficking and HIV-1 infection.

  7. Diabetes-induced upregulation of urotensin II and its receptor plays an important role in TGF-beta1-mediated renal fibrosis and dysfunction.

    PubMed

    Tian, Lin; Li, Cai; Qi, Jiping; Fu, Peng; Yu, Xiaoyan; Li, Xiaokun; Cai, Lu

    2008-11-01

    Urotensin II (UII) was identified as the ligand for a novel G protein-coupled receptor, GPR14. UII was found not only to have a potent vasoconstrictive action but also to have profibrotic effects in the heart. The present study was to define whether UII and GPR14 also play important roles in diabetes-induced renal fibrosis and dysfunction. Diabetic rats were induced using streptozotocin, and the rat proximal tubular epithelial cells (NRK-52E) were used for the in vitro mechanism study. Results showed that expression of UII and GPR14 was significantly upregulated at both mRNA and protein levels in the diabetic kidneys compared with controls. The upregulated expressions of UII and GPR14 in the kidney were accompanied by significant increases in the renal profibrotic factor transforming growth factor (TGF)-beta1 expression, the renal extracellular matrix (fibronectin and collagen IV) accumulation, and the renal dysfunction (increases in urinal N-acetyl-beta-d-glucosaminidase content, 24-h urinary retinol-binding protein excretion rate, and decrease in creatinine clearance rate). Exposure of NRK-52E cells to 10(-8) mol/l UII for 48 h caused a significant increase of TGF-beta1, but not ANG II, production that was GPR14- and calcium-dependent, since GPR14 small-interfering RNA and calcium channel blocker nimodipine or calcium chelator EDTA all could abolish the induction of TGF- beta1 by UII. Furthermore, exposure of NRK-52E cells to TGF-beta1 or ANG II also increased UII and GPR14 mRNA expressions. These results suggested that diabetes-induced upregulation of UII and GPR14, most likely through autocrine and/or paracrine mechanisms, plays an important role in TGF-beta1-mediated renal fibrosis and dysfunction. PMID:18796544

  8. Pseudo-piano playing motions and nocturnal hypoventilation in anti-NMDA receptor encephalitis: response to prompt tumor removal and immunotherapy.

    PubMed

    Uchino, Akiko; Iizuka, Takahiro; Urano, Yoshiaki; Arai, Masahide; Hara, Atsuko; Hamada, Junichi; Hirose, Ryuichi; Dalmau, Josep; Mochizuki, Hideki

    2011-01-01

    Tumor resection is recommended in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, however it is often difficult during an early stage of the disease. We report here the efficacy of early tumor removal in a patient with anti-NMDAR encephalitis. This 21-year-old woman was admitted to another hospital with rapidly progressive psychiatric symptoms, a decreased level of consciousness, and seizures. Abdominal CT showed a pelvic mass. On day 1 of admission to our center, she developed hypoventilation requiring mechanical support. She had orofacial dyskinesias with well-coordinated, pseudo-piano playing involuntary finger movements. Based on these clinical features, she was immediately scheduled for tumor resection on day 3. While awaiting surgery, she began to receive high-dose intravenous methylprednisolone. After tumor removal, she received plasma exchange, followed by intravenous immunoglobulin and additional high-dose methylprednisolone. Two weeks after tumor removal, she started following simple commands and progressive improvement, although she remained on mechanical ventilation for 10 weeks due to nocturnal central hypoventilation. Anti-NMDAR antibodies in serum/CSF were detected. Pathological examination showed immature teratoma with foci of infiltrates of B- and T-cells. Early tumor resection with immunotherapy facilitates recovery from this disease, but central hypoventilation may require long mechanical support. Non-jerky elaborate finger movements suggest antibody-mediated disinhibition of the cortico-striatal systems. PMID:21422691

  9. Pseudo-Piano Playing Motions and Nocturnal Hypoventilation in Anti-NMDA Receptor Encephalitis: Response to Prompt Tumor Removal and Immunotherapy

    PubMed Central

    Uchino, Akiko; Iizuka, Takahiro; Urano, Yoshiaki; Arai, Masahide; Hara, Atsuko; Hamada, Junichi; Hirose, Ryuichi; Dalmau, Josep; Mochizuki, Hideki

    2013-01-01

    Tumor resection is recommended in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, however it is often difficult during an early stage of the disease. We report here the efficacy of early tumor removal in a patient with anti-NMDAR encephalitis. This 21-year-old woman was admitted to another hospital with rapidly progressive psychiatric symptoms, a decreased level of consciousness, and seizures. Abdominal CT showed a pelvic mass. On day 1 of admission to our center, she developed hypoventilation requiring mechanical support. She had orofacial dyskinesias with well-coordinated, pseudo-piano playing involuntary finger movements. Based on these clinical features, she was immediately scheduled for tumor resection on day 3. While awaiting surgery, she began to receive high-dose intravenous methylprednisolone. After tumor removal, she received plasma exchange, followed by intravenous immunoglobulin and additional high-dose methylprednisolone. Two weeks after tumor removal, she started following simple commands and progressive improvement, although she remained on mechanical ventilation for 10 weeks due to nocturnal central hypoventilation. Anti-NMDAR antibodies in serum/CSF were detected. Pathological examination showed immature teratoma with foci of infiltrates of B- and T-cells. Early tumor resection with immunotherapy facilitates recovery from this disease, but central hypoventilation may require long mechanical support. Non-jerky elaborate finger movements suggest antibody-mediated disinhibition of the cortico-striatal systems. PMID:21422691

  10. SARI, a novel target gene of glucocorticoid receptor, plays an important role in dexamethasone-mediated killing of B lymphoma cells.

    PubMed

    Huang, Yinghui; Zhou, Jie; Huang, Yan; He, Jintao; Wang, Yuting; Yang, Chaohui; Liu, Dongbo; Zhang, Li; He, Fengtian

    2016-04-01

    Dexamethasone (Dex) has been commonly used in lymphoma and leukemia treatment, but the detailed mechanisms are not fully understood. Suppressor of AP-1 regulated by interferon (SARI) has tumor-selective growth inhibitory effect. However, it's unclear whether SARI is involved in the Dex-mediated lymphoma growth suppression. In this study, we found that Dex-treated B lymphoma tissues had a higher level of SARI. Dex repressed the growth of B lymphoma cells and upregulated SARI expression by activating glucocorticoid receptor (GR) in vitro and in vivo. Silencing of SARI attenuated the Dex-mediated growth suppression of B lymphoma cells and inhibition of AP-1 activity. Reporter assays revealed that activation of GR enhanced the transcriptional activity of SARI promoter. EMSA and ChIP assays showed that GR directly bound to the ER9 element in SARI promoter region. These results for the first time demonstrated that SARI is a novel target gene of GR, and the upregulation of SARI plays an important role in Dex's killing effect on B lymphoma cells, suggesting that SARI may serve as a novel target and a potential indicator of Dex sensitivity in B lymphoma treatment. PMID:26808579

  11. Stimulation of TM3 Leydig cell proliferation via GABAA receptors: A new role for testicular GABA

    PubMed Central

    Geigerseder, Christof; Doepner, Richard FG; Thalhammer, Andrea; Krieger, Annette; Mayerhofer, Artur

    2004-01-01

    The neurotransmitter gamma-aminobutyric acid (GABA) and subtypes of GABA receptors were recently identified in adult testes. Since adult Leydig cells possess both the GABA biosynthetic enzyme glutamate decarboxylase (GAD), as well as GABAA and GABAB receptors, it is possible that GABA may act as auto-/paracrine molecule to regulate Leydig cell function. The present study was aimed to examine effects of GABA, which may include trophic action. This assumption is based on reports pinpointing GABA as regulator of proliferation and differentiation of developing neurons via GABAA receptors. Assuming such a role for the developing testis, we studied whether GABA synthesis and GABA receptors are already present in the postnatal testis, where fetal Leydig cells and, to a much greater extend, cells of the adult Leydig cell lineage proliferate. Immunohistochemistry, RT-PCR, Western blotting and a radioactive enzymatic GAD assay evidenced that fetal Leydig cells of five-six days old rats possess active GAD protein, and that both fetal Leydig cells and cells of the adult Leydig cell lineage possess GABAA receptor subunits. TM3 cells, a proliferating mouse Leydig cell line, which we showed to possess GABAA receptor subunits by RT-PCR, served to study effects of GABA on proliferation. Using a colorimetric proliferation assay and Western Blotting for proliferating cell nuclear antigen (PCNA) we demonstrated that GABA or the GABAA agonist isoguvacine significantly increased TM3 cell number and PCNA content in TM3 cells. These effects were blocked by the GABAA antagonist bicuculline, implying a role for GABAA receptors. In conclusion, GABA increases proliferation of TM3 Leydig cells via GABAA receptor activation and proliferating Leydig cells in the postnatal rodent testis bear a GABAergic system. Thus testicular GABA may play an as yet unrecognized role in the development of Leydig cells during the differentiation of the testicular interstitial compartment. PMID:15040802

  12. Compartmental distribution of GABAB receptor-mediated currents along the somatodendritic axis of hippocampal principal cells

    PubMed Central

    Degro, Claudius E.; Kulik, Akos; Booker, Sam A.; Vida, Imre

    2015-01-01

    Activity of cortical principal cells is controlled by the GABAergic system providing inhibition in a compartmentalized manner along their somatodendritic axis. While GABAAR-mediated inhibitory synaptic transmission has been extensively characterized in hippocampal principal cells, little is known about the distribution of postsynaptic effects of GABABRs. In the present study, we have investigated the functional localization of GABABRs and their effector inwardly rectifying potassium (Kir3) channels by combining electrophysiological recordings in acute rat hippocampal slices, high-resolution immunoelectron microscopic analysis and single cell simulations. Pharmacologically isolated slow inhibitory postsynaptic currents were elicited in the three major hippocampal principal cell types by endogenous GABA released by electrical stimulation, photolysis of caged-GABA, as well as the canonical agonist baclofen, with the highest amplitudes observed in the CA3. Spatially restricted currents were assessed along the axis of principal cells by uncaging GABA in the different hippocampal layers. GABABR-mediated currents were present along the entire somatodendritic axis of principal cells, but non-uniformly distributed: largest currents and the highest conductance densities determined in the simulations were consistently found on the distal apical dendrites. Finally, immunocytochemical localization of GABABRs and Kir3 channels showed that distributions overlap but their densities diverge, particularly on the basal dendrites of pyramidal cells. GABABRs current amplitudes and the conductance densities correlated better with Kir3 density, suggesting a bottlenecking effect defined by the effector channel. These data demonstrate a compartmentalized distribution of the GABABR-Kir3 signaling cascade and suggest differential control of synaptic transmission, dendritic integration and synaptic plasticity at afferent pathways onto hippocampal principal cells. PMID:25852540

  13. Adult Play.

    ERIC Educational Resources Information Center

    Charles, John M.

    In its broadest context, play can be interpreted as any pleasurable use of discretionary time. Playfulness is an intrinsic feature of being human, and should be viewed in the light of a total lifestyle, not as an occurrence in an isolated time of life. Adult play appears to be an indefinable and controversial concept. A holistic approach should be…

  14. Wanna Play?

    ERIC Educational Resources Information Center

    Chenfeld, Mimi Brodsky

    2006-01-01

    In this article, the author talks about the importance of play in the lives of children and describes how games and imaginative play contribute to the development of children. From her decades-old collection of countless incidents demonstrating children's love for self-directed, informal, imaginative play, the author shares three incidents that…

  15. City Play.

    ERIC Educational Resources Information Center

    Dargan, Amanda; Zeitlin, Steve

    2000-01-01

    Today, fewer city blocks preserve the confidence of lifestyle and urban geography that sustain traditional games and outdoor play. Large groups of children choosing sides and organizing Red Rover games are no longer commonplace. Teachers must encourage free play; urban planners must build cities that are safe play havens. (MLH)

  16. COUP-TFI and -TFII nuclear receptors are expressed in amacrine cells and play roles in regulating the differentiation of retinal progenitor cells.

    PubMed

    Inoue, Mariko; Iida, Atsumi; Satoh, Shinya; Kodama, Tatsuhiko; Watanabe, Sumiko

    2010-01-01

    Chicken ovalbumin upstream promoter transcription factors (COUP-TFs) are members of the steroid/thyroid hormone receptor superfamily. We have shown that two homologous COUP-TF genes, COUP-TFI and COUP-TFII, are expressed in developing mouse retina with a unique gradient along the dorsal-ventral axis. In this work, we aimed to characterize the detailed expression patterns of COUP-TFs in mature retina. Their functions in retinal progenitor cell differentiation into subtypes of mature retinal cells were also examined. Immunostaining of frozen mouse retinal sections with antibodies against COUP-TFs and markers for retinal subtypes revealed that COUP-TFI and -TFII are expressed in amacrine cells, especially in a glycinergic subtype in mature mouse retina. Forced expression of COUP-TFI and -TFII in mouse retinal explant culture by retrovirus-mediated gene transfer promoted amacrine and cone photoreceptor cell differentiation, whereas that of rod photoreceptors decreased. Cell proliferation and apoptosis were not affected by the perturbation of COUP-TFI and -TFII expression levels. Using the Y79 retinoblastoma cell line, we observed that COUP-TFI and -TFII suppressed the transcriptional activation of the Nrl gene. We then analyzed one another member of COUP-TF transcription factors, COUP-TFgamma, whose structure is relatively distant from those of COUP-TFI and -TFII. It is expressed mainly in horizontal cells and has weak activity in inducing amacrine cells when COUP-TFgamma was ectopically expressed in retinal explants. In summary, we found that COUP-TFI and -TFII play roles in amacrine cell differentiation, and COUP-TFgamma has distinct expression pattern and roles during retinal development. PMID:19766631

  17. Toll-Like Receptor 9 Is Required for Full Host Resistance to Mycobacterium avium Infection but Plays No Role in Induction of Th1 Responses▿

    PubMed Central

    Carvalho, Natália B.; Oliveira, Fernanda S.; Durães, Fernanda V.; de Almeida, Leonardo A.; Flórido, Manuela; Prata, Luana O.; Caliari, Marcelo V.; Appelberg, Rui; Oliveira, Sérgio C.

    2011-01-01

    To investigate the role of Toll-like receptor 9 (TLR9) in innate immunity to Mycobacterium avium, TLR9, TLR2, and MyD88 knockout (KO) mice were infected with this bacterium. Bacterial burdens were higher in the spleens, livers, and lungs of infected TLR9 KO mice than in those of C57BL/6 mice, indicating that TLR9 is required for efficient control of M. avium infection. However, TLR9 KO or TLR2 KO spleen cells displayed normal M. avium-induced tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) responses. This finding was confirmed by determining the number of splenic CD4+ T cells producing IFN-γ by flow cytometry. Furthermore, TLR2 and MyD88, but not TLR9, played a major role in interleukin-12 and TNF-α production by M. avium-infected macrophages and dendritic cells (DCs). We also found that major histocompatibility complex class II molecule expression on DCs is regulated by TLR2 and MyD88 signaling but not by TLR9. Finally, lack of TLR9, TLR2, or MyD88 reduced the numbers of macrophages, epithelioid cells, and lymphocytes in M. avium-induced granulomas but only MyD88 deficiency affected the number of liver granulomas. In summary, our data demonstrated that the involvement of TLR9 in the control of M. avium infection is not related to the induction of Th1 responses. PMID:21300776

  18. Complement Factor B is the Downstream Effector of Toll-Like Receptors and Plays an Important Role in a Mouse Model of Severe Sepsis¶

    PubMed Central

    Zou, Lin; Feng, Yan; Li, Yan; Zhang, Ming; Chen, Chan; Cai, Jiayan; Gong, Yu; Wang, Larry; Thurman, Joshua M.; Wu, Xiaobo; Atkinson, John P.; Chao, Wei

    2013-01-01

    Severe sepsis involves massive activation of the innate immune system and leads to high mortality. Previous studies have demonstrated that various types of Toll-like receptors (TLRs) mediate a systemic inflammatory response and contribute to organ injury and mortality in animal models of severe sepsis. However, the downstream mechanisms responsible for TLR-mediated septic injury are poorly understood. Here, we show that activation of TLR2, TLR3 and TLR4 markedly enhanced complement factor B (cfB) synthesis and release by macrophages and cardiac cells. Polymicrobial sepsis, created by cecal ligation and puncture (CLP) in a mouse model, augmented cfB levels in the serum, peritoneal cavity and major organs including the kidney and heart. CLP also led to the alternative pathway (AP) activation, C3 fragment deposition in the kidney and heart, and cfB-dependent C3dg elevation. Bacteria isolated from septic mice activated the serum AP via a factor D-dependent manner. MyD88 deletion attenuated cfB/C3 up-regulation as well as cleavage induced by polymicrobial infection. Importantly, during sepsis, absence of cfB conferred a protective effect with improved survival and cardiac function, and markedly attenuated acute kidney injury. cfB deletion also led to increased neutrophil migratory function during the early phase of sepsis, decreased local and systemic bacterial load, attenuated cytokine production and reduced neutrophil reactive oxygen species production. Together, our data indicate that cfB acts as a downstream effector of TLR signaling and plays a critical role in the pathogenesis of severe bacterial sepsis. PMID:24154627

  19. Neonatal melanocortin receptor agonist treatment reduces play fighting and promotes adult attachment in prairie voles in a sex-dependent manner.

    PubMed

    Barrett, Catherine E; Modi, Meera E; Zhang, Billy C; Walum, Hasse; Inoue, Kiyoshi; Young, Larry J

    2014-10-01

    The melanocortin receptor (MCR) system has been studied extensively for its role in feeding and sexual behavior, but effects on social behavior have received little attention. α-MSH interacts with neural systems involved in sociality, including oxytocin, dopamine, and opioid systems. Acute melanotan-II (MTII), an MC3/4R agonist, potentiates brain oxytocin (OT) release and facilitates OT-dependent partner preference formation in socially monogamous prairie voles. Here we examined the long-term impact of early-life MCR stimulation on hypothalamic neuronal activity and social development in prairie voles. Male and female voles were given daily subcutaneous injections of 10 mg/kg MTII or saline between postnatal days (PND) 1-7. Neonatally-treated males displayed a reduction in initiated play fighting bouts as juveniles compared to control males. Neonatal exposure to MTII facilitated partner preference formation in adult females, but not males, after a brief cohabitation with an opposite-sex partner. Acute MTII injection elicited a significant burst of the immediate early gene EGR-1 immunoreactivity in hypothalamic OT, vasopressin, and corticotrophin releasing factor neurons, when tested in PND 6-7 animals. Daily neonatal treatment with 1 mg/kg of a more selective, brain penetrant MC4R agonist, PF44687, promoted adult partner preferences in both females and males compared with vehicle controls. Thus, developmental exposure to MCR agonists lead to a persistent change in social behavior, suggestive of structural or functional changes in the neural circuits involved in the formation of social relationships. PMID:24923239

  20. GPR39, a receptor of the ghrelin receptor family, plays a role in the regulation of glucose homeostasis in a mouse model of early onset diet-induced obesity.

    PubMed

    Verhulst, P J; Lintermans, A; Janssen, S; Loeckx, D; Himmelreich, U; Buyse, J; Tack, J; Depoortere, I

    2011-06-01

    GPR39, which may function as a Zn(2+) sensor, is a member of the G protein-coupled receptor family that also includes the receptor for the hunger hormone ghrelin. The down-regulation of GPR39 mRNA in adipose tissue of obese type 2 diabetic patients suggests that GPR39 may contribute to the pathogenesis of the disease. The present study aimed to investigate the role of GPR39 in the regulation of energy balance and glucose homeostasis in wild-type (GPR39(+/+) ) and GPR39 knockout mice (GPR39(-/-) ) with obesity-related type 2 diabetes. GPR39 mRNA levels in adipose tissue of fasted GPR39(+/+) mice fed a high-fat diet (HFD) for 30 weeks were reduced and correlated positively with blood glucose levels. Body weight, fat percentage and energy intake were increased in the HFD group but did not differ between both genotypes. Within the HFD group, blood glucose levels were lower in GPR39(-/-) than in GPR39(+/+) mice, despite significant reductions in prandial plasma insulin levels. The latter may not be a result of changes in β-cell hyperplasia because immunohistochemical staining of pancreata of mice on a HFD showed no differences between genotypes. The lower blood glucose levels may involve alterations in insulin sensitivity as revealed by glucose tolerance tests and respiratory quotient measurements that showed a preference of obese GPR39(-/-) mice for the use of carbohydrates as metabolic fuel. The increase in plasma ghrelin levels in GPR39(-/-) mice fed a HFD may contribute to the alterations in glucose homeostasis, whereas changes in gastric emptying or intestinal Zn(2+) absorption are not involved. The results obtained in the present study suggest that GPR39 plays a role in the pathogenesis of obesity-related type 2 diabetes by affecting the regulation of glucose homeostasis. PMID:21470317

  1. GHB receptor targets in the CNS: focus on high-affinity binding sites.

    PubMed

    Bay, Tina; Eghorn, Laura F; Klein, Anders B; Wellendorph, Petrine

    2014-01-15

    γ-Hydroxybutyric acid (GHB) is an endogenous compound in the mammalian brain with both low- and high-affinity receptor targets. GHB is used clinically in the treatment of symptoms of narcolepsy and alcoholism, but also illicitly abused as the recreational drug Fantasy. Major pharmacological effects of exogenous GHB are mediated by GABA subtype B (GABAB) receptors that bind GHB with low affinity. The existence of GHB high-affinity binding sites has been known for more than three decades, but the uncovering of their molecular identity has only recently begun. This has been prompted by the generation of molecular tools to selectively study high-affinity sites. These include both genetically modified GABAB knock-out mice and engineered selective GHB ligands. Recently, certain GABA subtype A (GABAA) receptor subtypes emerged as high-affinity GHB binding sites and potential physiological mediators of GHB effects. In this research update, a description of the various reported receptors for GHB is provided, including GABAB receptors, certain GABAA receptor subtypes and other reported GHB receptors. The main focus will thus be on the high-affinity binding targets for GHB and their potential functional roles in the mammalian brain. PMID:24269284

  2. Pretend play.

    PubMed

    Weisberg, Deena Skolnick

    2015-01-01

    Pretend play is a form of playful behavior that involves nonliteral action. Although on the surface this activity appears to be merely for fun, recent research has discovered that children's pretend play has connections to important cognitive and social skills, such as symbolic thinking, theory of mind, and counterfactual reasoning. The current article first defines pretend play and then reviews the arguments and evidence for these three connections. Pretend play has a nonliteral correspondence to reality, hence pretending may provide children with practice with navigating symbolic relationships, which may strengthen their language skills. Pretend play and theory of mind reasoning share a focus on others' mental states in order to correctly interpret their behavior, hence pretending and theory of mind may be mutually supportive in development. Pretend play and counterfactual reasoning both involve representing nonreal states of affairs, hence pretending may facilitate children's counterfactual abilities. These connections make pretend play an important phenomenon in cognitive science: Studying children's pretend play can provide insight into these other abilities and their developmental trajectories, and thereby into human cognitive architecture and its development. PMID:26263228

  3. Shadow Play

    ERIC Educational Resources Information Center

    Trundle, Kathy Cabe; Hilson, Margilee P.

    2012-01-01

    A bunny rabbit playfully hops across the wall. Then hands realign and fingers shift to make a hawk soar toward the ceiling. Most children have enjoyed the delightful experience of playing with shadow puppets. The authors build on this natural curiosity to help students link shadows to complex astronomical concepts such as seasons. The…

  4. Heteromeric Canonical Transient Receptor Potential 1 and 4 Channels Play a Critical Role in Epileptiform Burst Firing and Seizure-Induced Neurodegeneration

    PubMed Central

    Phelan, Kevin D.; Mock, Matthew M.; Kretz, Oliver; Shwe, U. Thaung; Kozhemyakin, Maxim; Greenfield, L. John; Dietrich, Alexander; Birnbaumer, Lutz; Freichel, Marc; Flockerzi, Veit

    2012-01-01

    Canonical transient receptor potential channels (TRPCs) are receptor-operated cation channels that are activated in response to phospholipase C signaling. Although TRPC1 is ubiquitously expressed in the brain, TRPC4 expression is the most restrictive, with the highest expression level limited to the lateral septum. The subunit composition of neuronal TRPC channels remains uncertain because of conflicting data from recombinant expression systems. Here we report that the large depolarizing plateau potential that underlies the epileptiform burst firing induced by metabotropic glutamate receptor agonists in lateral septal neurons was completely abolished in TRPC1/4 double-knockout mice, and was abolished in 74% of lateral septal neurons in TRPC1 knockout mice. Furthermore, neuronal cell death in the lateral septum and the cornu ammonis 1 region of hippocampus after pilocarpine-induced severe seizures was significantly ameliorated in TRPC1/4 double-knockout mice. Our data suggest that both TRPC1 and TRPC4 are essential for an intrinsic membrane conductance mediating the plateau potential in lateral septal neurons, possibly as heteromeric channels. Moreover, excitotoxic neuronal cell death, an underlying process for many neurological diseases, is not mediated merely by ionotropic glutamate receptors but also by heteromeric TRPC channels activated by metabotropic glutamate receptors. TRPC channels could be an unsuspected but critical molecular target for clinical intervention for excitotoxicity. PMID:22144671

  5. Heteromeric canonical transient receptor potential 1 and 4 channels play a critical role in epileptiform burst firing and seizure-induced neurodegeneration.

    PubMed

    Phelan, Kevin D; Mock, Matthew M; Kretz, Oliver; Shwe, U Thaung; Kozhemyakin, Maxim; Greenfield, L John; Dietrich, Alexander; Birnbaumer, Lutz; Freichel, Marc; Flockerzi, Veit; Zheng, Fang

    2012-03-01

    Canonical transient receptor potential channels (TRPCs) are receptor-operated cation channels that are activated in response to phospholipase C signaling. Although TRPC1 is ubiquitously expressed in the brain, TRPC4 expression is the most restrictive, with the highest expression level limited to the lateral septum. The subunit composition of neuronal TRPC channels remains uncertain because of conflicting data from recombinant expression systems. Here we report that the large depolarizing plateau potential that underlies the epileptiform burst firing induced by metabotropic glutamate receptor agonists in lateral septal neurons was completely abolished in TRPC1/4 double-knockout mice, and was abolished in 74% of lateral septal neurons in TRPC1 knockout mice. Furthermore, neuronal cell death in the lateral septum and the cornu ammonis 1 region of hippocampus after pilocarpine-induced severe seizures was significantly ameliorated in TRPC1/4 double-knockout mice. Our data suggest that both TRPC1 and TRPC4 are essential for an intrinsic membrane conductance mediating the plateau potential in lateral septal neurons, possibly as heteromeric channels. Moreover, excitotoxic neuronal cell death, an underlying process for many neurological diseases, is not mediated merely by ionotropic glutamate receptors but also by heteromeric TRPC channels activated by metabotropic glutamate receptors. TRPC channels could be an unsuspected but critical molecular target for clinical intervention for excitotoxicity. PMID:22144671

  6. Playing Teacher.

    ERIC Educational Resources Information Center

    Gilbert, Juan E.

    The acceptance of animation technologies is increasing. Video games, such as Sony PlayStation (SONY, 2002), have become part of the culture for young people from kindergarten through undergraduate school. Animation technologies have been implemented into educational systems in the form of animated pedagogical agents (Johnson, 2000). The research…

  7. Clay Play

    ERIC Educational Resources Information Center

    Rogers, Liz; Steffan, Dana

    2009-01-01

    This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

  8. Game playing.

    PubMed

    Rosin, Christopher D

    2014-03-01

    Game playing has been a core domain of artificial intelligence research since the beginnings of the field. Game playing provides clearly defined arenas within which computational approaches can be readily compared to human expertise through head-to-head competition and other benchmarks. Game playing research has identified several simple core algorithms that provide successful foundations, with development focused on the challenges of defeating human experts in specific games. Key developments include minimax search in chess, machine learning from self-play in backgammon, and Monte Carlo tree search in Go. These approaches have generalized successfully to additional games. While computers have surpassed human expertise in a wide variety of games, open challenges remain and research focuses on identifying and developing new successful algorithmic foundations. WIREs Cogn Sci 2014, 5:193-205. doi: 10.1002/wcs.1278 CONFLICT OF INTEREST: The author has declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website. PMID:26304308

  9. Sweet Play

    ERIC Educational Resources Information Center

    Leung, Shuk-kwan S.; Lo, Jane-Jane

    2010-01-01

    This article features Sweet play math, a "math by the month" activity that involves decorating and making sugar cubes. Teachers may want to substitute straws, paper squares, alphabet blocks, or such commercially made manipulatives as Unifix[R] cubes for the real sweets. Given no allergy concerns, teachers and students alike would enjoy some sweet…

  10. The Cannabinoid Receptor CB1 Interacts with the WAVE1 Complex and Plays a Role in Actin Dynamics and Structural Plasticity in Neurons

    PubMed Central

    Njoo, Christian; Agarwal, Nitin; Lutz, Beat; Kuner, Rohini

    2015-01-01

    The molecular composition of the cannabinoid type 1 (CB1) receptor complex beyond the classical G-protein signaling components is not known. Using proteomics on mouse cortex in vivo, we pulled down proteins interacting with CB1 in neurons and show that the CB1 receptor assembles with multiple members of the WAVE1 complex and the RhoGTPase Rac1 and modulates their activity. Activation levels of CB1 receptor directly impacted on actin polymerization and stability via WAVE1 in growth cones of developing neurons, leading to their collapse, as well as in synaptic spines of mature neurons, leading to their retraction. In adult mice, CB1 receptor agonists attenuated activity-dependent remodeling of dendritic spines in spinal cord neurons in vivo and suppressed inflammatory pain by regulating the WAVE1 complex. This study reports novel signaling mechanisms for cannabinoidergic modulation of the nervous system and demonstrates a previously unreported role for the WAVE1 complex in therapeutic applications of cannabinoids. PMID:26496209

  11. Central NPY-Y5 receptors activation plays a major role in fasting-induced pituitary-thyroid axis suppression in adult rat.

    PubMed

    Costa-e-Sousa, Ricardo Henrique; Souza, Luana Lopes; Calviño, Camila; Cabanelas, Adriana; Almeida, Norma Aparecida Santos; Oliveira, Karen Jesus; Pazos-Moura, Carmen Cabanelas

    2011-11-10

    Neuropeptide Y (NPY) inhibits TRH neurons in fed state, and hypothalamic NPY higher expression during fasting has been proposed to be involved in fasting-induced suppression of the hypothalamus-pituitary-thyroid (HPT) axis. We investigated the role of central Y5 receptors in the control of thyrotropin (TSH) and thyroid hormone (TH) secretion. Fed and fasting rats received twice daily central injections (3rd ventricle) of Y5 receptor antagonist (CGP71683; 15nmol/rat) for 72h. Fasted rats also received a single central injection of CGP71683 (15nmol/rat) at the end of 72h of fasting. In fed rats, Y5 receptor blockade reduced total food intake by 32% and body mass by almost 10% (p<0.01), corroborating the role of this receptor in food intake control. 72h-fasted rats exhibited a 4-fold increase in serum TSH (p<0.001), 1h after a single injection of Y5 antagonist. Also with multiple injections during 72h of fasting, Y5 blockade resulted in activation of thyroid axis, as demonstrated by a 3-times rise in serum T4 (p<0.001), accompanied by unchanged TSH and T3. In fed rats, the chronic central administration of CGP71683 resulted in reduced total serum T4 without changes in free T4 and TSH. Serum leptin and PYY were not altered by the NPY central blockade in both fed and fasted rats, suggesting no role of these hormones in the alterations observed. Therefore, the inhibition of central Y5 neurotransmission resulted in activation of thyroid axis during fasting suggesting that NPY-Y5 receptors contribute to fasting-induced TSH and TH suppression. PMID:21771616

  12. Age-related changes in tonic activation of presynaptic versus extrasynaptic γ-amniobutyric acid type B receptors in rat medial prefrontal cortex.

    PubMed

    Carpenter, Haley E; Kelly, Kyle B; Bizon, Jennifer L; Frazier, Charles J

    2016-09-01

    The present study examined the effect of age on both glutamatergic and γ-aminobutyric acid mediated (GABAergic) signaling in the rodent medial prefrontal cortex (mPFC), with an emphasis on revealing novel changes contributing to increased inhibition in age. Whole-cell patch clamp recordings were obtained from layer 2/3 mPFC pyramidal neurons in acute cortical slices prepared from either young (4 months) or aged (20-24 months) male F344 rats. Results indicated that GABAB receptors on GABAergic, but not on glutamatergic, inputs to layer 2/3 pyramidal cells are tonically activated by ambient GABA in young animals and further demonstrated that this form of tonic inhibition is significantly attenuated in aged mPFC. Moreover, concurrent with loss of tonic presynaptic GABAB autoreceptor activation, layer 2/3 pyramidal cells in aged mPFC are subjected to increased tonic activation of extrasynaptic GABAA and GABAB receptors. These data demonstrate a shift in the site of GABAB receptor-mediated inhibitory tone in the aged mPFC that clearly promotes increased inhibition of pyramidal cells in aged animals, and that may plausibly contribute to impaired executive function. PMID:27459929

  13. γ-Aminobutyric Acid Type A (GABAA) Receptor Subunits Play a Direct Structural Role in Synaptic Contact Formation via Their N-terminal Extracellular Domains.

    PubMed

    Brown, Laura E; Nicholson, Martin W; Arama, Jessica E; Mercer, Audrey; Thomson, Alex M; Jovanovic, Jasmina N

    2016-07-01

    The establishment of cell-cell contacts between presynaptic GABAergic neurons and their postsynaptic targets initiates the process of GABAergic synapse formation. GABAA receptors (GABAARs), the main postsynaptic receptors for GABA, have been recently demonstrated to act as synaptogenic proteins that can single-handedly induce the formation and functional maturation of inhibitory synapses. To establish how the subunit composition of GABAARs influences their ability to induce synaptogenesis, a co-culture model system incorporating GABAergic medium spiny neurons and the HEK293 cells, stably expressing different combinations of receptor subunits, was developed. Analyses of HEK293 cell innervation by medium spiny neuron axons using immunocytochemistry, activity-dependent labeling, and electrophysiology have indicated that the γ2 subunit is required for the formation of active synapses and that its effects are influenced by the type of α/β subunits incorporated into the functional receptor. To further characterize this process, the large N-terminal extracellular domains (ECDs) of α1, α2, β2, and γ2 subunits were purified using the baculovirus/Sf9 cell system. When these proteins were applied to the co-cultures of MSNs and α1/β2/γ2-expressing HEK293 cells, the α1, β2, or γ2 ECD each caused a significant reduction in contact formation, in contrast to the α2 ECD, which had no effect. Together, our experiments indicate that the structural role of GABAARs in synaptic contact formation is determined by their subunit composition, with the N-terminal ECDs of each of the subunits directly participating in interactions between the presynaptic and postsynaptic elements, suggesting the these interactions are multivalent and specific. PMID:27129275

  14. γ-Aminobutyric Acid Type A (GABAA) Receptor Subunits Play a Direct Structural Role in Synaptic Contact Formation via Their N-terminal Extracellular Domains*

    PubMed Central

    Brown, Laura E.; Nicholson, Martin W.; Arama, Jessica E.; Thomson, Alex M.

    2016-01-01

    The establishment of cell-cell contacts between presynaptic GABAergic neurons and their postsynaptic targets initiates the process of GABAergic synapse formation. GABAA receptors (GABAARs), the main postsynaptic receptors for GABA, have been recently demonstrated to act as synaptogenic proteins that can single-handedly induce the formation and functional maturation of inhibitory synapses. To establish how the subunit composition of GABAARs influences their ability to induce synaptogenesis, a co-culture model system incorporating GABAergic medium spiny neurons and the HEK293 cells, stably expressing different combinations of receptor subunits, was developed. Analyses of HEK293 cell innervation by medium spiny neuron axons using immunocytochemistry, activity-dependent labeling, and electrophysiology have indicated that the γ2 subunit is required for the formation of active synapses and that its effects are influenced by the type of α/β subunits incorporated into the functional receptor. To further characterize this process, the large N-terminal extracellular domains (ECDs) of α1, α2, β2, and γ2 subunits were purified using the baculovirus/Sf9 cell system. When these proteins were applied to the co-cultures of MSNs and α1/β2/γ2-expressing HEK293 cells, the α1, β2, or γ2 ECD each caused a significant reduction in contact formation, in contrast to the α2 ECD, which had no effect. Together, our experiments indicate that the structural role of GABAARs in synaptic contact formation is determined by their subunit composition, with the N-terminal ECDs of each of the subunits directly participating in interactions between the presynaptic and postsynaptic elements, suggesting the these interactions are multivalent and specific. PMID:27129275

  15. Torso, a Drosophila receptor tyrosine kinase, plays a novel role in the larval fat body in regulating insulin signaling and body growth.

    PubMed

    Jun, Jong Woo; Han, Gangsik; Yun, Hyun Myoung; Lee, Gang Jun; Hyun, Seogang

    2016-08-01

    Torso is a receptor tyrosine kinase whose localized activation at the termini of the Drosophila embryo is mediated by its ligand, Trunk. Recent studies have unveiled a second function of Torso in the larval prothoracic gland (PG) as the receptor for the prothoracicotropic hormone, which triggers pupariation. As such, inhibition of Torso in the PG prolongs the larval growth period, thereby increasing the final pupa size. Here, we report that Torso also acts in the larval fat body, regulating body size in a manner opposite from that of Torso in PG. We confirmed the expression of torso mRNA in the larval fat body and its reduction by RNA interference (RNAi). Fat body-specific knockdown of torso, by either of the two independent RNAi transgenes, significantly decreased the final pupal size. We found that torso knockdown suppresses insulin/target of rapamycin (TOR) signaling in the fat body, as confirmed by repression of Akt and S6K. Notably, the decrease in insulin/TOR signaling and decrease of pupal size induced by the knockdown of torso were rescued by the expression of a constitutively active form of the insulin receptor or by the knockdown of FOXO. Our study revealed a novel role for Torso in the fat body with respect to regulation of insulin/TOR signaling and body size. This finding exemplifies the contrasting effects of the same gene expressed in two different organs on organismal physiology. PMID:27126913

  16. Spatial profile and differential recruitment of GABAB modulate oscillatory activity in auditory cortex

    PubMed Central

    Oswald, Anne-Marie M.; Doiron, Brent; Rinzel, John; Reyes, Alex D.

    2009-01-01

    The interplay between inhibition and excitation is at the core of cortical network activity. In many cortices, including auditory cortex (ACx), interactions between excitatory and inhibitory neurons generate synchronous network gamma oscillations (30–70 Hz). Here, we show that differences in the connection patterns and synaptic properties of excitatory-inhibitory microcircuits permit the spatial extent of network inputs to modulate the magnitude of gamma oscillations. Simultaneous multiple whole-cell recordings from connected fast-spiking (FS) interneurons and pyramidal cells (PC) in L2/3 of mouse ACx slices revealed that for intersomatic distances <50 µm, most inhibitory connections occurred in reciprocally connected (RC) pairs; at greater distances, inhibitory connections were equally likely in RC and non-reciprocally connected (nRC) pairs. Furthermore, the GABAB mediated inhibition in RC pairs was weaker than in nRC pairs. Simulations with a network model that incorporated these features showed strong, gamma-band oscillations only when the network inputs were confined to a small area. These findings suggest a novel mechanism by which oscillatory activity can be modulated by adjusting the spatial distribution of afferent input. PMID:19692606

  17. Loss of striatal cannabinoid CB1 receptor function in attention-deficit / hyperactivity disorder mice with point-mutation of the dopamine transporter.

    PubMed

    Castelli, Maura; Federici, Mauro; Rossi, Silvia; De Chiara, Valentina; Napolitano, Francesco; Studer, Valeria; Motta, Caterina; Sacchetti, Lucia; Romano, Rosaria; Musella, Alessandra; Bernardi, Giorgio; Siracusano, Alberto; Gu, Howard H; Mercuri, Nicola B; Usiello, Alessandro; Centonze, Diego

    2011-11-01

    Abnormal dopamine (DA) transmission in the striatum plays a pivotal role in attention-deficit/hyperactivity disorder (ADHD). As striatal DA signalling modulates the endocannabinoid system (ECS), the present study was aimed at investigating cannabinoid CB1 receptor (CB1R) function in a model of ADHD obtained by triple point-mutation in the dopamine transporter (DAT) gene in mice, making them insensitive to cocaine [DAT cocaine-insensitive (DAT-CI) mice]. DAT-CI mice had a marked hyperactive phenotype, and neurophysiological recordings revealed that the sensitivity of CB1Rs controlling GABA-mediated synaptic currents [CB1Rs((GABA)) ] in the striatum was completely lost. In contrast, CB1Rs modulating glutamate transmission [CB1Rs((Glu)) ], and GABA(B) receptors were not affected in this model of ADHD. In DAT-CI mice, the blockade of CB1R((GABA)) function was complete even after cocaine or environmental manipulations activating the endogenous DA-dependent reward system, which are known to sensitize these receptors in control animals. Conversely, the hedonic property of sucrose was intact in DAT-CI mice, indicating normal sweet perception in these animals. Our results point to CB1Rs as novel molecular players in ADHD, and suggest that therapeutic strategies aimed at interfering with the ECS might prove effective in this disorder. PMID:22034972

  18. γ-Hydroxybutyric acid (GHB) is not an agonist of extrasynaptic GABAA receptors.

    PubMed

    Connelly, William M; Errington, Adam C; Crunelli, Vincenzo

    2013-01-01

    γ-Hydroxybutyric acid (GHB) is an endogenous compound and a drug used clinically to treat the symptoms of narcolepsy. GHB is known to be an agonist of GABAB receptors with millimolar affinity, but also binds with much higher affinity to another site, known as the GHB receptor. While a body of evidence has shown that GHB does not bind to GABAA receptors widely, recent evidence has suggested that the GHB receptor is in fact on extrasynaptic α4β1δ GABAA receptors, where GHB acts as an agonist with an EC50 of 140 nM. We investigated three neuronal cell types that express a tonic GABAA receptor current mediated by extrasynaptic receptors: ventrobasal (VB) thalamic neurons, dentate gyrus granule cells and striatal medium spiny neurons. Using whole-cell voltage clamp in brain slices, we found no evidence that GHB (10 µM) induced any GABAA receptor mediated current in these cell types, nor that it modulated inhibitory synaptic currents. Furthermore, a high concentration of GHB (3 mM) was able to produce a GABAB receptor mediated current, but did not induce any other currents. These results suggest either that GHB is not a high affinity agonist at native α4β1δ receptors, or that these receptors do not exist in classical areas associated with extrasynaptic currents. PMID:24244421

  19. γ-Hydroxybutyric Acid (GHB) Is Not an Agonist of Extrasynaptic GABAA Receptors

    PubMed Central

    Connelly, William M.; Errington, Adam C.; Crunelli, Vincenzo

    2013-01-01

    γ-Hydroxybutyric acid (GHB) is an endogenous compound and a drug used clinically to treat the symptoms of narcolepsy. GHB is known to be an agonist of GABAB receptors with millimolar affinity, but also binds with much higher affinity to another site, known as the GHB receptor. While a body of evidence has shown that GHB does not bind to GABAA receptors widely, recent evidence has suggested that the GHB receptor is in fact on extrasynaptic α4β1δ GABAA receptors, where GHB acts as an agonist with an EC50 of 140 nM. We investigated three neuronal cell types that express a tonic GABAA receptor current mediated by extrasynaptic receptors: ventrobasal (VB) thalamic neurons, dentate gyrus granule cells and striatal medium spiny neurons. Using whole-cell voltage clamp in brain slices, we found no evidence that GHB (10 µM) induced any GABAA receptor mediated current in these cell types, nor that it modulated inhibitory synaptic currents. Furthermore, a high concentration of GHB (3 mM) was able to produce a GABAB receptor mediated current, but did not induce any other currents. These results suggest either that GHB is not a high affinity agonist at native α4β1δ receptors, or that these receptors do not exist in classical areas associated with extrasynaptic currents. PMID:24244421

  20. The nuclear receptor gene nhr-25 plays multiple roles in the C. elegans heterochronic gene network to control the larva-to-adult transition

    PubMed Central

    Hada, Kazumasa; Asahina, Masako; Hasegawa, Hiroshi; Kanaho, Yasunori; Slack, Frank J.; Niwa, Ryusuke

    2010-01-01

    Developmental timing in the nematode Caenorhabditis elegans is controlled by heterochronic genes, mutations in which cause changes in the relative timing of developmental events. One of the heterochronic genes, let-7, encodes a microRNA that is highly evolutionarily conserved, suggesting that similar genetic pathways control developmental timing across phyla. Here we report that the nuclear receptor nhr-25, which belongs to the evolutionarily conserved fushi tarazu-factor 1/nuclear receptor NR5A subfamily, interacts with heterochronic genes that regulate the larva-to-adult transition in C. elegans. We identified nhr-25 as a regulator of apl-1, a homolog of the Alzheimer’s amyloid precursor protein-like gene that is downstream of let-7 family microRNAs. NHR-25 controls not only apl-1 expression but also regulates developmental progression in the larva-to-adult transition. NHR-25 negatively regulates the expression of the adult-specific collagen gene col-19 in lateral epidermal seam cells. In contrast, NHR-25 positively regulates the larva-to-adult transition for other timed events in seam cells, such as cell fusion, cell division and alae formation. The genetic relationships between nhr-25 and other heterochronic genes are strikingly varied among several adult developmental events. We propose that nhr-25 has multiple roles in both promoting and inhibiting the C. elegans heterochronic gene pathway controlling adult differentiation programs. PMID:20678979

  1. Of the multiple mechanisms leading to type 1 diabetes, T cell receptor revision may play a prominent role (is type 1 diabetes more than a single disease?).

    PubMed

    Wagner, D H

    2016-09-01

    A single determinant factor for autoimmunity does not exist; disease development probably involves contributions from genetics, the environment and immune dysfunction. Type 1 diabetes is no exception. Genomewide-associated studies (GWAS) analysis in T1D has proved disappointing in revealing contributors to disease prediction; the only reliable marker has been human leucocyte antigen (HLA). Specific HLAs include DR3/DR4/DQ2/DQ8, for example. Because HLA molecules present antigen to T cells, it is reasonable that certain HLA molecules have a higher affinity to present self-antigen. Recent studies have shown that additional polymorphisms in HLA that are restricted to autoimmune conditions are further contributory. A caveat is that not all individuals with the appropriate 'pro-autoimmune' HLA develop an autoimmune disease. Another crucial component is autoaggressive T cells. Finding a biomarker to discriminate autoaggressive T cells has been elusive. However, a subset of CD4 helper cells that express the CD40 receptor have been described as becoming pathogenic. An interesting function of CD40 on T cells is to induce the recombination-activating gene (RAG)1/RAG2 T cell receptor recombination machinery. This observation is contrary to immunology paradigms that changes in TCR molecules cannot take place outside the thymic microenvironment. Alteration in TCR, called TCR revision, not only occurs, but may help to account for the development of autoaggressive T cells. Another interesting facet is that type 1 diabetes (T1D) may be more than a single disease; that is, multiple cellular components contribute uniquely, but result ultimately in the same clinical outcome, T1D. This review considers the process of T cell maturation and how that could favor auto-aggressive T cell development in T1D. The potential contribution of TCR revision to autoimmunity is also considered. PMID:27271348

  2. Orphan G protein-coupled receptor GPR56 plays a role in cell transformation and tumorigenesis involving the cell adhesion pathway.

    PubMed

    Ke, Ning; Sundaram, Roshni; Liu, Guohong; Chionis, John; Fan, Wufang; Rogers, Cheryl; Awad, Tarif; Grifman, Mirta; Yu, Dehua; Wong-Staal, Flossie; Li, Qi-Xiang

    2007-06-01

    GPR56 is an orphan G protein - coupled receptor, mutations of which have recently been associated with bilateral frontoparietal polymicrogyria, a rare neurologic disease that has implications in brain development. However, no phenotype beyond central nervous system has yet been described for the GPR56-null mutations despite abundant GPR56 expression in many non - central nervous system adult tissues. In the present study, we show that higher GPR56 expression is correlated with the cellular transformation phenotypes of several cancer tissues compared with their normal counterparts, implying a potential oncogenic function. RNA interference-mediated GPR56 silencing results in apoptosis induction and reduced anchorage-independent growth of cancer cells via increased anoikis, whereas cDNA overexpression resulted in increased foci formation in mouse fibroblast NIH3T3 cell line. When GPR56 silencing was induced in vivo in several xenograft tumor models, significant tumor responses (including regression) were observed, suggesting the potential of targeting GPR56 in the development of tumor therapies. The expression profiling of GPR56-silenced A2058 melanoma cell line revealed several genes whose expression was affected by GPR56 silencing, particularly those in the integrin-mediated signaling and cell adhesion pathways. The potential role of GPR56 in cancer cell adhesion was further confirmed by the observation that GPR56 silencing also reduced cell adhesion to the extracellular matrix, which is consistent with the observed increase in anoikis and reduction in anchorage-independent growth phenotypes. The oncogenic potential and apparent absence of physiologic defects in adult human tissues lacking GPR56, as well as the targetable nature of G protein - coupled receptor by small molecule or antibody, make GPR56 an attractive drug target for the development of cancer therapies. PMID:17575113

  3. Activation of family C G-protein-coupled receptors by the tripeptide glutathione.

    PubMed

    Wang, Minghua; Yao, Yi; Kuang, Donghui; Hampson, David R

    2006-03-31

    The Family C G-protein-coupled receptors include the metabotropic glutamate receptors, the gamma-aminobutyric acid, type B (GABAB) receptor, the calcium-sensing receptor (CaSR), which participates in the regulation of calcium homeostasis in the body, and a diverse group of sensory receptors that encompass the amino acid-activated fish 5.24 chemosensory receptor, the mammalian T1R taste receptors, and the V2R pheromone receptors. A common feature of Family C receptors is the presence of an amino acid binding site. In this study, a preliminary in silico analysis of the size and shape of the amino acid binding pocket in selected Family C receptors suggested that some members of this family could accommodate larger ligands such as peptides. Subsequent screening and docking experiments identified GSH as a potential ligand or co-ligand at the fish 5.24 receptor and the rat CaSR. These in silico predictions were confirmed using an [3H]GSH radioligand binding assay and a fluorescence-based functional assay performed on wild-type and chimeric receptors. Glutathione was shown to act as an orthosteric agonist at the 5.24 receptor and as a potent enhancer of calcium-induced activation of the CaSR. Within the mammalian receptors, this effect was specific to the CaSR because GSH neither directly activated nor potentiated other Family C receptors including GPRC6A (the putative mammalian homolog of the fish 5.24 receptor), the metabotropic glutamate receptors, or the GABAB receptor. Our findings reveal a potential new role for GSH and suggest that this peptide may act as an endogenous modulator of the CaSR in the parathyroid gland where this receptor is known to control the release of parathyroid hormone, and in other tissues such as the brain and gastrointestinal tract where the role of the calcium receptor appears to subserve other, as yet unknown, physiological functions. PMID:16455645

  4. Pharmacokinetics of CGP 36,742, an orally active GABAB antagonist, in humans.

    PubMed

    Gleiter, C H; Farger, G; Möbius, H J

    1996-05-01

    A study was conducted to evaluate the pharmacokinetics of CGP 36 742 (3-aminopropyl-n-butyl-phosphinic acid), an orally active gamma-aminobutyric acid B (GABAB) antagonist, in humans. Pharmacokinetic results after a single oral (600 mg) dose included maximum observed concentration (Cmax), 27 mumol/L (95% CI 22.9, 30.8); time to Cmax (tmax), 3 hours (median); half-life (t1/2), 3.6 hours (95% CI 3.24, 3.9); renal clearance (ClR), 125 mL/min (95% CI 114, 136); and absolute bioavailability (Fabs), 0.44 (95% CI 0.33, 0.47). Administration with food decreased the oral systemic availability (Frel) by 30%. The volume of distribution (285 L/kg) was in the order of magnitude of extracellular body water. The absorbed fraction of the compound was excreted completely and unchanged via the kidney, thus renal function would be the limiting factor for excretion. The rate of absorption and amount absorbed did not differ significantly between elderly and young healthy male volunteers, both after single and multiple doses. There was no gender-related difference in pharmacokinetics in healthy elderly volunteers. CGP 36 742 showed an excellent safety profile: there were no clinically relevant changes in cardiovascular variables, body temperature, or blood chemistry. In the placebo-controlled trial, adverse experiences were rare and evenly distributed among participants receiving placebo and the study drug. In addition, a newly developed high-performance liquid chromatography (HPLC) method for measurement of CGP 36 742 concentrations in plasma and urine using fluorescence detection is described. PMID:8739022

  5. NTS adenosine A2a receptors inhibit the cardiopulmonary chemoreflex control of regional sympathetic outputs via a GABAergic mechanism.

    PubMed

    Minic, Zeljka; O'Leary, Donal S; Scislo, Tadeusz J

    2015-07-01

    Adenosine is a powerful central neuromodulator acting via opposing A1 (inhibitor) and A2a (activator) receptors. However, in the nucleus of the solitary tract (NTS), both adenosine receptor subtypes attenuate cardiopulmonary chemoreflex (CCR) sympathoinhibition of renal, adrenal, and lumbar sympathetic nerve activity and attenuate reflex decreases in arterial pressure and heart rate. Adenosine A1 receptors inhibit glutamatergic transmission in the CCR pathway, whereas adenosine A2a receptors most likely facilitate release of an unknown inhibitory neurotransmitter, which, in turn, inhibits the CCR. We hypothesized that adenosine A2a receptors inhibit the CCR via facilitation of GABA release in the NTS. In urethane-chloralose-anesthetized rats (n = 51), we compared regional sympathetic responses evoked by stimulation of the CCR with right atrial injections of the 5-HT3 receptor agonist phenylbiguanide (1-8 μg/kg) before and after selective stimulation of NTS adenosine A2a receptors [microinjections into the NTS of CGS-21680 (20 pmol/50 nl)] preceded by blockade of GABAA or GABAB receptors in the NTS [bicuculline (10 pmol/100 nl) or SCH-50911 (1 nmol/100 nl)]. Blockade of GABAA receptors virtually abolished adenosine A2a receptor-mediated inhibition of the CCR. GABAB receptors had much weaker but significant effects. These effects were similar for the different sympathetic outputs. We conclude that stimulation of NTS adenosine A2a receptors inhibits CCR-evoked hemodynamic and regional sympathetic reflex responses via a GABA-ergic mechanism. PMID:25910812

  6. M1 and M3 muscarinic receptors may play a role in the neurotoxicity of anhydroecgonine methyl ester, a cocaine pyrolysis product.

    PubMed

    Garcia, Raphael Caio Tamborelli; Dati, Livia Mendonça Munhoz; Torres, Larissa Helena; da Silva, Mariana Aguilera Alencar; Udo, Mariana Sayuri Berto; Abdalla, Fernando Maurício Francis; da Costa, José Luiz; Gorjão, Renata; Afeche, Solange Castro; Yonamine, Mauricio; Niswender, Colleen M; Conn, P Jeffrey; Camarini, Rosana; Sandoval, Maria Regina Lopes; Marcourakis, Tania

    2015-01-01

    The smoke of crack cocaine contains cocaine and its pyrolysis product, anhydroecgonine methyl ester (AEME). AEME possesses greater neurotoxic potential than cocaine and an additive effect when they are combined. Since atropine prevented AEME-induced neurotoxicity, it has been suggested that its toxic effects may involve the muscarinic cholinergic receptors (mAChRs). Our aim is to understand the interaction between AEME and mAChRs and how it can lead to neuronal death. Using a rat primary hippocampal cell culture, AEME was shown to cause a concentration-dependent increase on both total [(3)H]inositol phosphate and intracellular calcium, and to induce DNA fragmentation after 24 hours of exposure, in line with the activation of caspase-3 previously shown. Additionally, we assessed AEME activity at rat mAChR subtypes 1-5 heterologously expressed in Chinese Hamster Ovary cells. l-[N-methyl-(3)H]scopolamine competition binding showed a preference of AEME for the M2 subtype; calcium mobilization tests revealed partial agonist effects at M1 and M3 and antagonist activity at the remaining subtypes. The selective M1 and M3 antagonists and the phospholipase C inhibitor, were able to prevent AEME-induced neurotoxicity, suggesting that the toxicity is due to the partial agonist effect at M1 and M3 mAChRs, leading to DNA fragmentation and neuronal death by apoptosis. PMID:26626425

  7. M1 and M3 muscarinic receptors may play a role in the neurotoxicity of anhydroecgonine methyl ester, a cocaine pyrolysis product

    PubMed Central

    Garcia, Raphael Caio Tamborelli; Dati, Livia Mendonça Munhoz; Torres, Larissa Helena; da Silva, Mariana Aguilera Alencar; Udo, Mariana Sayuri Berto; Abdalla, Fernando Maurício Francis; da Costa, José Luiz; Gorjão, Renata; Afeche, Solange Castro; Yonamine, Mauricio; Niswender, Colleen M.; Conn, P. Jeffrey; Camarini, Rosana; Sandoval, Maria Regina Lopes; Marcourakis, Tania

    2015-01-01

    The smoke of crack cocaine contains cocaine and its pyrolysis product, anhydroecgonine methyl ester (AEME). AEME possesses greater neurotoxic potential than cocaine and an additive effect when they are combined. Since atropine prevented AEME-induced neurotoxicity, it has been suggested that its toxic effects may involve the muscarinic cholinergic receptors (mAChRs). Our aim is to understand the interaction between AEME and mAChRs and how it can lead to neuronal death. Using a rat primary hippocampal cell culture, AEME was shown to cause a concentration-dependent increase on both total [3H]inositol phosphate and intracellular calcium, and to induce DNA fragmentation after 24 hours of exposure, in line with the activation of caspase-3 previously shown. Additionally, we assessed AEME activity at rat mAChR subtypes 1–5 heterologously expressed in Chinese Hamster Ovary cells. l-[N-methyl-3H]scopolamine competition binding showed a preference of AEME for the M2 subtype; calcium mobilization tests revealed partial agonist effects at M1 and M3 and antagonist activity at the remaining subtypes. The selective M1 and M3 antagonists and the phospholipase C inhibitor, were able to prevent AEME-induced neurotoxicity, suggesting that the toxicity is due to the partial agonist effect at M1 and M3 mAChRs, leading to DNA fragmentation and neuronal death by apoptosis. PMID:26626425

  8. The reinforcing effects of ethanol within the nucleus accumbens shell involve activation of local GABA and serotonin receptors

    PubMed Central

    Ding, Zheng-Ming; Ingraham, Cynthia M.; Rodd, Zachary A.; McBride, William J.

    2015-01-01

    Ethanol is reinforcing within the nucleus accumbens shell (NACsh), but the underlying mechanisms remain unclear. Ethanol can potentiate the function of the GABAA, GABAB, and 5-HT3 receptors. Therefore, the current study tested the hypothesis that activation of these receptors would be involved in the reinforcing effects of ethanol in the NACsh. An intracranial self-administration (ICSA) procedure was used to assess the reinforcing effects of ethanol in the NACsh of alcohol preferring (P) rats. The ICSA consisted of 7 sessions: 4 sessions to establish 150 mg% ethanol self-infusion into the NACsh; sessions 5 and 6 with co-infusion of ethanol plus one concentration of the GABAA antagonist bicuculline (10 or 100 µM), the GABAB antagonist SCH 50911 (50, 75 or 100 µM), or the 5-HT3 receptor antagonist zacopride (10 or 100 µM); and session 7 with 150 mg% ethanol alone. All groups self-infused ethanol into the NACsh and readily discriminated the active from inactive lever during the acquisition sessions. Co-infusion of 100 µM, but not 10 µM, bicuculline or zacopride significantly decreased active responses during sessions 5 and 6. Co-infusion of 75 µM, but not 50 or 100 µM, SCH 50911 significantly attenuated responses for ethanol. Overall, the results suggest that the reinforcing effects of ethanol in the NACsh may be modulated by activation of local GABAA, GABAB and 5-HT3 receptors. PMID:25922425

  9. Fibroblast Growth Factor Receptor 3 activation plays a causative role in urothelial cancer pathogenesis in cooperation with Pten loss in mice

    PubMed Central

    Foth, Mona; Ahmad, Imran; van Rhijn, Bas W. G.; van der Kwast, Theodorus; Bergman, Andre M.; King, Louise; Ridgway, Rachel; Leung, Hing Y.; Fraser, Sioban; Sansom, Owen J.; Iwata, Tomoko

    2015-01-01

    Although somatic mutations and overexpression of the tyrosine kinase Fibroblast Growth Factor Receptor 3 (FGFR3) are strongly associated with bladder cancer, evidence for their functional involvement in the pathogenesis remains elusive. Previously we showed that activation of Fgfr3 alone is not sufficient to initiate urothelial tumourigenesis in mice. Here we hypothesise that cooperating mutations are required for Fgfr3-dependent tumourigenesis in the urothelium and analyse a mouse model in which an inhibitor of Pi3k-Akt signalling, Pten, is deleted in concert with Fgfr3 activation (UroIICreFgfr3+/K644EPtenflox/flox). Two main phonotypical characteristics observed in the urothelium were increased urothelial thickness and abnormal cellular histopathology, including vacuolisation, condensed cellular appearance, enlargement of cells and nuclei, and loss of polarity. These changes were not observed when either mutation was present individually. Expression patterns of known urothelial proteins indicated the abnormal cellular differentiation. Furthermore, quantitative analysis showed that Fgfr3 and Pten mutations cooperatively caused cellular enlargement, while Pten contributed to an increased cell proliferation. Finally, FGFR3 overexpression was analysed along the level of phosphorylated mTOR in sixty-six T1 urothelial tumours in tissue microarray, which supported the occurrence of functional association of these two signalling pathways in urothelial pathogenesis. Taken together, this study provides evidence supporting a functional role of FGFR3 in the process of pathogenesis in urothelial neoplasm. Given the wide availability of inhibitors specific to FGF signalling pathways, our model may open the avenue for FGFR3-targeted translation in urothelial disease. PMID:24519156

  10. Phenobarbital and propiconazole toxicogenomic profiles in mice show major similarities consistent with the key role that constitutive androstane receptor (CAR) activation plays in their mode of action.

    PubMed

    Currie, Richard A; Peffer, Richard C; Goetz, Amber K; Omiecinski, Curtis J; Goodman, Jay I

    2014-07-01

    Toxicogenomics (TGx) is employed frequently to investigate underlying molecular mechanisms of the compound of interest and, thus, has become an aid to mode of action determination. However, the results and interpretation of a TGx dataset are influenced by the experimental design and methods of analysis employed. This article describes an evaluation and reanalysis, by two independent laboratories, of previously published TGx mouse liver microarray data for a triazole fungicide, propiconazole (PPZ), and the anticonvulsant drug phenobarbital (PB). Propiconazole produced an increase incidence of liver tumors in male CD-1 mice only at a dose that exceeded the maximum tolerated dose (2500 ppm). Firstly, we illustrate how experimental design differences between two in vivo studies with PPZ and PB may impact the comparisons of TGx results. Secondly, we demonstrate that different researchers using different pathway analysis tools can come to different conclusions on specific mechanistic pathways, even when using the same datasets. Finally, despite these differences the results across three different analyses also show a striking degree of similarity observed for PPZ and PB treated livers when the expression data are viewed as major signaling pathways and cell processes affected. Additional studies described here show that the postulated key event of hepatocellular proliferation was observed in CD-1 mice for both PPZ and PB, and that PPZ is also a potent activator of the mouse CAR nuclear receptor. Thus, with regard to the events which are hallmarks of CAR-induced effects that are key events in the mode of action (MOA) of mouse liver carcinogenesis with PB, PPZ-induced tumors can be viewed as being promoted by a similar PB-like CAR-dependent MOA. PMID:24675475