[Electrophysiological and morphohistochemical study of adrenalectomy on the hippocampal neurons].

Chronic insufficiency of adrenal hormones is a pathology leading to brain dysfunction. In electrophysiological studies, by extracellular recording of spike activity of single hippocampal neurons (HN) caused by high-frequency stimulation of the entorhinal cortex (EC) in rats with unilateral removal of adrenal (adrenalectomy - AE), we analyzed mechanisms of adaptation of neural networks to chronic hormonal deprivation. The balance of excitatory and inhibitory responses, recorded in HN of intact rats was submitted to characteristic changes in dynamics of development of neurodegeneration: the dominating in norm inhibitory responses were decreased at all AE terms (from 42 % to 25 % by the 18th week). On the contrary, the minimal in norm percent of excitatory responses sharply increased (from 17 % to 60 %) at the 25-27th day after AE, which indicates a possible increase of cholinergic neurotransmission. There was recorded a high level of the mean frequency of peristimulus spiking from the 25-27th day to the 18th week after AE, which indicates the high glutamate level or pronounced activation of NMDA receptors. On the whole, the ratio of excitatory/inhibitory HN responses indicates discoordinated activity of neuronal chains of EC-HN under conditions of AE. Histochemical analysis revealed an increased sensitivity to AE in neurons of the CA1 fields. After disturbance of neuronal structure by the 5th day, 25-27 days after AE, there was observed proliferation cell elements in the CA1 field; as a result, by the 10th week, there is observed the complete filling of "devastated" areas of hippocampus and a sharp rise of phosphatase activity in nuclei of dentate gyrus. 18 weeks after AE, the majority of the CA1 field neurons are submitted to chromatolysis, and the phosphatase activity falls. The presented data make certain contribution to understanding of mechanisms of control of cognitive brain functions and plasticity in interconnection with the hormonal factor.

[Role of oxytocin in activation of spontaneous electrical activity of uterine body and uterine tubes in non-pregnant rats].

The work studies effects of various doses of oxytocin (0.01, 0.1, 1 and 10 microg/kg) on duration of discharges of spontaneous electrical activity and frequency of spikes in various parts of uterine tubes and of uterine body of non-pregnant rats. Under these conditions, changes in these parameters for ovarian parts of the uterine tubes had similar character unlike those in cervical parts of the tubes and in the middle part of the uterine body, so the latter parts can be grouped together owing to peculiarities of their changes. The longest duration of genesis of electric discharges has been shown for the ovarian part of uterine tubes at a concentration of 10 microg/kg of oxytocin. Morphological experiments revealed that among all studies areas the ovarian parts of uterine tubes were characterized by the highest amount of atypical cells that have the maximally pronounced functional activity.

[Effect of oxytocin on activation of spontaneous electrical activities registered from uterine corpus and uterine tubes in rats].

The effects if different concentrations of oxytocin (10(-2), 10(-1), 1 and 10 microg/kg) on burst duration and spikes frequency of spontaneous electrical activity in various parts of uterine horns and uterine corpus in non-pregnant rats have been shown. The changes in given parameters for ovarian parts of horns had similar characters unlike cervical parts of horns and middle part of uterine corpus under these conditions, so the last mentioned areas could be grouped together by the reason of similar changes in their parameters. Oxytocin in a concentration of 10(-1) microg/kg promoted the longest duration of spike electrical activity genesis in ovarian parts of horns. Morphological experiments showed that ovarian parts of horns had a great amount of atypical cells with strongly expressed functional activities.

[Demonstration of Ca2+-dependent acid phosphatase activity in cellular structures of rat brain].

A new method was developed to demonstrate Ca2+-dependent acid phosphatase activity, that is designed for the study of cytochemical organization of CNS cellular structures. Besides its histochemical significance, this method is of certain morphological interest, as it gives the results, intermediate between those obtained using Nissl's method and silver nitrate impregnation. The method proposed possesses selectivity, high reproducibility and gives clear-cut structural details. The morphological images obtained are highly informative and permit to evaluate the metabolism of the structures studied in the experiment. The method is inexpensive and is easily accessible for the solution of standard research tasks.

[The influence of BT-melanin on the recovery of conditioned instrumental reflexes in rats surviving after ablation of the sensorimotor cortex].

It has been shown the reinforcement of the corticofugal plasticity in adult rats after unilateral ablation of sensorimotor cortex accompanied by intramuscular injections of low concentrations of BT-melanin. In result the process of compensatory recovery in rats central nervous system is accelerated, confirmable by the rapid recovery of previously elaborated instrumental conditioned reflex in comparison with the control animals. It is assumed that the compensation of the motor deficit arised after the sensorimotor cortex ablation is ensured by the ability of two main motor systems of the brain (corticospinal and corticorubrospinal) to duplicate each other. This phenomenon of functional switching of descending influences has also been revealed in control group rats, not injected with BT-melanin. However the difference in time periods of operantly conditioned reflex recovery, for experimental and control groups, argues the apparent acceleration of this process, induced by the effects of BT-melanin. The obtained data considers the possibility of applied use of low concentrations of BT-melanin.

[Pacemaker activity in distal parts of the cat ureter].

Existence of two types of uncoordinated spontaneous activities of the cat ureterbladder area was shown: spikes and slow waves. The oscillation frequency of this area is two-fold lesser than the rhythm of renal waves. The activity concordance of these pacemakers occurs under conditions of ureter dissection in the middle. Normally pacemakers of this area seem to be a reserve mechanism of urine pushing through.

[Method for the demonstration of myelinated nerve fibers in the central nervous system]. / Vyiavlenie mielinovykh nervnykh volokon v tsentral'noi nervnoi sisteme.

The new method for the demonstration of myelinated nerve fibers in the central nervous system is developed. The method is based on the principle of fractional blocking of metalloorganic compounds and the fact of selective reaction of the trivalent (ferric) iron with myelin. The method proposed is not laborious and is simple in utilization.

[Effect of histamine on spontaneous rhythmogenesis of the guinea pig ureter]. / Osobennosti vozdeistviia gistamina na spontannyi ritmogenez mochetochnika morskoi svinki.

Histamine changed characteristics of the perinephric spontaneous spike activity and of the spreading electrical wave. It was shown that histamine could activate latent pacemakers of the ureter's middle area. Morphological picture of the histamine effect was also shown.

[Reaction of the brain capillaries to hypoxia in cats]. / Reaktsiia kapilliarov mozga koshki na gipoksiiu.

Using calcium-adenosinetriphosphate histoangiological method of Chilingarian, the morpho-functional characteristics of capillary section of microcirculatory bed were studied in cat's brain and dura mater following experimental hypoxia. Analysis of morphometric data has shown that short-term hypoxia resulted in dilation of brain capillary lumen by 15% in comparison with that in intact animals. Average diameter of dura mater capillaries was found to vary within the limits of control values. Dilation of brain capillaries should be considered as a compensatory-adaptational change aimed at maintenance of metabolic regulation of cerebral circulation.

[The differentiation of rhythmogenic characteristics of the ureter's different regions in guinea pigs]. / Differentsiatsiia ritmogennykh svoistv razlichnykh oblastei mochetochnika morskoi svinki.

Characteristics of rhythmogenic pacemakers of the ureter's perirenal middle and peribladder region morphologically and electrophysiologically are analysed in guinea pigs both in presence of spreading activity and breach of conductivity. It was shown that the action potential's amplitude of the middle region is the highest and duration of the spike activities from perirenal zone is maximal and all three regions are characterised by different functional conditions.

[Effects of pyramidotomy on instrumental reflexes in rats depend on the duration of its execution]. / Effekty piramidotomii na instrumental'nye refleksy u krys v zavisimosti ot vremeni ee provedeniia

The effects of unilateral transection of bulbar pyramids on instrumental conditioned reflexes in rats were shown to be in direct relationship with the time of its execution. In rats with stable conditioned reflexes, pyramidotomy impaired conditioned performance, on the average, for 3.9 days. However, preliminary transection of the pyramid delayed operant conditioning and its stabilization, on the average, by 16.5 day. The findings are discussed in terms of the mechanisms of switching over descending influences of the cortico-spinal and cortico-rubrospinal systems.

[Dynamics of instrumental reflex changes following transection of the corticospinal tract and ablation of the cerebral cortex sensorimotor region in rats]. / Dinamika izmenenii instrumental'nykh refleksov u krys posle pererezki kortikospinal'nogo trakta i udaleniia sensomotornoi oblasti kory mozga.

Unilateral transection of bulbar pyramid performed prior to ablation of the ipsilateral sensomotor cortex was shown to facilitate recovery of operant conditioning and compensatory processes in rats. There was no such corticofugal plasticity in ablation of the sensomotor cortex alone. The phenomenon may be explained by switching of descending influences on the cortico-rubrospinal system through participation of the loop: corticorubral projection--red nucleus--inferior olive--cerebellum--thalamus--cerebral cortex.

[Changes in the cerebral microcirculatory bed under molybdenum exposure]. / Izmeneniia mikrotsirkuliatornogo rusla golovnogo mozga pod vliianiem molibdena.

Histochemical study of brain hemisphere hemo-microcirculatory bed in rats treated with large doses of molybdenum demonstrated significant 30-55% narrowing of capillary diameter as compared to that in normal animals. This constriction is likely to cause capillary trophic insufficiency syndrome that is important in pathogenetic mechanisms of molybdenum-induced toxicosis.