Catecholamine sensitivity of the hypophyseal-adrenal system in the early ontogeny of rats]

The dynamics of the hypophyseal-suprarenal system reaction to catecholamines of different type of effect was studied in the Wistar rats during the first 16 days of life. The reaction to epinephrine was noted in 4 days old and to novodrin in 8 days old rats. Since the reaction to epinephrine acting on alpha- and beta-receptors appears ahead of that to novodrin acting selectively on beta-receptors, a suggestion was put forward to the effect that alpha-receptors matured more rapidly that beta-receptors. The increase of the system reaction to the stimulation of recepors sensitive to catecholamines was noted on the 12-14th days of life and appears to be related to the formation of central adrenergic mechanisms.     

The genesis of movement-related human brain potentials in different forms of motor pathology]

To study the role of subcortical structures and cerebellum nuclei in the genesis of the human brain potentials connected with motion patients were examined with parkinsonism and hyperkinetic form of children cerebral paralysis. In one group of patients the motor responses were recorded by means of long-term electrodes implanted with the medical purpose into the ventro-oral group of thalamus nuclei, subcortical nuclei and dentate cerebellum nuclei. In patients of the second group potentials, connected with motion were led from the scalp before and after one-moment destruction in the zone of the same structures. In ventro-oral and reticular thalamus nuclei lateral and medial segments of the pale globe and in the cerebellum dentate nucleus post-motor components were recorded which were considered as electrographic expression of motion realization and completion processes (P2 and N3) and also as slow negative oscillation (component N1), that pointed to participation of the studied structures not only in regulation of voluntary movement but also in the process of movement preparation. Absence of N2 component at recording motor responses from deep electrodes and its sufficient stability at scalp leads gave the reason to suggest that its genesis was connected with the cortex activity.     

Participation of the brain serotoninergic system in creating the stress reactivity of the hypophyseal-adrenal axis

The concentration of corticosteroids in the blood of rats was shown to increase in response to the immobilization stress at an earlier age than the brain serotonin metabolism changes. The level of corticosteroids in blood increased in response to the intraperitoneal serotonin injection also earlier than the reaction to the serotonin injection in the brain lateral ventricle sets up. The increase of the reaction of hypophysial-suprarenal system to stress during the period from the 12th till the 16th day of postnatal development coincided with the changes in serotonin metabolism in the brain stem and the reaction to serotonin injection in the brain lateral ventricle. It is suggested that the system of serotonin brain neurons connected with the hypophysial-suprarenal complex matures later tran the serotonin receptors in the periphery; the reaction to immobilization may be realized at the early developmental stages without the participation of brain serotonin.     

Participation of the hypophyseal-adrenal cortex system in thrombin clearance during immobilization stress]

The examination carried out with thrombin marked by 131J resulted in a considerable increase of the thrombin clearance rate in healty male rats during the stress (caused by an immobilization lasting 30 minutes) and in an increase of thrombin deposits in the liver. A further increase of thrombin clearance occurred by the combination of immobilization and administration of ACTH. Contrary to ACTH the thrombin clearance is not stimulated in healthy animals by hydrocortisone. Thrombin clearance and thrombin deposits in the liver are lowered in adrenalectomized rats. In these animals the administration of ACTH does not result in an increase of thrombin clearance. The rate of thrombin clearance is normalized in adrenalectomized animals after administering hydrocortisone without as well as under conditions of stress. In adrenalectomized animals having received hydrocortisone as well as in healthy animals the administration of ACTH will results in an increase of thrombin clearance. From these experiments the conclusion can be drawn that ACTH will increase the intensity of thrombin clearance in stress and that hydrocortisone plays a transmitting part here.     

Conditioning in resuscitated rats with originally different behavioral patterns

Male white rats divided in three groups on the basis of their behavior in the elevated plus-maze were subjected to 10-min cardiac arrest. Analysis of the results of their subsequent food and active avoidance conditioning revealed the effects of the following factors: (1) a factor of initial typological features of the higher nervous activity, (2) a factor of general brain mechanisms of postresuscitation, and (3) a factor of postresuscitation features in rats with different behaviors, which represented changes in different mechanisms of conditioned reflex performance in these animals.     

Role of the brain neurochemical systems in altering the reactivity of the hypophyseal-adrenal system in the gray rat selected for behavior

Studies have been made of the interrelationship between brain monoaminergic system and pituitary-adrenal function in two groups of the grey rat Rattus norvegicus Berk. One group consisted of non-aggressive rats selected for lack of agonism towards experimentator, the other one included aggressive animals. Domesticated animals exhibited the decreased reaction of the pituitary-adrenocortical complex to emotional stress as well as the decreased response of the endocrine system during stimulation of noradrenaline or serotonin mechanisms of the brain. In addition, noradrenaline and serotonin content of the brain decreased in domesticated rats during emotional stress to a lower extent, as compared to that in aggressive ones. Therefore, one of the sources of correlational changes in the activity of the pituitary-adrenocortical complex during selection for domesticated behaviour is the effect of selection on neurochemical, in particular monoaminergic systems of the brain.     

The recovery of the reactivity of the auditory system in the dolphin Tursiops truncatus to paired acoustic stimuli with different spectra]

Recovery cycles of the auditory brainstem responses were studied in the bottle-nosed dolphin, Tursiops truncatus, using paired acoustic clicks. The recovery time was longer if both clicks had identical spectra (50% recovery at 0.9 ms), as compared with that of different spectra (50% recovery at 0.35 ms). These results can explain a different recovery time of evoked responses after an artificial sound and after own locating one.     

The pain sensitivity and behavioral reactivity of rats in somatic and visceral pain states

The vocalization thresholds and latent periods of motile reaction have been studied in normal rats, at extremity trauma, and at intraperitoneal injection of an algogen [correction of allogene]. The dissociation of changes in pain sensitivity and motile reactivity in during, visceral and somatic pain conditions was observed. A strong hypoalgesia during visceral stimulation and hyperalgesia at trauma accompanied by inhibition of motile activity have been discussed from the point of view of their significance in defense reactions of the organism at pain conditions of various nature.     

The hormonal indices of the reactivity of the central links in the hypothalamo-hypophyseal-adrenocortical system of rats during postnatal ontogeny]

Radioimmunological assay has been made of the amount of ACTH in the adenohypophysis and blood plasma in adult male rats as well as in 1, 3, 5, 7, and 20 days old rat puppies 30 minutes after a surgical stress, i. e. cutting the skin at the back of the body. Reliable increase of ACTH level was originally observed in 7-day puppies, whereas in younger animals surgical stress resulted in the decrease of ACTH in the blood. Changes in vasopressin content of the blood and hypophysis exhibit significant variations, but on the whole mainly the decrease was observed in younger animals together with the increase from the 5-7th day of postnatal development of rats. Accumulation of vasopressin was noted in the median eminence after surgical stress in younger animals. The data obtained suggest that the early period of development of the hypothalamo-hypophyseal-adrenocortical system is characterized rather by paradoxal reaction than by non-reactivity, which may be associated with poor neurohormonal transport in the outer zone of the median eminence.     

Probing the reactivity of different forms of azurin by flavin photoreduction

The reactivity of a variant of the blue copper protein, azurin from Pseudomonas aeruginosa, was investigated with laser flash photolysis and compared with the reactivity of the wild-type (WT) protein. The variant was obtained by changing the Cu ligating His117 for a glycine. The mutation creates a gap in the ligand shell of the Cu that can be filled with external ligands or water molecules. The crystal structure of the H117G variant is reported. It shows that the immediate surrounding of the Cu site in the variant exhibits less rigidity than in the WT protein and that the loop containing the Cu ligands Cys112, His117 and Met121 in the WT protein has gained flexibility in the H117G variant. Flash photolysis experiments were performed with 5-deazariboflavin and 8α-imidazolyl-(N-propylyl)-amino riboflavin as electron donors to probe the reactivity of WT and H117G azurin, and of H117G azurin for which the gap in the Cu co-ordination shell was filled with imidazole. 8α-Imidazolyl-(N-propylyl)-amino riboflavin appears one to two orders less efficient as a photo-flash reductant than 5-deazariboflavin. The reactivity of the H117G variant in the absence of external ligands appears to be 2.5-fold lower than the WT reactivity (second-order rate constants of 51 ± 2 × 10(7) m(-1) ·s(-1) versus 21 ± 1 × 10(7) m(-1) ·s(-1) ), whereas the addition of imidazole restores reactivity to above the WT level (71 ± 4 × 10(7) m(-1) ·s(-1) ). The differences are discussed in terms of structural modifications and changes in reorganizational energy and electronic coupling. Database Structural data are available in the Protein Data Bank under the accession number 3N2J.     

Morphofunctional changes in the placenta and in the hypophyseal-adrenal system during low intensity infrared radiation in rats

Morphofunctional conditions of hypophysealadrenal axis and placenta following hypoxis hypoxia and an infrared treatment, were studied in rats. The data obtained involved high levels of the DNA, RNA, and lipidogenesis. Probable mechanisms of structural changes are discussed.     

The dynamic behavioral changes in rats after destruction of the locus coeruleus]

Destruction of locus coeruleus (LC) was conducted in adult rats (male rats of the Wistar line, 250-300 g) electrolytically or by means of 6-hydroxydopamine (6-OHDA). Behaviour of the intact animals sham-operated and of rats with destructed LC was evaluated before and every week after the operation during 5 weeks. Statistically significant alterations in the behaviour were revealed only in the initially low-active rats. These animals were characterized firstly, by low motor and exploratory activity in all tests (open field and automated devices), disturbance of the reactivity to novelty--only in one week after the operation with subsequent compensation of shifts; secondly, by low level of investigatory activity in the open field and absence of habituation to the repetitive tests--from the 21-st day after the operation.     

The effect of anesthetics on cardiovascular reactivity to isoprenaline in rats]

Compared study was performed in rats under chloral or urethanne anaesthesia after venous infusion of isoproterenol. Cardiovascular haemodynamics and capillary regional blood flows of digestive tract showed changes; cardiac output was increased only under chloral anaesthesia; nutritional flows were different according to anaesthesia.     

The hypophyseal-adrenal axis in the protein-calorie malnourished rat

Male rats were fed an 8% low protein diet for 30 consecutive days beginning at 20 days of age. On day 50, the effect of the diet was evaluated on the hypophyseal-adrenal axis and the observations compared with those noted in age-matched controls fed a standard laboratory diet. The malnourished animals had significantly larger adrenal gland weights, relative to body size, and higher levels of serum corticosterone. Additionally, the number of ACTH-secreting cells in the pituitary glands of these rats was 63.8% greater than that present in the controls. These results suggest that ACTH secretion and adrenocortical physiology are stimulated under conditions of experimentally induced protein-calorie malnutrition.