Effect of dalargin on the processes of memory and learning in the rat

In experiments on rats, the influence was studied of dalargin on the elaboration and preservation of various homogeneous and heterogeneous conditioned reflexes (CRs) elaborated in single and multiple pairings. The effect of dalargin on the processes of learning and memory was compared with the action of the peptide on the activity of hypothalamic neurones. Administration of dalargin delayed the elaboration of maze defensive CRs and practically did not affect the elaboration of two-way avoidance. The preservation of CR also deteriorated under the influence of dalargin. Administration of dalargin 10 min before the CRs testing did not prevent their reproduction. When using CRs elaborated in a single pairing, dalargin disturbed the preservation of the drinking CR and improved that of passive avoidance CR. Dalargin in this dose affected the emotional state of animals in the open field and did not significantly affect their motor activity. Dalargin suppressed impulse activity in 17 out of 22 tested neurones of the lateral hypothalamus, with maximum effect in 20-50 min after its administration. The obtained data show that the character of dalargin action on the elaboration of CR and mainly on its consolidation, depends on the character of the elaborated CR and is probably due to great extent to the effect of the peptide on the brain emotional mechanisms.     

The effect of ultrahigh-frequency electromagnetic radiation on learning and memory processes]

Low-intensity electromagnetic field (12.6 cm, 2375 MHz, power density 1 mW/cm2) produced retrograde amnesia in the rat passive avoidance test. No effect was registered of microwave irradiation on the open field behavior and the pain sensitivity. Functional activity of the m-cholinergic receptors decreased, but their number increased in the brain cortex. It is suggested that cholinergic system plays an important role in the effects of electromagnetic field on memory processes.     

The effect of vasopressin on memory processes in Macaca fascicularis]

The role of vasopressin (arginin-vasopressin) in the regulation of conditioned instrumental food-procuring reactions and different kinds of memory such as delayed reflexes, image, short-, and long-time memory was studied in monkeys. Motor and autonomic effects of vasopressin were assessed. It was found that in monkeys, vasopressin administration differently affected the simple conditioned food-procuring reactions and memory. During functional disorders of the higher nervous activity, vasopressin was more efficient in its action on memory and its restoration. Formation of two types of vasopressin effects on the higher nervous activity in evolution of mammals is discussed.     

The effect of a deficiency of the hormones of the peripheral endocrine glands on behavioral, learning and memory processes]

A comparative study of the effects of thyroid, adrenal, and gonadal deficit on capability for learning, retention of memory traces, and behavior was carried out in male rats under conditions of hormonal disbalance produced by extirpation of the endocrine glands. Behavior of animals was tested during the active and passive avoidance learning and in the open field. It was found out that the extirpation of the peripheral endocrine glands impairs learning and reproduction of the acquired reaction and alters the behavior. The results suggest that corticosteroid hormones take part in learning and behavior. Gonadal and thyroid hormones appear to exert a modulating influence on the higher nervous activity.     

Effect of cadmium chloride on the processes of learning and memory in rats

Intraperitoneal injection of cadmium chloride (4 mg/kg) to rats before elaboration or reproduction of two-way avoidance conditioned reflex (TACR) disturbs both these processes. Deterioration of elaboration does not affect connections fixation and their subsequent reproduction. Injection of the substance before the elaboration of passive avoidance conditioned reflex (PACR) depresses elaboration and consolidation. Injection of cadmium chloride before testing of PACR preservation does not influence the processes of engrams reproduction. The observed disturbances cannot be connected with changes of animals motor activity.     

Effect an ACTH analog on the processes of learning and memory in rats

On the basis of the idea of the important role of neurotransmitter systems in realization of neuropeptide effects, the participation was studied of the monoaminergic systems in the mechanisms of the ACTH analogue influence on the processes of learning and memory in control animals and animals with a changed functional state of the monoaminergic systems. In parallel the influence was studied of the ACTH analogue on the content of the endogenic monoamines in various brain structures of rats. It has been shown that administration of the ACTH analogue in a dose of 10 mcg affects the elaboration and preservation of conditioned reflexes (CRs) of passive avoidance, CRs of two-side avoidance and labyrinth CRs only in conditions of changed functional state of the monoaminergic systems. Amnesia, usually elicited by 5-oxytryptophane and disulfiram is prevented by administration of the ACTH analogue. Administration of the ACTH analogue is accompanied by the intensification of serotonine metabolism in the midbrain and medulla and by an increase of noradrenaline content in the hypothlamus.     

Computational modeling of evolutionary learning processes in the brain

The evolutionary selection circuits model of learning has been specified algorithmically. The basic structural components of the selection circuits model are enzymatic neurons, that is, neurons whose firing behavior is controlled by membrane-bound macromolecules called excitases. Learning involves changes in the excitase contents of neurons through a process of variation and selection. In this paper we report on the behavior of a basic version of the learning algorithm which has been developed through extensive interactive experiments with the model. This algorithm is effective in that it enables single neurons or networks of neurons to learn simple pattern classification tasks in a number of time steps which appears experimentally to be a linear function of problem size, as measured by the number of patterns of presynaptic input. The experimental behavior of the algorithm establishes that evolutionary mechanisms of learning are competent to serve as major mechanisms of neuronal adaptation. As an example, we show how the evolutionary learning algorithm can contribute to adaptive motor control processes in which the learning system develops the ability to reach a target in the presence of randomly imposed disturbances.     

Effects of dalargin on the proliferative processes of the gastric epithelium under repeated action of different stressors]

Using radiography with H-thymidine method we studied the synthesis of DNA process in pyloric parts of stomach epithelium in white rats, which have been five-fold effected by different kinds of stressors against a background of dalargin injections. In the first hour after animals were stressed, DNA synthesis was depressed. Dalargin injections caused DNA synthesis normalization in the first hour after hypoxia and hyperthermia. Since 24 hours after hyperthermia and immobilization against a background of dalargin injections the normalization of DNA synthesis took place, and after hypoxia the post-stressing IMN activation was growing week. One of the mechanisms of dalargin correction of DNA synthesis breach under the influence of stressors is a stabilization of noradrenaline and histamine concentration in tissue of the stomach.     

Effect of insulin and its polymeric analogs on learning and memory processes in the rabbit

The effect of insulin and its seven synthetic derivatives on spontaneous bioelectrical activity of the cerebral cortex of rabbits was described in the paper. The influence of these substances on consolidation of long-term memory of white rats was shown at normal state and during experimental neurosis. Insulin was supposed to influence the higher nervous activity not only through glucose metabolism but also by means of increase of permeability of biological membranes for amino acids.     

Effects of opioid peptide dalargin on reparative processes in wound healing

At intraperitoneal injection and local application of opioid peptide dalargin induces fibroblast proliferation (3-fold increase in the mitotic index) and growth of capillaries, accelerates the maturation of granulation tissue and of scar, epitheliazation of the defect, and considerably reduces the period of healing of skin wound in rats. The stimulating action of dalargin is associated with its effect on the microcirculation system and activation of the macrophage-fibroblast interaction. Possessing the triggering mechanism, the drug induces a cascade of inflammatory-reparative reactions, which reduce the duration of all healing stages.     

Higher olfactory processes: perceptual learning and memory.

The past year has seen several important findings emerge from studies of higher olfactory processes. The identification of synaptic long-term potentiation in the olfactory cortex, induced via repetitive burst stimulation at the theta rhythm, and physiological activity patterns associated with learning, some of which mimic long-term potentiation induction patterns, have suggested relationships between rhythmic activity, behavioral learning and synaptic plasticity. In addition, the construction of computational models of the olfactory bulb and cortex have generated testable behavioral and physiological predictions which have been supported by experimental evidence.     

Hippocampal brain amines in methotrexate-induced learning and memory deficit

Intrathecal methotrexate in children with leukemia is known to cause seizures, dementia, leukoencephalopathy, and cognitive dysfunction after long-term treatment. To investigate the cognitive dysfunction, male Wistar rats were given multiple intracerebroventricular injections of methotrexate. Its effect on behaviour was tested in the two-compartment conditioned avoidance task and dark-bright arena test. Levels of brain amines in the hippocampal region of the brain were estimated by HPLC. The qualitative and quantitative histopathological changes in the different regions of the hippocampus were studied by cresyl violet staining. Multiple injections (1 or 2 mg/kg) produced convulsions and learning and memory impairment but did not induce anxiolytic activity. They also reduced concentrations of all three brain amines (norepinephrine, dopamine, and serotonin) and the serotonin metabolite 5-hydroxyindoleacetic acid. The CA4 region of the hippocampus was severely affected by intraventricular methotrexate. Disruption of brain monoamines has been proposed as a cause of brain dysfunction from this chemotherapy, and that disruption may in turn involve cytotoxic effects of methotrexate on brain tissue. The outcomes of this study may have therapeutic implications in the management of cancer conditions, particularly in childhood lymphoblastic leukemia.     

The effect of electric stimulation of several zones of the brain on verbal memory in humans]

Investigations of patients with implanted in intracerebral electrodes have shown that within some subcortical structures there exist neuronal-glial populations in which the dynamics of their functional state, according to the results of local recording of slow processes (oxygen tension, local blood flow, impedance), clearly correlates with the correct performance of the tests on operative memory. Electrical stimulation of some of the zones significantly changes the volume of operative memory and influences the general state and higher psychic functions in the patients. The result of electrical stimulation of the brain is determined by the role of different zones in the mnestic act and by the stage at which the stimulation is performed. The role of the cerebral zones is discussed in which the change of the functional state correlated with errors in tests reproduction, the detectors of errors in securing human memory.     

The effect of altered 5-hydroxytryptamine levels on beta-endorphin content in rat brain

The purpose of the present study was to examine the effect of altering the concentration of 5-hydroxytryptamine (5-HT) on beta-endorphin (beta-Ep) content in the hypothalamus, thalamus, and periaqueductal gray (PAG)-rostral pons regions of the rat brain. The selective 5-HT reuptake inhibitor, fluoxetine (10 mg/kg), significantly lowered beta-Ep content in the hypothalamus and the PAG. Parachlorophenylalanine, which inhibits 5-HT synthesis, significantly elevated beta-Ep in all brain parts studied. Intracisternal injections of the neurotoxin, 5',7'-dihydroxytryptamine, with desmethylimipramine pretreatment, significantly increased beta-Ep content in the hypothalamus and the PAG. In adrenalectomized rats, fluoxetine significantly decreased beta-Ep levels in the hypothalamus and increased the levels in the PAG. The results indicate that 5-HT may modulate the levels of brain beta-Ep.     

Effects of dalargin on the processes of cell division in the gastric epithelium during stress

Influence of dalargine on cell division in stomach epithelium of male rats, stressed by 4-hour immobilization was studied using autoradiographic 3H-thymidine test. Norepinephrine and diene conjugates content in stomach tissue were also determined in these animals spectrofluorometrically. Dalargine (10 micrograms/kg) gas injected to experimental group 40 min before stressing. Dalargine prevented stress-induced DNA-synthesis disturbances and stabilized proliferating cells pool just after the stress. It also decreased proliferation processes depression in 12 and 24 hours after stress and accelerated compensatory DNA-synthesis.