Stimulation of protein synthesis in dystrophic brain cortex neurons of hypoxia-subjected rats by proliferation-activating protein isolated from nervous tissue of newborn animals.

Hypoxia causes mass diffuse dystrophy of brain cortex neurons, reduces RNA and protein synthesis in neurons and DNA synthesis in the total brain cortex in adult rats. Subsequent transplantation of embryonic nervous tissue (ENT) into the brain of hypoxia-subjected rats normalizes the structure of a considerable part of dystrophic neurons. A protein activator (molecular mass 30,000 D and PI 6.8) was isolated from intensively proliferating cerebellum tissue of newborn rats, dissolved in physiological solution, and injected into one of the hemispheres of hypoxia-subjected rats. The activator significantly stimulated the proliferation of recipient brain cells and normalized the protein biosynthesis in cortical neurons of the recipients like an ENT transplant. Injection into the brain of hypoxia-subjected rats of a physiological solution alone does not produce such an effect. The presented results have been obtained by the methods of autoradiography and biochemistry using 3H-leucine for estimating the intensity of protein synthesis by its incorporation into cells.

Normalization of protein synthesis and the structure of brain dystrophic neurons after the action of hypoxia, 10% NaCl and organ-specific RNA.

It was shown previously (Polezhaev and Alexandrova, 1986) that hypoxic hypoxia causes mass (up to 30%) diffuse dystrophy of brain cortex and hippocamp neurons in rats, disturbances in the higher nervous activity, reduction of protein, RNA synthesis in neurons and of DNA synthesis in the whole brain cortex. Transplantation of embryonic nervous tissue (ENT) in one of the hemispheres normalizes all the above abnormalities observed in some neurologic and mental diseases in humans. However, transplantation may entail injuries of parenchyma and brain blood vessels. This forces researchers to search for another biological method similar by its action but safer and simpler. ENT transplantation has a dual action: 1) formation of biologically active substances (BAS) releasing from the ENT transplant and from the host brain nervous tissue upon operation; 2) establishment of synaptic connections between the transplant and host neurons. Previously we (Vitvitsky, 1987) described the isolation of BAS from rat forebrain in the form of organ-specific RNA. The latter was injected intraperitoneally several times to post-hypoxic rats in which 30 min prior to that the blood-brain barrier (BBB) was opened by injecting intravenously and intraperitoneally 10% NaCl solution without damaging the host brain. At the beginning 10% NaCl increased the destruction of brain cortical neurons and then stimulated protein synthesis in them. RNA injections stimulated the synthesis in cortical neurons and normalized their structure. Thus, we propose a safe and simple method for normalization of dystrophic neurons which can be used after certain improvement for curing neurodegenerative and neuropsychic diseases in humans.

Normalization of protein synthesis in dystrophic neurons of cerebral cortex in rats after hypoxia, opening of the blood-brain barrier and treatment with organospecific RNA.

The possibility of normalization of protein synthesis intensity was explored in dystrophic neurons and in the total brain cortex of rats after acute hypoxic hypoxia. We avoided transplantation of embryonic nervous tissue (ENT) into the rat brain, as we did before, as well as operations and brain damages in opening of the blood-brain barrier (BBB) caused by hypoxia and intramuscular injections of organo (brain)-specific RNA. As shown by the autoradiographic and biochemical methods using radioactive isotopes (3H-leucine), hypoxia causes a statistically significant reduction in the intensity of protein synthesis which increases and becomes normalized after injection of brain-specific RNA into femoral muscles of animals. Thus, it is possible to normalize hypoxia-inhibited compensation-restoration processes in the brain cortex of animals and, probably, the function of the higher nervous activity using the new simple and harmless biological method. The data presented are of priority significance and important both for development of a number of fundamental biological problems and for medicine since the described method permits the treatment of some serious nervous and mental diseases in humans.

Stimulation of RNA synthesis in brain cortex of rats after hypoxia by transplantation of embryonic nervous tissue.

Our early studies (Polezhaev and Alexandrova, 1986) have shown that acute hypoxic hypoxia in rats causes mass (up to 36%) diffuse dystrophy of brain cortex neurons and that after transplantation of embryonic nervous tissue (ENT) into the brain of hypoxia-exposed rats the dystrophy and death of cortical neurons are reduced to 25% due to normalization of a part of dystrophic neurons. In the present work we studied changes in the RNA synthesis in neurons and in the total brain cortex of rats after hypoxia and subsequent transplantation of ENT into their brain by the autoradiographic and biochemical methods using 14C-adenine. It has been shown that under the action of hypoxia the RNA synthesis in neurons and in the total brain cortex of rats is reduced and after transplantation of ENT into the brain of these rats the RNA synthesis is stimulated and normalized both in neurons and in the total brain cortex.

Normalization of protein synthesis in brain cortex of rats after hypoxia by transplantation of embryonic nervous tissue.

It has been shown autoradiographically using 3H-lysine-3H-glycin mixture that acute hypoxic hypoxia leading to mass diffuse dystrophy of brain cortex neurons in rats causes a statistically significant decrease in the level of protein synthesis in cortical neurons. The biochemical study of the same material using 3H-leucine has demonstrated that the overall level of protein synthesis in the total cortical tissue (in nerve and non-nerve cells) is not reduced after hypoxia probably due to a high resistance of glial and other non-nerve cells to oxygen deficiency. Transplantation of embryonic nervous tissue into the brain of rats exposed to hypoxia results not only in normalization of the structure of a part of dystrophic neurons but also in a statistically significant increase in the level of protein synthesis which is retained up to the end of the experiment (i. e. for 120 days following the operation) in the total cortical tissue and reaches the normal value in neurons as established autoradiographically.

[Development of magnocellular neurosecretory neurons in embryonic hypothalamic tissue transplanted into the cavity of the 3d cerebral ventricle of adult rats]. / Razvitie magnotselliuliarnykh neirosekretornykh neironov émbrional'noi tkani gipotalamusa, peresazhennoi v polost' III zheludochka mozga vzroslykh krys.

Magnocellular neurosecretory cell (MSC) ontogenesis was comparatively assessed in normal rat hypothalamus and in fetal hypothalamic tissue transplanted into the third ventricle of the adult rat brain. 3H-thymidine uptake has shown that the time of origin of NSC in grafted tissue and supraoptic nucleus of normal rat fetuses was similar. NSC pericarions in grafts were well developed and contained neurosecretory material (NSM). Nuclear and nucleolar volumes did not differ from those in adult animals. Water deprivation was followed by a significant increase in nuclear and nucleolar volumes and NSM content in pericarions of grafted tissue, which suggests that raised synthetic activity was not accompanied by an increased NSM release. It is concluded that proliferation and specific differentiation of NSC precursor cells are invariably determined by genetic factors. The origin of neurosecretory nuclei and their specific connections is considerably influenced by conditions of tissue surroundings.

Changes of DNA synthesis in brain cortical cells after transplantation of embryonic nervous tissue into the brain of rats after hypoxia.

Autoradiographic and biochemical studies with 3H-thymidine have shown that after transplantation of embryonic nervous tissue of rats into the brain of adult rats, intact and subjected to acute hypoxic hypoxia causing mass dystrophy of neurons in the brain cortex of recipients, there occurs stimulation of DNA synthesis in non-nerve cells: glial cells, macrophages and endothelial cells. Stimulation is much more pronounced in the operated hemisphere than in the non-operated one and in intact rats than in hypoxia-subjected ones. On the whole, DNA synthesis was not observed in brain nerve cells except individual neurons located near the wound canal and the transplant.

DNA synthesis and mitotic division of cortical neurons in adult rats upon intrabrain transplantation of embryonic nervous tissue.

The possibility of DNA synthesis and mitotic division of brain neurons in mammals was experimentally studied. Brain cortex tissue of 17- and 20-day-old rat embryos was transplanted into the sensomotor region of the right brain hemisphere of adult Wistar rats weighing 160-200 g, intact and subjected to hypoxia. 3 days after operation part of animals was injected intraperitoneally with 3H-thymidine at a dose of 10 microCi/g b.w. and killed after 4 days. Brain tissue containing the transplant was used for preparing histological sections and the surrounding cortex tissue was used for obtaining squashed preparations. Preparations of the both experimental series were treated autoradiographically and stained with cresyl-videt. It has been established that in the both experimental series some recipient cortical neurons surrounding the transplant intensively incorporate 3H-thymidine in their nuclei (i.e. replicatively synthesize DNA) and a number of nerve cells are in the state of mitotic division. An electron-microscopic study has confirmed that part of mitotically dividing cells have characteristics of neurons: oval bodies without pseudopodia electron-dense cytoplasm with developed organelles and RNP-particles typical of neurons, axonal terminals on the body, and satellitary glia.