Taurine and β-alanine act on both GABA and glycine receptors in Xenopus oocyte injected with mouse brain messenger RNA

Horikoshi, Tetsumi; Asanuma, Atsushi; Yanagisawa, Keiji; Anzai, Kentaro; Goto, Sataro

doi:10.1016/0169-328x(88)90002-2

Cited by 87 publications

(54 citation statements)

References 43 publications

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“…2) on the IPSP which also agrees with studies on mammalian Purkinje cells showing the presence of GABAA receptors in vivo and in vitro (Bisti et al 1971;Kaneda, Wakamori & Akaike, 1989; see also Ito, 1984). However, the present experiments do not allow one to differentiate between taurine and GABA in the inhibitory response of Purkinje cells as the effects of both may be antagonized by bicuculline and picrotoxin (Fredericksson, Neuss, Morzorati & McBride, 1978;Horikoshi, Asanuma, Yanagisawa, Anzai & Goto, 1988). The relative locations of the inhibitory synapses with respect to the recording electrode is not known in this study, and this, together with the cable-like nature of the Purkinje cell imposes some limitations on the determination of the value of the reversal potential.…”

Section: Discussionmentioning

confidence: 99%

Stellate cell inhibition of Purkinje cells in the turtle cerebellum in vitro.

Midtgaard

1992

The Journal of Physiology

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SUMMARY1. The stellate cell-mediated inhibition of Purkinje cells was studied by intracellular recordings in an in vitro slice preparation of the turtle cerebellar cortex.A graded inhibitory postsynaptic potential (JPSP) was recorded in Purkinje cells upon stimulation of the parallel fibre-stellate cell pathway.2. The IPSP was abolished by bicuculline, and had a reversal potential around -75 mV, consistent with a GABAA receptor-operated Cl-conductance dominating the response investigated here.3. Paired recordings from synaptically coupled stellate cells and Purkinje cells demonstrated that the inhibitory input from a single stellate cell is sufficient to reduce the firing in a Purkinje cell.4. The extracellular-evoked IPSP interacted with the active postsynaptic membrane properties in the Purkinje cell. Interaction with both the Na+ plateau and the IA prolonged the responses to an IPSP, making the net effect of the inhibitory response dependent on the membrane potential in each postsynaptic neurone. 5. A precisely timed IPSP was particularly efficient in reducing dendritic Ca2" influx.6. The voltage-dependent Ca2+ component of a climbing fibre response (CFR) as well as of a parallel fibre (PF) input was reduced by the IPSP.7. It is suggested that Ca2+ spike-mediated reduction in Purkinje cell excitability may be prevented by the stellate cell IPSP-mediated reduction in Ca2+ influx.

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Section: Discussionmentioning

confidence: 99%

Stellate cell inhibition of Purkinje cells in the turtle cerebellum in vitro.

Midtgaard

1992

The Journal of Physiology

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“…Such interaction between taurine and both inhibitory transmitter receptors has been previously postulated. Expression of polyA¤ mRNA from various brain regions in Xenopus oocytes has shown that the GABAA receptor antagonist bicuculline partially inhibited the currents induced by high concentrations of taurine, GABA-and taurine-activated currents displaying cross-desensitization (Horikoshi et al 1988). In addition, inhibition by taurine of high K¤-evoked release of aspartate in cultured cerebellar granule cells has been shown to be partially sensitive to bicuculline (Wahl et al 1994).…”

Section: Activation Of Gabaa Receptors By Taurinementioning

confidence: 99%

“…It is believed to be an inhibitory neurotransmitter acting as an agonist on glycine receptors (Betz, 1992). It has also been suggested to interact with at least some subtypes of GABAA receptors (Horikoshi, Asanuma, Yanagisawa, Anzai & Goto, 1988;Bureau & Olsen, 1991;Quinn & Miller, 1992;Wahl, Elster & Schousboe, 1994). Moreover, the existence of specific taurine receptors has been speculated on the basis of the pharmacological specificity of taurine action on some preparations (Kudo, Akiyoshi & Akagi, 1988), although this has never been clearly demonstrated.…”

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confidence: 99%

Agonist action of taurine on glycine receptors in rat supraoptic magnocellular neurones: possible role in osmoregulation

Hussy

Deleuze

Pantaloni³

et al. 1997

The Journal of Physiology

202

167

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To evaluate the implication of taurine in the physiology of supraoptic neurones, we (i) investigated the agonist properties of taurine on glycine and GABAA receptors of supraoptic magnocellular neurones acutely dissociated from adult rats, using whole‐cell voltage clamp, (ii) studied the effects of taurine and strychnine in vivo by extracellular recordings of supraoptic vasopressin neurones in anaesthetized rats, and (iii) measured the osmolarity‐dependent release of endogenous taurine from isolated supraoptic nuclei by HPLC. GABA, glycine and taurine evoked rapidly activating currents that all reversed close to the equilibrium potential for Cl−, indicating activation of Cl− selective channels. Glycine‐activated currents were reversibly blocked by strychnine (IC50 of 35 nM with 100μm glycine), but were unaffected by the GABAA antagonist gabazine (1–3 μm). GABA‐activated currents were reversibly antagonized by 3 μm gabazine, but not by strychnine (up to 1 μm). Responses to 1 mm taurine were blocked by strychnine but not by gabazine and showed no additivity with glycine‐induced currents, indicating selective activation of glycine receptors. Responses to 10 mm taurine were partially antagonized by gabazine, the residual current being blocked by strychnine. Thus, taurine is also a weak agonist of GABAA receptors. In the presence of gabazine, taurine activated glycine receptors with an EC50 of 406 μm. Taurine activated at most 70% of maximal glycine currents, suggesting that it is a partial agonist of glycine receptors. In vivo, locally applied strychnine (300 mm) increased and taurine (1 mm) decreased the basal electrical activity of vasopressin neurones in normally hydrated rats. The effect of strychnine was markedly more pronounced in water‐loaded rats. Taurine, which is concentrated in supraoptic glial cells, could be released from isolated supraoptic nuclei upon hyposmotic stimulation. Decreases in osmolarity of 15 and 30% specifically enhanced basal release of taurine by 42 and 124%, respectively. We conclude that supraoptic neurones express high amounts of glycine receptors, of which taurine may be regarded as a major natural agonist. We postulate that taurine, which can be released in hyposmotic situations, acts on glycine receptors to exert an inhibitory control on magnocellular neurones during alterations of body fluid homeostasis, implicating an active participation of glial cells in this neuroendocrine regulatory loop.

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“…For instance, synaptoneurosomes obtained from adult rat hippocampus contain glycine in concentrations similar to GABA (36 nmol GABA/mg protein vs. 42 nmol glycine/mg protein) and release of both inhibitory amino acids using Ca 2ϩ -dependent and -independent mechanisms, suggesting the possibility of both vesicular and transporter-mediated release (Burger et al 1991;Engblom et al 1996). Additionally, taurine, a known GlyR agonist in other systems (Flint et al 1998;Horikoshi et al 1988;Hussy et al 1997) that is present in high concentrations in hippocampus (del Rio et al 1987;Oja 1994, 1997), can protect against excitotoxic cell death and depress pyramidal cell excitability (French et al 1986;Taber et al 1986). Presumably these effects of taurine in hippocampus are mediated via activation of GlyRs; however, this mechanism has never been tested.…”

Section: Introductionmentioning

confidence: 99%

Pharmacological Characterization of Glycine-Gated Chloride Currents Recorded in Rat Hippocampal Slices

Chattipakorn

McMahon

2002

Journal of Neurophysiology

139

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Chattipakorn, Siriporn C. and Lori L. McMahon. Pharmacological characterization of glycine-gated chloride currents recorded in rat hippocampal slices. J Neurophysiol 87: 1515-1525, 2002; 10.1152/jn. 00365.2001. An inhibitory role for strychnine-sensitive glycine-gated chloride channels (GlyRs) in mature hippocampus has been overlooked, largely due to the misconception that GlyR expression ceases early during development and to few functional studies demonstrating their presence. As a result, little is known regarding the physiological and pharmacological properties of native GlyRs expressed by hippocampal neurons. In this study, we used pharmacological tools and whole cell patch-clamp recordings of CA1 pyramidal cells and interneurons in acutely prepared hippocampal slices from 3-to 4-wk old rats to characterize these understudied receptors. We show that glycine application to recorded pyramidal cells and interneurons elicited strychnine-sensitive chloride-mediated currents (I gly ) that did not completely desensitize in the continued presence of agonist but reached a steady state at 45-60% of the peak amplitude. Additionally, the inhibitory amino acid, taurine, which has been shown to activate GlyRs in other systems, activated GlyRs expressed by both pyramidal cells and interneurons, although with much less potency than glycine, having an EC 50 10-fold higher. To examine the potential subunit composition of hippocampal GlyRs, we tested the effect of the GABA A receptor antagonist, picrotoxin, on I gly recorded from both cell types. At low micromolar concentrations of picrotoxin (Յ100 M), which selectively block ␣ homomeric GlyRs, I gly was partially attenuated in both cell types, indicating that ␣ homomeric receptors are expressed by pyramidal cells and interneurons. At picrotoxin concentrations Յ1 mM, ϳ10 -20% of the whole cell current remained, suggesting that ␣␤ heteromeric GlyRs are also expressed because this subtype of GlyR is relatively resistant to picrotoxin antagonism. Finally, we examined whether hippocampal GlyRs are modulated by zinc. Consistent with previous reports in other preparations, zinc elicited a bidirectional modulation of GlyRs, with physiological zinc concentrations (1-100 M) increasing whole cell currents and concentrations Ͼ100 M depressing them. Furthermore, the same concentration of zinc that potentiates I gly suppressed currents mediated by the N-methyl-D-aspartate subtype of the glutamate receptor. Thus we provide a pharmacological characterization of native GlyRs expressed by both major neuron types in hippocampus and show that these receptors can be activated by taurine, an amino acid that is highly concentrated in hippocampus. Furthermore, our data suggest that at least two GlyR subtypes are present in hippocampus and that GlyR-mediated currents can be potentiated by zinc at concentrations that suppress glutamate-mediated excitability.

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Taurine and β-alanine act on both GABA and glycine receptors in Xenopus oocyte injected with mouse brain messenger RNA

Cited by 87 publications

References 43 publications

Stellate cell inhibition of Purkinje cells in the turtle cerebellum in vitro.

Stellate cell inhibition of Purkinje cells in the turtle cerebellum in vitro.

Agonist action of taurine on glycine receptors in rat supraoptic magnocellular neurones: possible role in osmoregulation

Pharmacological Characterization of Glycine-Gated Chloride Currents Recorded in Rat Hippocampal Slices

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