|
| ||
|
|
||
Acetylcholine Transporter (acetylcholine + transporter)
Kinds of Acetylcholine Transporter Selected AbstractsPresynaptic diadenosine polyphosphate receptors: Interaction with other neurotransmitter systemsDRUG DEVELOPMENT RESEARCH, Issue 1-2 2001M. Teresa Miras-Portugal Abstract Diadenosine polyphosphates (ApnA n = 2,6) are natural compounds that can play a neurotransmitter role in the synaptic terminals of the central nervous system. Microfluorimetric studies of [Ca2+]i in single synaptic terminals have shown the presence of specific ionotropic receptors for nucleotides and dinucleotides. These dinucleotide receptors may or may not coexist at the same terminal. Aminergic terminals from rat basal ganglia have been immunologically characterised by the presence of the vesicular monoamine transporter 2 after the functional studies. Fifty-eight percent of these terminals respond to nucleotides, and of these, 17% respond only to Ap5A. Cholinergic terminals from rat midbrain were immunologically characterised by the vesicular acetylcholine transporter. Sixty-three percent of these terminals responded to nucleotides, and of these, 22% responded only to Ap5A. The presynaptic ionotropic dinucleotide receptors can coexist not only with the ATP receptors, but also with various subtypes of nicotinic receptors. GABAergic terminals from rat midbrain were immunologically characterised by the vesicular inhibitory amino acid transporter. Fifty-nine percent of these terminals responded to nucleotides, and of these, 17% responded only to Ap5A. The presynaptic dinucleotide receptors, when stimulated, are able to induce the GABA release from synaptosomal preparations. These data clearly show the broad interaction of nucleotides and dinucleotides with other neurotransmitter systems. Drug Dev. Res. 52:239,248, 2001. © 2001 Wiley-Liss, Inc. [source] Expression of functional NR1/NR2B-type NMDA receptors in neuronally differentiated SK-N-SH human cell lineEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2002Marina Pizzi Abstract The present study demonstrates that human SK-N-SH neuroblastoma cells, differentiated by retinoic acid (RA), express functional NMDA receptors and become vulnerable to glutamate toxicity. During exposure to RA, SK-N-SH cells switched from non-neuronal to neuronal phenotype by showing antigenic changes typical of postmitotic neurons together with markers specific for cholinergic cells. Neuronally differentiated cells displayed positive immunoreactivity to the vesicular acetylcholine transporter and active acetylcholine release in response to depolarizing stimuli. The differentiation correlated with the expression of NMDA receptors. RT-PCR and immunoblotting analysis identified NMDA receptor subunits NR1 and NR2B, in RA-differentiated cultures. The NR1 protein immunolocalized to the neuronal cell population and assembled with the NR2B subunit to form functional N -methyl- d -aspartate (NMDA) receptors. Glutamate or NMDA application, concentration-dependently increased the intracellular Ca2+ levels and acetylcholine release in differentiated cultures, but not in undifferentiated SK-N-SH cells. Moreover, differentiated cultures became vulnerable to NMDA receptor-mediated excitotoxicity. The glutamate effects were enhanced by glycine application and were prevented by the NMDA receptor blocker MK 801, as well as by the NR2B selective antagonist ifenprodil. These data suggest that SK-N-SH cells differentiated by brief treatment with RA may represent an unlimited source of neuron-like cells suitable for studying molecular events associated with activation of human NR1/NR2B receptors. [source] Trafficking of green fluorescent protein tagged-vesicular acetylcholine transporter to varicosities in a cholinergic cell lineJOURNAL OF NEUROCHEMISTRY, Issue 3 2001CORRECTION No abstract is available for this article. [source] Silencing of choline acetyltransferase expression by lentivirus-mediated RNA interference in cultured cells and in the adult rodent brainJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2009Julie Santamaria Abstract RNA interference (RNAi) is a potent mechanism for local silencing of gene expression and can be used to study loss-of-function phenotypes in mammalian cells. We used RNAi to knockdown specifically the expression of choline acetyltransferase (ChAT), the enzyme of acetylcholine biosynthesis, both in cultured cells and in the adult brain. We first identified a 19-nucleotide sequence in the coding region of rat and mouse ChAT transcripts that constitutes a target for potent silencing of ChAT expression by RNAi. We generated a lentiviral vector that produces both a small hairpin RNA (shRNA) targeting ChAT mRNAs and the enhanced green fluorescent protein (EGFP) reporter protein to facilitate identification of transduced cells. In the cholinergic cell line NG108-15, there was at least 90% less of the ChAT protein, as measured by assaying its enzymatic activity, 3 days postinfection with this vector than in cells infected with a control vector. The vector was used to transduce cholinergic neurons in vivo and reduced ChAT expression strongly and specifically in the cholinergic neurons of the medial septum in adult rats, without affecting the expression of the vesicular acetylcholine transporter. This lentiviral vector is thus a powerful tool for specific inactivation of cholinergic neurotransmission and can therefore be used to study the role of cholinergic nuclei in the brain. This lentiviral-mediated RNAi approach will also allow the development of new animal models of diseases in which cholinergic neurotransmission is specifically altered. © 2008 Wiley-Liss, Inc. [source] Identification of ,- and ,-opioid receptors as potential targets to regulate parasympathetic, sympathetic, and sensory neurons within rat intracardiac gangliaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 18 2010Shaaban A. Mousa Abstract Recent interest has been focused on the opioid regulation of heart performance; however, specific allocation of opioid receptors to the parasympathetic, sympathetic, and sensory innervations of the heart is scarce. Therefore, the present study aimed to characterize such specific target sites for opioids in intracardiac ganglia, which act as a complex network for the integration of the heart's neuronal in- and output. Tissue samples from rat heart atria were subjected to RT-PCR, Western blot, radioligand-binding, and double immunofluorescence confocal analysis of , (M)- and , (K)-opioid receptors (ORs) with the neuronal markers vesicular acetylcholine transporter (VAChT), tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP), and substance P (SP). Our results demonstrated MOR- and KOR-specific mRNA, receptor protein, and selective membrane ligand binding. By using immunofluorescence confocal microscopy, MOR and KOR immunoreactivity were colocalized with VAChT in large-diameter parasympathetic principal neurons, with TH-immunoreactive small intensely fluorescent (SIF) cells, and on nearby TH-IR varicose terminals. In addition, MOR and KOR immunoreactivity were identified on CGRP- and SP-IR sensory neurons throughout intracardiac ganglia and atrial myocardium. Our findings show that MOR and KOR are expressed as mRNA and translated into specific receptor proteins on cardiac parasympathetic, sympathetic, and sensory neurons as potential binding sites for opioids. Thus, they may well play a role within the complex network for the integration of the heart's neuronal in- and output. J. Comp. Neurol. 518:3836,3847, 2010. © 2010 Wiley-Liss, Inc. [source] Cholinergic axons in the rat ventral tegmental area synapse preferentially onto mesoaccumbens dopamine neuronsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 6 2006Natalia Omelchenko Abstract Cholinergic afferents to the ventral tegmental area (VTA) contribute substantially to the regulation of motivated behaviors and the rewarding properties of nicotine. These actions are believed to involve connections with dopamine (DA) neurons projecting to the nucleus accumbens (NAc). However, this direct synaptic link has never been investigated, nor is it known whether cholinergic inputs innervate other populations of DA and ,-aminobutyric acid (GABA) neurons, including those projecting to the prefrontal cortex (PFC). We addressed these questions by using electron microscopic analysis of retrograde tract-tracing and immunocytochemistry for the vesicular acetylcholine transporter (VAChT) and for tyrosine hydroxylase (TH) and GABA. In tissue labeled for TH, VAChT+ terminals frequently synapsed onto DA mesoaccumbens neurons but only seldom contacted DA mesoprefrontal cells. In tissue labeled for GABA, one-third of VAChT+ terminals innervated GABA-labeled dendrites, including both mesoaccumbens and mesoprefrontal populations. VAChT+ synapses onto DA and mesoaccumbens neurons were more commonly of the asymmetric (presumed excitatory) morphological type, whereas VAChT+ synapses onto GABA cells were more frequently symmetric (presumed inhibitory or modulatory). These findings suggest that cholinergic inputs to the VTA mediate complex synaptic actions, with a major portion of this effect likely to involve an excitatory influence on DA mesoaccumbens neurons. As such, the results suggest that natural and drug rewards operating through cholinergic afferents to the VTA have a direct synaptic link to the mesoaccumbens DA neurons that modulate approach behaviors. J. Comp. Neurol. 494:863,875, 2006. © 2005 Wiley-Liss, Inc. [source] Neurochemical characterization of extrinsic innervation of the guinea pig rectumTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2004Catharina Olsson Abstract The presence of markers for parasympathetic, sympathetic, and glutamatergic or peptidergic sensory innervation was investigated by using in vitro tracing with biotinamide, combined with immunohistochemistry, to characterise quantitatively extrinsic axons to myenteric ganglia of the guinea pig rectum. Of biotinamide-filled varicose axons, 3.6 ± 1.3% were immunoreactive for tyrosine hydroxylase (TH) and 16.0 ± 4.8% for vesicular acetylcholine transporter (VAChT). TH and vesicular monoamine transporter (VMAT1) showed high coexistence (83,100%), indicating that varicosities lacking TH immunoreactivity also lacked VMAT1. VAChT was detectable in 77% of choline acetyltransferase (ChAT)-immunoreactive varicosities. Calcitonin gene-related peptide (CGRP) was detected in 5.3 ± 1.6% of biotinamide-labeled varicosities, the vesicular glutamate transporter (VGluT) 1 in 2.8 ± 0.8%, and VGluT2 in 11.3 ± 4.2% of varicosities of extrinsic origin. Varicosities from the same axon showed consistent immunoreactivity. A novel type of nerve ending was identified, with branching, flattened lamellar endings, similar to the intraganglionic laminar endings (IGLEs) of the proximal gut. Rectal IGLEs were frequently immunoreactive for VGluT1 and VGluT2. Thus most varicose axons of extrinsic origin, which innervate rectal myenteric ganglia, lack detectable levels of immunoreactivity for TH, VMAT1, VAChT, ChAT, VGluT1/2, or CGRP, under conditions in which these markers are readily detectable in other axons. Although some unlabeled varicosities may belong to afferent axons that lack detectable CGRP or VGluT1/2 in the periphery, this suggests that a large proportion of axons do not release any of the major autonomic or sensory transmitters. We speculate that this may vary under particular circumstances, for example, inflammation or obstruction of the gut. J. Comp. Neurol. 470:357,371, 2004. © 2004 Wiley-Liss, Inc. [source] | ||||||||||