Memantine protects the cultured rat hippocampal neurons treated by NMDA and amyloid β1-42.

Alzheimer's disease (AD) is a devastating neurodegenerative condition with no effective treatments. Recent research highlights the role of NMDA receptors in AD development, as excessive activation of these receptors triggers excitotoxicity. Memantine, an NMDA receptor antagonist, shows promise in curbing excitotoxicity.

Resensitization of TRPV1 channels after the P2 receptor activation in sensory neurons of spinal ganglia in rats.

Introduction: TRPV1 channels are responsible for detecting noxious stimuli such as heat (>43°C), acid, and capsaicin. P2 receptors are involved in numerous functions of the nervous system, including its modulation and specific response to the application of ATP. In our experiments, we investigated the dynamics of calcium transients in DRG neurons associated with TRPV1 channel desensitization and the effect of activation of P2 receptors on this process.

Influence of amyloid beta on impulse spiking of isolated hippocampal neurons.

One of the signs of Alzheimer's disease (AD) is the formation of β-amyloid plaques, which ultimately lead to the dysfunction of neurons with subsequent neurodegeneration. Although extensive researches have been conducted on the effects of different amyloid conformations such as oligomers and fibrils on neuronal function in isolated cells and circuits, the exact contribution of extracellular beta-amyloid on neurons remains incompletely comprehended. In our experiments, we studied the effect of β-amyloid peptide (Aβ1-42) on the action potential (APs) generation in isolated CA1 hippocampal neurons in perforated patch clamp conditions.

The effect of cerium dioxide nanoparticles on the viability of hippocampal neurons in Alzheimer's disease modeling.

The possibilities of using nanoparticle materials based on cerium dioxide (CNPs) are exciting since they are low toxic and have specific redox, antiradical properties. It can be supposed that CNPs' biomedical use is also relevant in neurodegenerative diseases, especially Alzheimer's disease (AD). AD is known as the pathologies leading to progressive dementia in the elderly.

The monomers, oligomers, and fibrils of amyloid-β inhibit the activity of mitoBK channels by a membrane-mediated mechanism.

A causative agent of Alzheimer's disease (AD) is a short amphipathic peptide called amyloid beta (Aβ). Aβ monomers undergo structural changes leading to their oligomerization or fibrillization. The monomers as well as all aggregated forms of Aβ, i.

EFFECT OF TRPA1 RECEPTOR ACTIVATION ON TRPV1 CHANNEL DESENSITIZATION IN RAT DORSAL GANGLION NEURONS.

The activity of TRPA1 and TRPV1 channels, their sensitivity to selective activators - allyl isothiocyanate (AITC) and capsaicin (Caps), especially their interaction were studied. The method of microfluorescent microscopy and Ca2+ sensitive dye fura- 2AM. Registration of changes in the concentration of intracellular Ca2+ was performed by using the ratio of fluorescence signals measured at two wavelengths (R = F1/ F2).

[USING THE SERIAL RAMP RECORDINGS FOR RAPID TESTING OF THE GENERATING ABILITY OF IMPULSE ACTIVITY OF ISOLATED HIPPOCAMPAL NEURONS].

In this study we investigated changes of impulse activity of hippocampal neurons of the hippocampus by using ramp recordings. We have described the usage of serial ramp recordings of neuronal electrical activity for rapid testing of the generating ability of isolated hippocampal neurons. An analysis of the data has shown that the proposed protocol of serial ramp recordings allows to define additional characteristics of the neuronal impulse activity: (i) the thresholds for initiation of generation and suppression of the generation, (ii) the shape and amplitude of relationship between the interpulse intervals and neuronal depolarizations.

Modulation of calcium signalling by the endoplasmic reticulum in Carassius neurons.

It is known that endoplasmic reticulum (ER), being a calcium store participates in the regulation of intracellular calcium concentration. Ca-ATPase of the ER is one of the crucial agents providing the calcium-accumulating function of this intracellular structure. We studied the role of the ER in modulation of calcium signalling in Carassius neurons using a Ca2+-imaging technique.

Different signaling pathways involved in glucose- and cell swelling-induced insulin secretion by rat pancreatic islets in vitro.

Background: The objective was to compare signal transduction pathways exploited by glucose and cell swelling in stimulating insulin secretion.

Methods: Isolated rat (Wistar) pancreatic islets were stimulated in vitro by 20 mmol/l glucose or 30% hypotonic medium (202 mOsm/kg) in various experimental conditions.

Results: Glucose did not stimulate insulin release in calcium free medium.

Acetylcholine-induced calcium signalling in adrenaline- and noradrenaline-containing adrenal chromaffin cells.

Adrenal chromaffin cells secrete catecholamines in response to cholinergic receptor activation by acetylcholine (ACh). Characteristics of Ca(2+) transients induced by activation of nicotinic (nAChRs) and muscarinic (mAChRs) receptors were analyzed using Fura-2 fluorescent measurements on rat chromaffin cells. We first found two populations of chromaffin cells, which differently responded on AChR stimulation.

Action of hypoxia on different types of calcium channels in hippocampal neurons.

Whole-cell patch clamp and polarographic oxygen partial pressure (pO2) measurements were used to establish the sensitivity of high-voltage-activated (HVA) Ca2+ channel subtypes of CA1 hippocampal neurons of rats to hypoxic conditions. Decrease of pO2 to 15-30 mm Hg induced a potentiation of HVA Ca2+ currents by 94%. Using selective blockers of N- and L-types of calcium channels, we found that inhibition of L-type channels decreased the effect by 54%, whereas N-type blocker attenuated the effect by 30%.

Effect of hypoxia on calcium channels depends on extracellular calcium in CA1 hippocampal neurons.

Our previous studies have shown that short lasting hypoxia induces an increase of Ca(2+) influx into the cell through high voltage-activated Ca(2+) channels in hippocampal neurons. This effect was abolished by removing of free Ca(2+) from intracellular solution. The aim of this study was to compare hypoxic responses at different extracellular Ca(2+) concentrations ([Ca(2+)](e)) in hippocampal neurons to ascertain whether the hypoxic sensitivity is restricted to Ca(2+) ions.

Intracellular mechanisms of hypoxia-induced calcium increase in rat sensory neurons.

Elevation of cytosolic level of Ca(2+) was measured by spatial screening of freshly isolated dorsal root ganglion neurons loaded with Fura-2AM after subjecting them to a moderate hypoxic solution (pO(2)=10-40 mmHg). Short exposure of neurons to hypoxia resulted in a reversible elevation of intracellular Ca(2+) to about 120% in the cell center and to 80% in the cell periphery. Such elevation could be almost completely eliminated by removal of Ca(2+) or Na(+) from external medium or application of nifedipine, an L-type calcium channel blocker.

Scientific and technological aspects of oxygen-sensitive electrodes for measurements of oxygen partial pressure in patch-clamp experiments.

Anoxia/hypoxia induces dramatic changes in brain activity leading to the damages in brain structure. Several minutes of decrease in environmental oxygen partial pressure (P(O2)) can irreversibly destroy nerve cells. Therefore, investigations of intracellular mechanisms responsible for hypoxia-induced changes of mammalian nerve system are very important.

Mechanisms of up-regulation of single calcium channels by serotonin in Helix pomatia neurons.

Action of serotonin (5-HT) on single Ca(2+) channel activity was studied in identified neurons of snail Helix pomatia. Only one type of Ca(2+) channels of 5 pS unitary conductance was determined under patch-clamp cell-attached mode. Kinetic analysis have shown a monotonically declining distribution of channel open times (OT) with mean time constant of 0.

Selective blockade of N-type calcium channels by levetiracetam.

Purpose: We investigated the effect of the new antiepileptic drug (AED) levetiracetam (LEV) on different types of high-voltage-activated (HVA) Ca2+ channels in freshly isolated CA1 hippocampal neurons of rats.

Methods: Patch-clamp recordings of HVA Ca2+ channel activity were obtained from isolated hippocampal CA1 neurons. LEV was applied by gravity flow from a pipette placed near the cell, and solution changes were made by electromicrovalves.

Dual action of cytosolic calcium on calcium channel activity during hypoxia in hippocampal neurones.

The role of cytoplasmic calcium level (Ca(i)) in regulation of Ca channel activity during hypoxia was studied in hippocampal neurones from rats. Whole-cell patch clamp recordings in combination with measurements of O(2) partial pressure (pO(2)) were used. Lowering of pO(2) induced a potentiation of HVA Ca channel activity by 25.

Different secretory vesicles can be involved in depolarization-evoked exocytosis.

The relationship between Ca(2+) influx through voltage-activated Ca(2+) channels, resting intracellular Ca(2+) level (Ca(i)) and Ca(2+)-dependent exocytosis was studied in bovine adrenal chromaffin cells by using patch-clamp, capacitance, and fluorescent measurements. It was established that depolarization-induced exocytosis passed over two steps, both of which linearly depend on Ca(i). At Ca(i) lying below critical point (200-300 nM) the slope of the relationship was 4.

Electron microscopic evidence for multiple types of secretory vesicles in bovine chromaffin cells.

It has been previously shown that the neuron-like chromaffin cells from the bovine adrenal medulla are heterogeneous. Among other differences, the cells also differed in secretory vesicles represented in their cytoplasm. The present study investigates the types of secretory vesicles in bovine chromaffin cells by electron microscopy.

Ultrastructural features of medullary chromaffin cell cultures.

The ultrastructural organization on the fourth day of culture of chromaffin cells isolated from the bovine adrenal medulla was characterized based on electron microscopic and morphological analysis. We established that medullary chromaffin cells could be divided into four morphologically different subtypes. Most cells (49.

Different types of calcium channels and secretion from bovine chromaffin cells.

Bovine chromaffin cells possess several types of Ca2+ channels, and influx of Ca2+ is known to trigger secretion. However, discrepant information about the relative importance of the individual subtypes in secretion has been reported. We used whole-cell patch-clamp measurements in isolated cells in culture combined with fura-2 microfluorimetry and pharmacological manipulation to determine the dependence of secretion on different types of Ca2+ channels.

High-threshold calcium channel activity in rat hippocampal neurones during hypoxia.

Whole-cell patch clamp recordings in combination with direct control and measurements of O2 tension (pO2) in bath solution were used to determine the sensitivity of Ca2+ channels of cultured hippocampal neurones to hypoxia in glucose free solution. In all tested neurones, a lowering of pO2 to 4/50 mmHg did not induce changes either in magnitude, kinetics or voltage-current relations of total Ca2+ currents, which composed mainly from two types, L-type (64%) and N-type (31%) components. Hypoxia only induced a delay of Ca2+ current run-down about 27.

Diversity and properties of calcium channel types in NG108-15 hybrid cells.

We used an integral of the current-voltage relation as a new evaluation of Ca2+ current component composition in NG108-15 hybrid cells. We determined significant changes in the values and composition of Ca2+ currents during cell differentiation. Only low-voltage-activated Ca2+ currents could be observed in undifferentiated cells; after cell differentiation, high-voltage-activated currents appeared and the total Ca2+ current was increased about 30-fold.

Calcineurin involvement in the regulation of high-threshold Ca2+ channels in NG108-15 (rodent neuroblastoma x glioma hybrid) cells.

1. We examined the relationship between calcineurin (protein phosphatase 2B (PP2B) and voltage-operated Ca2+ channels (VOCCs) in NG108-15 cells. PP2B expression in NG108-15 cells was altered by transfection with plasmid constructs containing a full length cDNA of human PP2B beta(3) in sense (CN-15) and antisense (CN-21) orientation.