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Biomedical subjects

L V Polezhaev

Publications and source records attributed to L V Polezhaev.

At least 37 records · Page 2Linked to original sources
PubMed1986

Normalization of dystrophic brain cortex neurons after hypoxia and transplantation of embryonic nervous tissue in rats.

It was established by us previously that mass reversible and irreversible dystrophy and death of neurons occur in the cortex and hippocampus of adult rats after acute hypoxic hypoxia. Transplantation of embryonic nervous tissue into the brain of rats exposed to hypoxia leads to partial normalization of the nervous tissue and brain cortex and to the reduction in the number of irreversibly degenerative neurons. The objective of the present work is to find out how this visually detected normalization of brain cortex is achieved: by means of elimination of dead neurons and preservation of normal ones or by means of compensatory-restorative processes on the cellular and intracellular levels. To elucidate this question, adult Wistar rats were subjected to acute hypoxic hypoxia and cortex tissue pieces of 19-day-old rat embryos were transplanted into their brain and the brain of intact rats. Intact and hypoxia-subjected rats served as a control. Parts of their brain were injured by puncturing with a syringe needle and injecting 0.01 ml of physiological solution. The rats were killed 4 and 100 days after the operation, their brains were examined histologically and the number of normal nerve cells and those with signs of irreversible and reversible dystrophy or compensatory restoration per 1,000 neurons was determined: uninucleolate, binucleolate, binuclear and paired morphologically similar nerve cells. It has been established that normalization of brain cortex in rats after hypoxia and transplantation occurs not only due to elimination of dead neurons and preservation of normal ones but mainly due to transition of reversibly degenerative neurons into the normal state and, probably, partly due to compensatory-restorative processes on the cell level. Transplantation has a stronger influence than a single injury of the brain.

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PubMed1985

Transplantation of dissociated embryonic brain cells in the brain of adult normal rats and rats subjected to hypoxia.

3H-thymidine-labelled dissociated brain cells of rat embryos were implanted in the brain of adult normal and hypoxia-subjected rats. In both cases these cells survived successfully, differentiated into neurons and glial cells and remained viable throughout the whole experimental period (60 days). These cells were able to synthesize DNA and divide. Dissociated cells of rat embryo brains tended to aggregate after transplantation and were present not only as single neurons but also as large neuronal assemblies having the shape of islets and columns. These cells promoted considerable normalization of degenerated rat cortical neurons after hypoxia.

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PubMed1985

Morphological, biochemical and physiological changes in brain nervous tissue of adult intact and hypoxia-subjected rats after transplantation of embryonic nervous tissue.

Data of morphological, biochemical and physiological investigations of brain nervous tissue in adult intact and hypoxia-subjected rats after transplantation of rat embryonic nervous tissue are presented. It has been established that transplants survive and develop successfully in the brain of both intact and hypoxia-subjected rats. The Golgi technique reveals that transplanted neurons form dendrites and axons. They also establish afferent and efferent connections with neurons in different brain regions of the recipient, as has been demonstrated by the horseradish peroxidase (HRP) tract tracing technique. Hypoxia induces reversible as well as irreversible dystrophy of host brain neurons, and transplantation of embryonic brain tissue leads to considerable normalization of the state of reversibly dystrophic neurons. Biochemical investigations have revealed that the spectrum of cytoplasmic proteins of neurons and proteins of the whole brain cortex tissue changed after hypoxia are significantly normalized after subsequent transplantation. It should be also pointed out that there is a considerable increase in the number of proteins in certain fractions which is correlated with regeneration of reversibly dystrophic neurons and other cortical cells. Electrophysiological experiments revealed distinct but short-term EEG changes induced by hypoxia. 1-2 days after hypoxia all EEG parameters were back to normal and displayed no changes during the 2-3-month registration period.

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PubMed1984

Transplantation of various regions of embryonic brain tissue into the brain of adult rats.

Brain tissue from the cortex, midbrain (corpora quadrigemina ) or cerebellum was transplanted into the lateral ventricle or parenchyma of the right brain hemisphere of adult Wistar rats. Brain tissue transplants consisted of undifferentiated matrix cells and few neuroblasts. 30 and 110 days after operation transplants showed good development both in the lateral ventricle and inside parenchyma. They differentiated into organotypical and histotypical structures and cells similar to those formed in the normal development. Cortical structures developed from the cortex tissue, cerebellar structures from the cerebellum tissue, and nuclei white substance of corpora quadrigemina where formed from the midbrain tissue. Nerve and glial cells of transplants are well differentiated, tightly connected with the surrounding nervous tissue of the recipient, and remain viable by the end of the experiment. The immune response of the host to the transplant is not expressed. The behaviour of animals remains normal. The present experiments are the beginning of studies on grafting brain embryonal tissue to mammals with some nonhereditary and hereditary changes of the central nervous system (CNS) for our further investigations.

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PubMed1984

Transplantation of embryonic brain tissue into the brain of adult rats after hypoxic hypoxia.

Brain cortex tissue of 20-day-old rat embryos ( E20 ) was transplanted into the brain parietal region of adult Wistar rats 22 days following their exposure to acute hypoxic hypoxia. 91 days after hypoxia and 69 days after transplantation the rats were killed and their brain was studied histologically. Hypoxia has been found to cause strong dystrophy, irreversible degeneration (shrunken and lysis) and the death of numerous cortex neurons. Nevertheless the transplanted E20 rat brain tissue develops in 100% of cases in the brain of recipients. Transplants have a considerably large volume (7 mm3) and establish a close morphological connection with the neughbouring nervous tissue of the host's brain. Transplants contain viable nerve and glial cells. E20 rat brain transplants improve to a certain extent the state of hypoxia-exposed dystrophic neurons of the recipient's brain. The decay products released from the transplanted E20 rat brain tissue influence the recipient's brain tissue, and neurons of the transplants establish a close morphological, probably synaptic, connection with neurons of the host's brain tissue.

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PubMed1983

[Allotransplantation of embryonic brain tissue into the brains of adult mammals during hypoxic hypoxia].

In order to simulate some manifestations of nervous system pathologies in humans and to examine the feasibility of normalizing the status of cerebral neurons in the case of their reversible dystrophy, cortical tissue from the brain hemispheres of rat embryos was transplanted into the parietal region of the brain in mature Wistar rats which had been previously exposed to hypoxic hypoxia. Hypoxia caused dystrophy, irreversible degeneration (shrinking and lysis) and death of large numbers of neurons in the cortex of the large hemispheres. The transplanted embryonic cerebral tissue developed into the normal nerve and glial cells in the brain of all the recipients. These cells established close morphological bonding with the adjacent nerve tissue of the hosts, which was accompanied by improvement in the state of neurons affected by reversible dystrophy.

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