Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Serotonergic inhibition of the T-type and high voltage-activated Ca2+ currents in the primary sensory neurons of Xenopus larvae.
Sun QQ, Dale N.
???displayArticle.abstract???
The primary sensory Rohon-Beard (R-B) neurons of Xenopus larvae are highly analogous to the C fibers of the mammalian pain pathway. We explored the actions of 5-HT by studying the modulation of Ca2+ currents. In approximately 80% of the acutely isolated R-B neurons, 5-HT inhibited the high voltage-activated (HVA) currents by 16% (n = 29) and the T-type currents by 24% (n = 41). The modulation of the T-type and the HVA currents was mimicked by selective 5-HT1A and 5-HT1D agonists: 8-OH-DPAT and L-694,247. The effects of the agonists were blocked by their respective 5-HT1A or 5-HT1D antagonists: p-MPPI and GR127935, suggesting that both 5-HT1A and 5-HT1D receptors were involved. Approximately 70% of the actions of 5-HT on HVA currents was occluded by omega-conotoxin-GVIA (N-type channel blocker), whereas the rest of the modulation ( approximately 30%) was occluded by <100 nM omega-agatoxin-TK (P/Q-type channel blocker). This suggests that 5-HT acts on N- and P/Q-type Ca2+ channels. Neither the modulation of the T-type nor that of the HVA currents was accompanied by changes in their voltage-dependent kinetics. Cell-attached patch-clamp recordings suggest that the modulation of the T-type channel occurs through a membrane-delimited second messenger. We have studied the functional consequences of the modulation of T-type Ca2+ channels and have found that these channels play a role in spike initiation in R-B neurons. Modulation of T-type channels by 5-HT therefore could modulate the sensitivity of this sensory pathway by increasing the thresholds of R-B neurons. This is a new and potentially important locus for modulation of sensory pathways in vertebrates.
Bayliss,
Inhibition of N- and P-type calcium currents and the after-hyperpolarization in rat motoneurones by serotonin.
1995, Pubmed
Bayliss,
Inhibition of N- and P-type calcium currents and the after-hyperpolarization in rat motoneurones by serotonin.
1995,
Pubmed Beer,
L-694,247: a potent 5-HT1D receptor agonist.
1993,
Pubmed Beer,
An investigation of the 5-HT1D receptor binding affinity of 5-hydroxytryptamine, 5-carboxyamidotryptamine and sumatriptan in the central nervous system of seven species.
1992,
Pubmed Berger,
Serotonin enhances a low-voltage-activated calcium current in rat spinal motoneurons.
1990,
Pubmed Bruinvels,
5-HT1D binding sites in various species: similar pharmacological profile in dog, monkey, calf, guinea-pig and human brain membranes.
1992,
Pubmed Chen,
Mechanism of gating of T-type calcium channels.
1990,
Pubmed Clarke,
Sensory physiology, anatomy and immunohistochemistry of Rohon-Beard neurones in embryos of Xenopus laevis.
1984,
Pubmed
,
Xenbase Crisp,
Analgesic effects of serotonin and receptor-selective serotonin agonists in the rat spinal cord.
1991,
Pubmed Crunelli,
A T-type Ca2+ current underlies low-threshold Ca2+ potentials in cells of the cat and rat lateral geniculate nucleus.
1989,
Pubmed Dale,
The Isolation and Identification of Spinal Neurons That Control Movement in the Xenopus Embryo.
1991,
Pubmed
,
Xenbase Davidson,
Evidence that 5-hydroxytryptamine release in rat dorsal raphé nucleus is controlled by 5-HT1A, 5-HT1B and 5-HT1D autoreceptors.
1995,
Pubmed Del Mar,
Serotonin inhibits high-threshold Ca2+ channel currents in capsaicin-sensitive acutely isolated adult rat DRG neurons.
1994,
Pubmed De Waard,
Direct binding of G-protein betagamma complex to voltage-dependent calcium channels.
1997,
Pubmed
,
Xenbase Diversé-Pierluissi,
Transmitter-mediated inhibition of N-type calcium channels in sensory neurons involves multiple GTP-binding proteins and subunits.
1995,
Pubmed Dunlap,
Calcium channels. Integration hot-spot gets hotter.
1997,
Pubmed Eide,
The role of spinal cord 5-HT1A and 5-HT1B receptors in the modulation of a spinal nociceptive reflex.
1990,
Pubmed Feldman,
Omega Conus geographus toxin: a peptide that blocks calcium channels.
1987,
Pubmed Foehring,
Serotonin modulates N- and P-type calcium currents in neocortical pyramidal neurons via a membrane-delimited pathway.
1996,
Pubmed Formenti,
Inhibitory action of acetylcholine, baclofen and GTP-gamma-S on calcium channels in adult rat sensory neurons.
1991,
Pubmed Fraser,
Low-threshold transient calcium current in rat hippocampal lacunosum-moleculare interneurons: kinetics and modulation by neurotransmitters.
1991,
Pubmed Hamill,
Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.
1981,
Pubmed Hille,
Modulation of ion-channel function by G-protein-coupled receptors.
1994,
Pubmed Holohean,
Serotonin1A facilitation of frog motoneuron responses to afferent stimuli and to N-methyl-D-aspartate.
1992,
Pubmed Hoyer,
International Union of Pharmacology classification of receptors for 5-hydroxytryptamine (Serotonin).
1994,
Pubmed Hoyer,
"5-HT1R" or 5-HT1D sites? Evidence for 5-HT1D binding sites in rabbit brain.
1992,
Pubmed HUGHES,
The development of the primary sensory system in Xenopus laevis (Daudin).
1957,
Pubmed
,
Xenbase Ikeda,
Voltage-dependent modulation of N-type calcium channels by G-protein beta gamma subunits.
1996,
Pubmed Ismaiel,
5-HT1 and 5-HT2 binding profiles of the serotonergic agents alpha-methylserotonin and 2-methylserotonin.
1990,
Pubmed Jones,
Evidence that 5-HT1D receptors mediate inhibition of sympathetic ganglionic transmission in anaesthetized cats.
1995,
Pubmed Koike,
5-HT1A receptor-mediated inhibition of N-type calcium current in acutely isolated ventromedial hypothalamic neuronal cells.
1994,
Pubmed Kuenzi,
Effect of capsaicin and analogues on potassium and calcium currents and vanilloid receptors in Xenopus embryo spinal neurones.
1996,
Pubmed
,
Xenbase Kung,
A potential 5-HT1A receptor antagonist: p-MPPI.
1994,
Pubmed Kuoppamäki,
Clozapine and N-desmethylclozapine are potent 5-HT1C receptor antagonists.
1993,
Pubmed Liau,
Characterization of a novel and potent 5-hydroxytryptamine1A receptor antagonist.
1991,
Pubmed Llinás,
Electrophysiology of mammalian inferior olivary neurones in vitro. Different types of voltage-dependent ionic conductances.
1981,
Pubmed Lucas,
Molecular mechanisms of pain: serotonin1A receptor agonists trigger transactivation by c-fos of the prodynorphin gene in spinal cord neurons.
1993,
Pubmed Luebke,
Sensory neuron N-type calcium currents are inhibited by both voltage-dependent and -independent mechanisms.
1994,
Pubmed Luebke,
Multiple calcium channel types control glutamatergic synaptic transmission in the hippocampus.
1993,
Pubmed Middlemiss,
8-Hydroxy-2-(di-n-propylamino)-tetralin discriminates between subtypes of the 5-HT1 recognition site.
1983,
Pubmed Mlinar,
Block of current through T-type calcium channels by trivalent metal cations and nickel in neural rat and human cells.
1993,
Pubmed Neale,
Biochemical and pharmacological characterization of CGS 12066B, a selective serotonin-1B agonist.
1987,
Pubmed Penington,
A study of the mechanism of Ca2+ current inhibition produced by serotonin in rat dorsal raphe neurons.
1991,
Pubmed Roberts,
The neuroanatomy of an amphibian embryo spinal cord.
1982,
Pubmed
,
Xenbase Sillar,
Unmyelinated cutaneous afferent neurons activate two types of excitatory amino acid receptor in the spinal cord of Xenopus laevis embryos.
1988,
Pubmed
,
Xenbase Sillar,
Presynaptic inhibition of primary afferent transmitter release by 5-hydroxytryptamine at a mechanosensory synapse in the vertebrate spinal cord.
1994,
Pubmed
,
Xenbase Spitzer,
The development of the action potential mechanism of amphibian neurons isolated in culture.
1976,
Pubmed
,
Xenbase Suzuki,
T-type calcium channels mediate the transition between tonic and phasic firing in thalamic neurons.
1989,
Pubmed Tan,
Diverse actions of 5-hydroxytryptamine on frog spinal dorsal horn neurons in vitro.
1992,
Pubmed Teramoto,
Two types of calcium channels sensitive to omega-agatoxin- TK in cultured rat hippocampal neurones.
1995,
Pubmed Waeber,
5-HT1 receptor binding sites in the guinea pig superior colliculus are predominantly of the 5-HT1D class and are presynaptically located on primary retinal afferents.
1990,
Pubmed Wall,
GABAB receptors modulate an omega-conotoxin-sensitive calcium current that is required for synaptic transmission in the Xenopus embryo spinal cord.
1994,
Pubmed
,
Xenbase Wheeler,
Roles of N-type and Q-type Ca2+ channels in supporting hippocampal synaptic transmission.
1994,
Pubmed White,
Transient low-threshold Ca2+ current triggers burst firing through an afterdepolarizing potential in an adult mammalian neuron.
1989,
Pubmed Wickman,
Ion channel regulation by G proteins.
1995,
Pubmed Xu,
Serotonin receptor subtypes in spinal antinociception in the rat.
1994,
Pubmed Zhang,
Contribution of the low-threshold T-type calcium current in generating the post-spike depolarizing afterpotential in dentate granule neurons of immature rats.
1993,
Pubmed Zifa,
5-Hydroxytryptamine receptors.
1992,
Pubmed
