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Biomedical subjects

E V Loseva

Publications and source records attributed to E V Loseva.

At least 19 recordsLinked to original sources
PubMed2006

A special case of learning disorder in isolant rats as a model of disintegration.

The combination of two factors - isolation and ontogenesis (starting from 21 days) and subsequent training of rats to a cyclical habit - could in some animals (30%) lead to the formation of unusual behavioral strategies consisting of maintenance of the cyclical habit without reinforcement with food. This dissociation from the vital motivation is regarded as an analog of the disintegration phenomenon, a key step in psychoneurotic disorders. The most common type of disturbance in isolated animals was suppression of searching activity, with extreme learning difficulty, though a training process including a two-month break led to a significant increase in motor-searching activity in this situation. These behavioral abnormalities were accompanied by morphological changes in the sensorimotor cortex of the brain, with a relative thinning of layer 5 and selective decreases in the density of satellite glial cells and deviations from the normal correlational relationships between behavioral and neuroglial measures.

Animals↗
PubMed2005

Transplantation of cultured astrocytes attenuates degenerative changes in rats with kainic acid-induced brain damage.

Viability of astrocyte grafts introduced into CA1 pyramidal layer of the left dorsal hippocampus after injection of kainic acid into this brain region and the effects of these grafts on the hippocampus and amygdala were studied on Wistar rats. In rats with astrocyte grafts the degree of destruction in fields CA1-CA2 of the dorsal and ventral hippocampus, fields CA3-CA4 of the ventral hippocampus, and central and basolateral amygdala was lower compared to animals with kainic acid-induced hippocampal damage and control rats; destructions in the dentate fascia were absent. Our results suggest that astrocyte grafts stimulate neurogenesis in the mature brain of recipient rats with kainic acid-induced brain damage.

Amygdala↗
PubMed2005

The effects of Mexidol on the acquisition of food-related conditioned reflexes and synaptic ultrastructure in field CA1 of the rat hippocampus after single acoustic stimuli with ultrasonic components.

The effects of a complex acoustic signal with ultrasonic components on the ultrastructure of synapses field CA1 of the rat hippocampus were studied in conditions of two-week courses of the wide-spectrum antioxidant Mexidol (compared with an untreated group); the effects of complex acoustic signals on the dynamics of acquisition of a food-related conditioned reflex using a standard stimulus (a tone) and on the acquisition of a trace conditioned reflex to estimating time intervals were also studied, in the same groups of rats. Controls consisted of unstressed rats treated and not treated with Mexidol. Ultrastructural analysis of the redistribution of vesicles in the synaptic terminals of hippocampal field CA1 showed that synaptic transmission was impaired when assessed one day after exposure to the complex acoustic signal. Mexidol prevented impairment of synaptic transmission. The complex acoustic signal had negative effects on conditioned reflex activity in rats and Mexidol had normalizing actions on the acquisition of conditioned reflexes in stressed rats. These results lead to the conclusion that the antioxidant Mexidol can be applied to the prophylaxis of the impairments in CNS cognitive functions frequently seen in stress.

Acoustic Stimulation↗
PubMed2004

Human neural stem cells normalize rat behavior after hypoxia.

Transplants of cultured neural stem cells from human brain survived, retained multipotent activity, and produced a neuroprotective effect on degenerating neurons in the brain of adult rats subjected to hypoxic hypoxia. They normalized animal behavior and improved conditioning in two-way avoidance response paradigm in a shuttle box.

Animals↗
PubMed2004

Morphofunctional changes in neurons of hippocampal fields and neocortical layers in rats treated with Polydan.

Light microscopy revealed four types of neurons differing by staining intensity and size in each of the pyramidal neuron populations in the dorsal hippocampal fields and layer V of the neocortical somatosensory area and in granular cells of the dentate fascia and stellate cells of layer II of the same cerebrocortical area in rats. Treatment with Polydan according to different protocols led to redistribution of these types of cells, which attests to stimulation of synthetic processes in these brain areas, rather than to similar sequence of the involvement of different brain areas in this process. Polydan promoted the increase in the mean number of nucleoli in the nuclei of neurons of all types, the degree of this increase being different for each type. It seems that morphological signs (staining intensity and number and size of nucleoli in the nuclei) reflect certain functional states of the neurons in the homogeneous populations. Presumably, various factors can stimulate transition of neurons from one morphofunctional status into another.

Animals↗
PubMed2001

Comparison of reactive processes in the rat brain elicited by xenotransplantation of nervous tissues of chicken or pulmonate snail.

It is known that a histocompatibility system is not developed to the same extent in lower invertebrates as in vertebrate animals. We assumed that the xenografts from the newborn invertebrate nervous system would not exert destructive effects on the brain of the vertebrate recipient even without immunosuppressive therapy. In search of brain xenografts (XG) capable to survive in the brain of a recipient without intensive immunosuppression, we transplanted ganglia of terrestrial snails into the rat brain. We compared effects of transplantation of the XG taken from anterior brain of the 18-day embryo chicken (XGC) and from ganglia of a newborn terrestrial pulmonate snail (Helix aspersa L., XGSn). Part of the XGSn were stained by vital fluorescent dyes Bisbenzimid or Fast Blue before grafting. The XGSn were implanted into the neocortex parenchyma in each hemisphere. Rat brains with the XGC were examined 5 days after, and brains with the XGSn - 5 and 28 days after the transplantation. Nonstained sections with the XGSn labeled with fluorescent dyes prior to transplantation were investigated in fluorescent microscope and stained later with tionin and cresyl-violet. Quantitative videoimage analysis of lymphocyte aggregations, reactive gliosis, morphology of the XG areas, and implantation trace was performed. It was found that the XGSn transplantation did not elicit in the rat brain an intensive immunological conflict 5 and 28 days after transplantation. In contrast, the XGC rapidly elicited a strong immune response resulting in massive obliterations in the rat brain and were rejected in 5 days. Labeled snail glia and vessels were observed in the stained XGSn 28 days after transplantation by fluorescence imaging. Putative snail vessels grew into the rat brain from the place of snail tissue transplantation serving the humoral integration of the XG and the host brain. Migration of molluscan glial cells was observed in the brain of recipients.

Animals↗
PubMed2001

Development of neuronal ganglion xenografts from gastropoda in rat brain.

Survival of neuronal ganglia from newborn snail (Helix aspera L.) in the brain of adult rats was studied. Snail ganglion survived in the brain of warm-blooded animals for 6 months without inducing immune conflict. At early stages (5 days) after transplantation, xenografts increased in size and were several times larger than native ganglia from 10-day-old snails, thereafter (on days 28 and 180) they became smaller still surpassing the sizes of ganglia from snail of the corresponding age. Rapid enlargement of the xenograft was due to cell reactive processes in the ganglion. Deep penetration of large vessels from xenografts to rat brain was observed.

Animals↗
PubMed2000

The use of neural transplantation for suppression of seizure activity in genetically epilepsy-prone rats.

The possibility of correcting seizure activity with neural transplantation was studied in Wistar rats with audiogenic seizures and in Krushinskii-Molodkina rats with high level of audiogenic seizures. In Wistar rats seizures were absent during 24 weeks after combined bilateral transplantation of striatal and cerebellar tissue from newborn rats into the parietal cortex. The same transplantation performed in Krushinskii--Molodkina rats increased the latency of audiogenic seizures. In some rats the intensity of seizures decreased, but they did not completely disappeared. Suppression of seizure activity in Krushinskii-Molodkina rats was observed after transplantation of striatal and cerebellar tissue simultaneously into the parietal cortex and inferior colliculi.

Animals↗
PubMed1998

Cholinergic excitation of dendrites in neocortical neurons.

Discharge patterns were studied in response to iontophoretic application of acetylcholine to the soma and dendrites of 128 neocortical pyramidal neurons of layer V. Extracellular recordings were obtained from slices of the guinea-pig parietal cortex. All responses found were excitatory and were better expressed in spontaneously firing cells than in silent ones. Sensitivity to acetylcholine was approximately the same at somatic and dendritic sites in all the cells. Activation of muscarinic receptors gave rise to firing patterns with equal latencies and intensities when applied to both soma and dendrites. The latter suggests that membrane excitation elicited in dendrites by binding of acetylcholine to muscarinic cholinoreceptors is likely to propagate towards the soma through intracellular biochemical processes. Modulating effect of acetylcholine on output firing patterns, elicited by dendritic application of excitatory amino acids, included shortening of the somatic response latency and increase of response intensity and duration. We propose that, in contrast to glutamatergic excitation, the spread of cholinergic excitation along dendrites involves intra-cellular chemical signalling and results in changing the electrical properties of dendrites all over their length.

Acetylcholine↗
PubMed1991

Influence of brain embryonic tissue transplantation (early period) on rat's reactions of avoiding zoosocial and artificial stimuli.

The effect of the influence of brain tissue transplantation on behavior avoidance as zoosocial and artificial stimuli was examined in rats after unilateral transplantation of embryonic tissue to the cortex parietal region. Pieces of neocortex and hippocampus (NC + HC) were introduced to one group of twenty rats. Pieces of amygdala and hypothalamus (AM + HT) were introduced to twenty other animals composing a second group. Ten intact animals served as a control group. In the group receiving transplants of AM + HT, by one week after surgery the number of animals avoiding zoosocial stimulus was significantly increased. In the group receiving transplants of NC + HC, by one week after transplantation, a considerable increase in the time of avoiding artificial aversive stimuli was observed for most of the animals.

Amygdala↗
PubMed1991

Influence of neurotransplantation on rats' behavior with different conditions of reinforcement.

Recently, we have reported a marked rat lateralization in the T-maze choice. Embryonic rat tissue from neocortex, hippocampus, hypothalamus and amygdala was transplanted into intact rat brains in various combinations: 1) neocortex and hypothalamus (Neo + Hyp); 2) hippocampus and amygdala (Hipp + Amyg); 3) neocortex and hippocampus (Neo + Hipp); and 4) hypothalamus and amygdala (Hyp + Amyg). Once under conditions in which reinforcement was equally qualitative and equally probable, rats in all groups chose the T-maze arm contralateral to the side of implantation. In a second set of experiments, rats were presented a choice between quality and probability of reinforcement. The right arm of the T-maze contained a cup of water 33% of the time (high-quality but low-probability reinforcement). The left sleeve contained a solution of 0.15% quinine in water 100% of the time (low quality but high probability of reinforcement). Rats that received Neo + Hyp transplants chose the T-maze arm that always contained a drink cup with water significantly more often than they chose the arm that always contained the drink cup with quinine solution. Rats that received Hipp + Amyg transplants chose the arm containing the drink cup with quinine solution much more often than the arm that sometimes contained a cup of water. Rats with transplanted Neo + Hyp generally were more active than rats with transplanted Hipp + Amyg. These data suggest that the behavior of rats can be affected by selective transplantation of different brain tissue.

Amygdala↗
PubMed1990

[The action of neural transplantation on the brain of rats with a damaged temporal cortex].

Possibilities of transplantation of embryonic brain tissue into the left temporal cortex of the host brain damaged by kainic acid (KA) were investigated. In the group of rats with KA-damaged temporal cortex tissue necrosis and considerable destructions in some structures far from the temporal cortex were revealed. The contralateral hemisphere also had greater area of sections than ipsilateral hemisphere in this group. In the group of rats with viable transplants (T) from E-21 in the temporal cortex damaged by KA the destructions in the same structures and hemisphere asymmetry were negligible, that evidenced for a positive effect of neural transplantation. T from E-15 after its implantation into the cortex of the host brain were pushed out from the cortex on the surface of the brain. These T caused intensification of the negative effect of the KA influence. It was supposed that viable T in the area of the damaged cortex inactivated exciting mediators in this region and also perhaps substituted partly damaged cortex after T had formed connections with the host brain.

Animals↗
PubMed1989

The effect of embryonal amygdala grafts on the impairment of spatial working memory elicited in rats by kainate-induced amygdaloid damage.

The effect of epileptogenic lesion of amygdala on spatial working memory was examined in rats after unilateral (U, n = 9) or bilateral (B, n = 8) injection of 1 or 0.5 mu of 0.2% kainate into the amygdaloid complex. Another group of unilaterally lesioned rats (T, n = 9) received 8 days after kainate injection grafts of embryonal (E 20) amygdala into the damaged region. Twelve days after lesion the three experimental groups and an unoperated control group (C, n = 11) were trained during three weeks in the aversively motivated 8-arm radial water maze (RWM). Training decreased incidence of errors/8 choices from the initial 2.3 to 1.2 in the lesioned rats and to 0.4 in the controls. Transplantation did not enhance RWM acquisition but restored the symmetrical pattern of choices and normalized the emotionality of lesioned animals. Retraining the RWM task 3 months later revealed significant savings in the control group but not in the transplanted group. Histology showed in addition to large lesion at the injection site also distant lesions in the ipsilateral hippocampus, thalamus and neocortex and in the unilaterally injected rats also in the contralateral amygdala. Healthy, well integrated transplants found in 6 out of 9 transplanted rats reduced the incidence of remote lesions (particularly in the contralateral hemisphere). Performance of individual animals reflected the state of the transplant. It is concluded that the impairment of spatial working memory is due not only to destruction of amygdala but also to diffuse damage of the limbic system. The slowly developing seizure-induced distant lesions can be partly prevented by embryonal grafts.

Amygdala↗
PubMed1983

[Method of visually classifying synapses from a multiplicity of attributes].

Seven electron microscopic signs of synapses were recognized and classified visually. Altogether 2250 synapses of the stratum radiatum of the hippocamp of 15 white rats were examined on a statistical basis. Five rats (750 synapses) showed a significant decrease in the magnitudes of two signs of the synapses (the active zone length and the mean sectional area of the terminal) after the elaboration of the conditioned reflex. The concentration of synaptic vesicles adjucent to the active zone rose as compared to that seen in a passive control group (5 rats, 750 synapses). An active control group (5 rats) demonstrated a significant increase in the postsynaptic membrane thickness and sectional area of the terminal occupied by synaptic vesicles. The concentration of vesicles neighboring the active zone was noticeably lowered.

Animals↗
PubMed1981

[Quantitative histochemical determination of acetylcholinesterase activity in layers of the rat hippocampus].

A technique has been suggested for quantitative determination of the activity of acetylcholinesterase (AChE) in each layer of rat hippocamp histochemical preparations. The data obtained have been used for making up the maps of layer distribution of AChE activity. The maps have been prepared of AChe activity distribution for the field CA1, CA2 and CA3 of the hippocamp of rats decapitated in summer and autumn. The map for the field CA1 was compared with those made up with the aid of other quantitative histochemistry techniques. The maps for the field CA2 have been compared in rats decapitated in spring, summer and autumn. AChE activity has been found to be greater in spring than in summer or in autumn, with the relations between the layers being unchanged throughout all the seasons.

Acetylcholinesterase↗