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Biomedical subjects

G E Sviderskaia

Publications and source records attributed to G E Sviderskaia.

At least 19 recordsLinked to original sources
PubMed1992

[Animal motor behavior under increased pressure].

Changing pressure of the helium-oxygen mixture (6, 36, 70 and 100 Ata) induced a sharp increase of the grooming in guinea pigs. The greatest increase (up to 22.5 movements on the average) occurs during first days of the compression. During decompression, some instability of motor activity is revealed but the grooming still exceeds the control level (2.6). The changes of the grooming reflect physiological processes occurring in the CNS stem and spinal structures. The obvious pattern of the changes of grooming suggests some specific mechanisms of the high pressure effect upon the neural functions and reveals early symptoms of the high pressure neural syndrome.

Air↗
PubMedDate not supplied

[The effect of long-term hyperbarism on pregnant guinea pigs and their progeny].

The effect of hyperbarism has been investigated on 1-3-, 4-5- and 8-10-week pregnant rats and their offsprings. It was found that the mortality rate of pregnant rats is two times higher after hyperbaric exposures than in control animals. The animals exhibit the highest sensitivity at a stage of 8-10 weeks. Hyperbaric conditions significantly affect offsprings. Only 53% of newborn puppies were found to be normal, whereas 35% were born dead and 12% revealed various abnormalities. The highest sensitivity was observed during organogenesis (4-5 weeks), the mortality rate during this period reached 70%. The body mass in newborn puppies was significantly lower than in control animals. The most significant retardation in the development was observed in animals which were subjected to the effect of hyperbarism at the 4-5-th week of intrauterine life.

Animals↗
PubMedDate not supplied

[The effect of L-DOPA on potentials of the dorsal surface of the spinal cord evoked by the stimulation of primary afferents in newborn rat pups].

In experiments on 5-30-day rat puppies, studies have been made of the effect of L-DOPA (100 mg/kg, intraperitoneally) on the activity of interneurones of the dorsal horn of the spinal cord as revealed from the parameters of potentials of the dorsal surface of the spinal cord. The specific pattern of reaction in 5-day animals is manifested in a succession of inhibitory inhibition and increase in the activity of neurones monosynaptically activated by low-threshold afferents. Both the amplitude and duration of polysynaptic components of the potentials of the dorsal surface are rather high. From the 7th day, deep and stable inhibition is observed which is accompanied by a decrease in the amplitude of all components of the potential of the dorsal surface. At later stages of ontogenesis, a decrease is observed in the inhibitory effect of L-DOPA on the activity of interneurones which monosynaptically contact with low- and especially high-threshold afferents; in contrast to earlier stages, but similar to adult animals, evident inhibition was revealed in the activity of interneurones which have polysynaptic contacts with high-threshold afferents and afferents of flexor reflex. Thus, within the first weeks of postnatal life, basic qualitative changes are observed in the pattern of the reaction of interneurones of the dorsal horn to exogenic catecholamines.

Aging↗
PubMedDate not supplied

[Effect of epicortical stimulation on depolarization of primary afferents in rats during early postnatal ontogenesis].

Studies have been made on the parameters cord dorsum potentials (CDP) during stimulation of sensorimotor cortex in rats during first month of their postnatal life. First CDP were recorded from the 10th day, their latency being equal to about 80 msec, amplitude--65-70 microV, duration--more than 200 msec. During postnatal life of rats, the latent period decreases twice, the amplitude increases more than 3-fold, whereas the duration remains almost unchanged. These data indicate maturation of the descending pathways to the spinal cord, the increase in the propagation rate along these pathways and formation of segmentary mechanisms responsible for the generation of CDP. The effect of stimulation of the sensorimotor cortex on depolarization of primary afferent was also investigated. It was found that from the 2nd week of postnatal, life, formation of supraspinal control of afferent impulsation takes place.

Action Potentials↗
PubMedDate not supplied

[Primary excitatory rhythms in locomotor activity of scyphomedusae].

Periodic organization of autorhythmic motor activity which is typical of ontogenetically earlier stages of development of the nervous functions in vertebrates has been found in larval scyphomedusae. In hydromedusae which exhibit less complex nervous system, periodic organization of excitation persists also in adult individuals. It is suggested that already at the level of scyphomedusae, periodic form of organization of autorhythmic excitation in the nervous system was transformed in a category of recapitulating characters and in this quality passed along all phylogenetic pathways.

Animals↗
PubMedDate not supplied

[Depolarization of the primary afferents in stimulation of the brain stem structures of rats in ontogeny].

New data have presented concerning early development of supraspinal control of afferent impulsation to the central nervous system. Stimulation of the brain stem results in depolarization of the primary afferents and affects the level of depolarization caused by the evoked activity of segment afferents. Maturation of this mechanism takes place within first weeks of postnatal life.

Afferent Pathways↗
PubMedDate not supplied

[Effect of GABA on motor activity in the rat during the early postnatal period].

Effect of GABA on the motor activity of rats of the first month of life was studied in conditions of free behaviour in the maternal cage. It has been found that at the age of 1-10 days the injection of GABA increases, and at the age of 11-30 days decreases both the general motor activity and the grooming activity. It is suggested that a possible mechanism of the observed effect of GABA consists in the deepening of presynaptic inhibition, which results, during the earlier stages of postnatal ontogeny, in intensifying the autorhythmical activity of spinal motor centres, whereas during the later stages, when the autorhythmical activity of the spinal cord is replaced by reflex excitatory mechanisms, in depressing the latter.

Age Factors↗
PubMedDate not supplied

[Presynaptic inhibition in the rat spinal cord in ontogeny and its relationship to depression of monosynaptic reflexes].

Cheking the parameters of potentials from the dorsal surface of the spinal cord, studies have been made on the development of depolarization in the primary afferent terminations. It was shown that during the development of animals the amplitude of N- and P components increase indicating progressive development of afferent connections in the spinal cord and maturation of presynaptic inhibition mechanisms. Parallel studies were made on the depression of monosynaptic reflexes conditioned by stimulation of antagonists. It was shown that maximum inhibition develops 20-40 ms after the conditioning coinciding with the highest amplitude of P component. In new-born rats, the recovery of the reflex takes more time than depolarization of the primary afferent terminations, this difference indicating that the depression is only partially due to presynaptic inhibition. Homosynaptic depression plays an important role, its duration and intensity being more significant in new-born animals. The duration of homosynaptic depression decreases with age. Under these conditions, the main mechanism of limitation of afferent input involves the depolarization of the primary afferent terminations.

Afferent Pathways↗
PubMedDate not supplied

[The effect of excess catecholamines on grooming in rats in postnatal ontogeny].

During the first month of postnatal life, studies have been made of the effect of L-DOPA on grooming in rat puppies. It was found that within the first hour after injection of the drug, its inhibitory effect increases in the course of ontogenetic development. In some of the animals, the increase in grooming was observed, whereas in other ones the effect was absent. Inhibition concerns both the number of grooming outbursts and the duration of rhythmic phase. These changes are associated with the decrease of afferent input to the central nervous system and with inhibition of the activity of pacemakers of rhythmic motor excitation.

Aging↗
PubMedDate not supplied

[The development of grooming in the ontogeny of rats and mice].

Experiments have been made on rats and mice within the first month of postnatal life. Common age dynamics of grooming reactions for these animals was shown which consists of a sharp intensification of grooming movements at the 3rd week, i.e. at the period of "behavioral arousal", as well as of heterochronous onset of different types of movements which results from successive maturation of the brain structures in which rhythmic centres of these movements are located. Quantitative differences in grooming of rats and mice are presumably due to ecological peculiarities of these animals. Periodic pattern of realization of grooming, as well as the parameters of its rhythmic components suggests that stereotype behavioural reactions are governed by mechanisms of autorhythmic excitation which are typical for the early stages of the development of the nervous system.

Aging↗