Motor activity of rats after gamma irradiation in large doses

In experiments on 80 Wistar male rats their motor activity was studied using "Optovarimex" device which permitted to register the position of animals in space. The rats were subjected to total-body gamma-irradiation with doses of 6.5, 13, 50 and 100 Gy. The motor activity was studied 1, 24, 72 and 96 h following irradiation. Inhibition of the motor activity of animals was shown to depend upon radiation dose.     

Karyometric characteristics of the rat sensorimotor cortex in non-uniform gamma irradiation

Neurocyte nuclei increase in volume without structural changes in karyoplasm at early times after gamma-irradiation of rat head with doses of 50 to 100 Gy. Irradiation of 200 Gy causes a diminution of the nuclei volume while at a dose of 400 Gy the nuclei do not change their volume. A dose as high as 1000 Gy causes severe changes in the karyoplasm leading to nucleus swelling. At later times (24-72 h), the increase in the nuclei volume is associated with the changes in the karyoplasm structure. At one and the same dose, radiation causes either a decrease (irradiation of the head) or increase (exposure of the body) in the neurocyte nuclei volume. At early times after wholebody uniform irradiation no karyometric changes are detected. The nucleus swelling is more pronounced at lower dose-rates.     

Ensemble activity of neurons in the visual, frontal, and sensorimotor cortices and dorsal striatum during actualization of behavioral program under conditions of strategy choice

Unit and network activity of neurons in the visual, sensorimotor, and frontal cortical areas and dorsal striatum was investigated in cats under conditions of choice of the reinforcement value depending on its delay. The animals did not differ from each other in behavior. After immediate or delayed responses cats got low- or highly-valuable reinforcement, respectively. Single-unit activity in the visual and sensorimotor cortical areas and dorsal striatum was similar during performance of immediate and delayed responses. However, significant inhibition was observed in the frontal neurons during the delay period. The network activity of visual and frontal cortex displayed smaller number of interneuronal interactions during delayed responses as compared to immediate reactions. The network activity of neurons in the brain structures under study pointed to the interstructural interaction, but only during delayed reactions, steady interneuronal communication was observed between the frontal cortex and dorsal striatum. Thus, both types of estimation of cellular activity revealed differences in the ensemble organization during different types of behavior and showed specific reactions of neuronal ensembles.     

Dynamics of driven rhythm in neuronal assemblies in sensorimotor and visual cerebral cortices in rabbit

Coincident activity of pairs of neurons in the sensorimotor and visual areas of the cerebral cortex was studied in naive, learning, and trained rabbits during the formation of a hidden excitation focus in their central nervous system (a defensive dominanta) of the rhythmic nature. In the trained rabbits (as compared to the naive animals), percent of neuronal pairs (both neighboring and distant) in whose coincident activity the rhythm of stimulation prevailed was higher. In the visual cortex, percent of such pairs was significantly higher only for the distant neurons. Analysis of interaction between neurons in the visual and sensorimotor cortices revealed increasing the number of neuronal pairs with the driven rhythm while training. Such an increase was observed when both sensorimotor and visual neurons were considered as leading.     

Correlated activity of neurons in the sensorimotor cortices of the left and right hemispheres of rabbit brain during immobilization catatony

Spike trains of individual neurons in the sensorimotor cortex detected in simultaneous multiunit records from the left and right rabbit brain hemispheres were analyzed in the baseline state, during immobilization ("animal hypnosis"), and after the termination of this state. The crosscorrelation analysis of pulse series revealed a relationship between the moments of spike generation by neurons of the left and right hemispheres. A significant correlation between the spike trains was considered as an interaction between the neurons (i.e., mutual influence of the cells on each other). It was shown that the strength of the effects of left-hemispheric neurons on cells of the right hemisphere could significantly vary (as compared to baseline) at any stage of the experiment and in any of the time periods analyzed. The strength of the effects activity by neurons of the right-hemispheres on cells of the left-hemispheres significantly changed only after the termination of the immobilization state and in substantially lower time limits.     

Mechanism of circulatory disorders in animals irradiated at high doses

Some data are reported on pathoanatomical changes, a status of the microcirculatory channel and the coagulogram of animals affected by high doses of ionizing radiation. The signs of disseminated intravascular blood coagulation have been revealed. The authors discuss the relationship between clinical manifestations with coagulopathy development and circulatory disturbances during intestinal and cerebral forms of acute radiation sickness.     

Retention of tumorigenicity in radioresistant progeny of cells surviving exposure to high doses of gamma irradiation

The cell tumorigenic ability and the cell clonogenicity in semi-solid medium of highly radioresistant variant cell line, PIC-20 (the progeny of djungarian hamster fibroblast cell line DX-TK- surviving acute exposure to 20 Gy of gamma-irradiation), were examined. In the absence of additional radiation, no differences between tested features of non-irradiated PIC-20 cells and parental DX-TK- cells were observed. On the contrary, after gamma-irradiation with high doses the essential differences in the properties of the examined cell lines were revealed. After exposure to 10 Gy the surviving fraction of PIC-20 cells was 20 times higher than that of the parental cells. Both irradiated and non-irradiated PIC-20 cells produced colonies of similar size. It is revealed that even after irradiation with doses of 5, 10 or 15 Gy, the PIC-20 cells kept their tumorigenicity as high as non-irradiated ones. In all these cases the 90-100% of animals had the tumour, with the average latent period of tumour appearance after inoculation being the same both for irradiated and non-irradiated PIC-20 cells. After irradiation of parental DX-TK- cells with the highest dose of 15 Gy, the amount animals with tumour decreased by 70% and the average latent period of tumour appearance increased fivefold as compared with that for non-irradiated DX-TK- cells. The data obtained indicate that PIC-20 is highly radioresistant cells, which are able to proliferate both in semi-solid medium and in an animal organism even after radiation exposure to high doses.     

The functional activity of the central nervous system in the early postradiation periods after exposure to gamma quanta at different doses]

Behavioral reactions of rats at early postradiation period have been studied after irradiation in sublethal and lethal dose range. Changes in functional activity of the central nervous system develop in correlation with the stages of X-ray damage.     

Correlation between activities of neurons of sensorimotor and visual cortices after forming a hidden focus of excitation (defensive dominanta) in cortical representation of a forelimb in rabbits

The interaction between neurons of sensorimotor and visual cortices was investigated by cross-correlation analysis. In this interaction, we examined the role of sensorimotor neurons responding to light. In rabbits with a hidden focus of excitation, neurons of the sensorimotor cortex responding to light significantly more often formed correlation joints with cells of the visual cortex than neurons not responding to light. On the other hand, neurons of the visual cortex significantly more often formed correlation joints with neurons of the sensorimotor cortex not responding to light.     

A comparative analysis of the morphochemical changes in the neurons of the visual and sensorimotor cortices and the nucleus accumbens of rats administered tuftsin

White rats were treated with a single administration of tetrapeptide tuftsin (Thr-Lys-Pro-Arg) in the dose 300 mcg/kg (b.w). Using interferometry, the protein content and concentration were assessed 15, 30 and 60 minutes after injection. The area of the neuron cytoplasm and nucleus were measured too. The nucleoplasmic balance and dispersion were calculated. Significant alterations in the protein contents and cellular area, nucleoplasmic balance and dispersion were detected in neurons of visual, sensomotor cortex and of n. accumbens. A possible interrelation is discussed between tuftsin action and the functional activity of neurons, between the level of their protein metabolism and establishment of emotional and motor response.     

Enhancement of embryogenesis and plant regeneration from barley anther culture by low doses of gamma irradiation

Summary The effects of 0,5 and 10 Gy doses of gamma irradiation on the enhancement of embryogenesis and plant regeneration efficiency of three barley (Hordeum vulgare L.) genotypes, Igri, Arabi Abiad and AECS 76, were evaluated. Embryo yields at 5 and 10 Gy doses were significantly higher than those of the control (OGy). This effect was genotype-dependent. The most responsive genotype was Igri, with 592.8 embryos 32 anthers exposed to 10 Gy. However, despite a high embryo induction rate, the green plant regeneration rate was low. Arbi Abiad had a higher ability to generate green plants produced from, with 28. 13 plantlets obtained from 32 anthers at 10 Gy; irradiation had no significant effect on regeneration of Igri and AECS 76 genotypes. In general, the 10 Gy dose produced a much higher embryo yield than the 5 Gy dose. The root-tip chromosome number and the fertility of 298 regenerating green plants of cv. Igri revealed that 64% of the tested plants were spontaneously doubled haploids (DHs) and fertile.     

Effects of 10-day long exposure to gamma irradiation at low doses on bone marrow cells in mice

Effects of ten day long exposure to gamma-irradiation at low doses (mean dose rate of 1.5-2.0 m Gy/day, total dose of 15 m Gy) on hemopoietic (CFU-S) and stromal (CFU-F) progenitor cells from murine bone marrow were examined. The CFU-F content measured as in vitro fibroblastic colony number showed 1.5-4.5-fold increase. Additionally, the size of ectopic marrow transplants evaluated by counting myelokariocytes and CFU-S numbers also increased. No significant changes of CFU-S proliferation rate were found.     

Somatosensory and visual cortical unit activity in rabbits during receptive field testing and food-getting behavior

Somatosensory and visual cortical unit activity was compared in experiments on unrestrained rabbits during receptive field testing and natural "self-stimulation" of the receptive surfaces of surrounding objects in the course of food-getting behavior. Unit activity evoked by receptive field testing may correspond completely, partially, or not at all to its activity during food-getting behavior, i.e., neurons demonstrating connection during testing with particular receptive fields (parts of the body or retina) may preserve it, modify it, or lose it during food-getting behavior. Differences of activity during food-getting behavior were observed even in the case of neurons with identical receptive fields during testing. The possible nonidentity of the overall firing pattern of the neurons during food-getting behavior with the pattern which can be simulated by receptive field testing is discussed.Institute of Psychology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 16, No. 2, pp. 254–262, March–April, 1984.     

The activation of the immunosorptive properties of blood during its UV irradiation at therapeutic doses

UV irradiation of donor rhesus-positive blood in apparatus, applied in Soviet hospitals for autotransfusion of UV-irradiated blood produces a 2-fold increase of the blood capacity to bind antirhesus antibodies in blood or serum from sensibilized women. The above data can be used for increase in therapeutic effect of blood exchange transfusion in children with rhesus-conflict hemolytic disease.