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T L D'iakonova

Publications and source records attributed to T L D'iakonova.

At least 19 recordsLinked to original sources
PubMed2000

[Interaction of serotonin and nitric oxide (NO) in activation of the serotoninergic system in Helix].

Serotonin and the NO donors were shown to induce excitation in all serotoninergic neurones under study and to activate synchronous synaptic input in the Helix brain. The serotonin effects may be blocked by 5,7-DOT and N-monomethyl-L-arginine. The 5,7-DOT blocked activation of the NO-induced synchronous bursts but did not affect their activating effect. The data obtained suggest that serotonin and NO equally regulate the serotoninergic system's function in the snail brain. The effects of serotonin and NO are interconnected and interdependent. A possible role of the NO as a second messenger during serotonin activation and as a serotonin co-transmitter in presynaptic neurones, is discussed.

5,7-Dihydroxytryptamine↗
PubMed1998

[NO donors transform neuronal response to glutamate].

Electrophysiological experiments on three identified neurones were performed. Two NO donors, sodium nitroprusside (SNP) and sodium nitrite, as well as NO synthase inhibitor, were used. In each neurone, bath application of glutamate caused hyperpolarization and suppression of firing. Combined application of glutamate and SNP resulted in that the same cells responded to identical glutamate solutions with depolarization and excitation. Application of N-monomethyl-L-arginin (NMMA) arrested the glutamate-induced firing and depolarization. The findings suggest involvement of NO in the mechanism of transformation of glutamate-induced inhibition into excitation and a mediation of the latter by the N-methyl-D-aspartate-like receptors in the Helix brain.

Animals↗
PubMed1991

[The neurochemical mechanisms regulating the burst activity in isolated endogenous oscillators in the snail: the role of monoamines and opioid peptides].

Electrical activity of three different isolated identified bursting neurons in the Helix brain is studied. A new method for isolation of identified neurons is worked out. The data obtained demonstrate that all three neurons are endogenous oscillators: isolated neurons reveal spontaneous changes from inactive condition to regular activity, from regular activity to bursting one and on the contrary. Moreover it is shown that bursting activity in all three isolated neurons can be regulated by the same neurochemical agents: serotonin, enkephalins; combined action of dopamine and enkephalins stimulates bursting activity in these neurons, while dopamine inhibits it. The possible role of these neurochemical mechanisms in generation of rhythm for different rhythmical functions is discussed.

Animals↗
PubMed1988

[Neurons of the edible snail involved in controlling the rhythmic movements of the pneumostome].

Three neurons in left parietal ganglion of Helix pomatia have been described that can have a synchronous burst activity and involve rhythmic movements of the pneumostome. It is shown that the burst activity of these cells is a result of synchronous giant IPSP in one case and of generation of the membrane potential slow waves in another one. There is no synaptic or electrical connection between three cells. Serotonin stimulates generation of the membrane potential waves and burst activity by all three neurons. Investigation on isolated cells shows that these cells are not endogenic oscillators. Isolated neurons never have the burst spike activity, but only pronounced regulated one. Study on semi-intact preparations shows that the above neurons control rhythmic movements of the pneumostome.

Animals↗
PubMed1985

[Induction of slow membrane potential oscillations and burst activity in neuron PPa1 of Helix pomatia by a calcium ionophore and serotonin].

The nonbursting pattern of activity of the neuron RPa1 in preparations from dormant snails Helix lucorum was reversibly transformed into the bursting one by addition of Ca-ionophore A23187 (10(-6)-10(-5) M) or serotonin (10(-5)-10(-4) M) into the saline. The slow waves underlying bursts disappeared in presence of quinine (10(-4) M) thus suggesting involvement of Ca-dependent K-conductance in the mechanism of burst generation.

Action Potentials↗
PubMed1983

[Specificity of the selective sensitivity of electrosensitive neuron membranes to low-frequency sinusoidal stimulation].

A difference in sensitivity of mollusk's neuron to intracellular injection of sinusoidal current (1-10 Hz; 5.10(-10)--5.10(-9) A) was found as well as the complete cessation of activity at certain frequency--amplitude characteristics of the current ("windows" of blocked activity) and an increasing activity at other frequency--amplitude parameters of the current ("windows" of growing activity). This may be due to some properties of the neuron's electrosensitive membrane: the specifics of the voltage--current characteristics, membrane capacity as well as the property known as "force--duration" relationship. The key importance lies in the dependence of the hyperpolarization of the neuron upon the amplitude and the frequency of the sinusoidal irritant.

Action Potentials↗
PubMed1983

[Changes in the input resistance and membrane potential of a neuron developing a trace effect].

Trace effects in the change of spike activity, input resistance (Rinp) and membrane potential of neurons of the mollusk brain were studied in 36 "silent" brain neurons of Limnaea stagnalis in conditions of 20-min intracellular application of sinusoidal current with the threshold frequency 0.1 Hz. Some neurons revealed the effect of facilitation: the rise of activity with membrane depolarization and an increase of Rinp. Other neurons revealed the fall of activity accompanied by hyperpolarization and a decrease of Rinp. The change of Rinp as a trace effect is at its maximum at the frequency of the current used in the intracellular application. This suggests that the neuronal plasticity in "learning" is just based on the Rinp trace effects. Some of the neurons revealed no change in Rinp, membrane polarization or electrical response to applied stimulation. Possible origin of the above effects is discussed.

Animals↗
PubMed1982

[Effects of sinusoidal transmembrane currents on the electrical parameters of neurons].

The transmembrane resistance of molluscan neurons falls with increasing of sinusoidal current frequency from 0.1 to 10.0 Hz owing to the capacity properties of cell's membrane. Consequently, the low--frequency current of the same intensity is more effective. Transmembrane sinusoidal current can induce either hyperpolarization or depolarization of different neurons, apparently depending on the current--voltage relations in the membrane of these neurons. Sinusoidal current of low intensity can selectively increase the underthreshold rhythmic activity of neurons up to generation of action potentials at the frequency of neuron's own activity.

Animals↗
PubMed1980

[RNA synthesis in mammalian nerve cells in vitro].

Neurons of spinal ganglia of adult rabbits were cultivated during 4 days in rolling tubes, RNA synthesis of these neurons being determined by radioautography. In neurons of isolated ganglia, 1 hour following isolation, RNA synthesis was active and decreased up to 64% compared to the initial level only at the fourth day of cultivation. In small neurons, RNA synthesis was more active than in large ones. After addition of exogenous RNA precursors into the medium, the uptake of 3H-uridine increased, especially in large neurons.

Animals↗
PubMed1979

[Interferometric study of a single living neuron in relation to its electrical activity].

Interferometric microscopic study of living neurons of the isolated brain of Limnaea stagnalis has revealed some fluctuation of dry weight of the cytoplasm and the nucleolus in the absence of electrical activity of the neuron. The character of these changes was different for different neurons. During the neuron-induced generation of action potentials in response to the intracellular electrical stimulation, the changes in dry weight became similar for all neurons: the dry weight of the cytoplasm increased and the dry weight of the nucleolus decreased. This effect grew with the time of stimulation.

Animals↗
PubMed1977

[RNA synthesis in giant mollusk neurons following generation of action potentials in response to direct stimulation].

With the aid of autoradiographic and microelectrode methods, it was shown in vitro that the H3-uridine incorporation in the giant neuron decreased during generation of AP. Relationship between the changes of RNA synthesis in the neuron and the number of APs generated by the cell was nonlinear. The same character of the changes in RNA synthesis was shown elsewhere during stimulation via the nerve and generation by neuron of antidromic and ortodromic APs. The data obtained can be regarded as the evidence corroborating regulation of RNA synthesis in the neuron by activity of electro- and chemoexcitable membrane of the cell.

Action Potentials↗