Modulation of ligand-gated dopamine channels in Helix neurones

Green, K. A.; Cottrell, G. A.

doi:10.1007/s004240050402

Cited by 13 publications

(6 citation statements)

References 26 publications

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“…; Shaw et al . ; Green & Cottrell, ; Haj‐Dahmane & Andrade, ; Partridge & Valenzuela, ). Neurons given 100 μ m FFA for 20 min exhibited a markedly reduced I OAG caused by 25 μ m OAG ( n = 9) (Fig.…”

Section: Resultsmentioning

confidence: 99%

Diacylglycerol‐mediated regulation of Aplysia bag cell neuron excitability requires protein kinase C

Sturgeon

Magoski

2016

The Journal of Physiology

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Following synaptic input, the bag cell neurons of Aplysia undergo a long-term afterdischarge of action potentials to secrete egg-laying hormone and initiate reproduction. Early in the afterdischarge, phospholipase C (PLC) hydrolyses phosphatidylinositol-4,5-bisphosphate into inositol trisphosphate (IP3 ) and diacylglycerol (DAG). In Aplysia, little is known about the action of DAG, or any interaction with IP3 ; thus, we examined the effects of a synthetic DAG analogue, 1-oleoyl-2-acetyl-sn-glycerol (OAG), on whole-cell voltage-clamped cultured bag cell neurons. OAG induced a large, prolonged, Ca(2+) -permeable, concentration-dependent inward current (IOAG ) that reversed at ∼-20 mV and was enhanced by intracellular IP3 . A similar current was evoked by either another DAG analogue, 1,2-dioctanoyl-sn-glycerol (DOG), or activating PLC with N-(3-trifluoromethylphenyl)-2,4,6-trimethylbenzenesulfonamide (m-3M3FBS). IOAG was reduced by the general cation channel blockers Gd(3+) or flufenamic acid. Work in other systems indicated that OAG activates channels independently of protein kinase C (PKC); however, we found pretreating bag cell neurons with any of the PKC inhibitors bisindolylmaleimide, sphinganine, or H7, attenuated IOAG . However, stimulating PKC with phorbol 12-myristate 13-acetate (PMA) did not evoke current or enhance IOAG ; moreover, unlike PMA, OAG failed to trigger PKC, as confirmed by an independent bioassay. Finally, OAG or m-3M3FBS depolarized cultured neurons, and while OAG did not provoke afterdischarges from bag cell neurons in the nervous system, it did double the duration of synaptically elicited afterdischarges. To our knowledge, this is the first report of obligate PKC activity for IOAG gating. An interaction between phosphoinositol metabolites and PKC could control the cation channel to influence afterdischarge duration.

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Section: Resultsmentioning

confidence: 99%

Diacylglycerol‐mediated regulation of Aplysia bag cell neuron excitability requires protein kinase C

Sturgeon

Magoski

2016

The Journal of Physiology

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“…5A). FFA is routinely used at 100 -500 M to reduce I CAN in both invertebrates and vertebrates (Derjean et al 2005;GhamariLangroudi and Bourque 2002;Green and Cottrell 1997;Lee and Tepper 2007;Morisset and Nagy 1999;Pace et al 2007a;Partridge and Valenzuela 2000). At these high concentrations, above 100 M, FFA has multiple side effects, including partial inhibition of calcium channels and NMDA receptors (Wang et al 2006) and induction of calcium release from ER (Gardam et al 2008;Lee et al 1996;Shaw et al 1995) and mitochondria (Tu et al 2009).…”

Section: Discussionmentioning

confidence: 99%

Dopamine-induced oscillations of the pyloric pacemaker neuron rely on release of calcium from intracellular stores

Kadiri

Kwan

Webb

et al. 2011

Journal of Neurophysiology

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Kadiri LR, Kwan AC, Webb WW, Harris-Warrick RM. Dopamineinduced oscillations of the pyloric pacemaker neuron rely on release of calcium from intracellular stores. J Neurophysiol 106: 1288-1298, 2011. First published June 15, 2011 doi:10.1152/jn.00456.2011.-Endogenously bursting neurons play central roles in many aspects of nervous system function, ranging from motor control to perception. The properties and bursting patterns generated by these neurons are subject to neuromodulation, which can alter cycle frequency and amplitude by modifying the properties of the neuron's ionic currents. In the stomatogastric ganglion (STG) of the spiny lobster, Panulirus interruptus, the anterior burster (AB) neuron is a conditional oscillator in the presence of dopamine (DA) and other neuromodulators and serves as the pacemaker to drive rhythmic output from the pyloric network. We analyzed the mechanisms by which DA evokes bursting in the AB neuron. Previous work showed that DA-evoked bursting is critically dependent on external calcium (Harris-Warrick RM, Flamm RE. J Neurosci 7: [2113][2114][2115][2116][2117][2118][2119][2120][2121][2122][2123][2124][2125][2126][2127][2128] 1987). Using two-photon microscopy and calcium imaging, we show that DA evokes the release of calcium from intracellular stores well before the emergence of voltage oscillations. When this release from intracellular stores is blocked by antagonists of ryanodine or inositol trisphosphate (IP 3 ) receptor channels, DA fails to evoke AB bursting. We further demonstrate that DA enhances the calcium-activated inward current, I CAN , despite the fact that it significantly reduces voltage-activated calcium currents. This suggests that DA-induced release of calcium from intracellular stores activates I CAN , which provides a depolarizing ramp current that underlies endogenous bursting in the AB neuron.calcium-activated inward current; ryanodine; voltage clamp; central pattern generator RHYTHMIC ACTIVITY plays central roles in many aspects of nervous system function, ranging from motor control to perception. The neural mechanisms underlying rhythmogenesis are not well understood but include both network-driven oscillators and neuronal oscillators (Harris-Warrick 2010). Neuronal oscillators are single neurons that generate an endogenous oscillatory voltage pattern based on the ionic currents they express. The bursting properties of these neurons are subject to neuromodulation, which can alter cycle frequency and amplitude by modifying the properties of the neuron's ionic currents (Harris-Warrick and Johnson 2010;Lotshaw et al. 1986;Marder and Bucher 2001;Marder et al. 2005;Partridge et al. 1990).The pyloric network in the crustacean stomatogastric ganglion (STG) is an important system for studying the mechanisms of rhythmogenesis (Harris-Warrick 1993; Marder and Bucher 2001; Selverston and Ayers 2006). The pyloric circuit consists of 1 interneuron (the anterior burster, or AB) and 13 motoneurons. The AB neuron is a conditional oscillator: under the appropriate modul...

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“…This comparative approach is important because with endogenous release of 5-HT, where local concentrations may be higher (Marinesco and Carew 2002) or in individual preparations where the sensitivity to 5-HT may be greater than in the present study, the blockade by the antagonist that affects a particular process may be incomplete; only by examining the effects of both antagonists can one obtain an estimate of the relative contribution of the two classes of 5-HT receptors. It should be noted that methiothepin also affects dopamine receptors in gastropod mollusks (Drummond et al 1978;Green and Cottrell 1997;Lukyanetz and Kostyuk 1996;Pechenik et al 2002). This will not be a problem in cases where dopamine is found not to mimic the phenomenon being investigated (e.g., Abrams et al 1984).…”

Section: Discussionmentioning

confidence: 99%

Serotonin Receptor Antagonists Discriminate Between PKA- and PKC-Mediated Plasticity inAplysiaSensory Neurons

Dumitriu

Cohen²,

Wan³

et al. 2006

Journal of Neurophysiology

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. Serotonin receptor antagonists discriminate between PKA-and PKC-mediated plasticity in Aplysia sensory neurons. J Neurophysiol 95: 2713-2720, 2006. First published October 19, 2005 doi:10.1152/jn.00642.2005. Highly selective serotonin (5-hydroxytryptamine, 5-HT) receptor antagonists developed for mammals are ineffective in Aplysia due to the evolutionary divergence of neurotransmitter receptors and because the higher ionic strength of physiological saline for marine invertebrates reduces antagonist affinity. It has therefore been difficult to identify antagonists that specifically block individual signaling cascades initiated by 5-HT. We studied two broad-spectrum 5-HT receptor antagonists that have been characterized biochemically in Aplysia CNS: methiothepin and spiperone. Methiothepin is highly effective in inhibiting adenylyl cyclase (AC)-coupled 5-HT receptors in Aplysia. Spiperone, which blocks phospholipase C (PLC)-coupled 5-HT receptors in mammals, does not block AC-coupled 5-HT receptors in Aplysia. In electrophysiological studies, we explored whether methiothepin and spiperone can be used in parallel to distinguish between the AC-cAMP and PLC-protein kinase C (PKC) modulatory cascades that are initiated by 5-HT. 5-HT-induced broadening of the sensory neuron action potential in the presence of tetraethylammonium/nifedipine, which is mediated by modulation of the S-K ϩ currents, was used an assay for the AC-cAMP cascade. Spike broadening initiated by 5 M 5-HT was unaffected by 100 M spiperone, whereas it was effectively blocked by 100 M methiothepin. Facilitation of highly depressed sensory neuron-to-motor neuron synapses by 5-HT was used as an assay for the PLC-PKC cascade. Spiperone completely blocked facilitation of highly depressed synapses by 5 M 5-HT. In contrast, methiothepin produced a modest, nonsignificant, reduction in the facilitation of depressed synapses. Interestingly, these experiments revealed that the PLC-PKC cascade undergoes desensitization during exposure to 5-HT.

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Modulation of ligand-gated dopamine channels in Helix neurones

Cited by 13 publications

References 26 publications

Diacylglycerol‐mediated regulation of Aplysia bag cell neuron excitability requires protein kinase C

Diacylglycerol‐mediated regulation of Aplysia bag cell neuron excitability requires protein kinase C

Dopamine-induced oscillations of the pyloric pacemaker neuron rely on release of calcium from intracellular stores

Serotonin Receptor Antagonists Discriminate Between PKA- and PKC-Mediated Plasticity inAplysiaSensory Neurons

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