[Neurotensin influence on painful stress afteractions in rats with neurotoxic damages of serotoninergic structures of brain substantia nigra].

The purpose of the research was to reveal the features of neurotensin influence on behavior of rats with damages of 5-HT structures of substantia nigra. Changes of recall of passive avoidance conditioned reactions, and also painful stimulation aftereffects on locomotor activity of rats in "open field" were studied. It was shown that neurotoxin 5,7-DOT administration into substantia nigra impaired recall of passive avoidance reactions and as well weakened oppressive aftereffects of painful stimulation. Administration of serotonin 5-HT1A receptors antagonist p-MPPF insert similar influence on aftereffects of painful stimulation. Neurotensin microinjections into caudate nucleus just before painful stimulation prevented disturbances of defensive behavior and its aftereffects evoked by neurotoxin. Neurotensin administration into substantia nigra in 24 h after painful stimulation didn't exert any significant influence on passive avoidance reactions but increased motor activity against a background of its recall. Effects of neurotoxin administrations into substantia nigra connected with weakened of painful stress influence on motor activity in rats. The prevention of this effect development after neurotensin administrations into caudate nucleus may be specified by recovery of recall passive avoidance reactions destroyed by neurotoxin action and is explained by normalization of relationships balance of 5-HT and dopaminergic brain systems.

[Reproduction of passive avoidance reactions after neurotensin microinjection into nucleus accumbens of rat brain against the background of reserpine action].

The purpose of the study was to reveal the features of the influence of neurotensin injected into the nucleus accumbens on behaviour of rats after systemic administration of reserpine in the dose of 2 mg/kg. Reprodution of passive avoidance conditioned reactions, painful stimulation aftereffects on locomotor activity in the "open field", and behavior in the elevated plus-maze were studied. It was shown that reserpine administration impaired the reproduction of passive avoidance reactions and weakened the oppressing aftereffect of painful stimulation, which can be due to a decrease in anxiety in rats. Neurotensin prevented disorders in the defensive behavior evoked by reserpine and intensified the state of anxiety in the elevated plus-maze. The positive influence ofneurotensin on the reproduction of passive avoidance can be associated with the recovery of the anxiogenic effect of painful stimulation destroyed by reserpine. Thus, neurotensin injected into the nucleus accumbens could normalize the balance of brain monoaminergic systems.

[Emotional state variations in rats during recall of passive avoidance reactions after neurotensin administration into nucleus accumbens of the brain].

Behavioral effects of neurotensin administration into the nucleus accumbens were studied in rats with neurotoxic lesions of serotoninergic structures of the dorsal raphe nucleus or periaqueductal grey matter. Changes in recall of passive avoidance conditioned reactions and aftereffects of painful stimulation in the locomotor activity were studied in the "open field" and elevated plus-maze and T-maze tests. The toxin administration into the dorsal raphe nucleus did not impair the recall of the passive avoidance reactions, but enhanced the oppressive aftereffects of painful stimulation, which can specify the development of anxiety in rats. The toxin administration into the periaqueductal grey matter had an opposite effect, which can be considered as a manifestation of the panic state. Neurotensin weakened the above mentioned effects of the toxin and, depending on the evoked emotional disorders, produced the anxiolytic or antipanic effects.

Serotoninergic mechanisms of the effects of neurotensin on passive avoidance behavior in rats.

The aim of the present work was to identify the features of the actions of neurotensin on administration into the substantia nigra or dorsal cervical nucleus on the reproduction of passive avoidance reactions in rats. The results showed that the action of neurotensin administered into the substantia nigra was accompanied by sharp reductions in passive avoidance reactions, while administration into the dorsal cervical nucleus, conversely, led to increases in these reactions and slowing of their extinction. The effects of microinjections of the serotonin 5-HT(1A) receptor agonist 8-hydroxydipropylaminotetraline (8-OH-DPAT) into these brain structures were analogous to the effects of neurotensin. The different behavioral effects of administration of neurotensin corresponded to identifiable changes in the levels of serotonin and its metabolite 5-hydroxyindoleacetic acid in the caudate nuclei of the brain. These data led to the conclusion that the effects of neurotensin on passive avoidance behavior are associated with the regulation of the emotional state of the animals via actions on the functions of brain serotoninergic structures.

[Involvement of serotoninergic brain structures in the mechanisms of neurotensin effect on passive avoidance in rats].

The purpose of the research was to reveal the features of neurotensin (administered in substantia nigra or dorsal raphe nucleus) effect on recall of passive avoidance reactions in rats. It was shown that the effect of neurotensin injected into the substantia nigra was characterized by a sharp reduction of passive avoidance reactions. On the contrary, injection of the substance in the dorsal raphe nucleus led to an intensification of these reactions and delay of their extinction. The effects of microinjections of serotonin 1A receptor agonist, 8-hydroxy-dipropylaminotetralin (8-OH-DPAT), into the mentioned brain structures was similar to that of neurotensin. Changes in the content of serotonin and its metabolite 5- hydroxyindoleacetic acid (5-HIAA) in the caudate nucleus corresponded to various behavioral effects. The conclusion was made that neurotensin effect on the passive avoidance behavior is related to regulation of emotional state of animals mediated by its action on the function of the serotoninergic brain structures.

Aftereffects of microinjections of neurotensin into the substantia nigra of the brain on conditioned motor responses in rats with lesions to serotoninergic neurons.

The effects of neurotensin microinjections into the substantia nigra of the brain on the performance of motor reactions in response to positive (food reinforcement) and negative (unreinforced) conditioned signals were studied, along with the characteristic aftereffects of these microinjections in rats with lesions to serotoninergic neurons in the dorsal cervical nucleus. Lesions were produced by local administration of the selective neurotoxin 5,7-dihydroxytryptamine. Microinjections of neurotensin were found to weaken the disinhibitory effects of neurotoxin on extinction of intersignal responses and extinction of conditioned motor reactions in response to presentation of negative stimuli, but to have no marked effect on the performance of reactions evoked by positive conditioned signals. Changes persisted into subsequent experiments without peptide microinjections. Measurements of the level of preference of the animals for one quadrant of the experimental chamber showed that operated rats avoided occupying the test quadrant and preferred to locate themselves in the opposite quadrant. Neurotensin released this effect of the neurotoxin. These results lead to the conclusion that these behavioral effects of neurotensin are associated with its normalizing influences on the motivational-emotional state of the animals with lesions to serotoninergic neurons and may also be due to the formation in the animals of a contextual conditioned emotional state, which aids optimization of the adaptive functions of the brain.

[Effect of neurotensin on the behavior of rats with damaged serotoninergic neurons under immobilization stress].

It was shown that the immobilization of animals has led to reducing of vertical and horizontal locomotor activity in the "open field" and decreasing of number of conditioned food-procuring reactions into T-maze. The damages of serotoninergic neurons produced via local injections of selective neurotoxin 5, 7-dihydroxytriptamine into dorsal raphe nucleus intensified behavior alterations. Neurotensin administrations reduced effects of neurotoxin: the rats locomotor activity and quantity of conditioned reactions into T-maze were kept at the phone level just after immobilization as well as next two days. The results indicate the important protective significance of neurotensinergic brain structures for ensuring of adaptive behavior of animals with damaged serotoninergic neurons under emotional stress conditions. It is supposed that neurotensin normalizing influences on behavior is connected to a restoration of balance of dopamine-and serotoninergic brain structures interaction.

Effects of feedback caudate nucleus stimulation on spontaneous fast amygdaloid spindles and drive.

Experiments with single and repetitive stimulation of the head of the caudate nucleus (4-10 V, 0.3 msec) triggered by occurrence of fast amygdaloid spindles (35 c/s microV, 0.5 sec) were performed in six animals with chronically implanted cerebral electrodes. In conjunction with the anterior cortical recruiting response the stimulation increased the incidence of amygdaloid fast spindles and decreased the incidence of hippocampal theta activity and of searching eye movements. The associative training failed, however, to significantly modify in the background EEG, the mean incidence of the fast amygdaloid spindles or the rate of the sensorimotor rhythm of 12-18 c/s. Its only effect (after long repetition) was a displacement to the right of the regression line of the incidence of the two rhythms and a slight alteration in the slope. The possibility of activating the caudate nucleus inhibitory effects through the amygdala during internal inhibition phenomena is discussed.

Participation of caudate nucleus in different forms of voluntary activity in cats.

Different forms of behavior (instrumental conditioned reflexes, generalization tests, extrapolatory reflexes) were investigated before and after lesions of the caudate nucleus or pharmacological influence on its cholinergic systems. Postoperative deficit was small in well-elaborated forms of behavior and large in complex tasks. Chemical stimulation of the caudate nucleus was followed by depression of acquired forms of alimentary behavior.

Role of enkephalinergic brain structures in regulating motivated behavior in rats with lesioned serotoninergic neurons.

The behavioral effects of injections of enkephalin into the substantia nigra or dorsal raphe nucleus were studied in rats with lesioned serotoninergic structures. Lesions were produced by intracerebral administration of the neurotoxin 5,7-dihydroxytryptamine. Treated rats showed normalization of conditioned drinking reflex extinction. It is proposed that there is a tight connection between the normalizing effects of enkephalin on rat behavior in conditions of deficient brain serotoninergic system function and increases in the efficiency of presynaptic inhibition of dopaminergic neurons.

The effects of microinjection of neurotensin into the caudate nucleus of the rat brain on the performance and extinction of a conditioned motor reflex.

The studies reported here demonstrate that microinjection of neurotensin into the caudate nucleus of the rat brain facilitated extinction of a conditioned motor reflex with reinforcement provided by drinking. Neurotensin had positive effects on the process of post-extinction inhibition in subsequent experiments. Neurotensin microinjections had no marked effect on the performance of the conditioned reflex, though it weakened the emotional tension of the animals in an "open field" test. It is concluded that the functional importance of neurotensin at the level of the caudate nucleus is associated less with the regulation of motor function than with optimizing the motivational-emotional state of the animal.

Characteristics of the actions of neurotensin on motor reactions in rats in response to positive and negative conditioned signals.

This study addressed the effects of microinjections of neurotensin into the caudate nucleus and substantia nigra on the performance of motor reactions in response to positive and negative conditioned signals, as well as the post-effects of microinjections in subsequent experiments. Neurotensin had positive effects on the extinction of non-reinforced motor reactions. Neurotensin had no effect on the number of motor responses to the non-reinforced signal, though the number decreased in subsequent experiments. There was an increase in the latent period of responses as compared with controls. The effect of neurotensin at the level of the caudate nucleus was more marked than that at the level of the substantia nigra. Neurotensin microinjections had no marked effect on performance of conditioned responses to positive signals. The behavioral effects of neurotensin are associated with normalization of the interactions of the brain's monoaminergic systems. It is suggested that the positive actions of neurotensin on extinction of motor responses to negative signals result from the formation of a contextual conditioned emotional state in the animals, this facilitating optimization of conditioned reflex activity.

[Are the serotonin receptors life receptors?]. / Iavliutsia li serotoninovye retseptory "retseptorami zhizni"?

The paper gives evidence for the fact that serotonin and serotonin receptors are responsible for the occurrence of primary contractions of smooth muscles, primary cardiac contractions and primary brain electric activity (EEG genesis). It is concluded that the function of the smooth muscle, brain and heart cannot take place without serotonin and its receptors. This suggests that the serotonin receptors are life ones.

[Neurochemical mechanisms of caudate nucleus participation in the performance of food-getting behavior]. / K neirokhimicheskim mekhanizmam uchastiia khvostatykh iader v realizatsii pishchedobyvatel'nogo povedeniia.

The study was concerned with the significance of acetylcholine (ACh)- and dophaminergic (DA) systems of the caudate nucleus in the control of food-procuring behaviour in cats. Neurochemical stimulation of ACh-ergic structures of the caudate nucleus inhibited primarily the motor component of the conditioned food-procuring reflex. Neurochemical action on DA-ergic structures had a considerably less pronounced influence on this reflex. The analysis of changes in the amplitude of evoked potentials in the motor and somatosensory cortical areas to conditioned sound stimuli after microinjections in the caudate nucleus of ACh- and DA-trophic drugs did not reveal any antagonism between ACh- and DA-ergic systems of the caudate nucleus.

[Neuropharmacologic analysis of the process of developing extinctive inhibition in the lobectomized cat]. / Neirofarmakologicheskii analiz protsessa formirovaniia ugasatel'nogo tormozheniia u lobéktomirovannykh koshek.

Pharmacological action on cholinergic and monoaminergic brain structures in the process of food-procuring reflex extinction was studied in intact and lobectomized cats. Growing stimulation of cholinergic structures of lobectomized animals caused consecutive behavioural changes similar to those appearing during development of active reaction of intact animals to cancellation of the reflex reinforcement. In both cases influences on monoaminergic systems produced analogous effects, but suppressing influence of haloperidol injection on food-procuring activity of lobectomized cats was significantly weakened. Conclusion is made that the development of active reaction of the animal to cancellation of food reinforcement is due to an increasing activation of brain cholinergic structures and consecutive activation of monoaminergic structures. Disturbance of extinction functions in lobectomized cats may be connected with disturbance of monoaminergic systems balance as a result of hyperactivity of dopaminergic structures.

[Role of monoaminergic systems in the development of the effect of stimulation of acetylcholinergic brain structures in the cat]. / Rol' monoaminergicheskikh sistem v razvitii éffekta stimuliatsii atsetilkholinergicheskikh struktur mozga koshki.

The influence of systemic injection of anticholinesterase substance physostigmine on the behaviour of cats was studied under the conditions of pharmacological stimulation of monoaminergic cerebral systems. Development of the effect of the substance with an increase of its dose was accompanied by a successive alternation of three phases each representing an independent form of behaviour. Each form of behaviour originating in the process of acetylcholinergic stimulation increase was supposed to be caused by an involvement of corresponding monoaminergic system: serotonindopamine-, or noradrenergic one.

[Effect of stimulation of the acetylcholinergic system of the caudate nucleus on EEG indices of feeding behavior in the cat]. / Vliianie stimuliatsii atsetilkholinergicheskoi sistemy khvostatogo iadra na EEG-pokazateli pishchevogo povedeniia koshek.

The antagonistic dynamics of appearance of 30 c/s EEG-rhythm in the amygdala and 18 c/s rhythm in the parietal cortex during food-procuring behaviour of cats is considered as EEG manifestation of the interaction between motivation and reinforcement mechanisms. The study has not detected any distinct changes in the dynamics of the appearance of these EEG-rhythms after cholinomimetics injections into the caudate nucleus. A conclusion has been made that stimulation of acetylcholinergic structures of the caudate nucleus while depressing the motor component of the food-procuring reflex, does not significantly disturb the above mechanisms of alimentary behaviour.

[Effect of stimulation of GABA-ergic structures of the substantia nigra and caudate nucleus on food-getting behavior in the cat]. / Vliianie stimuliatsii GAMKergicheskikh struktur chernoi substantsii i khvostatogo iadra mozga na pishchedobyvatel'noe povedenie koshek.

A study was made of the functional significance of GABA-ergic structures of the substantia nigra (SN) and the caudate nucleus (CN) and their role in food-procuring behaviour of cats. Analysis was made of behavioral and EEG-effects of local GABA and the GABA antagonist, picrotoxin, microinjections into the studied brain structures. Stimulation of the GABA-ergic structures of the SN produced a sedative effect and depression of the cat food-procuring behaviour. Effects of stimulation of the CN GABA-ergic structures were to a great degree reverse. The conclusion has been made that GABA-ergic structures of the SN and the CN play different roles in controlling the CN inhibitory influence upon food-procuring behaviour.

[Dynamics of caudate nucleus involvement in the process of internal inhibition of the food-getting reflex]. / O dinamike vkliucheniia khvostatykh iader v protsess vnutrennego tormozheniia pishchedobyvatel'nogo refleksa

Changes of slow spindle electrical activity (12 to 14 cps) and evoked potentials in the cat caudate nuclei and the motor cortex were studied at different stages of elaboration of differentiation inhibition of a conditioned food-procuring reflex to acoustic stimuli. It has been shown that participation of the caudate nuclei in the inhibitory process begins at the stage of enhancement of food-procuring activity (second stage) and is apparently due to the animal's strong alimentary motivational excitation. At the third stage the inhibitory influence of caudate nuclei on the animal's motor activity in general, and the activity of the motor cortex in particular, develops to the full.

[Role of acetylcholinergic structures of the caudate nucleus in mechanisms of inhibition of a conditioned food-getting reflex in the cat]. / Rol' atsetilkholinergicheskikh struktur khvostatogo iadra v mekhanizmakh tormozheniia uslovnogo pishchedobyvatel'nogo refleksa u koshek.

The effect of acetylcholinergic structures stimulation on the acquisition and inhibition of a conditioned food-procuring reflex was studied in cats. Physostigmine injections (0.1 mg/kg) did not facilitate the extinction of the non-reinforced food-procuring reactions of caudatectomized cats in contrast to the intact or lobectomized ones. The conclusion is made that acetylcholinergic structures of the caudate nucleus play an important role in the central inhibitory mechanisms responsible for the extinction of nonreinforced reactions.