Search results for "Clamp"
showing 10 items of 243 documents
Synaptopodin regulates denervation-induced homeostatic synaptic plasticity
2013
Synaptopodin (SP) is a marker and essential component of the spine apparatus (SA), an enigmatic cellular organelle composed of stacked smooth endoplasmic reticulum that has been linked to synaptic plasticity. However, SP/SA-mediated synaptic plasticity remains incompletely understood. To study the role of SP/SA in homeostatic synaptic plasticity we here used denervation-induced synaptic scaling of mouse dentate granule cells as a model system. This form of plasticity is of considerable interest in the context of neurological diseases that are associated with the loss of neurons and subsequent denervation of connected brain regions. In entorhino-hippocampal slice cultures prepared from SP-de…
The expression level of the orphan nuclear receptor GCNF (germ cell nuclear factor) is critical for neuronal differentiation.
2004
The germ cell nuclear factor (GCNF) is essential for normal embryonic development and gametogenesis. To test the prediction that GCNF is additionally required for neuronal differentiation, we used the mouse embryonal carcinoma cell line PCC7-Mz1, which represents an advantageous model to study neuronal cells from the stage of fate choice until the acquirement of functional competence. We generated stable transfectants that express gcnf sense or antisense RNA under the control of a tetracycline-regulated promoter. After retinoic acid-induced withdrawal from the cell cycle, sense clones developed a neuron network with changed properties, and the time course of neuron maturation was shortened.…
A subset of ventral tegmental area dopamine neurons responds to acute ethanol
2015
The mechanisms by which alcohol drinking promotes addiction in humans and self-administration in rodents remain obscure, but it is well known that alcohol can enhance dopamine (DA) neurotransmission from neurons of the ventral tegmental area (VTA) and increase DA levels within the nucleus accumbens and prefrontal cortex. We recorded from identified DA neuronal cell bodies within ventral midbrain slices prepared from a transgenic mouse line (TH-GFP) using long-term stable extracellular recordings in a variety of locations and carefully mapped the responses to applied ethanol (EtOH). We identified a subset of DA neurons in the medial VTA located within the rostral linear and interfascicular n…
Identification and functional expression of HCx31.9, a novel gap junction gene
2002
By combining in silico and bench molecular biology methods we have identified a novel human gap junction gene that encodes a protein designated HCx31.9. We have determined its human chromosomal location and gene structure, and we have identified a putative mouse ortholog, mCx30.2. We have observed the presence of HCx31.9 in human cerebral cortex, liver, heart, spleen, lung, and kidney and the presence of mCx30.2 in mouse cerebral cortex, liver and lung. Moreover, preliminary data on the electrophysiological properties of HCx31.9 have been obtained by functional expression in paired Xenopus oocytes and in transfected N2A cells.
Effect of depolarizing GABAA-mediated membrane responses on excitability of Cajal-Retzius cells in the immature rat neocortex
2011
In immature neurons activation of ionotropic GABA receptors induces depolarizing membrane responses due to a high intracellular Cl− concentration ([Cl−]i). However, it is difficult to draw conclusions about the functional consequences of subthreshold GABAergic depolarizations, since GABAergic membrane shunting and additional effects on voltage-dependent ion channels or action potential threshold must be considered. To systematically investigate factors that determine the GABAergic effect on neuronal excitability we performed whole cell patch-clamp recordings from Cajal-Retzius cells in immature rat neocortex, using [Cl−]i between 10 and 50 mM. The effect of focal GABA application was quant…
Perlecan is critical for heart stability
2008
Aims Perlecan is a heparansulfate proteoglycan found in basement membranes, cartilage, and several mesenchymal tissues that form during development, tumour growth, and tissue repair. Loss-of-function mutations in the perlecan gene in mice are associated with embryonic lethality caused primarily by cardiac abnormalities probably due to hemopericards. The aim of the present study was to investigate the mechanism underlying the early embryonic lethality and the pathophysiological relevance of perlecan for heart function. Methods and results Perlecan-deficient murine embryonic stem cells were used to investigate the myofibrillar network and the electrophysiological properties of single cardiomy…
Nitric oxide and excitatory postsynaptic currents in immature rat sympathetic preganglionic neurons in vitro.
1997
Neuronal nitric oxide synthase immunoreactivity was localized to sympathetic preganglionic neurons of the intermediolateral cell column and cyclic GMP immunoreactivity to nerve fibers projecting into the intermediolateral cell column of 20-25-day-old rats. Whole-cell patch-clamp recordings were made from sympathetic preganglionic neurons in spinal cord slices of immature rats and the role of nitric oxide and cyclic GMP on excitatory postsynaptic currents was studied. Superfusing the slices with the nitric oxide precursor L-arginine (300 microM) increased the amplitude of evoked excitatory postsynaptic currents as well as the frequency of spontaneous miniature excitatory postsynaptic current…
GABAergic projections from the subplate to Cajal-Retzius cells in the neocortex.
2011
Subplate neurons and Cajal-Retzius cells play an important role in the corticogenesis. Despite morphological evidence, the question whether subplate neurons innervate Cajal-Retzius cells has not been studied yet. We report that electrical stimulation in the subplate resulted in evoked GABAergic inhibitory postsynaptic currents (eIPSCs) in Cajal-Retzius cells. The eIPSC latency showed minor variability and amounted to approximately 4 ms, suggesting the monosynaptic connection. During the first postnatal week: (i) eIPSC amplitude increased, (ii) eIPSC kinetics sped up, (iii) the size of readily releasable pool increased, and (iv) γ-aminobutyric acid release probability decreased. We conclude …
Modulation of voltage-gated K(+) channels Kv11 and Kv1 4 by forskolin.
2002
Forskolin (FSK) affects voltage-gated K + (Kv) currents in different cell types, but it is not known which of the various subunits form FSK-sensitive Kv channels. We compared the effect of the compound at Kv1.1 and Kv1.4 channels ectopically expressed in HEK 293 cells. Low FSK concentrations induced a phosphorylation-dependent potentiation of Kv1.1 currents. At higher concentrations, this effect was superimposed by a fast, cAMP-independent channel block. Kv1.4 currents were inhibited with lower potency by FSK but were not modified by phosphorylation. The variable effect of the compound might help to distinguish between Kv subunits expressed by native cells. 2002 Elsevier Science Ltd. All …
Analysis of phosphorylation-dependent modulation of Kv1.1 potassium channels.
2003
The voltage-gated potassium channel Kv1.1 contains phosphorylation sites for protein kinase A (PKA) and protein kinase C (PKC). To study Kv1.1 protein expression and cellular distribution in regard to its level of phosphorylation, the effects of PKA and PKC activation on Kv1.1 were investigated in HEK 293 cells stably transfected with Kv1.1 (HEK 293/1). Without kinase activation, HEK 293/1 cells carry unphosphorylated Kv1.1 protein in the plasma membranes, whereas large amounts of phosphorylated and unphosphorylated Kv1.1 protein were located intracellularly. Activation of PKA resulted in phosphorylation of intracellular Kv1.1 protein, followed by a rapid translocation of Kv1.1 into the pla…