Synthesis of glutaminic and aspartic acids in mitochondria of the visual analyzer of the dog brain during postnatal ontogenesis

It is revealed that glutaminic acid (GA) synthesis by direct reductive amination proves to be the most rapid in the mitochondria of the outer geniculate body (OGB) from the 1st till the 45th day of the postnatal development, and beginning from the 45th day till the 3-month age in visual cortex (field 17) (VC) and bigeminal bodies (BB). It is stated that GA synthesis by transamination in the mitochondria of VC, OGB, and BB proceeds less intensively than by a direct reductive amination at the early stage of postnatal development, being more rapid during the period from the 12-16th till the 45th day of postnatal development. Unlike GA synthesis in the mitochondria of the studied visual analyzer structures of canine brain AsA synthesis is more rapid in transamination reaction at the early stage of postnatal development. The high level of AsA synthesis was observed on the day when the puppies' eyes began to see clearly. The level of AsA synthesis by reductive amination and transamination in the mitochondria of VC, BB, and OGB at the early stage of postnatal development is lower than that of GA synthesis.     

Glutamate decarboxylase and GABA transaminase activity in the mitochondrial fraction of the dog brain limbic system during postnatal development

Overall glutamate decarboxylase (GDCase) activity in the initial mitochondrial fraction of the limbic structure is found to be regionally different it increases from the moment of birth up to 1 year, the midbrain reticular formation (RF), where the enzyme activity in the mitochondrial decreases in pups aged 3 month and reincreases in 1 year old dogs being the exception. Overall GABA-transaminase (GABA-T-ase) activity reaches the "adult" level and is the highest: in the hypothalamic and hippocampal mitochondria on the 1st postnatal day; in the limbic cortex (l1 and l2 fields), amygdala and midbrain RF--on the 12-16th postnatal days. During the period from 12-16 postnatal days up to the age of 1 year GABA-T-ase activity in the dog limbic system decreases reliably.     

Functional organization of limbic brain structures during conditioned reflex activity in the dog

In experiments on 3 dogs it was shown that instrumental defensive conditioned reflex (CR) to electrical stimulation of the hippocampus is generalized within the limbic system (LS). The rate of generalization depended on the place of testing stimuli in LS. Stimulation of the medial parts of LS at the stage of stabilized initial reflex did not produce the generalized CRs, while they appeared distinctly in response to stimulation of the lateral parts of LS. In the process of elaboration of heterogeneous CRs (defensive and alimentary) to electrical stimulation of the hippocampus, generalized conditioned reactions from some brain structures appeared in both situations to the same degree while from other structures--with considerable differences. These data point to a possible participation in the genesis of the generalized CRs both of signal and reinforcing brain mechanisms.     

Hypoxia-induced lipid peroxidation in the brain during postnatal ontogenesis

Reactive oxygen species (ROS) are common products of the physiological metabolic reactions, which are associated with cell signaling and with the pathogenesis of various nervous disorders. The brain tissue has the high rate of oxidative metabolic activity, high concentration of polyunsaturated fatty acids in membrane lipids, presence of iron ions and low capacity of antioxidant enzymes, which makes the brain very susceptible to ROS action and lipid peroxidation formation. Membranes of brain cortex show a higher production of thiobarbituric acid-reactive substances (TBARS) in prooxidant system (ADP.Fe(3+)/NADPH) than membranes from the heart or kidney. Lipid peroxidation influences numerous cellular functions through membrane-bound receptors or enzymes. The rate of brain cortex Na(+),K(+)-ATPase inhibition correlates well with the increase of TBARS or conjugated dienes and with changes of membrane fluidity. The experimental model of short-term hypoxia (simulating an altitude of 9000 m for 30 min) shows remarkable increase in TBARS in four different parts of the rat brain (cortex, subcortical structures, cerebellum and medulla oblongata) during the postnatal development of Wistar rat of both sexes. Young rats and males are more sensitive to oxygen changes than adult rats and females, respectively. Under normoxia or hypobaric hypoxia both ontogenetic aspects and sex differences play a major role in establishing the activity of erythrocyte catalase, which is an important part of the antioxidant defense of the organism. Rats pretreated with L-carnitine (and its derivatives) have lower TBARS levels after the exposure to hypobaric hypoxia. The protective effect of L-carnitine is comparable with the effect of tocopherol, well-known reactive species scavenger. Moreover, the plasma lactate increases after a short-term hypobaric hypoxia and decreases in L-carnitine pretreated rats. Acute hypobaric hypoxia and/or L-carnitine-pretreatment modify serum but not brain lactate dehydrogenase activity. The obtained data seem to be important because the variations in oxygen tension represent specific signals of regulating the activity of many specific systems in the organism.     

Lymphoid structures in the wall of the human esophagus during postnatal ontogenesis

Lymphoid aggregates in the wall of the human oesophagus have been studied in corpses of 107 persons died a sudden death and who had not any disease in the digestive organs and in the immune system (total plane preparations, slices stained with hematoxylin--eosin, azure-2-eosin and after van Gieson). The lymphoid aggregates are arranged as longitudinal chains. Their number increases from birth towards the second childhood, and then decreases towards the old age. In the upper oesophageal parts these aggregates are more numerous than in the lower ones. The lymphoid aggregates look like convexoconvex lenses. Their size is maximal during the second childhood, the longitudinal dimensions are nearly two times as great as their thickness. With time, the sizes of the formations become small. The arrangement density of the lymphoid cells in the subepithelial layer of the mucous membrane is maximal in newborns, and then it decreases up to the old age. The lymphoid aggregates are situated in the oesophageal wall, mainly, near the ducts of the oesophageal glands.     

Lipid peroxidation in tissues during subliminal electrostimulation of limbic system structures in the brain

The experiments on rats have shown that during prolonged subliminal electrostimulation of limbic brain system structures peroxidation is enhanced in the blood and tissues (myocardium, liver, parodontium), with it being realized via activation of sympathoadrenal and hypothalamo-hypophyseal systems and stipulated by the failure of physiologic antioxidative mechanisms.     

Effect of hyperglycemia and hyperthermia on liver mitochondrial respiration and blood glucose content of rats during postnatal ontogenesis]

Correlation between glucose level in blood and liver mitochondrial energetics of 1, 10, 20-days rats under hyperglycemia and high environmental temperature (38 degrees C) has been studied. Glucose feeding led to a significant increase of glucose content in blood, this increase being less at hyperthermia. Glucose feeding strengthened the oxidation of such intermediates as succinate (Krebs cycle), pyruvate and malate (hydrocarbonates) and caprylate (lipid). High environmental temperature with hyperglycemia suppresses the liver mitochondria breathing, hydrocarbon and lipid intermediates being used; the suppression is less in the presence of succinate. It is found that liver mitochondria of growing rats at different experimental conditions oxidize different intermediates with various rates. These data can be explained in the light of ontogenetic evolution of the energetic apparatus. It is supposed that exogenic glucose is the factor which activates growing processes of animals and to certain extent diminishes the negative influence of hyperthermia on the organism.     

Determination of gamma-aminobutyric and glutamic acids in rat brain by liquid chromatography with electrochemical detection

The determination of glutamic and gamma-aminobutyric acids in rat brain regions by derivatization with o-phthaldialdehyde-thiol, isocratic separation by liquid chromatography, and quantification by electrochemical detection provides a simple and precise method for assessing changes in glutamatergic and GABAergic neuronal systems. Gamma-aminobutyric acid was eluted in 30-35 minutes followed by a washout step with 90% methanol to remove all amino acid derivatives with longer retention times. Homoserine was used as an internal standard. Significant increases in gamma-aminobutyric acid content in nucleus accumbens and substantia nigra could be detected 20 minutes after injection of 400 mg/kg valproic acid.