[SUBUNITS OF MAMMAL DNA DEPENDENT RNA POLYMERASE III MODIFIED IN VIVO].

In subfractions of DNA-dependent RNA polymerase isolated from nuclei of 3T3 mouse fibroblasts, A431 epidermoid carcinoma cells and mature human placenta, we have identified three subunits modified by both phosphorylation and O-N-acetylglucosamine glucosilation. The subfractions of the human enzyme contained modified subunits with molecular weight of 60 and 45 kDa and a subunit of 52 kDa probably belonging to one of the basal factors of RNA Polymerase III transcription. The subfractions of 3T3 mouse cells RNA Polymerase III consisted of modificated subunits with molecular weight 49, 45 and 42 kDa, however, the 45 kDa subunit might be a component of the basal transcription factor of RNA Polymerase III, since it was not identified in mouse enzyme composition.

Local GABAergic modulation of the activity of serotoninergic neurons in the nucleus raphe magnus.

Experiments on rat brainstem sections in membrane potential clamping conditions addressed the effects of serotonin and GABA on serotoninergic neurons in the nucleus raphe magnus. Local application of serotonin stimulated inhibitory postsynaptic currents (IPSC) in 45% of the serotoninergic neurons studied. This response was not seen in the presence of the fast sodium channel blocker tetrodotoxin. The GABAA receptor antagonist gabazine blocked IPSC in both serotonin-sensitive and serotonin-insensitive neurons. Application of GABA evoked generation of a membrane current (IGABA), which was completely blocked by gabazine. These results indicate self-regulation of the activity of serotoninergic neurons in the nucleus raphe magnus via a negative feedback circuit involving local GABAergic interneurons.

Mechanisms of the respiratory activity of leptin at the level of the solitary tract nucleus.

Acute experiments on anesthetized laboratory rats were performed to study the effects microinjections of 10(-4) M leptin into the solitary tract nucleus on the extent of the Hering-Breuer inflation reflex in ventilatory reactions to hypercapnia. Local administration of leptin into this area led to inhibition of the Hering-Breuer reflex. The extent of ventilatory responses to hypercapnia, conversely, increased, which may provide evidence that leptin has a modulatory influence on central chemoreceptors. These physiological mechanisms of action probably play a leading role in mediating the stimulatory respiratory effects of leptin at the level of the solitary tract nucleus.

[Local GABA-ergic modulation of serotonergic neuron activity in the nucleus raphe magnus].

In voltage-clamp experimental on slices of the rat brainstem the effects of 5-HT and GABA on serotonergic neurons of nucleus raphe magnus were investigated. Local applications of 5-HT induced an increase in IPCSs frequency and amplitude in 45% of serotonergic cells. The effect suppressed by the blocker of fast sodium channels tetradotoxin. Antagonist of GABA receptor gabazine blocked IPSCs in neurons both sensitive and non-sensitive to 5-HT action. Applications of GABA induced a membrane current (I(GABA)), which was completely blocked by gabazine. The data suggest self-control of the activity of serotonergic neurons in nucleus raphe magnus by negative feedback loop via local GABAergic interneurons.

[Mechanisms of the respiratory activity of leptin at the level of the solitary tract nucleus].

In acute experiments on anaesthetised rats we investigated the effects of 10(-4) M leptin microinjected into the solitary tract nucleus on inspiratory-terminating Breuer-Hering reflex and ventilatory responses to hypercapnea. We found that the local administration of leptin into the area inhibited the inspiratory-terminating Breuer-Hering reflex. In contrast, ventilatory responses to hypercapnea were accentuated suggesting a modulatory effect of leptin on central chemoreceptors. The discovered physiological mechanisms are likely to play a key role for stimulating respiratory effects of leptin at the level of the solitary tract nucleus.

Respiratory responses to microinjections of leptin into the solitary tract nucleus.

The regulatory peptide leptin has a respiratory stimulating effect along with its well known hypothalamic effects. The present study, performed on anesthetized rats, addressed respiratory responses to microinjections of 10(-10)-10(-4) M leptin into the solitary tract nucleus, which contains a high concentration of leptin receptors. Injections of 10(-8)-10(-4) M leptin led to stimulation of respiration, inducing a dose-dependent increase in the level of pulmonary ventilation and an increase in respiratory volume, accompanied by an increase in bioelectrical activity in the inspiratory muscles; 10(-6) M leptin also induced a transient increase in respiratory rate due to shortening of inhalation and exhalation. A characteristic feature of the response was the appearance of "sighs" - deep, prolonged inhalations accompanied by increased volley activity on the electromyograms of the inspiratory muscles and lengthening of the subsequent intervolley interval. These leptin effects, along with data on the high concentrations of specific leptin receptors (ObRb) in the solitary tract nucleus, suggested that endogenous leptin has a role in controlling respiration at the level of the dorsal segment of the respiratory center.

[Respiratory responses to microinjections of leptin into the solitary tract nucleus].

Regulatory polypeptide leptin, apart from its well-known hypothalamic effects, stimulates ventilation. The present study on anaesthetised rats was undertaken to elucidate the respiratory effects of 10(-10)-10(-4) M leptin microinjected into the solitary tract nucleus, containing a high concentration of leptin receptors. Injections of 10(-8)-10(-4) M leptin induced dose-dependent increase in ventilation, tidal volume and electric activity of inspiratory muscles; 10(-6) M leptin additionally induced a short-term increase in respiratory frequency and a shortening of both inspiratory and expiratory duration. The respiratory responses to leptin is also characterised by appearance of sighs: deep and prolonged inspirations associated with an augmented burst in the activity of the inspiratory muscles and prolonged post-sigh inter-burst interval. The results taken together with evidence of high concentration of specific leptin ObRb-receptor in the solitary tract nucleus suggest involvement of endogenous leptin in the control of breathing via dorsal structures of the respiratory center.

[Dynamic phosphorylation of RNA polymerase III holoenzyme subunits from human epidermoid carcinoma cells A431 cultivated under different conditions].

Dynamic phosphorylation in vivo of individual subunits of holoenzyme RNA polymerase III subfractions IIIa and IIIb on serine/threonine and tyrosine aminoacid residues has been shown in human epidermoid carcinoma cells A431. Cells cultivation under starvation on embryonic serum caused a prolongation of the cell cycle, while cultivation at low concentration of epidermal growth factor (EGF) activated cell proliferation. Subunit 45 kDa is phosphorylated on serine/threonine residues in subfraction IIIa only in starving cells. This subunit of subfraction IIIb is unphosphorylated. Phosphorylation of this particular subunit is restored under induction by EGF at low concentration (0.1 ng/ml). The level of phosphorylation on tyrosine aminoacid residues of subunits of holoenzyme subfractions IIIa and IIIb is high in cells cultivated under starvation. Subunit 60 kDa has a higher level of phosphorylation as compared with subunits 45 and 38 kDa. Induction by EGF at low concentrations increases the level of phosphorylation of subunits 60 and 38 kDa in both subfractions of holoenzyme.

Correlates of measures of voluntary force with the functional state of the motor system.

Oscillation spectra were analyzed for prolonged isometric force recorded in healthy subjects of three age groups. Changes in the distributions of spectral components of the oscillations in force were noted, along with differences in the distributions of spectral density as exhaustion developed in the age groups. The amplitude-frequency ranges of changes in the spectral densities of oscillations in force characterized the activity at the suprasegmental and segmental levels of the motor system which support the voluntary control and automatic regulation of posture during the performance of movements. Correlates of the functional state of the motor system are discussed in terms of the voluntary and involuntary components of control. A significant increase in activity in the central structures of the movement control system was seen with the development of exhaustion, along with decreases in the frequency range of the activity of subcortical structures with age.

[Parameters of voluntary effort correlates with functional state of the motor control system].

The spectrum oscillations of a prolonged supported effort that was registered at isometric regimen in 3 age groups of healthy volunteers, were analyzed. Changes in distribution of spectral density of effort oscillations and distinction in distribution of spectral density as a reaction to fatigue in age groups, were shown. The revealed amplitude-frequency ranges of changes of spectral density of effort oscillations characterize activity of suprasegmental and segmental levels of motor control system fulfilling the voluntary movement control and the automatic regulation of posture. The correlates with functional state of motor control system are considered in the terms of voluntary and involuntary components of regulation. The substantial growth of activity in the central structures of motor control system in process of development of fatigue and the narrowing of the frequency range of activity of sub-cortical structures with age, were revealed.

[Subunits of human holoenzyme of DNA dependent RNA polymerase III phosphorylated in vivo].

Phosphorylation of human holoenzyme of DNA dependent RNA polymerase III subunits in vivo has been investigated. RNA polymerase III from human placenta nuclei and epidermoid carcinoma cells A431 was isolated as two subfractions (IIIa and IIIb) distinguished in the order of elution from DEAE Sephadex A-25 column chromatography and buoyant density at glycerol gradient centrifugation. The subfractions of RNA polymerase III holoenzyme consists of four subunits with molecular masses 60, 52, 45 and 38 kDa, respectively, phosphorylated in vivo. The subunits with molecular masses 60 and 45 kDa are phosphorylated both on tyrosine and serine/threonine residues. All these subunits belong to subunits of the molecules of RNA polymerase III proper. RNA polymerase III and RNA polymerase I have the 38 kDa subunit in common. The subunit with molecular mass 52 kDa is phosphorylated on serine/threonine residues and may be related to some basal transcription factors of RNA polymerase III.

[Features and mechanisms of realization the respiratory influences of the extrapyramydal system structures]. / Osobennosti i mechanizmy realizatsii respiratornykh vliianii struktur ékstrapiramidnoi sistemy.

In the publication the modern condition of the problem of suprabulbar regulation of breathing is analysed. The review on structure, neurochemistry and anatomic connections of the red nucleus and substantia nigra with the medullary respiratory center is submitted. The data on the respiratory effects of GABA and apomorphine microinjected into the red nucleus and substantia nigra as well as effects of their electrostimulation after the blockade of GABA and dopamine receptors in the respiratory center are discussed. The conceptual scheme of the mechanisms of realization the respiratory influences of the extrapyramydal system is offered.

Respiratory effects of sensorimotor cortex and their mechanisms in rats.

Acute experiments on anesthetized rats showed differential effect of various areas of the sensorimotor cortex on activity of the respiratory center. It is hypothesized that GABAergic structures of the solitary tract nucleus play an important role in the mechanisms of respiratory effects of the sensorimotor cortex.

Amygdalofugal modulation of Hering-Breuer inspiration-inhibiting reflex.

Acute experiments on rats showed that the central nucleus of the amygdaloid complex modulates realization of the Hering-Breuer inspiration-inhibiting reflex. It is hypothesized that amygdalobulbar interrelations are realized via modulation of respiratory reflexes by the amygdala. This interaction is mediated by the GABAergic system of the amygdala.

The pre-Bötzinger complex participates in generating the respiratory effects of thyroliberin.

Experiments on anesthetized rats were performed to study the effects of microinjection of thyroliberin (10 fM-100 microM) into the area of the pre-Bötzinger complex on respiratory and circulatory parameters. Thyroliberin dose-dependently increased respiration frequency, with shortening of inspiration and expiration. Tidal volume and the amplitude of the integrated EMG recorded from the inspiratory muscles decreased after administration of concentrated solutions. Using this dosage method, thyroliberin had weak effects on systemic hemodynamics. The data suggest that structures located in the area of the pre-Bötzinger complex take part in generating the respiratory effects of thyroliberin.

[Pre-Bötzinger complex participates in respiratory effects of thyroliberin]. / Kompleks pre-Betzingera uchastvuet v realizatsii respiratornykh éffektov tiroliberina.

Responses of the TRH microinjections into the pre-Bötzinger complex of adult anesthetised rats involved a dose-dependent increase in respiratory rate as well as shortening of inspiratory and expiratory duration. The tidal volume and inspiratory muscles' activity decreased following high concentrations of the TRH. The heart rate did not change. The findings suggest that the pre-Bötzinger complex is at least partly responsible for the TRH tachypnoic effect.

[The effect of thyroliberin microinjections into the area of the nucleus tractus solitarii on respiratory and circulatory indices]. / Vliianie mikroin''ektsii tiroliberina v oblast' iadra solitarnogo trakta na pokazateli dykhaniia i krovoobrashcheniia.

The TRH administration induced an increase in ventilation, essential changes in breathing pattern and activity of the inspiratory muscles in anesthetised rats. The doses 10(-12)-10(-8) M TRH decreased the heart rate, whereas 10(-10) M TRH increased the blood pressure. The data obtained suggest an important role of the nucleus tractus solitarii in realization of the TRH respiratory and circulatory effects. The data obtained corroborate the hypothesis of the participation of endogenous TRH in the respiratory and circulatory control.