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.

Neuronal organization of the reticular nucleus of the thalamus in adult humans.

The neuronal composition of the thalamic reticular nucleus was studied in serial sections of the sagittal and frontal projections impregnated with silver nitrate by the Golgi method. The neuronal composition of the reticular nucleus of the human thalamus was wider than has previously been described in animals and humans. This nucleus, apart from two types of large, sparsely branched, long-dendrite, reticular, aspiny, neurons, i.

Sexual dimorphism of neuroglial relationships in the frontal fields of the human brain.

Cytoglioarchitectonic and quantitative methods were used to study the characteristics of neuroglial relationships in fields in the frontal areas of the male and female brains. Series of frontal paraffin sections of thickness 20 microm stained by the Nissl method were used to study fields 8, 12, 47, and 10. In layers III and V of the right and left hemispheres, the densities of pyramidal neurons (N), satellite gliocytes (SG), and N surrounded by SG (SN) per 0.

Spontaneous activity and rhythm assimilation reactions in baby rabbit hippocampal neurons during learning: age-related characteristics.

The neural mechanisms of the age-related characteristics of memory formation were studied in experiments based on a model providing an analog of a conditioned reflex to time: trace assimilation of the rhythm with which neurons in hippocampal field CA1 were stimulated, in rabbits aged 1-4 weeks and 5-6 months. Stages of changes in neuron spike activity characteristic for developing animals were described. In animals studied one week after birth, there was a predominance of silent cells and cells with low spontaneous activity.

Ultrastructure of the sensorimotor cortex of pubertal offspring of alcoholic male rats.

The ultrastructure of neurons, astrocytes, and capillaries in the sensorimotor cortex of three-month-old offspring of alcoholic male rats (8 g/kg of 50% alcohol solution daily for four weeks) was studied. Apart from signs of delayed maturation of nerve and glial cell processes, some cortical areas showed destructive changes affecting a proportion of neurons along with elements of compensatory-adaptive processes in some nerve cells. Membrane and myelin-like intranuclear inclusions and changes in the Golgi complex were characteristic features of the damage to populations of cortical neurons.

NADPH-diaphorase-positive cells in the thalamic nuclei and internal capsule in humans.

The nuclei of the dorsal thalamus and reticular nucleus in humans were found to contain separated NADPH-diaphorase (NADPH-d)-positive neurons. Staining of NADPH-d-positive neurons and all their processes, along with previous studies of neurons in the nuclei of the dorsal thalamus based on the Golgi method, allowed the type of these cells to be identified as sparsely branched. The main, densely branched, efferent neurons did not contain NADPH-d.

Characteristics of the development of the sensorimotor cortex in rats aged 7-8 days in roller cultures of free-floating brain slices.

The development and formation of the neuronal architectonics of organotypic structures of the sensorimotor cortex in rats aged 7-8 days were studied in roller cultures. Free-floating slices were cultured for 2-3 weeks. Serial paraffin sections of cultured tissue were stained with fast cresyl violet as described by Nissl.

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.

Structural-functional organization of neurons in the cerebral cortex of rats with different levels of resistance to emotional stress in conditions of exposure to delta sleep-inducing peptide.

Wistar rats with different levels of resistance to emotional stress (ES) were subjected to stress and brain sections stained with Nissl cresyl violet were used for quantitative analysis of the structural organization of neurons in layer V of the sensorimotor cortex. Some animals received delta sleep-inducing peptide (DSIP) 1 h before stress. Control ES-susceptible rats, as compared with resistant rats, had lower levels of normochromic and moderately hypochromic neurons.

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.

The role of the substantia nigra in cognitive activity in cats.

The role of the substantia nigra in cognitive processes of different levels of complexity was studied using an original method. Neurosurgical or neurochemical exclusion of the substantia nigra in cats led to significant impairment of conditioned reflex activity, generalization and abstraction processes; these recovered with pharmacological treatment directed to the dopaminergic system, with partial recovery after treatment directed to the GABAergic and cholinergic systems. Treatment directed to the serotoninergic system was ineffective.

The action of mexidol on the state of conditioned reflex activity after traumatic brain lesions.

It is demonstrated that even partial damage to the hippocampus is accompanied by impairments to counting time intervals lasting several months (1200-1500 presentations) without alteration of other complex conditioned reflex responses. After treatment with mexidol, which has a wide spectrum of actions, paticularly antioxidant. antihypoxic, and antistress, rats showed a normal process of acquisition of a conditioned reflex to time.

Comparison of the cholinergic system in neocortical field Ep in cats with strong and weak cognitive abilities.

Comparative analysis of the cholinergic system of the neocortex, consisting of the terminals of neurons from the magnocellular basal nuclei and intracortical neurons, in cats with strong and weak abilities to solve abstraction and generalization tasks was performed by isolating subfractions of synaptic membranes and synaptoplasm from "light" (C) and "heavy" (D) synaptosomes from associative field Ep and measuring choline acetyltransferase and acetylcholinesterase activities, protein content, and sulfhydryl group concentrations. These experiments showed that all measures were significantly lower in subfractions from C synaptosomes from cats with strong cognitive abilities. This leads to the conclusion that relatively small numbers of cholinergic synapses form in field Ep of the brains of cats with strong cognitive abilities, while their location in the C fraction demonstrates that they correspond to neurons of the magnocellular basal nuclei.

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.

Decreases in Ca2+-dependent K+-currents due to cyclic guanosine monophosphate are not dependent on phosphorylation.

Two-microelectrode voltage clamping experiments were performed on isolated snail neurons to measure the Ca2+-dependent. potential-dependent K+ current (I(C)), with assessment of the effects of penetrating cGMP analogs on this current - dibutyryl cGMP (dcGMP) and 8-Br-cGMP. Both of these penetrating cGMP analogs rapidly and reversibly decreased the amplitude of I(C).

Morphochemical features of plastic rearrangements of hippocampal neurons after rhythmic stimulation of the limbs in elderly rabbits.

The process of aging is accompanied by significant derangements to brain function, which are expressed particularly as the well-known phenomenon of memory disturbance [4,5]. Since memory functions are based on plastic rearrangements, in which the key role is played by metabolic processes, we elected to study the interactions between nerve cell activity and the state of protein biosynthesis during the formation of temporal associations in animals of different ages [3]. An interferometric method was considered appropriate in this regard as a method for estimating the dry weight of the cytoplasm and nucleus in neurons; this serves as a measure of their protein contents [1,2].

Reciprocal inhibition of the AMPA and NMDA components of excitatory postsynaptic potentials in field CA1 of the rat hippocampus in vitro.

The mutual effects of components of excitatory postsynaptic potentials (EPSP) induced by activation of glutamate receptors sensitive to alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) were studied on living slices of rat hippocampus. Evoked responses were recorded in the radial layer (stratum radialis) in field CA1 after stimulation of collateral-commissural fibers. The contribution of the NMDA component to the total EPSP was altered by extracellular application of solutions containing different concentrations of magnesium.

Cyclic GTP imitates the potentiating effect of the nootrope vinpocetine on the high-threshold A-current in mollusk neurons.

Isolated common snail neurons were studied using two-microelectrode potential clamping to record high-threshold (threshold = 10 mV) rapidly-inactivating potassium current (I(Aht)); the effects of the nootrope vinpocetine on this current were studied and were compared with the effects of cyclic nucleotides. Intracellular application of dibutyryl derivatives of cyclic adenosine monophosphate (dcAMP) and guanosine monophosphate (dcGMP) was used. The results showed that vinpocetine potentiates or fails to alter I(Aht) in different cells, while dcGMP imitates the effect of vinpocetine.

Intracellular studies of the interaction between paired-pulse facilitation and the delayed phase of long-term potentiation in the hippocampus.

The mechanisms of the early (up to 1 h) and late (up to 3 h) phases of long-term potentiation were studied by analyzing the interaction between long-term potentiation and presynaptic paired-pulse facilitation. "Minimal" excitatory postsynaptic potentials were measured in pyramidal neurons in field CA1 of rat hippocampal slices in conditions of paired-pulse stimulation of the radial layer. In most neurons, paired-pulse facilitation decreased after induction of long-term potentiation, and this reduction lasted throughout the recording period (up to 3.