Dynamics of protein concentration in the neurons of a chronic "mirror" epileptiform focus

Protein content in the neurons of layers III and V in the rat brain anterior-parietal cortex and the lateral thalamic nucleus was studied 11 and 63 days after cobalt implantation. In the course of the experiment, protein content increased by 44--49% in the neurons of layer III and decreased by 24--32% in the thalamic neurons. In small and large pyramids of layer V, protein content decreased by 21--28%, 11 days after cobalt implantation, and approached normal content by the 63rd day. It was concluded that according to morpho-functional characteristic of certain neuronal types (associative, in layer III, predominantly efferent, in layer V and associative neurons in subcortical formations of the lateral thalamic nucleus) their protein changes in response to convulsive activity were different.     

Histone alteration in the nuclei of different types of neurons in a "mirror" epileptiform focus in rat brain]

Total histones estimated after M. Alfred and I. Geschwind were studied cytophotometrically in nuclei of neurons of different types (layers III and V in the frontal-parietal cortex and in the thalamic lateral nucleus) of the "mirror" epileptiform focus in the rat brain on the 11th and 63d day after cobalt implantation. On the 11th day of the experiment, integral optic density of the histones decreased by 33%, 25% and 37%, and the area of the nuclei -- by 27%, 24% and 35% in the neurons of layers II and V in the frontal-parietal cortex and in the thalamic lateral neucleus, respectively. On the 63d, integral optic density of the histones in the neurons mentioned increased respectively by 42%, 52% and 42%, and the area of the nuclei -- by 21%, 43% and 27%. Concentration of the histones in the nuclei decreased by 3--9% on the 11th day and increased, except layer V, by 9--18% on the 63d of the experiment. Interconnection between changes in histone content and total proteins in cytoplasm of functionally different neurons in the "mirror" epileptiform focus is disscussed, with special reference to histones as a regular of genetic activity for protein synthesis.     

Catecholamine content of the rat brain at different stages of experimental alcoholism

Changes in the noradrenaline (NA) content in the hypothalamus, dopamine (DA) and homovanillic acid (HVA) in the striatum were determined in rats after chronic alcohol administration. A single injection of alcohol (2.5 g/kg i.p.) provoked a 30% decrease in NA only in rats predisposed to ethanol intake. Voluntary intake of 15% ethanol for 10 days made the NA content return to normal, the 4-month use of ethanol did not change whereas the 8-month use reduced the NA content by 17%, DA by 31% and raised the content of HVA by 25%. Twenty-four hours after alcohol abstinence the HVA content dropped by 13%. It is concluded that the noradrenergic system is involved in the formation and development of alcohol motivation and that the dopaminergic system participates in the development of the physical dependence and abstinence.     

Effect of adrenocorticotropic hormone on nucleic acid and protein synthesis and content in the brain of rat embryos in the early stages of neurogenesis]

The injection of adrenocorticotropic hormone (ACTH) of prolonged effect at the doses of 4 and 10 M. U. to the intact rats from the 11th till the 15th day of pregnancy resulted in the twofold increase of protein content in the brain and its decrease in the liver of 15 days old embryos, as compared with the control ones. The content of DNA, RNA and proteins in the placenta of experimental animals increased as well. The rate of incorporation of 3H-thymidine in the liver DNA and 14C-leucine in the liver and brain acid-soluble protein decreased within small intervals of time following the treatment. The total radioactivity of proteins in the liver, brain and placenta calculated per DNA unit was similar to the control one whereas the specific radioactivity of total protein in the liver of experimental embryos was higher than in the control.     

Characteristics of the late A-response of vasoconstrictor neurons in cats decerebrated at different brain stem levels]

In cats decerebrated at the level of the rostral border of the midbrain (the mesencephalic animals) and in those decerebrated at different pontine levels, including the ponto-bulbar junction level, and the most rostral parts of the medulla oblongata (the "pontine" animals), or more caudal parts (the bulbar animals), single stimulus of the tibial nerve A-fibres elicited a late response in the renal nerve consisting of excitatory and inhibitory components. The excitatory component was relatively small or absent in 53% of the "pontine" animals, in 42% of the mesencephalic animals, and in 18% of the bulbar animals. The "pontine" animals had the most active and most excitable system of the inhibitory component generation. However, the signs of a comparatively more powerful inhibitory component of the A-afferent action of the vasoconstrictor neurones in the "pontine" animals were not as constant as to explain completely the transition of somatic A-afferent hypertensive reflexes into the hypotensive ones, occurring in separating the ponto-bulbar structure and the rostral parts of the medulla oblongata from the mesencephalon.     

ATP concentration in thrombocytes at different stages of ontogenesis]

Intraplatelet ATP levels were measured in rabbits of different ages by the firefly technique. Adult and 7-8 day rabbits platelets proved to contain 8.9 +/- 0.9 muM ATP/10(11) cells and 5.8 +/- 0.7 muM ATP/10(11) cells, respectively. The decreased ATP level in the 7-day rabbits' platelets was not related to the platelet isolation procedure.     

Colocalization of dentin matrix protein 1 and dentin sialoprotein at late stages of rat molar development.

Dentin matrix protein 1 (DMP1) and dentin sialophosphoprotein (DSPP) are acidic proteins found in the extracellular matrices of bones and teeth. Recent data from gene knockouts, along with those of gene mutations, indicate that these two phosphoproteins are critical for bone and tooth development and/or maintenance. However, the precise functions of the two proteins have not been elucidated. In order to gain insights into their functions in tooth formation, we performed systematic, comparative investigations on the immunolocalization of DMP1 and dentin sialoprotein (DSP, a cleaved fragment of DSPP), using the rat first molar at different developmental stages as a model. Immunohistochemistry (IHC) was performed with specific, monoclonal antibodies against the COOH-terminal fragments of DMP1 and against DSP. In 1-day- and 1-week-old rats, weak immunoreactions for DMP1 were observed in dentinal tubules while stronger reactions for DSP were seen in the tubules and predentin. In rats older than 2 weeks, immunoreactions for DMP1 were found in dentinal tubules, predentin and odontoblasts. In 5-week- and 8-week-old rats, strong immunoreactions for DMP1 were widely distributed in odontoblasts and predentin. The distribution pattern of DSP was strikingly similar to that of DMP1 after 2 weeks and the localization of each was distinctly different from that of bone sialoprotein (BSP). The unique colocalization of DMP1 and DSPP in tooth development suggests that the two proteins play complementary and/or synergistic roles in formation and maintenance of healthy teeth.     

Effect of aminazin and haloperidol on the content of glial fibrillar acid protein in the rat brain]

The immune-enzyme analysis was used to determine the quantity of glial fibrillar acid protein in the water-soluble extracts of frontal and limbic cortex, caudate nucleus, medulla oblongata of rats before and after administration of aminazin and haloperidol. The obtained results testify to a decrease of the protein content under the action of both neuroleptics only in the limbic brain cortex of rats.     

Total RNA content and blood flow in rat brain after RNA administration

The changes in blood flow through selected brain structures and the changes in the total RNA content of cells of these structures were examined after a single administration of yeast RNA to 6-month-old male rats. The total content of ribosomal RNA in cells of the limbic system (septum, hippocampus, hypothalamus) increased 48 hrs after the administration of 100 mg i.p. yeast RNA , dropped after 7 days (in hypothalamus), 21 and 30 days (in hippocampus), 30 days (in septum). In cells of the limbic system as a whole there is a higher total RNA content in experimental rats. No changes were observed in the cells of parietal brain cortex. Blood flow increased in limbic structures 21 and 30 days after RNA administration and in septum and in hippocampus also 90 days after application. No changes were observed in parietal brain cortex, bulbi olfactorii, cerebellum and brain stem. Histochemical changes correlated positively with blood flow changes in the limbic system 14, 21, 30 and 90 days after RNA application. The body weight of experimental rats did not differ from that of control animals. The changes in haemodynamic parameters were transient and were demonstrated as fluctuations in heart rate, cardiac output, and peripheral resistance. Blood pressure experienced no changes.     

Effect of GABA ascorbinate on epileptiform reactions of cortical neurons and some metabolic consequences of hypoxia in the rat brain

In the first series of experiments on immobilized anesthetized rats we studied the effects of GABA ascorbinate (A-GABA) in combination with sodium thiopental on the epileptiform reactions of cortical neurons. It is demonstrated that when combined with a classic anticonvulsant, barbiturate, A-GABA effectively suppressed neuronal epileptiform reactions. This makes it possible to considerably decrease the dose of inected barbiturate. In the second experimental series, we studied the effects of acute cerebral hypoxia on the content of overall macroergic phosphates (MP) and Na, K-ATPase activity in the cortex. We also tested the possibility of corecting the hypoxia-related shifts of the above indices by treatment with GABA, A-GABA, or their combination with a vitamin complex (VC). A successive increase in the efficacy of the above agents from GABA to A-GABA+ VC was observed with respect to the above two indices. The mechanisms of the A-GABA effects on GABA receptor-channel complexes and the prospects for using A-GABA in combination with barbiturates and VC for treatment of various brain pathologies are discussed.     

Capsid structure and its stability at the late stages of bacteriophage SPP1 assembly

The structure of the bacteriophage SPP1 capsid was determined at subnanometer resolution by cryo-electron microscopy and single-particle analysis. The icosahedral capsid is composed of the major capsid protein gp13 and the auxiliary protein gp12, which are organized in a T=7 lattice. DNA is arranged in layers with a distance of ∼24.5 Å. gp12 forms spikes that are anchored at the center of gp13 hexamers. In a gp12-deficient mutant, the centers of hexamers are closed by loops of gp13 coming together to protect the SPP1 genome from the outside environment. The HK97-like fold was used to build a pseudoatomic model of gp13. Its structural organization remains unchanged upon tail binding and following DNA release. gp13 exhibits enhanced thermostability in the DNA-filled capsid. A remarkable convergence between the thermostability of the capsid and those of the other virion components was found, revealing that the overall architecture of the SPP1 infectious particle coevolved toward high robustness.     

Immunologic assessment of preparations of the RS virus at the stages of its purification and concentration

The work demonstrates the immunogenic potency of some preparations of RS virus, differing in the degree of their purification and introduced by multiple intranasal administration. The immunogenic potency of these preparations was manifested by the synthesis of antibodies determined in the coagglutination test (the specificity of these antibodies was confirmed in the reaction of the neutralization of RS virus), as well as by sensitization determined in the leukocyte migration inhibition test. Immunization with concentrated virus was more effective than immunization with the preparation of virion fraction. The intranasal administration of live RS virus to mice induced the appearance of a morphologically determined disease which was not prevented by the development of immune response accompanying the disease. The conclusion was made that further improvement in the system of testing the preparations of RS virus was necessary.     

Production of monoclonal antibody to deltorphin-I and its immunocytochemical application to adult rat brain and cultured rat brain neurons

A monoclonal anti-deltorphin-I antibody specifically recognizing its NH2-terminal region was produced. In the adult rat brain sections, it recognized immunoreactive nerve fibers mainly in the bed nucleus of stria terminalis, central nucleus of amygdala, lateral hypothalamus, hippocampus, substantia nigra, periaqueductal gray and locus ceruleus. Occasionally, positive somata were localized in the bed nucleus of stria terminalis, central nucleus of amygdala, supraoptic and periventricular nuclei. In primarily cultured neurons from various brain regions of new-born rats, the antibody immunostained strongly neuronal somata and processes. The abundant DADTI-immunoreactive substance in the cultured neurons promises to provide an alternative pathway to search for the counterpart of deltorphins in mammals.     

The production of "pure" cultures of neurons from the brain of human embryos]

A method has been developed for preparing essentially pure primary cultures of neurons from 10-12 week old fetal human brain. This method is based on the 1) capacity of neurons to form multicellular aggregates, 2) cultivation in chemically defined medium, and 3) treatment with cytosine arabinoside as antimitotic agent. This procedure allowed the preparation of highly purified (95 per cent and more) neuronal aggregate cultures. Ultrastructural analysis of these cultures following one and 8 days has revealed their partial differentiation during cultivation.     

Diurnal rhythm of cell proliferation at the late stages of precancerous changes in the liver induced by ortho-aminoazo-toluene]

Orthoaminoazotoluol was administered to mice for a period of nine months. Circadian rhythms of mitotic activity and the number of the DNA-synthesizing cells were determined by autoradiography (with the use of 3H-thymidine) at the second (adenomatous nodes) and the third (primary hepatoma) stages of carcinogenesis in the developing tumours and the surrounding liver parenchyma. The listed structures proved to have a single-peak rhythm of mitotic activity with the maximum of mitoses at 4-7 a. m.; the labeled nuclei circadian rhythm was double-peaked with the maximum at 7 p. m. and 4 a. m. The mean 24-hour values of both indices at the second and third stages of hepatocarcinogenesis were much greater than in the surrounding non-tumour tissue of the liver.