An EEG analysis of the structural interrelationships of the thalamofrontal system in the recovery of conditioned-reflex behavior in amygdalectomized rats]

Unilateral damage of the baso-lateral amygdala in white non-strain rats led to decrease of the number of instrumental responses and increase of their latencies in the course of the first two weeks after the surgery. This period was characterized by increase of the delta- and theta-frequency bands in electrograms of the orbito-frontal cortex and dorsomedial nucleus of the thalamus. During the next two weeks this increase was observed only in the orbito-frontal cortex. Functional reorganization of interconnections between the limbic and thalamo-cortical brain structures is supposed to underly phenomena observed.     

Complex form of adaptive behavior in rats

Two problems have been dealth with: a) are rats able by self-learning to form purposive associations, involving elements of reasoning object activity and b) at what age period are they most capable of purposive tool activity. The experiments were performed on 55 rats aged from two to three, five to six and eight to ten months. It was established that tool activity in rats appeared on the 14th to 34th experimental day in 14.5% of all the experimental animals. By age groups the activity was distributed as follows; at the age of two to three months the problem presented was solved by 10% of the individuals, at five to six months -- by 30% and at eight to ten months, by 0%. Thus tool thinking as one of the forms of animals' higher adaptation to surroundings, is inherent not only in anthropoids but in species much lower in the evolutionary scale. By the form of its realization thinking activity in rats is less plastic than in apes and in our experimental conditions, it was not exhibited by all the rats.     

Passive avoidance in amygdalectomized rats as affected by methylphenidate and midantan

It is shown that disturbance of conditioned reaction of passive avoidance in Wistar rats, elicited after bilateral amygdalectomy, may be compensated by administration of indirect dopamine agonist--methylphenidate. Two-fold administration proved to be effective: that before learning and that before testing. Two-fold administration of another dopamine agonist--amantadine did not restore the disturbed conditioned reaction. The results are discussed in the aspect of the role of different dopamine brain systems in passive avoidance and possible specificity of the drugs action.     

The effect of adren- and serotoninergic substances on the behavior of amygdalectomized rats and on the aggressiveness evoked by intra-amygdaloid administration of acetylcholine]

The effect of serotoninergic (serotonin, 1-trytophane, imipramime, methysergide), catecholaminergic (noradrenaline, amphetamine, dopamine, 1-DOPA, iproniazid) and cholinergic drugs (physostigmine, atropine, benactyzine) on emotional reactions and orienting-motor activity, as well as the effect of these drugs on shock-elicited aggressiveness enhanced by intraamygdaloid microinjection of acetylcholine was investigated in experiments on amygdalectomized male albino rats. In amygdalectomized animals, as compared to control false-operated rats, the stimulating effect of amphetamine, imipramine, tryptophane and m-cholinoblockators was enhanced and their inhibitory effect was weakened. Bilateral microinjection of cholinergic drugs (acetylcholine, physostigmine and carbacholine) and noradrenaline into the amygdaloid body intensified emotional reactivity and aggressiveness. Microinjection of serotonin and dopamine inhibited aggressiveness and caused facilitaion of orienting-motor activity. It is suggested that the adrenergic system intensifies and serotoninergic system depresses the m-cholinergic trigger mechanism of aggressive behavior in limbico-diencephalic structures.     

Characteristics of the thermoregulatory reactions of mice and rats to mediator-active substances

The effect of dopaminomimetics (apomorphine, piribedil, bromocriptine), cholinomimetics (oxotremorine, arecoline, pylocarpine), and neuroleptics (chlorpromazine, haloperidol, triperidol) on rectal temperature (Tr) and temperature of different parts of the skin has been investigated in albino mice and rats of either sex. In rats these drugs cause the decrease of Tr and significantly increase tail temperature (Tt), as well as the temperature of the fore- and hindpaws (Tfp and Thp correspondingly). In mice the drug-induced fall of Tr is more significant than in rats; however, only neuroleptics essentially increase Tfp and Thp, the increase in Tt being inconsistent and small. Cholinomimetics and usually dopaminomimetics decrease Tt. Cholinomimetics do not affect and dopaminomimetics cause only transient and small rise in Tfp and Thp. The data do not confirm the key role of enhanced heat dissipation through the skin as a mechanism of hypothermic effect of cholino- and dopaminomimetic drugs in mice under the room temperature. In contrast to mice, thermoregulatory skin reactions to drugs in rats are much more pronounced, and together with palmar and plantar surfaces of the paws the same role in thermoregulationss is played by the skin of the tail.     

Electrophysiological characteristics of depressive conditions with passive strategy of the adaptive behavior in rats

Wistar rats strain with passive strategy of the adaptive behavior were selected in T-maze labyrinth. The rats were exposed to water-immerssions stress and after 10 days from their brain the olfactory cortex slices were prepared. The evoked focal potentials were registered in slices. It is shown that the amplitudes of the AMPA and NMDA EPSPs were reduced as compared to control (rats without stress). The amplitude of the GABABergic inhibitory postsynaptic potentiation was increased after stress. Additions of the corticotropin-releasing hormone (10(-10) M) in incubation medium result in reversible inhibition of synaptic transmission. Tetanic stimulation of the slices induced of the long-term posttetanic depression in 84 % slices and in 12 %--to the long-term posttetanic potentiation. It is indicates that the significant disturbances in synaptic transmission in slices. Thus the activation of the corticotrophinergic mechanisms in cortical structures not promots the removal of the rats depressive state with passive strategy of the adaptive behavior induced by inescapable stress.     

Characteristics of open field behavior of Wistar and Sprague-Dawley rats

The open field test (OFT) was carried out on Wistar and Sprague-Dawley rats between the ages of 3 to 20 weeks. At that time, the behavior of each naive rat was observed for two 3-minute periods separated by an interval of 24 h (Day). The OFT scores varied depending on the day and the age. Comparatively higher activity was observed in the extent of ambulation and rearing at 5 weeks old, rearing and preening at 7 weeks old, and preening and defecation at 11 weeks old in the Sprague-Dawley rats compared with the Wistar rats.     

Morpho-functional alterations of the adrenal cortex in rats with active and passive strategy of adaptive behavior

In rats with the active (KHA strain) and passive (KLA strain) coping strategies, a post-stress depression develops respectfully on the 1st or 10th day after the inescapable stress. The present study revealed an increase of adrenal weight and blood corticosterone levels on a day following the inescapable stress, as well as marked fluctuations of blood glucose in one and five days post-stress in KHA rats. By the 10th day, these indices returned their basal levels. In contrast, the stress reactivity of KLA rats was lower in all terms and their corticosterone levels remained reduced on the 10th day after stress. In KLA rats, the fasciculate zone was reduced but reticulated zone grew in Ith day following the stress, while in KHA rats the inescapable stress resulted in growth fasciculate zone and concomitant reduction of reticulate zone, both evident on the 10th post-stress day. The data indicate that the development of post-stress depression in KLA rats is probably associated with exhaustion of adrenocortical function.     

Alteration of active and passive Wistar rats adaptive behavior in water-immersion model of depression

Animals with active and passive behavioral strategy were selected among male Wistar rats by testing them in the T-maze. Using the results of rats testing in T-maze index of behavioral activity and index of behavioral passivity were calculated. The development of post-stress psychopathology and ils correlation with initial behavioral strategy were studied under water-immersion stress conditions consiclering individual alteration of adaptive behavior. Two paradigms were used--one time trial (stress) and two times trial (stress-restress). It was found that active and passive rats being subjected to inescapable aversive exposure develop different types of post-stress depression and only passive animals show the signs of posttraumatic stress disorder.     

Simulation of adaptive behavior

Behaviors as diverse as swimming, withdrawal, escape, locomotion and feeding have been simulated using neuroethological and neurophysiological data obtained from a variety of animals. These simulations are providing new insights into the neural circuitry that generates adaptive behavior, as well as new ideas for the design of artificial autonomous devices.     

Characteristics of the role of spatial memory in the choice reactions of white rats

Behaviour of the rats, previously learnt to come back to one and the same place of reinforcement was studied in conditions of periodical changes of this place. It was found that after detection of the new place of reinforcement, the rats could optimize their behaviour according to disposition of this place. Optimization of behaviour consisted in shifts of running direction towards the new reinforcement place and (or) in selective displacements before blinds, according to the places of reinforcement in the experiment. It is suggested that an increase of the role of working memory and apparatus of probabilistic prognosis at choice lies in the basis of optimization.     

Dynamics of adaptive reactions at the cellular level during training of rats to hypoxia. Review of research

Adaptive changes of the tissue energy metabolism occur during training of rats to hypoxia. A gradual increase in glycolysis and in the activity of glycolytic enzymes of the tissues is observed. Dynamics of the changes in the oxidative metabolism studied at the mitochondrial level are shown. There are also some changes in the blood system such as the production in the bone narrow of erythrocytes possessing some biochemical properties specific for fetal animals.

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Zusammenfassung Während des Hypoxie-Trainings von Ratten treten Anpassungsvorgänge im Gewebsstoffwechsel auf, die sich in einem graduellen Anstieg der Glykolyse und der Aktivität der glykolytischen Enzyme der Gewebe äussern. Die Dynamik der Anpassungsvorgänge des oxydativen Stoffwechsels der Mitochondrien wird berichtet. Auch im Blut sind Veränderungen nachzuweisen wie die Ausschüttung von Erythrocyten aus dem Knochenmark mit Eigenschaften, wie sie im Fetalblut angetroffen werden.

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Resume Durant la période d'entrainement à l'hypoxie, on constate chez les rats des modifications du métabolisme des tissus dus à une adaptation. Ces modifications se traduisent par une augmentation progressive de la glycolyse et de l'activité des enzymes glycolytiques des tissus. On note des processus dynamiques d'adaptation du métabolisme oxydatif au niveau des mitochondries. On peut également déceler des modifications du systèmes sanguin telles que la production à partir de la moelle osseuse d'érythrocytes aient des propriétés semblables à celles que l'on rencontre dans le sang des foetus.

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Presented during the Fifth International Biometeorological Congress, 1–7 September 1969, Montreux, Switzerland.     

The role of corticotropin-releasing hormone in alteration of adaptive behavior of the active and passive rats after inescapable stress

Effects of corticotropin-releasing hormone (CRH) on the formation of post-stress psychopathology were studied using of two genetic strains KHA (Koltushi high Avoidance) and KLA (Koltushi low Avoidance) selected on high or low acquisition of active avoidance, respectively. These strains are characterized by higher (KHA) and lower (KLA) behavioral activity in open field and adopted, respectively, active and passive strategies in stressful conditions. A widely used experimental paradigm of learned helplessness where behavioral depression was produced by inescapable uncontrollable footshock has been applied in our study. KHA rats demonstrated psychopathology already 1st day following exsposure to the stress faktor, and the depression progressed by the 5th and 10th post-stress days. Intranasal application of CRH facilitated the development of depression in active rats. In KLA rats, which originally displayed low exploratory activity associated with high anxiety, the inescapable stress at first enhanced the exploratory behavior but 10 days later these rats displayed a progressive decline of exploration and locomotion. Initially, the application of CRH also enhanced the exploratory behavior in these rats, but to 10th post-stress day promoted development of depressive state. The results suggest that CRH in different ways affects the formation of depressive state in rats with different strategies of adaptive behavior.     

Corticotropin-releasing hormone in the regulation of adaptive behavior

Recent findings on the role of corticotropin-releasing hormone (CRH) in the regulation of stress and its consequences are summarized and analyzed in the review. Being involved in stress-activating system this neurohormone is referred to as a neurochemical factor triggering and integrating both endocrine and behavioral functions. The CRH distribution in hypothalamus and extrahypothalamic brain regions relevant to its involvement in the controlling of endocrine processes and behavior is viewed in details. Distinct behavioral outcomes of stress and the contribution of amygdalar, hippocampal, and striatal CRH-structures, implicated in general organism response to external influences, are widely discussed. From this viewpoint the mechanisms involved in the development of post-stress psychopathology, as well as drug addiction and alcoholism are treated.