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  • ?-Aminobutyric acid type B receptor changes in the rat striatum and substantia nigra following intrastriatal quinolinic acid lesions. 21290407

    Changes in the regional distribution of the metabotropic GABA type B receptors (GABA(B)) were investigated in a rat model of Huntington's disease. Animals received a unilateral intrastriatal injection of quinolinic acid (QA), and GABA(B) immunoreactivity was monitored 3, 11, and 21 days postinjection in the striatum and substantia nigra (SN). Two antibodies, recognizing either the GABA(B1) or the GABA(B2) receptor subtypes, were used. QA injection rapidly induced a protracted increase in GABA(B1) or GABA(B2) immunoreactivity in the lesioned striatum, despite the neuronal loss. In the SN, a continuous increase in GABA(B1) and GABA(B2) immunoreactivity was observed at all time points in the ipsilateral pars reticulata (SNr), whereas the pars compacta (SNc) was unaffected by this phenomenon. This increase was supported by a densitometric analysis. At day 21 postlesion induction, intensely labeled stellate cells and processes were found in the ipsilateral SNr, in addition to immunoreactive neurons. Double labeling of GABA(B1) and glial fibrillary acidic protein (GFAP) showed that the stellate cells were reactive astrocytes. Hence, part of the sustained increase in GABA(B) immunoreactivity that takes place in the SNr and possibly the striatum may be ascribed to reactive astrocytes. It is suggested that GABA(B) receptors are up-regulated in these reactive astrocytes and that agonists might influence the extent of this astroglial reaction.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB5394

  • The RXR-type endoplasmic reticulum-retention/retrieval signal of GABAB1 requires distant spacing from the membrane to function. 15805225

    Functional gamma-aminobutyric acid type B (GABA(B)) receptors are normally only observed upon coexpression of GABA(B1) with GABA(B2) subunits. A C-terminal arginine-based endoplasmic reticulum (ER) retention/retrieval signal, RSRR, prevents escape of unassembled GABA(B1) subunits from the ER and restricts surface expression to correctly assembled heteromeric receptors. The RSRR signal in GABA(B1) is proposed to be shielded by C-terminal coiled-coil interaction of the GABA(B1) with the GABA(B2) subunit. Here, we investigated whether the RSRR motif in GABA(B1) remains functional when grafted to ectopic sites. We found that the RSRR signal in GABA(B1) is inactive in any of the three intracellular loops but remains functional when moved within the distal zone of the C-terminal tail. C-terminal deletions that position the RSRR signal closer to the plasma membrane drastically reduce its effectiveness, supporting that proximity to the membrane restricts access to the RSRR motif. Functional ectopic RSRR signals in GABA(B1) are efficiently inactivated by the GABA(B2) subunit in the absence of coiled-coil dimerization, supporting that coiled-coil interaction is not critical for release of the receptor complex from the ER. The data are consistent with a model in which removal of RSRR from its active zone rather than its direct shielding by coiled-coil dimerization triggers forward trafficking. Because arginine-based intracellular retention signals of the type RXR, where X represents any amino acid, are used to regulate assembly and surface transport of several multimeric complexes, such a mechanism may apply to other proteins as well.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB3408
    Nombre del producto:
    Anti-Tubulin Antibody, beta, clone KMX-1

  • Evidence for oligomerization between GABAB receptors and GIRK channels containing the GIRK1 and GIRK3 subunits. 20846323

    The stimulation of inhibitory neurotransmitter receptors, such as ?-aminobutyric acid type B (GABA(B) ) receptors, activates G protein-gated inwardly-rectifying K(+) (GIRK) channels, which influence membrane excitability. There is now evidence suggesting that G protein-coupled receptors and G protein-gated inwardly-rectifying K(+) [GIRK/family 3 of inwardly-rectifying K(+) (Kir3)] channels do not diffuse freely within the plasma membrane, but instead there are direct protein-protein interactions between them. Here, we used bioluminescence resonance energy transfer, co-immunoprecipitation, confocal and electron microscopy techniques to investigate the oligomerization of GABA(B) receptors with GIRK channels containing the GIRK3 subunit, whose contribution to functional channels is still unresolved. Co-expression of GABA(B) receptors and GIRK channels in human embryonic kidney-293 cells in combination with co-immunoprecipitation experiments established that the metabotropic receptor forms stable complexes with GIRK channels. Using bioluminescence resonance energy transfer, we have shown that, in living cells under physiological conditions, GABA(B) receptors interact directly with GIRK1/GIRK3 heterotetramers. In addition, we have provided evidence that the receptor-effector complexes are also found in vivo and identified that the cerebellar granule cells are one neuron population where the interaction probably takes place. Altogether, our data show that signalling complexes containing GABA(B) receptors and GIRK channels are formed shortly after biosynthesis, probably in the endoplasmic reticulum and/or endoplasmic reticulum/Golgi apparatus complex, suggesting that this might be a general feature of receptor-effector ion channel signal transduction and supporting a channel-forming role for the GIRK3 subunit.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB2255
    Nombre del producto:
    Anti-GABA B Receptor R2 Antibody

  • The level and distribution of the GABA(B)R1 and GABA(B)R2 receptor subunits in the rat's inferior colliculus. 23189044

    The type B γ-aminobutyric acid receptor (GABA(B) receptor) is an important neurotransmitter receptor in the midbrain auditory structure, the inferior colliculus (IC). A functional GABA(B) receptor is a heterodimer consisting of two subunits, GABA(B)R1 and GABA(B)R2. Western blotting and immunohistochemical experiments were conducted to examine the expression of the two subunits over the IC including its central nucleus, dorsal cortex, and external cortex (ICc, ICd, and ICx). Results revealed that the two subunits existed in both cell bodies and the neuropil throughout the IC. The two subunits had similar regional distributions over the IC. The combined level of cell body and neuropil labeling was higher in the ICd than the other two subdivisions. Labeling in the ICc and ICx was stronger in the dorsal than the ventral regions. In spite of regional differences, no defined boundaries were formed between different areas. For both subunits, the regional distribution of immunoreactivity in the neuropil was parallel to that of combined immunoreactivity in the neuropil and cell bodies. The density of labeled cell bodies tended to be higher but sizes of cell bodies tended to be smaller in the ICd than in the other subdivisions. No systematic regional changes were found in the level of cell body immunoreactivity, except that GABA(B)R2-immunoreactive cell bodies in the ICd had slightly higher optic density (OD) than in other regions. Elongated cell bodies existed throughout the IC. Many labeled cell bodies along the outline of the IC were oriented in parallel to the outline. No strong tendency of orientation was found in labeled cell bodies in ICc. Regional distributions of the subunits in ICc correlated well with inputs to this subdivision. Our finding regarding the contrast in the level of neuropil immunoreactivity among different subdivisions is consistent with the fact that the GABA(B) receptor has different pre- and postsynaptic functions in different IC regions.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Secondary hyperalgesia in the monoarthritic rat is mediated by GABAB and NK1 receptors of spinal dorsal horn neurons: a behavior and c-fos study. 16809001

    Secondary hyperalgesia in the monoarthritic rat is accompanied by a decrease in nociceptive activation of spinal neurons expressing GABA(B) receptors and by the opposite effect in the cells expressing neurokinin 1 (NK1)-receptors. In order to ascertain the relative role of each receptor, the effects of intrathecal administration of SP-saporin (SP-SAP), baclofen or both were evaluated, using a model of secondary hyperalgesia that consists of mechanical stimulation of the hindlimb skin close to an inflamed joint. Four days after the induction of monoarthritis by intraarticular injection of Complete Freund's Adjuvant (CFA), a cannula was implanted at T(13)-L(1) level and 10 microl of saline or SP-SAP (10(-6) M) were intrathecally (i.t.) injected. Fourteen days after CFA-injection, half of the animals from each group received i.t. injections of 10 microl saline and the remainder were injected with the same volume of baclofen (1 microg). Ten minutes later, the animals were behaviorally evaluated by the von Frey test or submitted to noxious mechanical stimulation to analyze c-fos expression. The von Frey thresholds increased after the treatments, but more pronouncedly after baclofen or SP-SAP plus baclofen. In segments L(2)-L(3), the spinal area that receives input from the stimulated skin close to the inflamed joint, the numbers of Fos-immunoreactive neurons were reduced after the three treatments both in the superficial and deep dorsal horn. In segments T(13)-L(1), the numbers of Fos-immunoreactive neurons were significantly reduced after treatment with SP-SAP plus baclofen in both dorsal horn regions, and in the deep dorsal horn after baclofen treatment. We conclude that both GABA(B) and NK1 receptors of spinal dorsal horn neurons participate in secondary hyperalgesia in the monoarthritic rat, although the decrease in GABA inhibition appears to play a more important role than the increase in SP-mediated effects.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB5060
    Nombre del producto:
    Anti-Substance P Receptor Antibody, pain

  • Presynaptic GABA(B) receptors decrease neurotransmitter release in vestibular nuclei neurons during vestibular compensation. 22871524

    Unilateral damage to the peripheral vestibular receptors precipitates a debilitating syndrome of oculomotor and balance deficits at rest, which extensively normalize during the first week after the lesion due to vestibular compensation. In vivo studies suggest that GABA(B) receptor activation facilitates recovery. However, the presynaptic or postsynaptic sites of action of GABA(B) receptors in vestibular nuclei neurons after lesions have not been determined. Accordingly, here presynaptic and postsynaptic GABA(B) receptor activity in principal cells of the tangential nucleus, a major avian vestibular nucleus, was investigated using patch-clamp recordings correlated with immunolabeling and confocal imaging of the GABA(B) receptor subunit-2 (GABA(B)R2) in controls and operated chickens shortly after unilateral vestibular ganglionectomy (UVG). Baclofen, a GABA(B) agonist, generated no postsynaptic currents in principal cells in controls, which correlated with weak GABA(B)R2 immunolabeling on principal cell surfaces. However, baclofen decreased miniature excitatory postsynaptic current (mEPSC) and GABAergic miniature inhibitory postsynaptic current (mIPSC) events in principal cells in controls, compensating and uncompensated chickens three days after UVG, indicating the presence of functional GABA(B) receptors on presynaptic terminals. Baclofen decreased GABAergic mIPSC frequency to the greatest extent in principal cells on the intact side of compensating chickens, with concurrent increases in GABA(B)R2 pixel brightness and percentage overlap in synaptotagmin 2-labeled terminals. In uncompensated chickens, baclofen decreased mEPSC frequency to the greatest extent in principal cells on the intact side, with concurrent increases in GABA(B)R2 pixel brightness and percentage overlap in synaptotagmin 1-labeled terminals. Altogether, these results revealed changes in presynaptic GABA(B) receptor function and expression which differed in compensating and uncompensated chickens shortly after UVG. This work supports an important role for GABA(B) autoreceptor-mediated inhibition in vestibular nuclei neurons on the intact side during early stages of vestibular compensation, and a role for GABA(B) heteroreceptor-mediated inhibition of glutamatergic terminals on the intact side in the failure to recover function.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • GABA(B) receptors do not internalize after baclofen treatment, possibly due to a lack of β-arrestin association: study with a real-time visualizing assay. 22517292

    The mechanism of agonist-induced GABA(B) receptor (GABA(B) R) internalization is not well understood. To investigate this process, we focused on the interaction of GABA(B) R with β-arrestins, which are key proteins in the internalization of most of the G protein-coupled receptors, and the agonist-induced GABA(B) R internalization and the interaction of GABA(B) R with β-arrestin1 and β-arrestin2 were investigated in real time using GABA(B) R and β-arrestins both of which were fluorescent protein-tagged. We then compared these profiles with those of μ-opioid receptors (μOR), well-studied receptors that associate and cointernalize with β-arrestins. When stimulated by the specific GABA(B) R agonist baclofen, GABA(B) R composed of GABA(B1a) R (GB(1a) R) and fluorescent protein-tagged GABA(B2) R-Venus (GB₂ R-V) formed functional GABA(B) R; they elicited G protein-activated inwardly rectifying potassium channels as well as nontagged GABA(B) R. In cells coexpressing GB(1a) R, GB₂ R-V, and β-arrestin1-Cerulean (βarr1-C) or β-arrestin2-Cerulean (βarr2-C), real-time imaging studies showed that baclofen treatment neither internalized GB₂ R-V nor mobilized βarr1-C or βarr2-C to the cell surface. This happened regardless of the presence of G protein-coupled receptor kinase 4 (GRK4), which forms a complex with GABA(B) R and causes GABA(B) R desensitization. On the other hand, in cells coexpressing μOR-Venus, GRK2, and βarr1-C or βarr2-C, the μOR molecule formed μOR/βarr1 or μOR/βarr2 complexes on the cell surface, which were then internalized into the cytoplasm in a time-dependent manner. Fluorescence resonance energy transfer assay also indicated scarce association of GB₂ R-V and β-arrestins-C with or without the stimulation of baclofen, while robust association of μOR-V with β-arrestins-C was detected after μOR activation. These findings suggest that GABA(B) Rs failure to undergo agonist-induced internalization results in part from its failure to interact with β-arrestins.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AP180
    Nombre del producto:
    Donkey Anti-Goat IgG Antibody, Species Adsorbed

  • Opposite Effects of KCTD Subunit Domains on GABAB Receptor-mediated Desensitization. 23035119

    GABA(B) receptors assemble from principle and auxiliary subunits. The principle subunits GABA(B1) and GABA(B2) form functional heteromeric GABA(B(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 GABA(B2), 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.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB5394

  • GABAA receptors are expressed and facilitate relaxation in airway smooth muscle. 18408071

    Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system and exerts its actions via both ionotropic (GABA(A)) channels and metabotropic (GABA(B)) receptors. GABA(A) channels are ubiquitously expressed in neuronal tissues, and in mature neurons modulate an inward chloride current resulting in neuronal inhibition due to membrane hyperpolarization. In airway smooth muscle (ASM) cells, membrane hyperpolarization favors smooth muscle relaxation. Although GABA(A) channels and GABA(B) receptors have been functionally identified on peripheral nerves in the lung, GABA(A) channels have never been identified on ASM itself. We detected the mRNA encoding of the GABA(A) alpha(4)-, alpha(5)-, beta(3)-, delta-, gamma(1-3)-, pi-, and theta-subunits in total RNA isolated from native human and guinea pig ASM and from cultured human ASM cells. Selected immunoblots identified the GABA(A) alpha(4)-, alpha(5)-, beta(3)-, and gamma(2)-subunit proteins in native human and guinea pig ASM and cultured human ASM cells. The GABA(A) beta(3)-subunit protein was immunohistochemically localized to ASM in guinea pig tracheal rings. While muscimol, a specific GABA(A) channel agonist, did not affect the magnitude or the time to peak contractile effect of substance P, it directly concentration dependently relaxed a tachykinin-induced contraction in guinea pig tracheal rings, which was inhibited by the GABA(A)-selective antagonist gabazine. Muscimol also relaxed a contraction induced by an alternative contractile agonist histamine. These results demonstrate that functional GABA(A) channels are expressed on ASM and suggest a novel therapeutic target for the relaxation of ASM in diseases such as asthma and chronic obstructive lung disease.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • GABA B RECEPTOR R1 CONTROL PEPTIDE

    Tipo de documento:
    Certificado de análisis
    Número de lote:
    2899912
    Referencia del producto:
    AG324
    Nombre del producto:
    GABA B Receptor R1, control peptide for AB1531