Opioid peptides as possible neuromodulators of the afferent synaptic transmission in the frog semicircular canal

Andrianov, G.N.; Ryzhova, I. V.

doi:10.1016/s0306-4522(99)00159-1

Cited by 20 publications

(11 citation statements)

References 44 publications

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“…It was suggested that the receptors are located postsynaptically and that L-glutamate is involved in the mechanism of action of opioids [5]. The effects of dalargin on excitation induced by L-glutamate support the hypothesis that the action of opioid peptides may be connected mostly with inhibition of a non-NMDA subtype of glutamate recep-tors [6].…”

Section: Introductionsupporting

confidence: 57%

“…This point of view is supported by the fact that in a number of preparations opioid peptides co-exist in some nerve terminals with principal efferent neurotransmitter ACh. The relevant literature on this subject has been recently very well reviewed by some authors [1,5,13,14]. Although most of the results on colocalization of opioid peptides and ACh have been detected in the efferent synapses on inner and outer hair cells in the cochlea, such a co-localization has also been proposed for vestibular efferents [1].…”

Section: Discussionmentioning

confidence: 99%

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Lack of Evidence of an Interaction between Leu-Enkephalin and Muscarinic-Like Responses in the Frog Semicircular Canal

Andrianov

Ryzhova²

2003

Neurosignals

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Using multiunit recording of action potentials from the whole vestibular nerve, we studied whether opioid peptide leu-enkephalin (Enk) may modulate muscarinic-like responses in semicircular organs of the frog. When acetylcholine (ACh) (0.1–1 mM) was applied with 1 nM Enk, the maximal frequency increase induced by ACh was reduced.However,the frequency decrease of ACh responses under Enk did not differ from the frequency decline in basal spike discharge induced by Enk alone. Administration of atropine (1 µM) left the response to Enk intact and blocked the excitatory effect of ACh. No modification of the ACh response under Enk was observed in the presence of the non-selective opioid receptor antagonist naloxone (10 µM). This study suggests that no interaction exists between the ACh-mediated excitatory action on resting activity in the isolated semicircular canal preparation and the suppressive action of Enk.

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Section: Introductionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Lack of Evidence of an Interaction between Leu-Enkephalin and Muscarinic-Like Responses in the Frog Semicircular Canal

Andrianov

Ryzhova²

2003

Neurosignals

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“…A small change in the concentration of the drugs caused either no response or a near maximal decrease of impulse activity. Compared to the dose-response curves of other modulatory substances [4,13,23] , that of DOP agonists were much steeper; as a result, reductions in the firing rate under DOP agonists were highly concentration-dependent.…”

Section: Discussionmentioning

confidence: 99%

“…Many substances, including opioid peptides [3][4][5][6][7][8] , calcitonin gene-related peptide, GABA, histamine, taurine, substance P and others [1][2][3]9] have been proposed as potential neuromodulator candidates. Recent studies extended the evidence for the involvement of metabotropic glutamate receptors in modulation of excitatory neurotransmission at the afferent hair cell synapses in the vestibular organs of frogs [3,[10][11][12][13] .…”

Section: Introductionmentioning

confidence: 99%

Dopaminergic Modulation of Afferent Synaptic Transmission in the Semicircular Canals of Frogs

Andrianov

Ryzhova²,

Tobias³

2009

Neurosignals

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Using multiunit recording of action potentials from the whole nerve with the aid of external perfusion, we investigated the effects of dopamine (DOP) agonists that are involved in modulatory actions on synaptic transmission in the isolated labyrinth preparations of frogs. The external application of DOP (0.1–1 mM), the D₁ agonist chloro-APB hydrobromide (CAPB, 50–100 μM) and the D₂ agonist quinerolane (QUI, 50–100 μM) induced a dose-dependent and reversible decline in the resting discharge frequency. In this concentration range, the potency of applied CAPB considerably exceeded that of QUI. AMPA, NMDA and ACPD responses were inhibited by the D₁ and D₂ agonists, implicating both subtypes of DOP receptors in the modulation of both ionotropic and metabotropic glutamate receptors. The inhibitory action of the DOP agonists on L-glutamate responses persisted in a high Mg²⁺ solution in conditions of selective activation of the postsynaptic membrane. The results obtained suggest that DOP may interact with both D₁ and D₂ receptor subtypes, most likely located postsynaptically on the afferent nerve fibers. This dopaminergic control mechanism may result in the reduction of the activated firing rate, thus preventing over-excitation and excitotoxic injury of the afferent dendrites after the external application of L-glutamate and excessive receptor stimulation.

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“…A number of substances, including opioid peptides (Guth et al, 1998a;Andrianov and Ryzhova, 1999, 2003Lioudyno et al, 2000;Vega and Soto, 2003), adenosine, calcitonin gene-related peptide, ATP, taurine, aspartate, histamine, potassium ions, substance P and others (Bledsoe et al, 1988;Akoev and Andrianov, 1993;Guth et al, 1998a;Dememes and Ryzhova, 1997) have been advanced as potential candidates. The involvement of metabotropic glutamate receptors in modulation of the excitatory afferent transmission has also been analyzed in the vestibular end organs (Guth et al, 1998b;Hendricson and Guth, 2002a,b;Andrianov et al, 2005).…”

Section: Introductionmentioning

confidence: 98%

The role of defensins in the excitability of the peripheral vestibular system in the frog: Evidence for the presence of communication between the immune and nervous systems

2007

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Opioid peptides as possible neuromodulators of the afferent synaptic transmission in the frog semicircular canal

Cited by 20 publications

References 44 publications

Lack of Evidence of an Interaction between Leu-Enkephalin and Muscarinic-Like Responses in the Frog Semicircular Canal

Lack of Evidence of an Interaction between Leu-Enkephalin and Muscarinic-Like Responses in the Frog Semicircular Canal

Dopaminergic Modulation of Afferent Synaptic Transmission in the Semicircular Canals of Frogs

The role of defensins in the excitability of the peripheral vestibular system in the frog: Evidence for the presence of communication between the immune and nervous systems

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