Leptin participation in the processes of nervous impulse transmission and its influence on the formation of neuro-mental development of children

Review of publications on the functional features of leptin in the central nervous system in children. The participation of leptin mechanisms in the transmission of nerve impulses, the effect of leptin on cognitive functions in children. The article reveals the general mechanisms of maturation of the central nervous system in children, the participation of leptin and leptin receptors in the formation of cognitive abilities in children. Possible interrelationships of impairments in cognitive development and lipid metabolism including obesity are revealed.

Physiological requirements for action potential conduction, sensory awareness, and motor control

Nervous system function depends on electrical and chemical signals. The nervous impulse is a fluctuation in voltage across the neuronal cell membrane, generated by ion currents through ion-selective, voltage-sensitive membrane channels. Neuronal information is encoded in the temporal pattern of such impulses propagated along the nerve fibres at speeds that may reach about 100 m/s in fibres electrically isolated by myelin. Signal transmission to other cells via synaptic contacts occurs mainly via chemical transmitters that control membrane ion channels and give rise to electrical responses in receiving cells, with plasticity in the process making the system capable of learning and memory storage. Since impulse generation as well as synaptic transmission depends on ion flux across the membrane, energy-dependent ion pumps are critical for maintaining the ion concentration gradients necessary for the nervous signals. As a consequence, the nervous system consumes a lot of energy and is sensitive to any lack of energy.

Morphology of spinal ganglia of different segmentary levels in the domestic dog

The spinal ganglia, which perform the function of the first link on the afferent impulses’ way from the receptors to the central nervous system, recognize internal and external irritations, and are the first to transform them into a nervous impulse. As the representatives of the peripheral nervous system, they are some of the main objects of the studies in contemporary neuromorphology. Based on the results of anatomic, neurohistological, histochemical, morphometric and statistical methods of the studies, we conducted a complex survey, revealing the morphology of spinal ganglia of different segmental levels in the domestic dog. In particular, we determined the differences in the microscopic structure and morphometric parameters of cervical, thoracic, lumbar and sacral spinal ganglia and the ganglia of the cervical and lumbar enlargements in mature domestic dogs. The study showed that the spinal ganglia of domestic dogs can have different skeletotopy, different shape and sizes due to their species peculiarity. Also, the surveyed animals, according to the results of our studies, had the cervical and thoracic spinal ganglia of oval, while the lumbar and sacral – spindle-like shapes. According to the results of morphometry, the area of the spinal ganglia in lengthwise section differed: the smallest area belonged to the thoracic, the largest to the sacral spinal ganglia. The density of neuronal arrangement per 0.1 mm2 of the area of the spinal ganglia correlated with their sizes: the highest parameter was identified for the thoracic spinal ganglia, the lowest – for the sacral. The conducted studies revealed that histo- and cyto-structure of the spinal ganglia is characteristic of notable differentiation of the nervous cells of small sizes. Therefore, we differentiated neurons of the spinal ganglia into large, medium and small. The highest quantity of large neurons was found in the sacral ganglia, and largest amount of medium-sized neurons – in the ganglia of the lumbar enlargement. In other ganglia, small neurons dominated. Correspondingly, different nuclear-cytoplasmic ratio in these neurons was determined, indicating different extent of morphofunctional condition of nervous cells. We determined content of localization and separation of nucleic acids in histostructure of the spinal cord at the tissue and cellular levels.

Quantized Three-Ion-Channel Neuron Model for Neural Action Potentials

The Hodgkin-Huxley model describes the conduction of the nervous impulse through the axon, whose membrane's electric response can be described employing multiple connected electric circuits containing capacitors, voltage sources, and conductances. These conductances depend on previous depolarizing membrane voltages, which can be identified with a memory resistive element called memristor. Inspired by the recent quantization of the memristor, a simplified Hodgkin-Huxley model including a single ion channel has been studied in the quantum regime. Here, we study the quantization of the complete Hodgkin-Huxley model, accounting for all three ion channels, and introduce a quantum source, together with an output waveguide as the connection to a subsequent neuron. Our system consists of two memristors and one resistor, describing potassium, sodium, and chloride ion channel conductances, respectively, and a capacitor to account for the axon's membrane capacitance. We study the behavior of both ion channel conductivities and the circuit voltage, and we compare the results with those of the single channel, for a given quantum state of the source. It is remarkable that, in opposition to the single-channel model, we are able to reproduce the voltage spike in an adiabatic regime. Arguing that the circuit voltage is a quantum variable, we find a purely quantum-mechanical contribution in the system voltage's second moment. This work represents a complete study of the Hodgkin-Huxley model in the quantum regime, establishing a recipe for constructing quantum neuron networks with quantum state inputs. This paves the way for advances in hardware-based neuromorphic quantum computing, as well as quantum machine learning, which might be more efficient resource-wise.

Proteomics Analysis Reveals the Implications of Cytoskeleton and Mitochondria in the Response of the Rat Brain to Starvation

Long-term starvation provokes a metabolic response in the brain to adapt to the lack of nutrient intake and to maintain the physiology of this organ. Here, we study the changes in the global proteomic profile of the rat brain after a seven-day period of food deprivation, to further our understanding of the biochemical and cellular mechanisms underlying the situations without food. We have used two-dimensional electrophoresis followed by mass spectrometry (2D-MS) in order to identify proteins differentially expressed during prolonged food deprivation. After the comparison of the protein profiles, 22 brain proteins were found with altered expression. Analysis by peptide mass fingerprinting and MS/MS (matrix-assisted laser desorption-ionization-time of flight mass spectrometer, MALDI-TOF/TOF) enabled the identification of 14 proteins differentially expressed that were divided into 3 categories: (1) energy catabolism and mitochondrial proteins; (2) chaperone proteins; and (3) cytoskeleton, exocytosis, and calcium. Changes in the expression of six proteins, identified by the 2D-MS proteomics procedure, were corroborated by a nanoliquid chromatography-mass spectrometry proteomics procedure (nLC-MS). Our results show that long-term starvation compromises essential functions of the brain related with energetic metabolism, synapsis, and the transmission of nervous impulse.

AQP-4 AND ITS ROLE IN MAINTAINING THE HYDRIC BALANCE IN THE BRAIN

Aquaporins are a vast family of channel proteins whose main role is the bidirectional transport, depending on the osmotic gradient, of water across the lipid membranes, which have low permeability for this solvent. The aquaporins are also involved in the lipid metabolism, the cell proliferation and migration processes, the transport of glycerol, neuroexcitation and epithelial fluids secretion, having numerous roles such as ensuring the water transport in the central nervous system, the production of CSF, aqueous humor and saliva, epithelial hydration, urine concentration and nervous impulse transmission. Up to now, in mammals there have been identified 13 types of aquaporins, each of them annotated from 0 to 12 (Aqp 0 – Aqp 12). Of these, aquaporin-4 (AQP-4) – located in the astroglia - is the most abundant aquaporin in the brain. Although this type of aquaporin is also present inside the brain parenchyma, especially in the astroglial processes lining the neuronal synapses, AQP-4 is mainly located in the astroglial end-feet adjacent to the ependymocyes or endothelial cells, where its main role is to ensure the bidirectional transport of water between the astroglia and the cerebrospinal fluid (CSF) or blood vessels. The presence of AQP-4 on the surface of astroglial processes promotes, in the initial stages of ischemia, the formation of the cytotoxic oedema, but has a protective role against vasogenic oedema. This review aims to describe the roles of AQP-4, and especially the role that this protein has in maintaining the hydric balance in the brain.

Applied Technology in Evoked Auditory Response In Vivo Animal Cochlea by 980nm Pulsed Laser Light

Optical cochlear implant is an emerging applied technology of stimulating auditory neurons by using pulsed laser light as a stimulus to evoke neural activity instead of electrical currents. Laser stimulation has more potential in accuracy and high frequency resolution than electrical stimulation. In this paper we demonstrated a fiber laser system (980nm) to irradiate on guinea pig cochlear in vivo for the first time. The pulsed laser stimulation successfully evoked auditory nervous impulse, similar to acoustic stimulation. And the performance under different laser pulse intensity and pulse width is further tested and discussed. The results show that the 980nm pulsed laser stimulation with microsecond level width is effective and safe to evoke auditory response. Photoacoustic or photothermal effects maybe the main mechanism. In the end, we put forward some prospects of the applied technology in cochlear implant.