Block of postjunctional muscle-type acetylcholine receptors in vivo causes train-of-four fade in mice

A variety of brain cells participates in neurovascular coupling by transmitting and modulating vasoactive signals. The present study aimed to probe cell type-dependent cerebrovascular (i.e., pial and penetrating arterial) responses with optogenetics in the cortex of anesthetized mice. Two lines of the transgenic mice expressing a step function type of light-gated cation channel (channelrhodopsine-2; ChR2) in either cortical neurons (muscarinic acetylcholine receptors) or astrocytes (Mlc1-positive) were used in the experiments. Photo-activation of ChR2-expressing astrocytes resulted in a widespread increase in cerebral blood flow (CBF), extending to the nonstimulated periphery. In contrast, photo-activation of ChR2-expressing neurons led to a relatively localized increase in CBF. The differences in the spatial extent of the CBF responses are potentially explained by differences in the involvement of the vascular compartments. In vivo imaging of the cerebrovascular responses revealed that ChR2-expressing astrocyte activation led to the dilation of both pial and penetrating arteries, whereas ChR2-expressing neuron activation predominantly caused dilation of the penetrating arterioles. Pharmacological studies showed that cell type-specific signaling mechanisms participate in the optogenetically induced cerebrovascular responses. In conclusion, pial and penetrating arterial vasodilation were differentially evoked by ChR2-expressing astrocytes and neurons.

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N-cholinergic facilitation of glutamate release from an individual retinotectal fiber in frog

Visual Neuroscience ◽

10.1017/s0952523801184051 ◽

2001 ◽

Vol 18 (4) ◽

pp. 549-558 ◽

Cited By ~ 16

Author(s):

A. KURAS ◽

N. GUTMANIENĖ

Keyword(s):

Nicotinic Acetylcholine Receptors ◽

Action Potentials ◽

Acetylcholine Receptors ◽

Kynurenic Acid ◽

Glutamate Release ◽

Synaptic Potentials ◽

Lower Vertebrates ◽

Optic Fibers ◽

Retinotectal Transmission

Nicotinic acetylcholine receptors are localized on retinotectal axons' terminals in lower vertebrates. The effects of activation of these receptors by endogenous acetylcholine were observed under stimulation of mass optic fibers. This study was designed to determine whether endogenous acetylcholine facilitates frog retinotectal transmission, provided only the synapses of an individual optic axon are activated, and to evaluate the feasible extent of nicotinic facilitation in these synapses by applied agonist. To this end, the effects of cholinergic drugs on the extracellular action and synaptic potentials recorded from the terminal arborization of a separate retinotectal fiber (in layer F of the tectum) were investigated in vivo. Glutamatergic nature of retinotectal synapses was reexamined by treatment with kynurenic acid. Both kynurenic acid (0.25–1 mM) and d-tubocurarine chloride (10–15 μM) significantly depressed the synaptic potentials. Carbamylcholine chloride (50–150 μM) evoked a large augmentation of the synaptic potentials and a slight but statistically significant decrease of the action potentials. D-tubocurarine reduced the effect of carbamylcholine. Pilocarpine hydrochloride (50 μM) had only a weak effect. The paired-pulse facilitation of the synaptic potentials changed significantly under the action of carbamylcholine and d-tubocurarine. The obtained results suggest that the glutamate release from activated synapses of individual retinotectal axons is facilitated by endogenous acetylcholine via presynaptic nicotinic receptors. Under used stimulation conditions, this modulation mechanism was employed only partially since its activation by applied carbamylcholine could enhance synaptic transmission up to 2.8 times.

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Globular and asymmetric acetylcholinesterase in frog muscle basal lamina sheaths.

The Journal of Cell Biology ◽

10.1083/jcb.102.3.762 ◽

1986 ◽

Vol 102 (3) ◽

pp. 762-768 ◽

Cited By ~ 12

Author(s):

M Nicolet ◽

M Pinçon-Raymond ◽

F Rieger

Keyword(s):

Basal Lamina ◽

Acetylcholine Receptors ◽

Muscle Fibers ◽

Frog Muscle ◽

Motor Endplate ◽

Molecular Forms ◽

Nonionic Detergent ◽

Plasmic Membrane ◽

Triton X

After denervation in vivo, the frog cutaneus pectoris muscle can be led to degenerate by sectioning the muscle fibers on both sides of the region rich in motor endplate, leaving, 2 wk later, a muscle bridge containing the basal lamina (BL) sheaths of the muscle fibers (28). This preparation still contains various tissue remnants and some acetylcholine receptor-containing membranes. A further mild extraction by Triton X-100, a nonionic detergent, gives a pure BL sheath preparation, devoid of acetylcholine receptors. At the electron microscope level, this latter preparation is essentially composed of the muscle BL with no attached plasmic membrane and cellular component originating from Schwann cells or macrophages. Acetylcholinesterase is still present in high amounts in this BL sheath preparation. In both preparations, five major molecular forms (18, 14, 11, 6, and 3.5 S) can be identified that have either an asymmetric or a globular character. Their relative amount is found to be very similar in the BL and in the motor endplate-rich region of control muscle. Thus, observations show that all acetylcholinesterase forms can be accumulated in frog muscle BL.

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The Prototoxin lynx1 Acts on Nicotinic Acetylcholine Receptors to Balance Neuronal Activity and Survival In Vivo

Neuron ◽

10.1016/j.neuron.2006.07.025 ◽

2006 ◽

Vol 51 (5) ◽

pp. 587-600 ◽

Cited By ~ 89

Author(s):

Julie M. Miwa ◽

Tanya R. Stevens ◽

Sarah L. King ◽

Barbara J. Caldarone ◽

Ines Ibanez-Tallon ◽

...

Keyword(s):

Neuronal Activity ◽

Nicotinic Acetylcholine Receptors ◽

Acetylcholine Receptors ◽

Nicotinic Acetylcholine

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Processing of ARIA and release from isolated nerve terminals

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1999.0394 ◽

1999 ◽

Vol 354 (1381) ◽

pp. 411-416 ◽

Cited By ~ 14

Author(s):

Bomie Han ◽

Gerald D. Fischbach

Keyword(s):

Neuromuscular Junction ◽

Action Potential ◽

Acetylcholine Receptors ◽

Molecular Layer ◽

Postsynaptic Membrane ◽

High Density ◽

Small Contribution ◽

Presynaptic Nerve Terminal ◽

Voltage Gated

The neuromuscular junction is a specialized synapse in that every action potential in the presynaptic nerve terminal results in an action potential in the postsynaptic membrane, unlike most interneuronal synapses where a single presynaptic input makes only a small contribution to the population postsynaptic response. The postsynaptic membrane at the neuromuscular junction contains a high density of neurotransmitter (acetylcholine) receptors and a high density of voltage–gated Na + channels. Thus, the large acetylcholine activated current occurs at the same site where the threshold for action potential generation is low. Acetylcholine receptor inducing activity (ARIA), a 42 kD protein, that stimulates synthesis of acetylcholine receptors and voltage–gated Na + channels in cultured myotubes, probably plays the same roles at developing and mature motor endplates in vivo . ARIA is synthesized as part of a larger, transmembrane, precursor protein called proARIA. Delivery of ARIA from motor neuron cell bodies in the spinal cord to the target endplates involves several steps, including proteolytic cleavage of proARIA. ARIA is also expressed in the central nervous system and it is abundant in the molecular layer of the cerebellum. In this paper we describe our first experiments on the processing and release of ARIA from subcellular fractions containing synaptosomes from the chick cerebellum as a model system.

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Imaging Muscarinic Cholinergic Receptors in Human Brain in vivo with SPECT, [123I]4-Iododexetimide, and [123I]4-Iodolevetimide

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.1992.80 ◽

1992 ◽

Vol 12 (4) ◽

pp. 562-570 ◽

Cited By ~ 48

Author(s):

Hans W. Müller-Gärtner ◽

Alan A. Wilson ◽

Robert F. Dannals ◽

Henry N. Wagner ◽

J. James Frost

Keyword(s):

Human Brain ◽

Muscarinic Receptor ◽

Muscarinic Receptors ◽

Acetylcholine Receptors ◽

Brain Regions ◽

Muscarinic Acetylcholine Receptors ◽

Emission Computed Tomography ◽

Nonspecific Binding ◽

Muscarinic Acetylcholine

A method to image muscarinic acetylcholine receptors (muscarinic receptors) noninvasively in human brain in vivo was developed using [123I]4-iododexetimide ([123I]IDex), [123I]4-iodolevetimide ([123I]ILev), and single photon emission computed tomography (SPECT). [123I]IDex is a high-affinity muscarinic receptor antagonist. [123I]ILev is its pharmacologically inactive enantiomer and measures nonspecific binding of [123I]IDex in vitro. Regional brain activity after tracer injection was measured in four young normal volunteers for 24 h. Regional [123I]IDex and [123I]ILev activities were correlated early after injection, but not after 1.5 h. [123I]IDex activity increased over 7–12 h in neocortex, neostriatum, and thalamus, but decreased immediately after the injection peak in cerebellum. [123I]IDex activity was highest in neostriatum, followed in rank order by neocortex, thalamus, and cerebellum. [123I]IDex activity correlated with muscarinic receptor concentrations in matching brain regions. In contrast, [123I]ILev activity decreased immediately after the injection peak in all brain regions and did not correspond to muscarinic receptor concentrations. [123I]IDex activity in neocortex and neostriatum during equilibrium was six to seven times higher than [123I]ILev activity. The data demonstrate that [123I]IDex binds specifically to muscarinic receptors in vivo, whereas [123I]ILev represents the nonspecific part of [123I]IDex binding. Subtraction of [123I]ILev from [123I]IDex images on a pixel-by-pixel basis therefore reflects specific [123I]IDex binding to muscarinic receptors. Owing to its high specific binding, [123I]IDex has the potential to measure small changes in muscarinic receptor characteristics in vivo with SPECT. The use of stereoisomerism directly to measure nonspecific binding of [123I]IDex in vivo may reduce complexity in modeling approaches to muscarinic acetylcholine receptors in human brain.

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LC-MS Supported Studies on the in Vitro Metabolism of both Enantiomers of Flubatine and the in Vivo Metabolism of (+)-[18F]Flubatine—A Positron Emission Tomography Radioligand for Imaging α4β2 Nicotinic Acetylcholine Receptors

Molecules ◽

10.3390/molecules21091200 ◽

2016 ◽

Vol 21 (9) ◽

pp. 1200 ◽

Cited By ~ 7

Author(s):

Friedrich-Alexander Ludwig ◽

René Smits ◽

Steffen Fischer ◽

Cornelius Donat ◽

Alexander Hoepping ◽

...

Keyword(s):

Positron Emission Tomography ◽

Nicotinic Acetylcholine Receptors ◽

Acetylcholine Receptors ◽

In Vitro Metabolism ◽

Emission Tomography ◽

In Vivo Metabolism ◽

Nicotinic Acetylcholine ◽

Positron Emission

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Preclinical Pharmacology of CW002

Anesthesiology ◽

10.1097/aln.0000000000001254 ◽

2016 ◽

Vol 125 (4) ◽

pp. 732-743 ◽

Cited By ~ 6

Author(s):

Hiroshi Sunaga ◽

John J. Savarese ◽

Jeff D. McGilvra ◽

Paul M. Heerdt ◽

Matthew R. Belmont ◽

...

Keyword(s):

Mean Arterial Pressure ◽

Arterial Pressure ◽

Blocking Agent ◽

Neuromuscular Blocking ◽

Safety And Efficacy ◽

Circulatory Effects ◽

Autonomic Changes ◽

Train Of Four

Abstract Background CW002, a novel nondepolarizing neuromuscular blocking agent of intermediate duration, is degraded in vitro by l-cysteine; CW002-induced neuromuscular blockade (NMB) is antagonized in vivo by exogenous l-cysteine.1 Further, Institutional Animal Care and Use Committee–approved studies of safety and efficacy in eight anesthetized monkeys and six cats are described. Methods Mean arterial pressure, heart rate, twitch, and train-of-four were recorded; estimated dose producing 95% twitch inhibition (ED95) for NMB and twitch recovery intervals from 5 to 95% of baseline were derived. Antagonism of 99 to 100% block in monkeys by l-cysteine (50 mg/kg) was tested after bolus doses of approximately 3.75 to 20 × ED95 and after infusions. Vagal and sympathetic autonomic responses were recorded in cats. Dose ratios for [circulatory (ED20) or autonomic (ED50) changes/ED95 (NMB)] were calculated. Results ED95s of CW002 in monkeys and cats were 0.040 and 0.035 mg/kg; l-cysteine readily antagonized block in monkeys: 5 to 95% twitch recovery intervals were shortened to 1.8 to 3.6 min after 3.75 to 10 × ED95 or infusions versus 11.5 to 13.5 min during spontaneous recovery. ED for 20% decrease of mean arterial pressure (n = 27) was 1.06 mg/kg in monkeys; ED for 20% increase of HR (n = 27) was 2.16 mg/kg. ED50s for vagal and sympathetic inhibition in cats were 0.59 and >>0.80 mg/kg (n = 14 and 15). Dose ratios for [circulatory or autonomic changes/ED95 (NMB)] were all more than 15 × ED95. Conclusions The data further verify the neuromuscular blocking properties of CW002, including rapid reversal by l-cysteine of 100% NMB under several circumstances. A notable lack of autonomic or circulatory effects provided added proof of safety and efficacy.

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