Effect of prolonged differentiation on functional maturation of human pluripotent stem cell-derived neuronal cultures.

Long-term neural differentiation of human pluripotent stem cells (hPSCs) is associated with enhanced neuronal maturation, which is a necessity for creation of representative in vitro models. It also induces neurogenic-to-gliogenic fate switch, increasing proportion of endogenous astrocytes formed from the common neural progenitors. However, the significance of prolonged differentiation on the neural cell type composition and functional development of hPSC-derived neuronal cells has not been well characterized.

Reconstructed Serine 288 in the Left Flipper Region of the Rat P2X7 Receptor Stabilizes Nonsensitized States.

Serine 275, a conserved residue of the left flipper region of ATP-gated P2X3 receptors, plays a key role in both agonist binding and receptor desensitization. It is conserved in most of the P2X receptors except P2X7 and P2X6. By combining experimental patch-clamp and modeling approaches, we explored the role of the corresponding residue in the rat P2X7 receptor (rP2X7) by replacing the phenylalanine at position 288 with serine and characterizing the membrane currents generated by either the wild-type (WT) or the mutated rP2X7 receptor.

Nucleotide homeostasis and purinergic nociceptive signaling in rat meninges in migraine-like conditions.

Extracellular ATP is suspected to contribute to migraine pain but regulatory mechanisms controlling pro-nociceptive purinergic mechanisms in the meninges remain unknown. We studied the peculiarities of metabolic and signaling pathways of ATP and its downstream metabolites in rat meninges and in cultured trigeminal cells exposed to the migraine mediator calcitonin gene-related peptide (CGRP). Under resting conditions, meningeal ATP and ADP remained at low nanomolar levels, whereas extracellular AMP and adenosine concentrations were one-two orders higher.

The role of NMDA and mGluR5 receptors in calcium mobilization and neurotoxicity of homocysteine in trigeminal and cortical neurons and glial cells.

Recent studies suggested contribution of homocysteine (HCY) to neurodegenerative disorders and migraine. However, HCY effect in the nociceptive system is essentially unknown. To explore the mechanism of HCY action, we studied short- and long-term effects of this amino acid on rat peripheral and central neurons.

Highly conserved tyrosine 37 stabilizes desensitized states and restricts calcium permeability of ATP-gated P2X3 receptor.

Tyrosine 37 in the first transmembrane (TM1) domain is highly conserved in ATP-gated P2X receptors suggesting its fundamental role. We tested whether Y37 contributes to the desensitization of P2X3 receptors, which is currently not well understood. By combining electrophysiological, imaging and modeling approaches, we studied desensitization of various Y37 P2X3 mutants and potential partners of Y37.

Synthesis, photolysis studies and in vitro photorelease of caged TRPV1 agonists and antagonists.

The synthesis of a range of caged TRPV1 agonists and antagonists is reported. The photolysis characteristics of these compounds, when irradiated with a 355 nm laser, have been studied and in all cases the desired compound was produced. Photolysis of a caged TRPV1 agonist in cultured trigeminal neurons produced responses that were consistent with the activation of TRPV1 receptors.

Dendritic Ca2+ signalling due to activation of alpha 7-containing nicotinic acetylcholine receptors in rat hippocampal neurons.

Neuronal nicotinic acetylcholine receptors (nAChRs) are in the superfamily of Cys-loop ligand-gated ion channels, which are widely expressed in the brain. Among the many different subtypes of nAChRs known to be expressed in the rat brain, the alpha 7-containing nAChRs are considered to be the most permeable to Ca2+. Utilizing highly localized and rapid iontophoretic agonist delivery, combined with patch-clamp electrophysiology and fura-2 fluorescence imaging techniques, we examined the alpha 7 nAChR-mediated currents and [Ca2+]i transients in the dendrites of rat hippocampal CA1 interneurons in the slice.

Ca2+ permeability of nicotinic acetylcholine receptors in rat hippocampal CA1 interneurones.

Neuronal nicotinic acetylcholine receptors (nAChRs) are widely expressed in the brain where they are involved in a variety of physiological processes, including cognition and development. The nAChRs are ligand-gated cationic channels, and different subtypes are known to be differentially permeable to Ca2+; the alpha7-containing nAChRs are generally considered to be the most permeable. Ca2+ can activate and regulate a variety of signal transduction cascades, and the influx of Ca2+ through these receptors may have implications for synaptic plasticity.

Regulation of nicotinic acetylcholine receptor channel function by acetylcholinesterase inhibitors in rat hippocampal CA1 interneurons.

Neuronal nicotinic acetylcholine receptors (nAChRs) are involved in cognition and may play a role in Alzheimer's disease (AD). Known inhibitors of acetylcholinesterase (AChE) are used to treat AD and are known cognitive enhancers; however, their mechanism of action relating to AD is not fully understood. We tested several AChE inhibitors, including huperzine A, tacrine, and 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide (BW284c51), on nAChRs in rat hippocampal CA1 interneurons in slices using patch-clamp techniques.

Functional mapping and Ca2+ regulation of nicotinic acetylcholine receptor channels in rat hippocampal CA1 neurons.

Diverse subtypes of nicotinic acetylcholine receptors (nAChRs), including fast-desensitizing alpha7-containing receptors thought to be Ca2+-permeable, are expressed in the CNS, where they appear to regulate cognitive processing and synaptic plasticity. To understand the physiological role of nAChRs in regulating neuronal excitability, it is important to know the distribution of functional receptors along the surface of neurons, whether they can increase [Ca2+]i, and/or are regulated by Ca2+. We mapped the distribution of receptors on the membrane of rat hippocampal CA1 stratum radiatum interneurons and pyramidal cells in acute slices by recording nAChR-mediated currents elicited by local UV laser-based photolysis of caged carbachol in patch-clamped neurons.

Two different mechanisms underlie reversible, intrinsic optical signals in rat hippocampal slices.

Intrinsic optical signals (IOSs) induced by synaptic stimulation and moderate hypotonic swelling in brain tissue slices consist of reduced light scattering and are usually attributed to cell swelling. During spreading depression (SD), however, light-scattering increases even though SD has been shown to cause strong cell swelling. To understand this phenomenon, we recorded extracellular voltage, light transmission (LT), which is inversely related to light scattering, and interstitial volume (ISV) simultaneously from the same site (stratum radiatum of CA1) in both interface and submerged hippocampal slices.