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Your search keyword '"Ovsepian SV"' showing total 3 results
Start Over Author "Ovsepian SV" Language russian
3 results on '"Ovsepian SV"'

1. [Intracellular recording of the frog dorsal root single fibres' responses mediated by the GABAA and 5-HT-receptors].

Author

Ovsepian SV and Veselkin NP

Subjects
Animals, Bicuculline pharmacology, In Vitro Techniques, Neurons, Afferent drug effects, Neurons, Afferent physiology, Rana ridibunda, Spinal Cord drug effects, Spinal Nerve Roots physiology, Action Potentials drug effects, GABA Antagonists pharmacology, Receptors, GABA-A metabolism, Receptors, Serotonin metabolism, Serotonin pharmacology, Spinal Nerve Roots drug effects, gamma-Aminobutyric Acid pharmacology
Abstract

The effects of GABA, bicuculline and 5-HT on primary afferents in the isolated spinal cord of the frog Rana ridibunda were studied. Bath application of GABA (1 mM) reduced the primary afferent depolarisation (PAD) in IX segment of the spinal cord evoked by X dorsal root stimulation (57 +/- 8% of initial level, n = 5, p < 0.05). The action potentials (AP) recorded in dorsal root afferents was also suppressed under the GABA action (74 +/- 9%, p < 0.05). Bath application of bicuculline (50 microM) reduced the PAD (21 +/- 7%), n = 6, p < 0.05), meanwhile the AP in dorsal root afferents was resistant against the bicuculline action. Bath application of 5-HT (25 microM) depressed the PAD (34 +/- 7%, n = 7, p < 0.05) and the amplitude of the AP recorded from the single afferent fibre in dorsal column (76 +/- 6%, n = 7, p < 0.05). In contrast to GABA, 5-HT more effectively suppressed the late phase of the PAD evoked by X dorsal root stimulation and caused (76 +/- 6%, n = 7, p < 0.05) an alteration of the AP shape. All effects induced by these drugs were reversible. The mechanisms of GABA and 5-HT modulation of spinal cord afferent income are discussed.

Published
2004

2. [The study of the role of the GABA A and GABA B receptors in presynaptic inhibition of primary afferents of spinal cord of the frog Rana ridibunda].

Author

Ovsepian SV and Veselkin NP

Subjects
Animals, Baclofen pharmacology, Bicuculline pharmacology, GABA Agonists pharmacology, GABA Antagonists pharmacology, In Vitro Techniques, Membrane Potentials drug effects, Membrane Potentials physiology, Motor Neurons drug effects, Motor Neurons metabolism, Presynaptic Terminals drug effects, Rana ridibunda physiology, Receptors, GABA-A drug effects, Receptors, GABA-B drug effects, Spinal Cord drug effects, Synaptic Transmission drug effects, Synaptic Transmission physiology, gamma-Aminobutyric Acid pharmacology, Afferent Pathways physiology, Baclofen analogs & derivatives, Presynaptic Terminals physiology, Receptors, GABA-A physiology, Receptors, GABA-B physiology, Spinal Cord physiology
Published
2002

3. [Participation of the GABA B receptors in presynaptic inhibition of the spinal cord descending projections fibers in the frog Rana ridibunda].

Author

Ovsepian SV and Veselkin NP

Subjects
Action Potentials physiology, Animals, Excitatory Postsynaptic Potentials drug effects, GABA Agonists pharmacology, GABA Antagonists pharmacology, GABA-B Receptor Agonists, GABA-B Receptor Antagonists, In Vitro Techniques, Motor Neurons physiology, Neurons, Efferent physiology, Rana ridibunda, Spinal Cord cytology, Spinal Nerve Roots physiology, Synapses physiology, gamma-Aminobutyric Acid pharmacology, Excitatory Postsynaptic Potentials physiology, Nerve Fibers physiology, Neural Inhibition physiology, Receptors, GABA-B physiology, Spinal Cord physiology
Abstract

(-)-Baclophen was found to depress in a dose-dependent and reversible way the excitatory post-synaptic potentials (EPSPS) of motor neurons and the ventral root potentials evoked by stimulation of fibres of the ipsi- and contralateral ventral columns. The (-)-baclophen depressing effect could be eliminated with saclophen. Picrotoxin eliminated the depressing effect of the GABA on the descending EPSPS. Depressing effects of (-)-baclophen and GABA upon the ventral root potentials were also shown. The data obtained in pharmacological analysis corroborate to a certain extent existence of the GABAB receptor presynaptic inhibition in descending fibres monosynaptically corrected with the spinal cord motor neurons in the frog Rana ridibunda.

Published
2002

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