Changes in some indices of the cardiovascular system in different mental tasks

In order to study the effects of the type of mental activity on the function of the cardiovascular system in humans, the following indices were used: the heart rate (HR), RR interval, variation magnitude (VM), systolic wave amplitude (SWA), and pulse wave transit time (PWTT). These indices were recorded when the subjects solved verbal-logical or spatial mental tasks. The HR was substantially increased during solving of the spatial tasks as compared to solving of the verbal-logical tasks, whereas the SWA showed the opposite changes. The latencies of the performance of the tasks of various types were similar in the subjects; therefore, the changes in the autonomic indices did not depend on the difficulties of the mental tasks. They rather depended on specific features of the mental processes involved in the performance of the tasks of different types. Thus, changes in the HR and the decreased SWA, which was related to elevated blood pressure, represent the effect of the sympathetic nervous system on the heart function during solving verbal-logical tasks. Our data demonstrate that the HR and blood pressure can be used as additional indices for the development of new techniques for assessment of different types of mental processes together with the indices of electrical brain activity.     

Changes in collagen structure under the influence of mechanical dispersion

Air-dry collagen isolated from cattle retinal layer by means of alkaline-salt treatment was crushed in a laboratory vibro-mill at 80-150 degrees K. Mechanochemical transformations were studied by means of viscosimetry, polarimetry, ESR-spectroscopy and electron microscopy. Mechanical tensions induce breakage of covalent bonds of polypeptide chains, accompanied by a decrease of protein molecular mass, and of lateral interactions, which results in loosening of collagen structure and partial denaturation.     

Changes in the tetrapolar rheographic indices of adult and old rats under stress]

Experiments with adult (8-10 months) and old (24-26 months) male rats were carried out to investigate the effect of stress on the values of central hemodynamics and inotropic cardiac function--stroke volume, minute volume, stroke index, as well as output volume rate, output volume rate index and systolic frequency. It is found that stress causes more significant disturbance of inotropic function in old rats as compared with adult animals. This disorder occurs earlier in old rats. Probably it is a result of more pronounced damaging effect of the stress on the myocardium of old rats against the background of decreased compensatory systemic abilities.     

Changes in the expression of monoaminergic genes under the influence of repeated experience of agonistic interactions: from behavior to gene

The role of genetic and environmental factors as well as brain neurochemistry in regulating aggressive and submissive behaviors in animals are considered. We present a review of data on changes in brain monoaminergic activity (synthesis, catabolism, receptors) and on the expression of monoaminergetic genes under repeated daily agonistic confrontations in male mice. A repeated experience of aggression was shown to result in the total activation of the dopaminergic system and the inhibition of the serotonergic one. This was accompanied by a decrease in the mRNA level of the catechol-O-methyltransferase gene in the midbrain and an increase of the mRNA level of the dopamine transporter and tyrosine hydroxylase genes in the ventral tegmental area of aggressive male mice. Repeated experience of social defeats produced dynamic changes in the serotonergic system of some brain areas and an increase of the mRNA level of the serotonin transporter and monoamine oxidase A genes in the midbrain raphe nuclei. Theoretical and methodological possibilities of the proposed ethological approach for studying molecular mechanisms of agonistic behavior are discussed in the context of the fundamental problem of investigating the ways of regulation from behavior to gene.     

Changes of neurochemical and electrophysiological indices of rat brain under ethanol intoxication

It was found that acute ethanol intoxication caused an imbalance of the neurotransmitters in the CNS: accumulation of GABA and serotonin and depletion of catecholamines. Alcohol depression was characterized by suppression of the evoked potentials of the various rat brain structures. Under chronic ethanol intoxication of animals, relative stabilization of the electrophysiological indices of the rat brain activity was observed. This reflects the CNS adaptation to the constant ethanol presence in the blood. This state was also characterized by the relative stabilization of the serotonin system and by the increase of the catecholamine level. Withdrawal of ethanol after prolonged consumption caused accumulation of catecholamines in rat brain, depletion of serotonin and GABA, and increased excitability of the nervous structures. The changes of activity of the GABA- and monoaminergic systems are coupled to manifestation of symptoms of alcohol depression and convulsive reactions during ethanol withdrawal.     

Changes in the emotionally conditioned behavior of rats under the influence of the hexapeptide fragment GLLDLK of the protein inhibitor of diazepam binding]

It is shown that suboccipital injection of 100 micrograms of the gexapeptide GLLDLK (the fragment of endogenous peptide--the inhibitor of diazepam binding) modified (for 1-3 days) the emotionally conditioned behaviour of the rats (the test of "emotional resonance"). This modification was realized in some reinforcement of different behavioural patterns and had signs of anxiety and depression. In the test "social hierarchy" the injection of GLLDLK didn't change significantly the hierarchy in the whole rat society, but in the recipient behaviour the exploratory activity has been changed, the time of grooming increased and the quantity of social contacts decreased.