The effect of repeated administration of insulin on pain threshold and gamma-aminobutyric acid level in mouse brain

In experiments on male Albino-Swiss mice weighing 18-22 g insulin given in doses of 2 i.u./kg caused no change in the time of reaction to pain, while the same dose administered daily for 7 days potentiated the analgesic action of morphine (3 mg/kg s.c.). Glucose caused no change in this effect of insulin. After 14 days of insulin treatment the time of reaction to pain in the animals subjected to the action of morphine returned to its initial value. Twenty-four hours after the last administration of morphine the level of gamma-aminobutyric acid (GABA) was found to be decreased in the animals receiving insulin with glucose. These results suggest that the central action of insulin is dependent not only on hypoglycaemia produced by it, but may be due also to its direct action on the central structures and an indirect action mediated by its effect on other neurotransmitter systems.     

Motor asymmetry of the forelimbs of the rat

Preference was studied of one of the forelimbs during performance of different manipulating movements in white rats. High degree of "handedness" was observed in all studied movements. However it was not absolute--no animals performed all movements by one and the same limb. Degree and character of "handedness" were different for different movements, though the number of "righthanded" rats in most tests as a whole exceeded the number of "lefthanded" ones. The "handedness" depends on the individuality of the animal, the character of the motor task, learning and interference of different motor tasks during training.     

Role of motor activity in the development of hypothyroid rat pups

Studies have been made on the role of the thyroid in the development of rats. In the first group of experiments, newborn rat received within a month mercazolyl which inhibits the activity of the thyroid; in animals of the second group, mercazolyl injections were combined with cold exposures which stimulated motor activity in animals. It was found that hypothyroid rats in both groups exhibit retardation of growth as compared to normal animals. However, retardation is less significant in animals of the second group, as it is indicated by smaller changes in the protein content and total mass of skeletal muscles.     

Rhythmic components of the EEG of 6-month-old children

Spectral EEG characteristics were studied in 12 six-month healthy children in a state of attention, attracted by visual stimuli and also at lowering of the level of visual afferentation and in drowsiness. 12 parts of EEG records free from artefacts were used, with analysis epoch 5 s and discretion frequency 100 counts/s. Three independent rhythmic EEG components have been revealed in alertness state, corresponding by criteria of functional reactivity and topographic localization to theta, alpha and mu EEG rhythms of the adult man. It is suggested that formation of dominating EEG rhythm with age occurs due to changes in dominant relations of the key rhythmic successions with independent genesis.     

Cytochemical and functional evaluation of ACTH responsive isolated rat adrenocortical cells. The maintenance of sex differences

The critical evaluation of isolation methods for obtaining the adrenocortical cell suspension due to trypsin or collagenase digestion was done. Some collagenase advantages were indicated by morphological observations on the staining smears as well as by ACTH stimulation test. The cytochemical reactions for enzyme activities had the limited applications for those purposes. It also appeared that commonly applied dye exclusion tests were inadequate for characterization of cell suspension. The possible role of the adrenocortical cell debris in the basal corticosterone production was pointed out. The maintenance of the sex dimorphism and the functional differences in the adrenocortical cells isolated from male and female rats have been observed.     

Autoradiographic, ultrastructural and interferometric analyses of the temperature effect on the synthesis and migration of ribosomes in root meristem cells of Helianthus annuus L. relation to S phase initiation

Experimental model consisted in blocking cells in G1 phase by cold treatment (12 h, 10 degrees C); following 3 h of postincubation at 20 degrees C, cells initiated S phase. In the present studies it has been shown that 2 h postincubation at 20 degrees C of cold-treated young seedlings of Helianthus annuus L. results in transformation of inactive meristematic nucleoli, characterized by small sizes, reduced amount of dry mass and granular component and by the presence of few and large fibrillar centres into large active nucleoli displaying high dry mass and granular component contents, numerous and small fibrillar centres. After 3 h of postincubation at 20 degrees C, nucleoli lose their granular component, decrease in size and dry mass content. At this moment cytoplasm enriches in ribosomes and its dry mass increases. Maximum of nucleolar activity is preceded by an accumulation of proteins in nucleoli. It is concluded that an enhanced transport of ribosomes is one of the conditions of S phase initiation.     

Sub-compartmentation of the 'cytosolic' glucose 6-phosphate pool in cultured rat hepatocytes

[14C]Glucose release either from endogenous 14C-prelabelled glycogen or from added 14C-labelled glucose 6-phosphate was measured in filipin-treated, permeabilized hepatocytes in 48 h culture. [14C]Glucose output from prelabelled glycogen was not altered by the addition of 5 mM glucose 6-phosphate to the incubation medium. Conversely, [14C]glucose release from 5 mM labelled glucose 6-phosphate was not influenced by different glycogen concentrations in the cells. Moreover, in the permeabilized cells the anion transport inhibitor DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid) inhibited only the liberation of [14C]glucose from labelled glucose 6-phosphate but not from glycogen. It is therefore concluded that there exist at least 2 separate, mutually non-accessible glucose 6-phosphate pools in cultured rat hepatocytes, one linked to glycogenolysis and the other to gluconeogenesis.     

Degradation dynamics of lignocellulose materials by wood-rottingPleurotus fungi

When grown on wheat straw,Pleurotus decomposes both the lignin and the cellulose components of the substrate. The course of degradation differs during growth and fructification. The losses of dry mass during growth were about 20 %. The absolute amount of hemicelluloses, cellulose and lignin was decreasing. Hemicelluloses and lignin were degraded at a higher rate than cellulose. The total mass losses of the substrate after fructification were 32 to 45 %. Cellulose was consumed at a higher rate than lignin.