Neuronal mechanisms of interaction of Deiters nucleus with the cerebral cortex.

The effects of stimulation of the vestibular nerve and five different cerebral cortex areas on the neuronal activity of the lateral vestibular nucleus of Deiters were studied. Stimulation of the cerebral cortex is shown to lead to antidromic and synaptic activation of Deiters neurons. The synaptic potentials of Deiters neurons evoked from the cerebral cortex were of mono- and polysynaptic origin. In particular, stimulation of the cerebral cortex evoked in Deiters neurons mono- and polysynaptic excitatory postsynaptic potentials. Collaterals of vestibulospinal neurons reaching different cortex fields as well as convergence of influences from these cortex fields on Deiters neurons were revealed. Inhibitory effects of the cerebral cortex on Deiters neurons were of polysynaptic origin and occurred rarely. The topical correlation between Deiters nucleus and different areas of the cerebral cortex was found. The peculiarities and functional significance of the effects obtained are discussed.     

Neuronal organization of the large-cell segment of the cat's red nucleus]

When studying the neuronal organization of the large-cell part of the red nucleus in cats by the Golgi and Golgi-Kopsch methods three types of neurons have been revealed: large (50-90 mu), medium-sized (20-50 mu) and small cells (8-20 mu). long axon and short-axon neurons were found as well as long-dendrite cells with few thorns (the length of the dendrites form 600-900 mu) and short-dendrite cells (up to 400 mu). On basis ofanalysis of neuronal groups found in the large-cell part of the red nucleus of the cat a neuronal map of this part of the central nervous sytem is composed.     

Neuronal activity of raphe nuclei of the brain stem in the cat

Evoked potentials were recorded in the system of raphe nuclei in experiments on unanesthetized, immobilized cats. Somatic stimulation proved to be the most effective of the different stimulations used (light flash, sound click, electrical stimulation of the skin of the limbs). Sound and light stimulation did not evoke pronounced responses, or the latter (to sound) were of a very low amplitude and irregular. In the second series of experiments on cats narcotized with nembutal (30–35 mg/kg) the spontaneous activity and activity evoked by somatic stimulation of single neurons of the caudal part of the raphe nuclei were studied. The overwhelming majority of neurons were characterized by spontaneous activity which changed (inhibited or facilitated) under the effects of somatic (especially repeated) stimulation; most of them reacted to stimulation of the skin of any limb. In the case of paired stimulation of the skin of limbs on different sides at large intervals (40–60 msec), inhibition of the test discharge occurred, whereas at small intervals summation (simple addition) of the impulses occurred. In their general characteristics the neurons of the raphe nuclei apparently differ little from the neurons of the reticular formation of the brain stem.Institute of Electrophysiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 3, No. 1, pp. 32–42, January–February, 1971.     

The interaction between co-cultured human nucleus pulposus cells and mesenchymal stem cells in a bioactive scaffold

Mesenchymal stem cells (MSCs) can differentiate into nucleus pulposus (NP) cells upon being co-cultured with NP cells. Important growth factors and morphogens secreted by MSCs during the differentiation process also enhance the biological properties of NP cells. In this study, the interactions between human NP cells and MSCs co-cultured in different cell-ratio (100% NP, 75% NP with 25% MSCs, 50% NP with 50% MSCs, 25% NP with 75% MSCs, and 100% MSCs) in a three-dimensional gelatin/chondroitin-6-sulfate/hyaluronan tri-copolymer scaffold were examined. Results showed that the cell proliferation was increased when NP and MSCs were co-cultured. Real-time PCR and immunohistochemical staining revealed that all co-culture groups produced type II collagen which represent normal NP cells but not type I collagen secreted by degenerated NP cells. FADD expression, which modulates cell survival and extracellular matrix homeostasis, was maintained in a stable status for co-cultured groups. The cultures containing 75% NP cells with 25% MSCs showed high level of collagen production and glycosaminoglycan content. Moreover, 75% NP cells with 25% MSCs had upregulated SOX9 that contributes to the improvement in type II collagen mRNA expression and protein production. These findings showed the NP/MSC cell-ratio influenced the cell functions dramatically. The co-culture of NP/MSC cells in a bioactive scaffold is a promising treatment for intervertebral disc diseases.     

Neuronal mechanisms of motor signal transmission in the thalamic ventrooral nucleus in spasmodic torticollis patients

A microelectrode technique was used to study the neuronal mechanisms of motor signal transmission in the ventrooral internus nucleus (Voi) of the motor thalamus during voluntary and involuntary pathological (dystonic) movements in patients with spasmodic torticollis. Voi cell elements proved highly reactive to various functional (mostly motor) tests. An activity analysis of 55 Voi neurons detected during nine stereotactic operations revealed, first, a difference in neuronal mechanisms of motor signal transmission for voluntary movements that do or do not involve the affected axial muscles of the neck and for passive and abnormal involuntary dystonic movements. Second, a sensory component was found to play a key role in the mechanisms of sensorimotor interactions during voluntary and involuntary dystonic head and neck movements activating the axial muscles of the neck. Third, rhythmic and synchronized activity of Voi neurons was shown to play an important role in motor signal transmission during voluntary and passive movements. The Voi nucleus was directly implicated in the mechanisms of involuntary head movements and tension of the neck muscles in spasmodic torticollis. The results can be used to identify the Voi nucleus of the thalamus during stereotactic neurosurgery in order to select the optimal destruction or stimulation target and to reduce the postoperative effects in spasmodic torticollis patients.     

Electrophysiological properties of neurons of the red nucleus in rat brain slices

In experiments on rat brain slices, we carried out intracellular recording from neurons of the red nucleus (RN). Passive electrical properties of these neurons (input resistance, membrane time constant) were evaluated. We detected voltage-dependent rebound depolarization and time dependent inward rectification when passing hyperpolarizing pulses of current through the cell. Injections of depolarizing currents caused rhythmical firing of the neurons; the frequency of these firings depends upon the strength of injected current. Rhythmical firings were also characterized by rapid frequency adaptation when currents of different frequency were injected. Stimulation of regions of slices presumably corresponding to the decussion of the brachium conjunctivum mainly evoked EPSPs with a "fast" rise time in RN neurons. This suggests activation of synaptic input from the cerebellar nucleus interpositus. Stimulation of this same region sometimes evoked EPSP-IPSP mixtures and "pure" IPSPs in RN neurons.L. A. Orbeli Institute of Physiology, Armenian Academy of Sciences, Erevan. Translated from Neirofiziologiya, Vol. 23, No. 5, pp. 607–616, September–October, 1991.     

The interaction between ruthenium red and the isolated sarcoplasmic reticulum

The multivalent anions, ATP and oxalate, present at 5mM concentrations in incubation mixtures with isolated sarcoplasmic reticulum (SR) preparations, reduce the binding of ruthenium red (RR) to the SR. When oxalate is omitted from the incubation mixture and ATP is used at reduced concentrations, it is possible to observe an inhibitory effect of RR on calcium uptake by the SR and on ATPase activity. However, this inhibition is only partial and it remains clear that calcium transport in the SR is much less susceptible to inhibition by RR than is calcium transport in mitochondria. The effect of multivalent anions in suppressing the effect of RR, a hexavalent cation, is probably due to the formation of soluble complexes with RR.     

Neuronal synapse interaction reconstituted between live cells and supported lipid bilayers

In the nervous system, homophilic and heterophilic adhesion molecules participate in the induction and differentiation of presynaptic transmitter release sites. We focus on the heterophilic interaction between postsynaptic neuroligin-1 (Nlg) and presynaptic beta-neurexin (Nrx). Nlg has previously been shown to trigger presynaptic differentiation in a Nrx-expressing axon even when presented on a non-neuronal cell or on beads coated with lipid bilayers. We have now developed a new method to measure single molecule and ensemble distribution of Nrx and Nlg at the contact site between a non-neuronal Nrx-expressing cell and a flat supported glycosylphosphoinositol-neuroligin-1 (GPI-Nlg) lipid bilayer and relate them to adhesion as measured by cell migration and gravity dissociation. We find that within minutes after cell-bilayer contact, Nrx accumulates at the contact site and the contact area is expanded. The strength of cell-bilayer adhesion depends on the morphology of Nrx accumulation, with the focal concentration strengthening adhesion. The results suggest that Nlg-Nrx interaction rapidly establishes a weak, but specific, adhesion between dynamic pre- and postsynaptic processes, which may ultimately require additional molecules for synapse stabilization.     

Neuronal interaction between melanin-concentrating hormone- and alpha-melanocyte-stimulating hormone-containing neurons in the goldfish hypothalamus

Intracerebroventricular (ICV) administration of melanin-concentrating hormone (MCH) inhibits food intake in goldfish, unlike in rodents, suggesting that its anorexigenic action is mediated by alpha-melanocyte-stimulating hormone (alpha-MSH) but not corticotropin-releasing hormone. This led us to investigate whether MCH-containing neurons in the goldfish brain have direct inputs to alpha-MSH-containing neurons, using a confocal laser scanning microscope, and to examine whether the anorexigenic action of MCH is also mediated by other anorexigenic neuropeptides, such as cholecystokinin (CCK) and pituitary adenylate cyclase-activating polypeptide (PACAP), using their receptor antagonists. MCH- and alpha-MSH-like immunoreactivities were distributed throughout the brain, especially in the diencephalon. MCH-containing nerve fibers or endings lay in close apposition to alpha-MSH-containing neurons in the hypothalamus in the posterior part of the nucleus lateralis tuberis (NLTp). The inhibitory effect of ICV-injected MCH on food intake was not affected by treatment with a CCK A/CCK B receptor antagonist, proglumide, or a PACAP receptor (PAC(1) receptor) antagonist, PACAP((6-38)). ICV administration of MCH at a dose sufficient to inhibit food consumption also did not influence expression of the mRNAs encoding CCK and PACAP. These results strongly suggest that MCH-containing neurons provide direct input to alpha-MSH-containing neurons in the NLTp of goldfish, and that MCH plays a crucial role in the regulation of feeding behavior as an anorexigenic neuropeptide via the alpha-MSH (melanocortin 4 receptor)-signaling pathway.     

Nanomaterials modulate stem cell differentiation: biological interaction and underlying mechanisms

Stem cells are unspecialized cells that have the potential for self-renewal and differentiation into more specialized cell types. The chemical and physical properties of surrounding microenvironment contribute to the growth and differentiation of stem cells and consequently play crucial roles in the regulation of stem cells’ fate. Nanomaterials hold great promise in biological and biomedical fields owing to their unique properties, such as controllable particle size, facile synthesis, large surface-to-volume ratio, tunable surface chemistry, and biocompatibility. Over the recent years, accumulating evidence has shown that nanomaterials can facilitate stem cell proliferation and differentiation, and great effort is undertaken to explore their possible modulating manners and mechanisms on stem cell differentiation. In present review, we summarize recent progress in the regulating potential of various nanomaterials on stem cell differentiation and discuss the possible cell uptake, biological interaction and underlying mechanisms.     

Possible mechanisms of involvement of the subthalamic nucleus and structures interconnected with this nucleus in movement disorders evoked by dopamine depletion

A possible mechanism of involvement of the subthalamic nucleus (STN) in movement disorders evoked by dopamine deficit is suggested. Multifunctional role of the STN is based on following reasons. Various STN cells participate in the cortico-basal ganglia-thalamocortical loop and in the basal ganglia-pedunculopontine-basal ganglia loop. Complexity of neural circuits is determined by functional heterogeneity of neurons in the nuclei, reciprocally connected with the STN, as well as by opposite modulation of activity of these neurons by dopamine due to activation of different types of pre- and postsynaptic receptors. Dopamine influences activity of STN neurons directly, through pre- and postsynaptic receptors. It is assumed that high-frequency stimulation of the STN can reduce or eliminate Parkinsonian symptoms not only owing to inhibition of activity of GABAergic neurons in the output basal ganglia nuclei, projected into the thalamus or pedunculopontine nucleus, but also due to excitation of glutamatergic or cholinergic neurons in the output nuclei, and due to potentiation of excitatory inputs to preserved dopaminergic neurons and subsequent rise in dopamine concentration.     

益生菌与肠黏膜互作的分子机制研究进展

益生菌是一类定植于动物肠道,可辅助动物消化功能,维护肠道菌群平衡并可影响肠道免疫系统,有益于动物健康的重要调节性菌群。该类菌群与动物肠上皮细胞间互作的分子机制包括菌体表面分子如磷脂壁酸（phosphatidicacid,LTA）、表面层蛋白（Slayerprotein）等与宿主的粘附相关蛋白分子结合,通过占位效应抑制有害菌群在肠道内的定植;益生菌还可刺激肠道细胞分泌B防御素2、细菌素和有机酸等可抑制甚至杀灭有害菌群;在益生菌作用下,肠道上皮细胞可增强粘液糖蛋白、紧密连接蛋白occludin和ZO-1等分子的表达,加厚并加固肠道黏膜屏障;益生菌相关抗原可通过与抗原递呈细胞表面模式识别受体（TLRs等）分子结合,激活递呈细胞,启动各免疫细胞的交互作用,调节肠道免疫状态。