Search PubMed⌕ Search

Biomedical subjects

G N Akoev

Publications and source records attributed to G N Akoev.

At least 55 records · Page 3Linked to original sources
PubMed1991

[Structural-functional changes in the peripheral nerves after administration of several drugs].

Structural and functional changes in the sciatic nerve induced by some drugs were studied using morphological and electrophysiological methods. It was stated that the application of this drug on the nerve causes different degenerating changes. Electrophysiological data, using the regeneration of action potential, proved the presence of structural changes in the nerve after application of mentioned drugs and showed partly preserved conduction of the nerve trunks.

Action Potentials↗
PubMed1990

[Skin mechanoreceptor functioning in the white rat during transcranial electrostimulation].

Functional properties of skin afferents were studied by the method of registration of spike activity from single nerve fibres, innervated non-hairy skin in white rats. It was found that mechanoreceptor units varied by the threshold intensity of applied stimulus. These units were divided to three functional groups: low-, medium- and high-threshold units. Transcranial electrical stimulation (TES) strongly affected on the functional characteristics of skin afferents. Full suppression of responses was observed in 18-20 min. irrespective of the category of units. A local intracutaneous injection of naloxon eliminated the effect of TES. It is supposed that endogenous opioid peptides regulate an afferent discharge on the level of sensory endings during TES.

Animals↗
PubMed1990

[The effect of transcranial electrostimulation of the opioid structures of the brain on peripheral nerve regeneration in the rat].

Transcranial electrical stimulation of opioid brain structures was studied for its effect on the sciatic nerve of rat after transection and microsurgical restoration of the nerve. It was shown that electrical stimulation accelerated regeneration of sensory and motor fibres of the sciatic nerve. Participation of endogenous opioid peptides in the regeneration of peripheral nerves is discussed.

Animals↗
PubMed1990

[Changes in the excitability of the skin mechanoreceptors in the rat against a background of transcranial electrostimulation].

Alterations in excitability of low-, medium- and high-threshold single mechanoreceptors (SMRs) of hairless hind paw skin elicited by transcranial electrical stimulation (TES) in analgesic regime were studied in anesthetized rats. Evoked impulsations of low- and medium-threshold SMRs were blocked by TES that lasted for about 1 and 5 min, respectively. TES for 18-20 min in duration abolished the reactions of high threshold SMRs activated only by nociceptive stimuli. Inhibitory effects of TES on all SMR types under study were eliminated by preliminary intraperitoneal or local intracutaneous (near SMRs location) injection of naloxone. Possible mechanisms of analgesic TES effects are discussed. An assumption is made that alterations of the SMR function are connected with an increase of the output of endogenous opioid peptides from the brain during TES.

Animals↗
PubMed1989

[Substantiation of the use of terrilytin in the treatment of spinal cord disorders in tuberculous spondylitis].

Experiments on mice and studies with organotype cultures of the spinal ganglion showed that terrilytin, a proteolytic enzyme had neurite stimulating activity and promoted regeneration of the spinal marrow tissue after affection (squeeze). On the basis of this property and a previously observed favourable effect of the enzyme on microcirculation, the capacity for more rapid rarefaction and elimination of caseous masses and prevention of excessive fibrosis, it was recommended for use in treatment of cerebrospinal disorders in tuberculous spondylitis. A procedure for the treatment was developed. The clinical trials with 46 patients (22 in the main group and 24 in the control group) showed high efficiency of the procedure.

Amylases↗
PubMed1989

[Analysis of the effect of quisqualate, N-methyl-D- aspartate and several blockers of amino acid receptors on synaptic transmission in the ampullae of Lorenzini].

Effects of bath-application of quisqualate (Q), N-methyl-D-aspartate (NMDA) and antagonists of NMDA-receptors: D-amino-adipate (AA), 2-amino-4-phosphonobutyrate (APB), 2-amino-5-phosphonovalerate (APV) and Mg2+ as well as acidic amino acid antagonist: D-glutamylglycine (DGG) on the synapse between the electroreceptor cells and afferent fibres were studied in the ampullae of Lorenzini. Q (threshold concentration 10(-8) M) and NMDA (threshold concentration 10(-5) M) strongly excited afferent fibres. Neither AA nor APB influenced the resting and evoked activities. APV blocked the synaptic transmission. Mg2+ (30-50 mM) blocked the responses to NMDA, while Q-induced responses were not affected, APV preferentially blocked NMDA-induced responses and in lesser degree--L-aspartate (L-ASP)-induced responses. DGG blocked the synaptic transmission. It is supposed that the synaptic receptor could represent a homogeneous receptor with different binding sites to the known agonists.

2-Amino-5-phosphonovalerate↗
PubMed1989

[The growth and morphophysiological study of the bushy tissue receptor in a nerve tissue culture].

The conditions for growing bush receptors on collagen substrate in presence of 2-4 ng/ml highly purified brain neurite stimulating protein were determined in the study of spinal ganglia cultures of 10-11-day chicken embryos. The degree of neurite branching and sinuosity and the distribution density of preterminals of cultured bush-like receptors are like those of chicken embryos' natural interoceptors. The ultrastructure of end receptor plates in culture resembles that of natural mechanoreceptor terminals. Cultural receptors are characterized by spontaneous electrophysiological activity. They respond to tactile irritation with bursts of discharges.

Animals↗
PubMed1989

[Effect of neurite-stimulating protein on the growth and proliferation of peripheral glia cells].

Proliferative activity of peripheral glia was investigated in the organotypic culture of peripheral nerves of 9-10-day old chick embryos. The neurite-stimulating protein, a stimulator of the neurite growth in the organotypic culture of spinal ganglia, being added to the culture media sharply increased the mitotic activity of glia: on the 3d day its level was 3.5 times higher as compared with the control one.

Animals↗
PubMed1989

[The effect of the opioid peptide dalargin on the regeneration of the rat sciatic nerve].

The effect of synthetic analog of leucine enkephalin hexapeptide dalargin on regeneration of peripheral nerves involved an activation of the sensory and motor fibers regeneration after transection and microsurgical restoration of the rat sciatic nerve. Endogenous opioid peptides seem to take part in the regulation of structural homeostasis of the nervous system.

Animals↗
PubMed1988

[Comparative analysis of brain neurite-stimulating protein and nerve growth factor by using a culture of chick embryo sensory neurons].

The effect of brain neurite-stimulating protein (BNSP) on growth and differentiation of nerve cells was studied in cultured chick embryo neurons BNSP stimulated axon growth. Its chemical characteristics were different from those of neurotrophic factor (NGF). The effect of NGF antiserum was not blocked by the BNSP action. The neurite-stimulating effect of BNSP can be used for stimulation of regenerating processes in the nervous tissue.

Animals↗
PubMed1988

[Kinetics of the inactivation of tetrodotoxin-sensitive sodium channels in the spinal ganglion neurons of rats].

The assessment of TTX-sensitive sodium transmembrane ionic current induced by depolarizing shifts in the MP performed in neurons of isolated dorsal root ganglion of adult rats revealed that the kinetics of the inactivation of TTX-sensitive sodium channels was more complicated than suggested by Hodgkin and Huxley for gating devices, the behaviour of the inactivation system following at least two exponential kinetics.

Animals↗
PubMed1988

[Possible role of the potential-dependent potassium channels in the generation of responses of the pacinian corpuscles].

Action of TEA (20 mM) and 4-AP (5 mM) on mechano- and electrically excitable membranes of the Pacinian corpuscles was studied by means of the air gap technique in constantly perfused preparations. Extracellular recordings of receptor and action potentials have shown that application of TEA causes prolongation of the receptor potential and inhibition of its amplitude by 40%. 4-AP has no effect on the mechanosensitive membrane. TEA and 4-AP induce a 2-3 fold increase of the action potential duration in the first Ranvier node. The computations based on the Dodge model help revealing that inhibition of voltage-sensitive potassium channels which participate in the first-order coding of the intact receptor accounts for this increase.

4-Aminopyridine↗
PubMed1988

[Effect of antagonists of excitatory amino acids on synaptic transmission in the electroreceptors (Lorenzini's ampullae) in skates].

Ampullae of Lorenzini isolated from the skate (Raja clavata) have been investigated in vitro electrophysiologically to determine the nature of the transmitter at the synapse between the electroreceptor cells and afferent fibres. Glutamic acid diethyl ester (GDEE), glutamic acid dimethyl ester (GDME), kynurenic acid (KENYA), cis-2,3-piperidine dicarboxylic acid (PDA) reversibly decreased the resting and stimulus-induced activity. These antagonists also blocked postsynaptic responses induced by glutamate and aspartate. D-alpha-aminoadipic acid (DAA) had no effect on the afferent activity. These findings suggest that glutamate, aspartate or a related compound may be a transmitter at this synapse. An important physiological role of quisqualate receptors in ampullae of Lorenzini is also inferred from these experiments.

2-Aminoadipic Acid↗
PubMed1988

[Restoration of the innervation of the extremity of the rat after joining the ends of the damaged nerve with a microsurgical suture].

Morphofunctional restoration of the cut ischemic nerve has been studied after its connection by means of a microsurgical suture. The investigations have been performed on 20 male rats. In 6 months after the operation the average diameter of the regenerating nervous fibers is 5.0-6.5 mcm and, as in an intact nerve they have a wavy course. Myelin decay products and inflammatory infiltrates are revealed in the nerve but sometimes. All the parts of the plantar skin are well reinnervated. Cutaneous epidermis of the sole and the digital pads possesses an extremely rich innervation. Characteristics of M-responses, registered from the m. gastrocnemius, approaches the norm in 2 months after the operation. In 10% of fibers of the regenerating ischiatic nerve impulse activity begins to be registered in 20-30 days after the operation. Gradually the borders of the receptor fields become wider and in 3 months they spread all over the whole sole. In 5-6 months the impulse reaction of the regenerating nerve fibers does not differ from that in non-operated animals. Thus, use of the microsurgical suture results in a successful regeneration of the rat ischemic nerve and in a rather short time. The restorative dynamics of the extremity tissue innervation can be presented as following: at first somatic muscles get innervation and then, as the afferent fibers grow in the periphery, the plantar skin and the skin of the digital pads is the last to get innervation.

Animals↗
PubMed1987

Effects of kainic acid on synaptic transmission in electroreceptors (the ampullae of Lorenzini) of skates.

1. Effects of kainic acid (KA) on resting and evoked activities of the ampullary electroreceptor were studied in marine skates (Raja clavata). 2. Perfusion of the basal membrane with 10(-6)-10(-9) M KA produced significant and reversible changes in impulse activity depending on initial firing rate. 3. When synaptic transmission was blocked by perfusion with elevated Mg2+, the resting and evoked activities were restored if KA was added. 4. The results are consistent with the view that KA is a potent excitant of the ampullae receptors and its effects appear to be presynaptic.

Animals↗