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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The success of axon regeneration after nerve injury should be judged by the extent to which the target organs regain their function. Recovery of muscle contraction involves axon regeneration, reestablishment of nerve-muscle connections, recovery of transmission, and muscle force. All these processes were investigated under the same experimental conditions and correlated in order to better understand their time-course and interdependence. The sciatic nerve of a rat was crushed in the thigh. The ingrowth of regenerating motor axons into the soleus (SOL) and extensor digitorum longus (EDL) muscles was monitored by measuring the activity of choline acetyltransferase (ChAT), a marker enzyme for cholinergic nerve terminals, in the muscles. The electron microscopic cytochemistry of acetylcholine esterase (AChE) was used to estimate the reestablishment of neuromuscular junctions in these two muscles. The recovery of muscle contraction was followed by measuring the force of isometric contraction in the triceps surae muscle in vivo. The pattern of ChAT recovery during reinnervation was similar in the EDL and SOL. The statistically significant increase of ChAT activity in these muscles, 14 d after the nerve crush, signified the entry of regenerating axons into the calf muscles. Electron microscopic cytochemistry revealed the first small nerve endings in contact with the denervated end plates 12 d after denervation. Subsequently, the number of reinnervated motor end plates and the surface area of the neuromusclar junctions steadily increased. The recovery of muscle force started between d 14 and 21 after the nerve crush. Thirty-five days after denervation, the difference between the muscle force of the reinnervated muscle and the control became statistically insignificant. Morphological normalization of the motor end plates was practically complete 33 d after denervation, concomitant with the normalization of the muscle force. At that time, however, ChAT activity in both muscles was still clearly subnormal (33.5% in EDL and 45% of the control in SOL) and therefore does not reflect the true extent of muscle force recovery. Yet, it seems that in spite of this, the regenerated nerve terminals contained sufficient amounts of acetylcholine (ACh) to trigger normal muscle contractions.
Mol Chem Neuropathol 1991 Oct
PMID:Biochemical, morphological, and functional changes during peripheral nerve regeneration. 177 90

A putative precursor of the 67 kDa choline acetyltransferase (Acetyl-CoA: choline-O-acetyltransferase; EC 2.3.1.6) polypeptide from Drosophila was examined using polyclonal antibodies. The central purpose of the study was to probe the suspected precursor with anti-peptide antibodies that could identify a cleavable amino terminal domain, since such a structure could be responsible for targeting the enzyme to the presynaptic terminal. Antisera were produced to both a plasmid-expressed fusion-free enzyme protein and a 26-amino acid-long peptide reproducing sequence from the enzyme. Both antisera were capable of precipitating enzyme activity from crude supernatants. Western blotting with the antibody to the plasmid-expressed enzyme visualized a major polypeptide at 75 kDa and minor polypeptides at 67 and 54 kDa. Affinity-purified IgG to the synthetic peptide only recognized the 75 kDa component and was unable to recognize purified 67 kDa enzyme protein. Timed autolysis of the enzyme in crude homogenates demonstrated both a 67 kDa polypeptide that was present prior to homogenization and a species that appeared as a product of the autolysis. The evidence from this study is consistent with the expectation that the 75 kDa band, visualized on Western blots with antisera to the enzyme, is an authentic enzyme protein. These data further suggested that the 75 kDa protein is an amino-terminally extended precursor of the 67 kDa enzyme that can be cleaved to generate the 67 kDa species.
Brain Res Mol Brain Res 1991 Feb
PMID:The amino terminus of the putative Drosophila choline acetyltransferase precursor is cleaved to yield the 67 kDa enzyme. 185 26

Complementary DNA clones containing the entire coding region of choline acetyltransferase (ChAT) were isolated from the spinal cords of rat and mouse. The cDNAs of rat and mouse coded for 640 and 641 amino acids, respectively, and showed 95% mutual homology and 80% homology with the cDNA of porcine ChAT. Northern blot analysis revealed a single band of 4.4 kb in the spinal cord and brain in each species. Introduction of the cDNAs into Chinese hamster ovary cells and neuron-derived cell lines, N1E115 and NG108-15, expressed a high ChAT activity, which was inhibited by a specific ChAT inhibitor. In situ hybridization using the rat cRNA probe revealed specific labeling of the motoneurons in the spinal cord and neurons in various forebrain nuclei of the rat where the existence of cholinergic neurons has been demonstrated immunohistochemically.
Brain Res Mol Brain Res 1990 Feb
PMID:Complementary DNAs for choline acetyltransferase from spinal cords of rat and mouse: nucleotide sequences, expression in mammalian cells, and in situ hybridization. 216 42

In the present work we characterized both the presynaptic and postsynaptic components of cholinergic transmission in a primary culture of corticostriatal neurons prepared from newborn rat brain. This culture preparation contains a small population of choline acetyltransferase (ChAT) immunoreactive neurons, corresponding to approximately 3% of the total cell number, and synthesizes increasing amounts of acetylcholine (ACh) from the third day in vitro (DIV), which reaches a plateau around the 10 day of culture. Muscarinic cholinergic receptors (mAChR), measured by the binding of the muscarinic antagonist [3H]quinuclidinyl benzilate ([3H]QNB), are detectable from the fifth DIV and increase linearly during the time of culture. At the twelfth DIV, the density of mAChRs (approximately 600 fmol/mg protein) is comparable to the density of mAChR in adult rat cortex. These receptors are coupled to second messenger systems, since muscarinic agonists inhibit adenylate cyclase activity and stimulate phosphoinositide breakdown with efficacies and potencies similar to those found in adult rat cortex. Moreover, by using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique, we were able to demonstrate the presence of the m1, m3, and m4 mAChR subtype mRNAs in this neuronal culture at 12 DIV. Our data suggest that corticostriatal neuronal cultures develop in vitro ACh-synthesizing neurons and functionally active cholinergic receptors. This therefore makes them ideally suited to study the development and properties of brain mAChR subtypes.
J Mol Neurosci 1990
PMID:Primary cultures of corticostriatal cells from newborn rats: a model to study muscarinic receptor subtypes regulation and function. 217 49

Nerve growth factor (NGF) receptor mRNA was found to be widely distributed throughout the human central nervous system, with the highest levels in the basal forebrain; this suggests that NGF may function as a retrograde trophic messenger for basal forebrain magnocellular cholinergic nerve cells. The degeneration of the latter constitutes one of the main features of Alzheimer's disease and it may be responsible for some of the cognitive impairment that characterizes the disease. No evidence was obtained for an insufficient synthesis of NGF receptor mRNA in the basal forebrain in Alzheimer's disease, where NGF receptor-like immunoreactivity was confined to neuronal cell bodies. NGF could thus be therapeutically beneficial. It could be expected to induce basal forebrain cholinergic cells to hypertrophy, synthesize more choline acetyltransferase and extend neurites.
Brain Res Mol Brain Res 1989 Jan
PMID:Nerve growth factor receptor mRNA distribution in human brain: normal levels in basal forebrain in Alzheimer's disease. 253 4

We have studied the effects of Ca2+ antagonists and agonists on the development of choline acetyltransferase (ChAT), tyrosine hydroxylase (TOH) and acetylcholinesterase (AChE) in cultures of rat sympathetic neurons maintained for 6-9 days in low K+ (5 mM) or high K+ (35 mM) medium. Previous experiments have shown that high K+ medium increases TOH activity and TOH-mRNA level up to 3.5-fold and depresses the development of AChE, in particular of its asymmetric A12 form. Moreover, high K+ medium inhibits ChAT induction by 90% in muscle-conditioned medium (Raynaud et al., Dev. Biol., 119 (1987) 305-312; 121 (1987) 548-558). None of the Ca2+ antagonists tested affected the development of ChAT, TOH or AChE in low K+ medium. In high K+ medium, nitrendipine (3 microM) or fluspirilene (1 microM) fully restored ChAT induction by conditioned medium to the level observed in low K+ medium. Other drugs (1 microM) gave partial reversion: flunarizine greater than (+)-PN 200-110 greater than (-)-D-888 greater than cinnarizine = lidoflazine. On the other hand, ChAT induction was not restored by a calmodulin inhibitor, calmidazolium (1 microM). Fluspirilene, PN 200-110, and nitrendipine also totally abolished TOH induction by high K+ medium; fluspirilene (1 microM) suppressed the inhibitory effect of high K+ medium on AChE development and restored the development of A12 AChE. Conditioned medium also depresses AChE and blocks the development of A12 AChE (Swerts et al., Dev. Biol., 103 (1984) 230-234), but these effects were insensitive to fluspirilene. The Ca2+ agonist Bay K 8644 (1 microM) potentiated the effects of elevated K+ on both ChAT and TOH. The data suggest that the effects of long-term depolarization on ChAT, TOH and AChE are mediated by Ca2+ entry specifically through voltage-sensitive channels of the L-type. Our results on cultured sympathetic neurons raise the possibility that Ca2+ antagonists, which are widely used clinically, may affect the expression of neurotransmitter phenotypic traits in vivo and interfere with trans-synaptic induction of enzymes.
Brain Res Mol Brain Res 1989 Nov
PMID:The role of Ca2+ channels of the L-type in neurotransmitter plasticity of cultured sympathetic neurons. 257 96

Experiments were performed to determine the cellular associations of the molecular forms of acetylcholinesterase (AChE) in adult rat heart. For this purpose, a cardiac muscle and a non-muscle fraction were isolated from rat heart ventricles after perfusion with collagenase and hyaluronidase, extracts of these fractions were subjected to ultracentrifugation on linear density gradients of sucrose (5-20%), and fractions of these gradients were analyzed for AChE activity. The results show that only globular AChE molecular forms were present in isolated cardiac muscle cells. Globular AChE forms were also present in the non-muscle cells fraction but in different proportions. The proportions of globular AChE forms plus the high specific activity of choline acetyltransferase in the non-muscle cell fraction suggest that this fraction contains cholinergic nerve fragments. The results of this study also show that asymmetric AChE is released during the perfusion of heart with the digestive enzymes, which suggests that asymmetric AChE is bound to the extracellular matrix of heart.
J Mol Cell Cardiol 1989 Oct
PMID:Acetylcholinesterase molecular forms in muscle and non-muscle cells of rat heart. 258 21

The presence of unusually high levels of choline acetyltransferase (ChAT, EC 2.3.1.6) in human and animal filarial parasites has been demonstrated. The levels of ChAT were highest in male worms of Brugia malayi and Brugia pahangi, with specific activities in crude extracts of about 2.27 and 1.26 mumol min-1 (mg protein)-1, respectively. The enzyme levels in these worms were over 10-20 times higher than in male worms of Litomosoides carinii. The ChAT levels were about 2-5 times higher in male than in female worms. The enzyme was also present in appreciably high levels in microfilariae of Brugia species, L. carinii and Wuchereria bancrofti. The levels of ChAT in male worms of Brugia species were several thousand-fold higher than in the intestinal nematodes Trichuris muris and Necator americanus, and were over three orders of magnitude higher than in mammalian brain. Unlike the mammalian ChAT, the parasite enzyme was extremely stable. The parasite enzyme was not inhibited by any of the antifilarial agents except suramin. The filarial ChAT was strongly inhibited by sulphydryl reagents and diethylpyrocarbonate. Ethacrynic acid (EA), a diuretic and a sulphydryl reagent, irreversibly inhibited the filarial ChAT activity at low concentrations. In contrast, EA inhibited the activity of mammalian brain ChAT at much higher concentrations. The motility of adult worms and microfilariae was irreversibly inhibited by low concentrations of EA. Furthermore, the inhibition of motility was paralleled by the inactivation of ChAT in these parasites. These studies indicate that ChAT activity appears to be vital for parasite's survival and that acetylcholine might play a key role in the control of worm motility.
Mol Biochem Parasitol 1989 Jul
PMID:Filarial parasites exhibit unusually high levels of choline acetyltransferase activity. 266 8

Several presynaptic cholinergic markers were measured in subcellular fractions of the rat cardiac atrium. A P2 fraction consisting of isolated terminals, free mitochondria, glycogen and other subcellular organelles was prepared first by sucrose density centrifugation. No intact cells were recovered in this fraction, as determined by electron microscopy. Hemicholinium-3 sensitive choline transport coupled to acetylcholine synthesis was concentrated over 10-fold in the P2 fraction compared to minced atria when expressed per mg protein. Six subfractions were recovered after centrifugation of the P2 fraction over a sucrose-metrizamide density gradient. One of these (fraction 4) consistently contained higher levels of choline acetyltransferase activity and hemicholinium-3 sensitive [3H]acetylcholine synthesis than were present in the P2 fraction of the other five subfractions. Electron microscopy of fraction 4 revealed isolated nerve terminals among other subcellular organelles. Kinetic analysis of total [3H]choline uptake in the P2 fraction revealed two apparent uptake processes, with Kts of approximately 11 microM and 219 microM. [3H]Acetylcholine synthesis was partially sodium-dependent in the P2 fraction, and reached a maximal level between choline concentrations of 100 to 200 microM. Some of the newly synthesized [3H]-acetylcholine in the P2 fraction was released by 50 mM K+ depolarization in a calcium-dependent manner, arguing for a neuronal localization. This depolarization-induced release was attenuated by 10 to 100 microM oxotremorine in an atropine-sensitive manner, but was not affected by 1 microM tetrodotoxin.
J Mol Cell Cardiol 1989 Mar
PMID:Cholinergic properties of rat atrial subcellular preparations. 274 56

The heterogeneity of a synaptosomal preparation was studied by the use of affinity partitioning in combination with centrifugal counter-current distribution. Hexaethonium-poly(ethyleneglycol) was used as the extracting agent. The fractions were analyzed for: light scattering, protein, choline acetyltransferase, L-glutamate decarboxylase, glutamine synthetase, 2',3'-cyclicnucleotide-3'-phosphohydrolase, acetylcholinesterase and succinate dehydrogenase. The material was fractionated into three main fractions which differed in their content of marker-enzymes.
Mol Cell Biochem 1989 Jun 01
PMID:Heterogeneity of a crude synaptosomal preparation, studied by affinity partitioning using hexaethonium-poly(ethylene glycol). 277 Jul 19


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