Blood testosterone in rats: correlation of the level of individual anxiety and its impairment after "death threat".

Studies of identical groups of male Wistar rats after preliminary selection to give groups including extreme behavioral types with low and high rankings on the anxiety scale showed that blood testosterone concentrations in intact rats (controls) correlated negatively with anxiety ranking, i.e., minimal hormone concentrations (no greater than 5 nM) corresponded to high levels of anxiety - with a predominance of passive defensive behavioral components on testing. Short-term exposure to a "death threat" situation (sight of a boa attacking and eating two individuals from the group of rats) impaired this correlational relationship in a manner comparable to the sequelae of chronic neuroticization by unavoidable pain stimulation. Impairments were manifest as scatter in measures in low-anxiety animals (3-21 nM). This characteristic, reflecting the multitude of adaptive pathways in the population in threat situations, distinguishes this type of action from neuroticization by unavoidable pain stimulation, which leveled out individual differences and decreased the hormone level.

[Blood testosterone in rats: correlation with individual anxiety and its derangement after the "death threat"].

After preliminary testing on a multiparameter scale, test and experimental groups of Wistar male rats were formed on the principle of identical distribution of individuals with different anxiety levels. A negative Spearman correlation between the testosterone blood concentration and the level of anxiety was observed in intact rats: the minimum hormonal concentrations (lower than 5 nmol/l) were found in rats with high anxiety, whereas the maximum concentrations (up to 16 nmol/l) corresponded to the higher anxiety level (prevalence of passive defense reactions during testing). After a sort-term exposure to life-threatening situation (viewing of a boa's attacking and devouring two victim rats from the test group), the correlation was deranged because of appearance of a scatter in testosterone blood concentration (from 3 to 21 nmol/l) in rats with low anxiety. Neurotization with inescapable pain stimulation also deranged the initial anxiety-testosterone correlation, but, as distinct from the exposure to life-threatening situation, eliminated individual differences in testosterone concentration at its low level. The results suggest the existence of multiple ways of adaptation to life-threatening situations in a rat population.

A special case of learning disorder in isolant rats as a model of disintegration.

The combination of two factors - isolation and ontogenesis (starting from 21 days) and subsequent training of rats to a cyclical habit - could in some animals (30%) lead to the formation of unusual behavioral strategies consisting of maintenance of the cyclical habit without reinforcement with food. This dissociation from the vital motivation is regarded as an analog of the disintegration phenomenon, a key step in psychoneurotic disorders. The most common type of disturbance in isolated animals was suppression of searching activity, with extreme learning difficulty, though a training process including a two-month break led to a significant increase in motor-searching activity in this situation. These behavioral abnormalities were accompanied by morphological changes in the sensorimotor cortex of the brain, with a relative thinning of layer 5 and selective decreases in the density of satellite glial cells and deviations from the normal correlational relationships between behavioral and neuroglial measures.

[A special case of learning disruption as a model of a disintegration phenomenon].

Combination of two factors in rats such as the isolation (during 2-4 months, beginning from the 21st day of age) and procedure of space cyclic learning results in a rare kind of behavioral strategy (in 30% animals), when the cyclic behavior is realized without food reinforcement. Such a dissociation between the vital motivation and searching behavior may be considered as an analogue of the disintegration phenomenon in neuropsychotic patients. The deep depression of learning owing to lowering of search represents the dominant type of behavioral disorders in isolants. The cyclic habit training, including a 2-months pause between two sessions, significantly increases behavioral search activity. The behaviors are accompanied by morphological shifts in the sensomotor cortex: significant decrease of the fifth layer (giant pyramids) thickness, selective lowering in the satellite glia density and elimination of normal behavior-glia correlations.

Monitoring of the oxidation-reduction state of brain structures in freely moving rats during sleep-waking cycles by potentiometric recording.

Freely mobile mongrel male rats weighing 300-350 g were used for studies of changes in the oxidative-reductive (redox) state of brain tissue during cycles of waking, slow-wave sleep, and paradoxical sleep, by recording the potential of the oxidative-reductive state of brain tissue with platinum electrodes implanted into the cerebral cortex ad hippocampus. Electromyograms were also recorded from the cervical muscles, and overall movement activity was also recorded. A common platinum reference electrode was implanted into the nasal bones. These experiments showed that in rats, episodes of waking and paradoxical sleep occurred on the background of increases in the oxidation-reduction potential state of brain tissue at a series of brain points, which we termed "metabolically active." Transitions from waking and paradoxical sleep to slow-wave sleep were accompanied by decreases in the potential of the redox state. The magnitude of changes in the tissue redox state varied up to 100 mV. It is suggested that transitions from waking and paradoxical sleep to slow-wave sleep are accompanied by dynamic changes in the balance of brain tissue energy metabolism between the main energy sources. Oxidative phosphorylation dominates in waking and paradoxical sleep, while aerobic glycolysis dominates slow-wave sleep. We suggest that this latter should be interpreted as a decrease in the potential of the tissue redox state and the formation within the tissue of oscillations during slow-wave sleep. Formation of oscillations is typical for acceleration of glycolytic processes. Recently published data suggest that the major compartment or aerobic glycolysis is the astroglia.

[Potentiometric monitoring of the redox state of brain structures of freely-moving rats in sleep-wake cycles]. / Monitoring okislitel'no-vosstanovitel'nogo sostoianiia struktur golovnogo mozga svobodno-podvizhnoi krysy v tsiklakh bodrstvovanie-son putem potentsiometricheskoi registratsii.

Variations of brain tissue redox state potential (E) of freely-moving white rats (300-350 g) in cycles of wakefulness (W), slow-wave sleep (SWS), and paradoxical sleep (PS) were measured by platinum electrodes symmetrically implanted into the frontal and occipital cortices and hippocampus. In addition, EMG of neck muscles and general motor activity of animals were recorded. The common reference electrode was implanted in the nasal bone. It was shown that in some brain sites (called active), episodes of W and PS were accompanied by a rise of E, and during transitions from W and PS to SWS, E dropped. The value of E varied in the range of 100 mV. It is suggested that transitions from W and PS to SWS are accompanied by shifts in the balance between the main energy sources. Oxidative phosphorylation prevails in W and PS, whereas aerobic glycolysis is the main source of energy during SWS. We think that this suggestion is supported both by a decrease in E in SWS and its oscillations typical of glucolytic processes [Aon et al., 1992]. Recent literature data [Bitter et al., 1996] suggest that astroglia is the main compartment for aerobic glycolysis.

[Behavioral consequences of isolation in early ontogeny in rats: selectivity of anxiety conditions]. / Povedencheskie posledstviia izoliatsii v rannem ontogeneze u krys: selektivnost' trevozhnykh sostoianii.

Multiparameter scale for evaluation of anxiety-phobic state in rats reveals significant enhancement of anxiety in rat pups after 6-week isolation (beginning from the 21st day from birth) as compared to grouped controls of the same litter: the locomotion and exploration that appear in test areas are suppressed, and species-specific fear reactions are enhanced. These changes considered as signs of situational anxiety are not eliminated by 2.5-month keeping in groups. Nevertheless, they are not correlated with parameters of the acoustic startle reflex that (by the data of literature) is thought to be related with fear and anxiety. On the basis of the discrepancy it is proposed that state of anxiety is selective. This suggestion is confirmed by individual behavioral variations characterized by a combination of a low level of situational anxiety and a high level of acoustic anxiety observed in both experimental and control groups. These variations may explain the existence of atypical "emotional resonance"-like behavior according to P.V. Simonov. Attention is given to selectively enhanced acoustic startle reflex in the group of active control as an evidence for critical importance of any manipulations with social context in early ontogeny.

[The learning characteristics of rats under free-choice conditions]. / Osobennosti obuchenia krys v usloviiakh svobodnogo vybora.

The ability to organize a four-link operant food-procuring habit in a multiple alternative maze using the free-choice method was studied in albino rats. Three types of animals were observed which were different in the character of learning. The learning curve of 20% of rats had of exponential character (type I). Some animals (37%) acquired the skill through "insight" and the process of learning in these cases could be described by a logistic regression function (type II). The remaining rats (43%) refused from solving the intricate task and were able to acquire only the simplest form of a response, i.e., running to feeders. It is suggested that learning differences between the I and II types of animals may be associated with different strategies of problem solving: "procedural" (algorithmic) and "conceptual" (semantic).

Is the electrical activity of the brain always electrical? (The factors forming the potential of the metallic electrode during its direct contact with the brain).

This article is devoted to an analysis of the factors forming slow changes in the potential of a metallic electrode coming into direct contact with living tissue. Data are presented in this paper according to which, the electrochemical activity of the tissue also participates, in addition to electrical activity, in the formation of the electrode potential. The article is in the nature of a discussion.

[The comparative efficiency of exploratory and conditioned-reflex feeding behaviors: the relative improvement in the former and the lag in the latter in amygdalectomy in rats]. / Sravnitel'naia éffektivnost' poiskovogo i uslovnoreflektornogo pishchevogo povedeniia: otnositel'noe uluchshenie pervogo i otstavanie vtorogo pri amigdaléktomii u krys.

Food-taking behaviour of two groups of rats (normal ones, N, and those with amygdalar lesions, AL) was compared to each other in two experimental situations: running to the feeding-cup in a new situation and the same after the learning procedure. In the first case the efficiency of food-taking behaviour was found to be higher in AL rats than that in N rats. On the contrary, in the second situation, the efficiency of food-taking was lower in AL rats. This difference was supposed to be connected with two factors: motivation (in a new situation) and mastering the environment (after learning). It was assumed that after AL the rats with a deficit of analytical-synthetic process became primarily oriented towards inborn programs. A sudden increase of food reinforcement resulted in AL rats in a reduce of feeding activity and an increase of general activity resembling much the effect of 5-HT in the limbic system.

[Is the electrical activity of the brain always electrical? (The factors that generate the potential of a metal electrode in direct contact with the brain)]. / Vsegda li élektricheskaia aktivnost' mozga--élektricheskaia? (O faktorakh, obrazuiushchikh potentsial metallicheskogo élektroda pri neposredstvennom ego kontakte s golovnym mozgom).

In the paper are analysed the factors creating slow potential changes of a metal electrode directly contacting with the living tissue. In the paper are presented the data according to which electrochemical tissue activity participates in creating the electrode potential besides the electrical activity. The paper carries a discussion character.

[A comparison of the take of embryonic amygdala and visual cortex transplants in the rat brain in connection with the possible compensation of functional disorders]. / Sopostavlenie prizhivleniia transplantatov émbrional'noi amigdaly i zritel'noi kory v mozge krysy v sviazi s vozmozhnost'iu kompensatsii funktsional'nykh narushenii.

Transplantation of embryonic (E17-18) visual cortex and amygdala was performed into corresponding damaged areas of the adult rat brain. It was shown in Nissl and Golgi preparations (by comparing qualitative and quantitative findings) that 2-6 months after operation the grafts were successful in case of putting them into the corresponding brain areas (cortex to cortex, or amygdala to amygdala). Graft's integration resulted in a selective increase of dendrite length and ramification towards the area of graft-host interface both in amygdala and visual cortex grafts. In case of inadequate graft-host integration the stratification of the grafted visual cortex could be observed. The structural reorganization of grafted neurones is compared with physiological and behavioural findings during the recovery processes in damaged brain.

[Can the function of the extirpated amygdaloid complex be compensated for by the transplantation of embryonic nerve tissue?]. / Mozhno li kompensirovat' funktsiiu udalennogo mindalevidnogo kompleksa mozga putem transplantatsii émbrional'noi nervnoi tkani?

In 20 white rats bilateral coagulation of the amygdalar complex was produced; on the fifth day to one half of them transplantation was performed by introducing stereotaxically on the left side 0.2-0.5 mm3 of the brain embryonal tissue from the corresponding area of the amygdala of 20-days embryo; in control saline was administered. After two months the rats were sacrificed to determine the activity of antiradical defense by superoxide dismutase (SOD) and the level of lipids peroxide oxidation (LPO) in the cerebral cortex. The transplantation decreased LPO even more and increased SOD as compared to amygdalectomy, e. i. caused still greater deviations from the norm (in this meaning--paradoxal effect), what apparently corresponds to intensification of adaptative-compensatory processes caused by amygdalectomy. The transplantation did not reverse the rats behaviour to the initial one and did not eliminate memory defect in the test of conditioned reaction of passive avoidance (like pyrazetam); it had different direction influence on "drinking under current" in conflict situation, only in particular cases approaching it to the norm.