[The behavioral reactions of rats in the early period following uniform whole-body gamma irradiation at an absolutely lethal dose]. / Nekotorye povedencheskie reaktsii krys v rannie sroki posle obshchego ravnomernogo gamma-oblucheniia v absoliutno letal'noi doze.

Rats were irradiated with gamma rays (30 Gy) and spontaneous behavioral activity in an "open field" as well as formation of conditioned reflex of adversive behavior were registered in 1, 7-8 and 24 hr after exposure. The statistically verified depression of behavioral activity was found 24 hr after irradiation, while the prolongation of the latent period of conditioned reflex occurred as early as 1 hr after irradiation. The results obtained are discussed from the point of view of GABA system involvement in the changes observed.

[The use of the multivariate estimation method for the objective evaluation of the effect of antihypoxic therapy in the first 24 hours after an absolutely lethal radiation injury]. / Primenenie metoda mnogomernogo otsenivaniia dlia ob''ektivizatsii vliianiia antigipoksicheskoi terapii v pervye sutki posle absoliutno letal'nogo luchevogo porazheniia.

Three groups of rats (intact, irradiated with 30 Gy of gamma rays and treated after irradiation with the use of pharmacological and metabolic drugs protecting brain against hypoxia were studied. In 24 hours after the influence the animals have undergone the neurobehavioral testing and then were sacrificed, a number of neurochemical parameters depicting energy metabolism and metabolic GABA bypath in brain were studied (general number of parameters were 24). Using classical method of t-statistics only enhancement of labelled GABA catabolism and deterioration of general behavioral activity were verified, the modifying effect of the pharmacological and metabolic protection against hypoxia was not found. Using methods of multidimensional evaluation the protective and sanogenic character of the used method of therapy was verified. Thus, using discrimination analysis (Mahalanobis criterion) high similarity of intact and treated groups of animals was estimated. It was confirmed using methods of coupled and multiple correlation and method of route coefficients. The statistical connections between neurochemical and neurobehavioral parameters were found which can be useful for understanding of the mechanisms of the early postradiation syndrome development.

[Functional interrelationships between dehydrogenases and transaminases in various regions of the rat brain as affected by small doses of gamma-radiation]. / Funktsional'nye vzaimootnosheniia mezhdu degidrogenazami i transaminazami v razlichnykh otdelakh golovnogo mozga krys pri deistvii malykh doz gamma-izlucheniia.

Wistar rats were exposed to 10, 20 and 40 sGy of gamma-irradiation. Maximal activity of 2-oxoglutarate- and succinate dehydrogenases, as well as of aspartate-2-oxoglutarate and pyruvate-2-oxoglutarate in the brain tissue was measured within 30 days after the exposure. Dehydrogenase activity was measured in the brain cortex, limbic system and in the cerebellum; transaminase activity was determined in the brain cortex, diencephalic zone and in the hypophysis. It was found that small doses of irradiation resulted in an oscillating increase of dehydrogenase activity with a decrease of the amplitude by the 30th day of the experiment. As the dose of irradiation increases, the periods of normal activity change into phases of inhibition of dehydrogenase action, the period of oscillations diminishes. Transaminase activity, as a rule, changes in a phase in a reversible manner as compared with dehydrogenase activity. These observations are discussed from the point of view of structural relations between these two systems in the intramitochondrial supramolecular structures, the so-called metabolons.

[The possible participation of the GABA metabolic system in the mechanisms of the protective action of L-aspartate in hypoxia in an enclosed space]. / O vozmozhnom uchastii sistemy metabolizma GAMK v mekhanizmakh zashchitnogo deistviia L-aspartata pri gipoksii zamknutogo prostranstva.

L-Aspartate given intradermally in a dose of 100 mg.kg-1 to mice 2-3 minutes before placement to a hypoxic chamber was shown to prolong the mean animal lifespan by 38% and to delay hypoxic convulsions by 38-40%. The agent was ascertained to maintain the higher glutamate decarboxylase (GD) activity and GABA levels in the brain during hypoxia and prevent GD activity and GABA levels from their drastic diminution when hypoxic convulsions occurred.

[Relation of binding by metabolism of gamma-aminobutyric acid and various reactions of the Krebs cycle in the rat brain]. / Sootnosheniia mezhdu sviazyvaniem, metabolizmom gamma-aminomaslianoi kisloty i nekotornymi reaktsiiami tsikla Krebsa v golovnom mozge krys.

The comparison has been made for the following items: intensity of pyruvate alpha-ketoglutarate, succinate oxidation, the gamma-aminobutyric acid (GABA) formation rate, utilization, total content of GABA, glutamate and alanine, the bound/free form ratio of GABA and glutamate, intensity of binding and desorption of exogenic [I-14C]GABA in homogenates of the cortex, cerebellum and brainstem of the Wistar rats. It is revealed that the intensity of ketoacids oxidation is significantly lower in the cerebellum than in the cortex, but the maximal activity of the enzymes of GABA formation and utilization is higher, due to which considerable oxidation of alpha-ketoglutarate transforming into succinate is possible proceeding the GABA shunt pathway. The cortex homogenates contrary to the cerebellum ones are characterized by the reliably higher intensity of ketoacid oxidation and by insignificant contribution of the GABA-shunt to the succinate production. These differences are in line with the reliably higher content of endogenic bound GABA in the cortex as compared to the cerebellum, with a higher level of binding of exogenic labelled GABA and with less pronounced desorption of the label from neurostructures. An assumption is advanced that the observed differences are related to the known high sensitivity of the cortex and to relative resistance of cerebellum to hypoxia and hypoglycemia.

[The effect of calcium pantothenate and homopantothenate on [14C]-GABA absorption by slices of rat cerebral cortex]. / Vliianie pantotenata i gomopantotenata kal'tsiia na pogloshchenie [14C]-GAMK srezami kory golovnogo mozga krys.

Calcium D-pantothenate (Ca D-P) and calcium D-homopantothenate (Ca D-HP) (pantogam) exhibiting antagonism in a number tests of pharmacological screening were shown to inhibit the absorption of [14C]-GABA (0.2 microM) by the rat brain cortex slices (3 mm) incubated in calcium-free medium. The effect of Ca D-HP manifests at its low concentrations (10(-6) M) and that of Ca D-P at high concentrations (10(-6) M). The data obtained are discussed in relation to the possible influence of the anion and cation components of the studied compounds.

[Uptake of [14C]GABA by rat brain slices; the effect of Ca2+]. / Pogloshchenie [14C]GAMK srezami kory golovnogo mozga krys; vliianie Ca2+.

The [14C]GABA uptake by slices (0.3 mm thick) of Wistar rat brain cortex was studied for its dependence on the GABA concentration in the medium, time of incubation and the presence of Ca2+. This process is characterized by the absence of saturation; the uptake by slices increases sharply when the concentration of exogenous [14C]GABA reaches 200 microM. Bicucullin (10(-4) M), an antagonist of GABA, inhibits the accumulation of GABA in the concentration of 0.2 microM by 60%, that evidences for a considerable contribution of the receptor binding to this process. The [14C]GABA uptake when Ca2+ is absent in the incubation medium and when its concentration is 10(-3) M is practically the same and comparatively low concentrations of Ca2+ (10(-6)-10(-4] decrease the GABA uptake.

[Effect of vitamin B3-active compounds on the content of free and combined gamma-aminobutyric acid and glutamic acid in the brain of mice]. / Vliianie B3-vitaminoaktivnykh soedinenii na soderzhanie svobodnykh i sviazannykh gamma-aminomaslianoi i glutaminovoi kislot v golovnom mozgu myshei.

The bound and free GABA and glutamic acid content in the brain of F1 (CBA X C57B1/6) hybrid mice was investigated by the Eliott method. A tendency to a decrease of GABA and glutamate content in the brain with their practically constant bound/free ratio was observed 24 h after calcium-D-pantothenate injections (150 mumole/kg, 9 injections for 3 days). Calcium-D-homopantothenate injected in the same way caused a significant decrease in the GABA content, and a sharp drop of the bound/free GABA ratio. The effect is not associated with the influence of calcium ions in the composition of the injected compounds.