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Introduction. The available literature provides relatively little information on the morphology of the autonomic head ganglia in rodents including their neurochemical codding. Material and methods. Morphological investigations of the otic ganglion of the chinchilla were performed using the modified acetylcholinesterase method. The cellular structure was investigated with histological techniques and neurochemical properties were studied with the double-labelling immunofluorescence method. Results. Macromorphological investigations allowed the otic ganglion to be identified as a compact, oval agglomeration of neurons and nerve fibers. Multidimensional cross-sections revealed densely arranged neuronal perikarya and two populations of nerve cells differing in size were distinguished. The large cells (40–50 μm) accounted for about 80% of the neurons in the cross-sections. Moreover, a small number of intraganglionic nerve fibers was observed. Immunohistochemical staining revealed that over 85% of the neuronal cell bodies in the otic ganglion contained immunoreactivity to VAChT or ChAT. VIP-immunoreactive perikarya comprised approximately 10% of the ganglionic cells. Double staining revealed the presence of VAChT+ and NOS+ neurons which amounted to about 45% of the nerve cells in the otic ganglion. NOS+ only perikarya comprised approx. 15% of all the neurons. Immunoreactivity to enkephalins, substance P, somatostatin, and galanin was expressed in single nerve cell bodies and nerve fibers except numerous substance P+ intraganglionic nerve fibers. Some of them were stained also for CGRP. Single neurons stained for tyroxine hydroxylase. Conclusions. Our results, compared with findings in other rodent species suggest the existence of interspecies differences in the morphology, cellular structure, and immunohistochemical properties of the head autonomic ganglia in mammals. [ABSTRACT FROM AUTHOR]

Abstract Background The autonomic nervous system is frequently affected in some neurodegenerative diseases, including Parkinson’s disease and Dementia with Lewy bodies. In vivo imaging methods to visualize and quantify the peripheral cholinergic nervous system are lacking. By using [18F]FEOBV PET, we here describe the peripheral distribution of the specific cholinergic marker, vesicular acetylcholine transporters (VAChT), in human subjects. We included 15 healthy subjects aged 53–86 years for 70 min dynamic PET protocol of peripheral organs. We performed kinetic modelling of the adrenal gland, pancreas, myocardium, renal cortex, spleen, colon, and muscle using an image-derived input function from the aorta. A metabolite correction model was generated from venous blood samples. Three non-linear compartment models were tested. Additional time-activity curves from 6 to 70 min post injection were generated for prostate, thyroid, submandibular-, parotid-, and lacrimal glands. Results A one-tissue compartment model generated the most robust fits to the data. Total volume-of-distribution rank order was: adrenal gland > pancreas > myocardium > spleen > renal cortex > muscle > colon. We found significant linear correlations between total volumes-of-distribution and standard uptake values in most organs. Conclusion High [18F]FEOBV PET signal was found in structures with known cholinergic activity. We conclude that [18F]FEOBV PET is a valid tool for estimating VAChT density in human peripheral organs. Simple static images may replace kinetic modeling in some organs and significantly shorten scan duration. Clinical Trial Registration Trial registration: NCT, NCT03554551. Registered 31 May 2018. https://clinicaltrials.gov/ct2/show/NCT03554551?term=NCT03554551&draw=2&rank=1 .

Little is known about the effects of acrylamide (AMD) on the stomach. So, this study evaluated the effect of oral AMD exposure (20 mg/kg b.wt) on oxidative status, apoptotic, and inflammatory reactions in rat's stomach for 60 days. To explore novel targets of AMD toxicity, a more detailed molecular and immune-expression study was performed. Besides, the possible protective effect of green synthesized zinc oxide nanoparticles (G-ZNP) (10 mg/kg b.wt) was explored. The results revealed that AMD significantly provoked oxidative and lipid peroxidative damage of the stomach in terms of increased ROS and MDA but reduced SOD, CAT, GSH, and GSH/GSSG. Additionally, the stomachs of AMD-exposed rats showed a significant increment of PGE2 but reduced NO. Histopathologically, AMD induced a significant increase in PAS stain and the immunoexpression of iNOS and NF-κB in the glandular stomach. A significant upregulation of CART, VACHT, EGFR, caspase-3, NOS-1, and miR-27a-5p was evident in the stomach of the AMD group. Yet, G-ZNP oral dosing significantly rescued the AMD-induced oxidative damage, apoptotic reaction, inflammatory effect, and altered miR-27a-5p and gene expressions in the stomach. Conclusively, these findings demonstrated the efficacy of G-ZNP in protecting against the harmful impacts of acrylamide on stomach tissues. • The underlying mechanisms of acrylamide (AMD)-induced stomach damage was explored. • MiR-27a-5p/ROS/NF-κB pathway was altered in AMD-exposed rats. • The PGE2 levels were increased, but NO levels were reduced in the AMD-exposed rat's stomach. • Green-fabricated zinc oxide nanoparticles rescue AMD -induced stomach injury. [ABSTRACT FROM AUTHOR]

Background: The autonomic nervous system is frequently affected in some neurodegenerative diseases, including Parkinson's disease and Dementia with Lewy bodies. In vivo imaging methods to visualize and quantify the peripheral cholinergic nervous system are lacking. By using [18F]FEOBV PET, we here describe the peripheral distribution of the specific cholinergic marker, vesicular acetylcholine transporters (VAChT), in human subjects. We included 15 healthy subjects aged 53–86 years for 70 min dynamic PET protocol of peripheral organs. We performed kinetic modelling of the adrenal gland, pancreas, myocardium, renal cortex, spleen, colon, and muscle using an image-derived input function from the aorta. A metabolite correction model was generated from venous blood samples. Three non-linear compartment models were tested. Additional time-activity curves from 6 to 70 min post injection were generated for prostate, thyroid, submandibular-, parotid-, and lacrimal glands. Results: A one-tissue compartment model generated the most robust fits to the data. Total volume-of-distribution rank order was: adrenal gland > pancreas > myocardium > spleen > renal cortex > muscle > colon. We found significant linear correlations between total volumes-of-distribution and standard uptake values in most organs. Conclusion: High [18F]FEOBV PET signal was found in structures with known cholinergic activity. We conclude that [18F]FEOBV PET is a valid tool for estimating VAChT density in human peripheral organs. Simple static images may replace kinetic modeling in some organs and significantly shorten scan duration. Clinical Trial Registration Trial registration: NCT, NCT03554551. Registered 31 May 2018. https://clinicaltrials.gov/ct2/show/NCT03554551?term=NCT03554551&draw=2&rank=1. [ABSTRACT FROM AUTHOR]

Insecticides targeting the nervous system have been the most widely used to control arthropod pests due to their fast onset of action leading to efficient crop protection. With their continued use, resistance has and will become an inevitable challenge that demands continued efforts in identifying and developing new insecticidal chemistries acting on novel targets. In a recent publication, the results of a comprehensive study investigating the mode of action of novel chemical scaffolds based on the 2-(3-ethylsulfonyl-2-pyridyl)-heterocycles, alkylsulfones, was presented, concluding that their primary target is the vesicular acetylcholine transporter. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

It is well known that cholinergic hypofunction contributes to cardiac pathology, yet, the mechanisms involved remain unclear. Our previous study has shown that genetically engineered model of cholinergic deficit, the vesicular acetylcholine transporter knockdown homozygous (VAChT KDHOM) mice, exhibit pathological cardiac remodeling and a gradual increase in cardiac mass with aging. Given that an increase in cardiac mass is often caused by adrenergic hyperactivity, we hypothesized that VAChT KDHOM mice might have an increase in cardiac norepinephrine (NE) levels. We thus investigated the temporal changes in NE content in the heart from 3-, 6-, and 12-mo-old VAChT mutants. Interestingly, mice with cholinergic hypofunction showed a gradual elevation in cardiac NE content, which was already increased at 6 mo of age. Consistent with this finding, 6-mo-old VAChT KDHOM mice showed enhanced sympathetic activity and a greater abundance of tyrosine hydroxylase positive sympathetic nerves in the heart. VAChT mutants exhibited an increase in peak calcium transient, and mitochondrial oxidative stress in cardiomyocytes along with enhanced G protein-coupled receptor kinase 5 (GRK5) and nuclear factor of activated T-cells (NFAT) staining in the heart. These are known targets of adrenergic signaling in the cell. Moreover, vagotomized-mice displayed an increase in cardiac NE content confirming the data obtained in VAChT KDHOM mice. Establishing a causal relationship between acetylcholine and NE, VAChT KDHOM mice treated with pyridostigmine, a cholinesterase inhibitor, showed reduced cardiac NE content, rescuing the phenotype. Our findings unveil a yet unrecognized role of cholinergic signaling as a modulator of cardiac NE, providing novel insights into the mechanisms that drive autonomic imbalance. [ABSTRACT FROM AUTHOR]

Nine fluorine-containing vesicular acetylcholine transporter (VAChT) inhibitors were synthesized and screened as potential PET tracers for imaging the VAChT. Compound 18a was one of the most promising carbonyl-containing benzovesamicol analogs; the minus enantiomer, (-)-18a displayed high potency (VAChT Ki=0.59 ± 0.06 nM) and high selectivity for VAChT versus σ receptors (>10,000-fold). The radiosynthesis of (-)-[(18)F]18a was accomplished by a two-step procedure with 30-40% radiochemical yield. Preliminary biodistribution studies of (-)-[(18)F]18a in adult male Sprague-Dawley rats at 5, 30, 60 and 120 min post-injection (p.i.) were promising. The total brain uptake of (-)-[(18)F]18a was 0.684%ID/g at 5 min p.i. and by 120 min p.i. slowly washed out to 0.409 %ID/g; evaluation of regional brain uptake showed stable levels of ∼0.800 %ID/g from 5 to 120 min p.i in the VAChT-enriched striatal tissue of rats, indicating the tracer had crossed the blood brain barrier and was retained in the striatum. Subsequent microPET brain imaging studies of (-)-[(18)F]18a in nonhuman primates (NHPs) showed high striatal accumulation in the NHP brain; the standardized uptake value (SUV) for striatum reached a maximum value of 5.1 at 15 min p.i. The time-activity curve for the target striatal region displayed a slow and gradual decreasing trend 15 min after injection, while clearance of the radioactivity from the cerebellar reference region was much more rapid. Pretreatment of NHPs with 0.25mg/kg of the VAChT inhibitor (-)-vesamicol resulted in a ∼90% decrease of striatal uptake compared to baseline studies. HPLC metabolite analysis of NHP plasma revealed that (-)-[(18)F]18a had a good in vivo stability. Together, these preliminary results suggest (-)-[(18)F]18a is a promising PET tracer candidate for imaging VAChT in the brain of living subjects.

PurposeThe vesicular acetylcholine transporter (VAChT) is a specific biomarker for imaging presynaptic cholinergic neurons. Herein, two potent and selective (11)C-labeled VAChT inhibitors were evaluated in rodents and nonhuman primates for imaging VAChT in vivo.ProceduresFor both (-)-[(11)C]2 and (-)-[(11)C]6, biodistribution, autoradiography, and metabolism studies were performed in male Sprague Dawley rats. Positron emission tomography (PET) brain studies with (-)-[(11)C]2 were performed in adult male cynomolgus macaques; 2 h dynamic data was acquired, and the regions of interest were drawn by co-registration of the PET images with the MRI.ResultsThe resolved enantiomers (-)-2 and (-)-6 were very potent and selective for VAChT in vitro (K i  35-fold selectivity for VAChT vs. σ receptors); both radioligands, (-)-[(11)C]2 and (-)-[(11)C]6, demonstrated high accumulation in the VAChT-enriched striatum of rats. (-)-[(11)C]2 had a higher striatum to cerebellum ratio of 2.4-fold at 60 min; at 30 min, striatal uptake reached 0.550 ± 0.086 %ID/g. Uptake was also specific and selective; following pretreatment with (±)-2, striatal uptake of (-)-[(11)C]2 in rats at 30 min decreased by 50 %, while pretreatment with a potent sigma ligand had no significant effect on striatal uptake in rats. In addition, (-)-[(11)C]2 displayed favorable in vivo stability in rat blood and brain. PET studies of (-)-[(11)C]2 in nonhuman primates indicate that it readily crosses the blood-brain barrier (BBB) and provides clear visualization of the striatum; striatal uptake reaches the maximum at 60 min, at which time the target to nontarget ratio reached ~2-fold.ConclusionsThe radioligand (-)-[(11)C]2 has high potential to be a suitable PET radioligand for imaging VAChT in the brain of living subjects.

PurposeThe vesicular acetylcholine transporter (VAChT) is a specific biomarker for imaging presynaptic cholinergic neurons. The syntheses and C-11 labeling of two potent enantiopure VAChT inhibitors are reported here.ProceduresTwo VAChT inhibitors, (±)-2 and (±)-6, were successfully synthesized. A chiral HPLC column was used to resolve the enantiomers from each corresponding racemic mixture for in vitro characterization. The radiosyntheses of (-)-[(11)C]2 and (-)-[(11)C]6 from the corresponding desmethyl phenol precursor was accomplished using [(11)C]methyl iodide or [(11)C]methyl triflate, respectively.ResultsThe synthesis of (-)-[(11)C]2 was accomplished with 40-50 % radiochemical yield (decay-corrected), SA > 480 GBq/μmol (EOB), and radiochemical purity >99 %. Synthesis of (-)-[(11)C]6 was accomplished with 5-10 % yield, SA > 140 GBq/μmol (EOB), and radiochemical purity >97 %. The radiosynthesis and dose formulation of each tracer was completed in 55-60 min.ConclusionsTwo potent enantiopure VAChT ligands were synthesized and (11)C-labeled with good radiochemical yield and specific activity.

The model genetic organism Drosophila melanogaster, commonly known as the fruit fly, uses many of the same neurotransmitters as mammals and very similar mechanisms of neurotransmitter storage, release and recycling. This system offers a variety of powerful molecular-genetic methods for the study of transporters, many of which would be difficult in mammalian models. We review here progress made using Drosophila to understand the function and regulation of neurotransmitter transporters and discuss future directions for its use.

Abstract The choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) are fundamental to neurophysiological functions of the central cholinergic system. We confirmed and quantified the presence of extracellular ChAT protein in human plasma and also characterized ChAT and VAChT polymorphisms, protein and activity levels in plasma of Alzheimer's disease patients (AD; N = 112) and in cognitively healthy controls (EC; N = 118). We found no significant differences in plasma levels of ChAT activity and protein between AD and EC groups. Although no differences were observed in plasma ChAT activity and protein concentration among ChEI-treated and untreated AD patients, ChAT activity and protein levels variance in plasma were higher among the rivastigmine-treated group (ChAT protein: p = 0.005; ChAT activity: p = 0.0002). Moreover, AD patients homozygous for SNP rs1880676 A allele exhibited higher levels of ChAT activity. Considering this is the first study to report the influence of genetic variability of CHAT locus over ChAT activity in AD patients plasma, it opens a new set of important questions on peripheral cholinergic signaling in AD.

• New set of human HB9 and VACHT targeted iPSC reporter lines for purification of motor neurons and other cholinergic neurons. • The Cre-lox amplification of reporter expression is compatible with live-imaging and long-term culture studies. • Cre based reporters expressing CD14 receptor are useful for motor neuron purification at scale. Reliable and consistent pluripotent stem cell reporter systems for efficient purification and visualization of motor neurons are essential reagents for the study of normal motor neuron biology and for effective disease modeling. To overcome the inherent noisiness of transgene-based reporters, we developed a new series of human induced pluripotent stem cell lines by knocking in tdTomato, Cre, or CreERT2 recombinase into the HB9 (MNX1) or VACHT (SLC18A3) genomic loci. The new lines were validated by directed differentiation into spinal motor neurons and immunostaining for motor neuron markers HB9 and ISL1. To facilitate efficient purification of spinal motor neurons, we further engineered the VACHT-Cre cell line with a validated, conditional CD14-GFP construct that allows for both fluorescence-based identification of motor neurons, as well as magnetic-activated cell sorting (MACS) to isolate differentiated motor neurons at scale. The targeting strategies developed here offer a standardized platform for reproducible comparison of motor neurons across independently derived pluripotent cell lines. [ABSTRACT FROM AUTHOR]

Sensory and motor systems in insects with hemimetabolous development must be ready to mediate adaptive behavior directly on hatching from the egg. For the desert locust S. gregaria, cholinergic transmission from antennal sensillae to olfactory or mechanosensory centers in the brain requires that choline acetyltransferase (ChAT) and the vesicular acetylcholine transporter (vAChT) already be present in sensory cells in the first instar. In this study, we used immunolabeling to demonstrate that ChAT and vAChT are both expressed in sensory cells from identifiable sensilla types in the immature antennal nervous system. We observed ChAT expression in dendrites, neurites and somata of putative basiconic-type sensillae at the first instar stage. We also detected vAChT in the sensory axons of these sensillae in a major antennal nerve tract. We then examined whether evidence for cholinergic transmission is present during embryogenesis. Immunolabeling confirms that vAChT is expressed in somata typical of campaniform sensillae, as well as in small sensory cell clusters typically associated with either a large basiconic or coeloconic sensilla, at 99% of embryogenesis. The vAChT is also expressed in the somata of these sensilla types in multiple antennal regions at 90% of embryogenesis, but not at earlier (70%) embryonic stages. Neuromodulators are known to appear late in embryogenesis in neurons of the locust central complex, and the cholinergic system of the antenna may also only reach maturity shortly before hatching. [ABSTRACT FROM AUTHOR]

To develop a PET imaging agent to visualize brain cholinergic neurons and synaptic changes caused by Alzheimer's disease, (−)‐ and (+)‐o‐[11C]methyl‐trans‐decalinvesamicol ([11C]OMDV) were isolated and investigated for differences in not only their binding affinity and selectivity to vesicular acetylcholine transporter (VAChT), but also their in vivo activities. [11C]OMDV has a high binding affinity for VAChT both in vitro and in vivo. Racemic OMDV and o‐trimethylstannyl‐trans‐decalinvesamicol (OTDV), which are precursors for synthesis of [11C]OMDV, were separated into (−)‐optical isomers ((−)‐OMDV and (−)‐OTDV) and (+)‐optical isomers ((+)‐OMDV and (+)‐OTDV) by HPLC. In the in vitro binding assay, (−)‐OMDV(7.2 nM) showed eight times higher binding affinity (Ki) to VAChT than that of (+)‐OMDV(57.5 nM). In the biodistribution study, the blood–brain barrier permeability of both enantiomers ((−)‐[11C]OMDV and (+)‐[11C]OMDV) was similarly high (about 1.0%ID/g) at 2 min post‐injection. However, (+)‐[11C]OMDV clearance from the brain was faster than (−)‐[11C]OMDV. In the in vivo blocking study, accumulation of (−)‐[11C]OMDV in the cortex was markedly decreased (approximately 30% of control) by coadministration of vesamicol, and brain uptake of (−)‐[11C]OMDV was not significantly altered by coadministration of (+)‐pentazocine or (+)‐3‐(3‐hydroxyphenyl)‐N‐propylpiperidine ((+)‐3‐PPP). PET‐CT imaging revealed inhibition of the rat brain uptake of (−)‐[11C]OMDV by coadministration of vesamicol. In conclusion, (−)‐[11C]OMDV, which is an enantiomer of OMDV, selectively binds to VAChT with high affinity in the rat brain in vivo. (−)‐[11C]OMDV may be utilized as a potential PET ligand for studying presynaptic cholinergic neurons in the brain. [ABSTRACT FROM AUTHOR]

The expression and distribution of a protein can provide critical information about its function in a cell. For some neuronal proteins this information may include neurotransmitter (NT) usage and sites of NT release. However, visualizing the expression of a protein within a given neuron is often challenging because most neurons are intricately intermingled with numerous other neurons, making individual neuronal expression difficult to discern, especially since many neuronal genes are expressed at low levels. To overcome these difficulties for the Drosophila vesicular acetylcholine transporter (vAChT), attempts were made to generate conditional Drosophila vAChT alleles containing two tandem copies of epitope tags. In the course of these attempts, a strategy for multimerizing DNA repeats using the Gibson cloning reaction was serendipitously discovered. Attempts at optimization routinely yielded six or seven copies of MYC and OLLAS epitope tag coding sequences, but occasionally as many as 10 copies, thus potentially enhancing the sensitivity of protein detection up to an order of magnitude. As proof-of-principle of the method, conditionally expressible genome-edited 7XMYC-vAChT and 6XOLLAS-vAChT were developed and characterized for conditionality, synaptic vesicle specificity, and neurotransmitter specific-expression. The utility of these conditional vAChT variants was demonstrated for cholinergic neurotransmitter phenotyping and defining the polarity of cholinergic neurons, important information for understanding the functional role of neurons of interest in neural circuits and behavior. The repeat multimerization method is effective for DNA repeats of at least 56 bp and should be generally applicable to any species. [ABSTRACT FROM AUTHOR]

In addition to driving contraction of skeletal muscles, acetylcholine (ACh) acts as an anti-synaptogenic agent at neuromuscular junctions (NMJs). Previous studies suggest that aging is accompanied by increases in cholinergic activity at the NMJ, which may play a role in neuromuscular degeneration. In this study, we hypothesized that moderately and chronically reducing ACh could attenuate the deleterious effects of aging on NMJs and skeletal muscles. To test this hypothesis, we analyzed NMJs and muscle fibers from heterozygous transgenic mice with reduced expression of the vesicular ACh transporter (VAChT; VKDHet), which present with approximately 30% less synaptic ACh compared to control mice. Because ACh is constitutively decreased in VKDHet, we first analyzed developing NMJs and muscle fibers. We found no obvious morphological or molecular differences between NMJs and muscle fibers of VKDHet and control mice during development. In contrast, we found that moderately reducing ACh has various effects on adult NMJs and muscle fibers. VKDHet mice have significantly larger NMJs and muscle fibers compared to age-matched control mice. They also present with reduced expression of the pro-atrophy gene, Foxo1, and have more satellite cells in skeletal muscles. These molecular and cellular features may partially explain the increased size of NMJs and muscle fibers. Thus, moderately reducing ACh may be a therapeutic strategy to prevent the loss of skeletal muscle mass that occurs with advancing age.

Introduction: Reduced expression of the vesicular acetylcholine transporter (VAChT) leads to changes in the distribution and shape of synaptic vesicles (SVs) at neuromuscular junctions (NMJs), suggesting vesicular acetylcholine (ACh) as a key component of synaptic structure and function. It is poorly understood how long-term changes in cholinergic transmission contribute to age- and disease-related degeneration in the motor system.Methods: In this study we performed confocal imaging, electrophysiology, electron microscopy, and analyses of respiratory mechanics of the diaphragm NMJ components in 12-month-old wild-type (WT) and VAChTKDHOM mice.Results: Diaphragms of NMJs of the VAChTKDHOM mice were similar to those in WT mice in number, colocalization, and fragmentation of pre-/postsynaptic components. However, they had increased spontaneous SV exocytosis, miniature endplate potential frequency, and diminished MEPP amplitude. No impairment in respiratory mechanics at rest was observed, probably due to the large neurotransmission safety factor of the diaphragm.Discussion: The present findings help us to understand the consequences of reduced ACh release at the NMJs during aging. [ABSTRACT FROM AUTHOR]

In addition to driving contraction of skeletal muscles, acetylcholine (ACh) acts as an anti-synaptogenic agent at neuromuscular junctions (NMJs). Previous studies suggest that aging is accompanied by increases in cholinergic activity at the NMJ, which may play a role in neuromuscular degeneration. In this study, we hypothesized that moderately and chronically reducing ACh could attenuate the deleterious effects of aging on NMJs and skeletal muscles. To test this hypothesis, we analyzed NMJs and muscle fibers from heterozygous transgenic mice with reduced expression of the vesicular ACh transporter (VAChT; VKDHet), which present with approximately 30% less synaptic ACh compared to control mice. Because ACh is constitutively decreased in VKDHet, we first analyzed developing NMJs and muscle fibers. We found no obvious morphological or molecular differences between NMJs and muscle fibers of VKDHet and control mice during development. In contrast, we found that moderately reducing ACh has various effects on adult NMJs and muscle fibers. VKDHet mice have significantly larger NMJs and muscle fibers compared to age-matched control mice. They also present with reduced expression of the pro-atrophy gene, Foxo1, and have more satellite cells in skeletal muscles. These molecular and cellular features may partially explain the increased size of NMJs and muscle fibers. Thus, moderately reducing ACh may be a therapeutic strategy to prevent the loss of skeletal muscle mass that occurs with advancing age. [ABSTRACT FROM AUTHOR]

The pedunculopontine tegmental nucleus (PPT) and laterodorsal tegmental nucleus (LDT) are heterogeneous brainstem structures that contain cholinergic, glutamatergic, and GABAergic neurons. PPT/LDT neurons are suggested to modulate both cognitive and noncognitive functions, yet the extent to which acetylcholine (ACh) signaling from the PPT/LDT is necessary for normal behavior remains uncertain. We addressed this issue by using a mouse model in which PPT/LDT cholinergic signaling is highly decreased by selective deletion of the vesicular ACh transporter (VAChT) gene. This approach interferes exclusively with ACh signaling, leaving signaling by other neurotransmitters from PPT/LDT cholinergic neurons intact and sparing other cells. VAChT mutants were examined on different PPT/LDT-associated cognitive domains. Interestingly, VAChT mutants showed no attentional deficits and only minor cognitive flexibility impairments while presenting large deficiencies in both spatial and cued Morris water maze (MWM) tasks. Conversely, working spatial memory determined with the Y-maze and spatial memory measured with the Barnes maze were not affected, suggesting that deficits in MWM were unrelated to spatial memory abnormalities. Supporting this interpretation, VAChT mutants exhibited alterations in anxiety-like behavior and increased corticosterone levels after exposure to the MWM, suggesting altered stress response. Thus, PPT/LDT VAChT-mutant mice present little cognitive impairment per se, yet they exhibit increased susceptibility to stress, which may lead to performance deficits in more stressful conditions. [ABSTRACT FROM AUTHOR]

Abstract Endogenous acetylcholine (ACh), which depends of the levels of vesicular ACh transport (VAChT) to be released, is the central mediator of the cholinergic anti-inflammatory system. ACh controls the release of cytokine in different models of inflammation. Diesel exhaust particles (DEP) are one of the major environmental pollutants produced in large quantity by automotive engines in urban center. DEP bind the lung parenchyma and induce inflammation. We evaluated whether cholinergic dysfunction worsens DEP-induced lung inflammation. Male mice with decreased ACh release due to reduced expression of VAChT (VAChT-KD mice) were submitted to DEP exposure for 30 days (3 mg/mL of DEP, once a day, five days a week) or saline. Pulmonary function and inflammation as well as extracellular matrix fiber deposition were evaluated. Additionally, airway and nasal epithelial mucus production were quantified. We found that DEP instillation worsened lung function and increased lung inflammation. Higher levels of mononuclear cells were observed in the peripheral blood of both wild-type (WT) and VAChT-KD mice. Also, both wild-type (WT) and VAChT-KD mice showed an increase in macrophages in bronchoalveolar lavage fluid (BALF) as well as increased expression of IL-4, IL-6, IL-13, TNF-α, and NF-κB in lung cells. The collagen fiber content in alveolar septa was also increased in both genotypes. On the other hand, we observed that granulocytes were increased only in VAChT-KD peripheral blood. Likewise, increased BALF lymphocytes and neutrophils as well as increased elastic fibers in alveolar septa, airway neutral mucus, and nasal epithelia acid mucus were observed only in VAChT-KD mice. The cytokines IL-4 and TNF-α were also higher in VAChT-KD mice compared with WT mice. In conclusion, decreased ability to release ACh exacerbates some of the lung alterations induced by DEP in mice, suggesting that VAChT-KD animals are more vulnerable to the effects of DEP in the lung. Graphical abstract fx1 Highlights • DEP exposure modulates BALF inflammatory cells content. • DEP exposure increases collagen and elastic fibers in mice lung tissue. • VAChT deficient mice exposures to DEP were more susceptible to lung alterations. • Lung Inflammation, IL-4 and TNF-α expression were increased in VAChT deficient mice. • First study to report the interaction of cholinergic deficiency and DEP exposure. [ABSTRACT FROM AUTHOR]

Acrylamide is found in food products manufactured with high-temperature processing, and exposure to acrylamide contained in food products may cause a potential risk to human health. The aim of this investigation was to demonstrate the changes in the population of CART-, nNOS-, and VAChT-immunoreactive enteric neurons in the porcine stomach in response to supplementation of low and high acrylamide doses. The study was carried out with 15 Danish landrace gilts divided into three experimental groups: the control group—animals were administered empty gelatine capsules; the low-dose group—animals were administrated a tolerable daily intake (TDI) dose (0.5 µg/kg of body weight (b.w.)/day) of acrylamide capsules, and the high-dose group—animals were administrated high-dose (ten times higher than TDI: 5 µg/kg b.w./day) acrylamide capsules for 28 days. Using the double immunofluorescence staining method, it was established that supplementation with low and high doses of acrylamide resulted in alterations of the porcine stomach neuron phenotype, which was reflected in an increased number of CART-, VAChT-, and nNOS-immunoreactive neurons. These changes were accompanied by an increased density of CART-, VAChT-, and nNOS-positive fibres. The results suggest that the enteric nervous system plays an important role in protecting the gastrointestinal tract during acrylamide intoxication.

Abstract Although the basic schema of the body plan is similar among different species of amniotes (mammals, birds, and reptiles), the lung is an exception. Here, anatomy and physiology are considerably different, particularly between mammals and birds. In mammals, inhaled and exhaled airs mix in the airways, whereas in birds the inspired air flows unidirectionally without mixing with the expired air. This bird-specific respiration system is enabled by the complex tubular structures called parabronchi where gas exchange takes place, and also by the bellow-like air sacs appended to the main part of the lung. That the lung is predominantly governed by the parasympathetic nervous system has been shown mostly by physiological studies in mammals. However, how the parasympathetic nervous system in the lung is established during late development has largely been unexplored both in mammals and birds. In this study, by combining immunocytochemistry, the tissue-clearing CUBIC method, and ink-injection to airways, we have visualized the 3-D distribution patterns of parasympathetic nerves and ganglia in the lung at late developmental stages of mice and chickens. These patterns were further compared between these species, and three prominent similarities emerged: (1) parasympathetic postganglionic fibers and ganglia are widely distributed in the lung covering the proximal and distal portions, (2) the gas exchange units, alveoli in mice and parabronchi in chickens, are devoid of parasympathetic nerves, (3) parasympathetic nerves are in close association with smooth muscle cells, particularly at the base of the gas exchange units. These observations suggest that despite gross differences in anatomy, the basic mechanisms underlying parasympathetic control of smooth muscles and gas exchange might be conserved between mammals and birds. Highlights • 3-D patterns of parasympathetic nerves are visualized in mouse and chicken lungs. • Comparison of these patterns reveals three prominent similarities between mouse and chicken. • VAChT-positive postganglionic fibers and ganglia are widely distributed in the lung. • Gas exchange units are devoid of parasympathetic nerves. • Parasympathetic nerves are in close association with smooth muscle cells. [ABSTRACT FROM AUTHOR]

The gastrointestinal (GI) tract is innervated by nerve processes derived from the intramural enteric neurons and neurons localized outside the digestive tract. This study analysed the neurochemical characterization of nerves in the wall of the porcine oesophagus using single immunofluorescence technique. Immunoreactivity to vesicular acetylcholine transporter (VAChT), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), somatostatin (SOM), galanin (GAL), neuronal isoform of nitric oxide synthase (nNOS), substance P (SP), leucine enkephalin (LENK), calcitonin gene‐related peptide (CGRP) or dopamine beta‐hydroxylase (DBH) was investigated in intramuscular and intramucosal nerves of the cervical, thoracic and abdominal oesophagus. The results indicate that all of the substances studied were present in the oesophageal nerves. The density of particular populations of fibres depended on the segment of the oesophagus. The most numerous were fibres immunoreactive to VIP in the longitudinal and circular muscle layers of the abdominal oesophagus: The number of these fibres amounted to 16.4 ± 0.8 and 18.1 ± 3.1, respectively. In turn, the least numerous were CGRP‐positive fibres, which were present only in the circular muscle layer of the cervical oesophagus and mucosal layer of the abdominal oesophagus in the number of 0.3 ± 0. The obtained results show that nerves in the porcine oesophageal wall are very diverse in their neurochemical coding, and differences between particular parts of the oesophagus suggest that organization of the innervation clearly depends on the fragment of this organ. [ABSTRACT FROM AUTHOR]

Memory extinction is referred to as a learning process in which a conditioned response (CR) progressively reduces over time as an animal learns to uncouple a response from a stimulus. Extinction occurs when the rat is placed into a context without shock after training. Docosahexaenoic acid (DHA, C22:6, n-3) is implicated in memory formation in mammalian brains. In a two-way active shuttle-avoidance apparatus, we examined whether DHA affects the extinction memory and the expression of brain cognition-related proteins, including gastrin-releasing peptide receptor (GRPR), brain-derived neurotrophic factor receptor (BDNFR) tyrosine kinase receptor B (TrKB), and N-methyl-D-aspartate receptor (NMDAR) subunits NR2A and NR2B. Also, the protein levels of GRP, BDNF, postsynaptic density protein-95 (PSD-95), and vesicular acetylcholine transporter (VAChT), and the antioxidative potentials, in terms of lipid peroxide (LPO) and reactive oxygen species (ROS), were examined in the hippocampus. During the acquisition phase, the rats received a conditioned stimulus (CS-tone) paired with an unconditioned stimulus (UCS foot shock) for three consecutive days (Sessions S1, S2, and S3, each consisting of 30-trials) after 12 weeks of oral administration of DHA. After a three-day interval, the rats were re-subjected to two extinction sessions (S4, S5), each comprising 30 trials of CS alone. During the acquisition training in S1, the shock-related avoidance frequency (acquisition memory) was significantly higher in the DHA-administered rats compared with the control rats. The avoidance frequency, however, decreased with successive acquisition trainings in sessions S2 and S3. When the rats were subjected to the extinction sessions after a break for consolidation, the conditioned response (CR) was also significantly higher in the DHA-administered rats. Interestingly, the freezing responses (frequency and time) also significantly decreased in the DHA-administered rats, thus suggesting that a higher coping capacity was present during fear stress in the DHA-administered rats. DHA treatments increased the mRNA levels of GRPR, BDNF receptor TrKB, and NMDAR subunit NR2B. DHA also increased the protein levels of GRP, BDNF, PSD-95, and VAChT, and the antioxidative potentials in the hippocampus. These results suggest the usefulness of DHA for treating stress disorders. [ABSTRACT FROM AUTHOR]

Herein, new ligands for the vesicular acetylcholine transporter (VAChT), based on a benzovesamicol scaffold, are presented. VAChT is acknowledged as a marker for cholinergic neurons and a positron emission tomography tracer for VAChT could serve as a tool for quantitative analysis of cholinergic neuronal density. With an easily accessible triflate precursor, aminocarbonylations were utilized to evaluate the chemical space around the C5 position on the tetrahydronaphthol ring. Synthesized ligands were evaluated for their affinity and selectivity for VAChT. Small, preferably aromatic, N -substituents proved to be more potent than larger substituents. Of the fifteen compounds synthesized, benzyl derivatives ( ± )-7i and ( ± )-7l had the highest affinities for VAChT. Compound ( ± )-7i was chosen to investigate the importance of stereochemistry for binding to VAChT and selectivity toward the σ 1 and σ 2 receptors. Enantiomeric resolution gave ( + )-7i and (−)-7i , and the eutomer showed seven times better affinity. Although racemate ( ± )-7i was initially promising, the affinity of (−)-7i for VAChT was not better than 56.7 nM which precludes further preclinical evaluation. However, the nanomolar binding together with the ready synthesis of [ 11 C]-( ± )-7i shows that (−)-7i can serve as a scaffold for future optimizations to provide improved 11 C-labelled VAChT PET tracers. [ABSTRACT FROM AUTHOR]

The vesicular acetylcholine transporter (VAChT) is an important target for in vivo imaging of neurodegenerative processes using positron emission tomography (PET). So far the development of VAChT PET radioligands is based on the single known lead compound vesamicol. In this study we investigated a recently published spiroindoline based compound class (Sluder et al., 2012), which was suggested to have potential in the development of VAChT ligands. Therefore, we synthesized a small series of N , N -substituted spiro[indoline-3,4′-piperidine] derivatives and determined their in vitro binding affinities toward the VAChT. In order to investigate the selectivity, the off-target binding toward σ 1 and σ 2 receptors was determined. The compounds possessed VAChT affinities with K i values in the range of 39–376 nM. Binding affinities toward the σ 1 and σ 2 receptors are in a similar range indicating that the strong structural difference between the spiroindolines and vesamicol did not improve the selectivity. The observed potential to additionally bind to σ receptors let us assume that the herein investigated spiroindolines are not suitable to replace vesamicol as lead compound for the development of VAChT ligands. [ABSTRACT FROM AUTHOR]

Depression is extremely harmful to modern society. Despite its complex spectrum of symptoms, previous studies have mostly focused on the monaminergic system in search of pharmacological targets. However, other neurotransmitter systems have also been linked to the pathophysiology of depression. In this study, we provide evidence for a role of the cholinergic system in depressive-like behavior of female mice. We evaluated mice knockdown for the vesicular acetylcholine transporter (VAChT KD mice), which have been previously shown to exhibit reduced cholinergic transmission. Animals were subjected to the tail suspension and marble burying tests, classical paradigms to assess depressive-like behaviors and to screen for novel antidepressant drugs. In addition, brain levels of serotonin and dopamine were measured by high performance liquid chromatography. We found that female homozygous VAChT KD mice spent less time immobile during tail suspension and buried less marbles, indicating a less depressive phenotype. These differences in behavior were reverted by central, but not peripheral, acetylcholinesterase inhibition. Moreover, female homozygous VAChT KD mice exhibited higher levels of dopamine and serotonin in the striatum, and increased dopamine in the hippocampus. Our study thus shows a connection between depressive-like behaviors and the cholinergic system, and that the latter interacts with the monoaminergic system. [ABSTRACT FROM AUTHOR]

The identification of neurotransmitter type used by a neuron is important for the functional dissection of neuronal circuits. In the model organism Drosophila melanogaster, several methods for discerning the neurotransmitter systems are available. Here, we expanded the toolbox for the identification of cholinergic neurons by generating a new line FRT-STOP-FRT-VAChT::HA that is a conditional tagged knock-in of the vesicular acetylcholine transporter (VAChT) gene in its endogenous locus. Importantly, in comparison to already available tools for the detection of cholinergic neurons, the FRT-STOP-FRT-VAChT::HA allele also allows for identification of the subcellular localization of the cholinergic presynaptic release sites in a cell-specific manner. We used the newly generated FRT-STOP-FRT-VAChT::HA line to characterize the Mi1 and Tm3 neurons in the fly visual system and found that VAChT is present in the axons of both cell types, suggesting that Mi1 and Tm3 neurons provide cholinergic input to the elementary motion detectors, the T4 neurons. [ABSTRACT FROM AUTHOR]

Vesicular acetylcholine transporter (VAChT) function is essential for organismal survival, mediating the packaging of acetylcholine (ACh) for exocytotic release. However, its expression pattern in the Drosophila brain has not been fully elucidated. To investigate the localization of VAChT, we developed an antibody against the C terminal region of the protein and we show that this antibody recognizes a 65KDa protein corresponding to VAChT on an immunoblot in both Drosophila head homogenates and in Schneider 2 cells. Further, we report for the first time the expression of VAChT in the antennal lobe and ventral nerve cord of Drosophila larva; and we independently confirm the expression of the protein in mushroom bodies and optic lobes of adult Drosophila . Importantly, we show that VAChT co-localizes with a synaptic vesicle marker in vivo, confirming previous reports of the localization of VAChT to synaptic terminals. Together, these findings help establish the vesicular localization of VAChT in cholinergic neurons in Drosophila and present an important molecular tool with which to dissect the function of the transporter in vivo. [ABSTRACT FROM AUTHOR]

Summary Cyclic AMP (cAMP) signaling augments synaptic transmission, but because many targets of cAMP and protein kinase A (PKA) may be involved, mechanisms underlying this pathway remain unclear. To probe this mechanism, we used optogenetic stimulation of cAMP signaling by Beggiatoa -photoactivated adenylyl cyclase (bPAC) in Caenorhabditis elegans motor neurons. Behavioral, electron microscopy (EM), and electrophysiology analyses revealed cAMP effects on both the rate and on quantal size of transmitter release and led to the identification of a neuropeptidergic pathway affecting quantal size. cAMP enhanced synaptic vesicle (SV) fusion by increasing mobilization and docking/priming. cAMP further evoked dense core vesicle (DCV) release of neuropeptides, in contrast to channelrhodopsin (ChR2) stimulation. cAMP-evoked DCV release required UNC-31/Ca 2+ -dependent activator protein for secretion (CAPS). Thus, DCVs accumulated in unc-31 mutant synapses. bPAC-induced neuropeptide signaling acts presynaptically to enhance vAChT-dependent SV loading with acetylcholine, thus causing increased miniature postsynaptic current amplitudes (mPSCs) and significantly enlarged SVs. [ABSTRACT FROM AUTHOR]

Sympathetic neurons have the capability to segregate their neurotransmitters (NTs) and co-transmitters to separate varicosities of single axons; furthermore, in culture, these neurons can even segregate classical transmitters. In vivo sympathetic neurons employ acetylcholine (ACh) and other classical NTs such as gamma aminobutyric acid (GABA). Herein, we explore whether these neurons in vivo segregate these classical NTs in the superior cervical ganglia of the rat. We determined the topographical distribution of GABAergic varicosities, somatic GABAA receptor, as well as the regional distribution of the segregation of ACh and GABA. We evaluated possible regional differences in efficacy of ganglionic synaptic transmission, in the sensitivity of GABAA receptor to GABA and to the competitive antagonist picrotoxin (PTX). We found that sympathetic preganglionic neurons in vivo do segregate ACh and GABA. GABAergic varicosities and GABAA receptor expression showed a rostro-caudal gradient along ganglia; in contrast, segregation exhibited a caudo-rostral gradient. These uneven regional distributions in expression of GABA, GABAA receptors, and level segregation correlate with stronger synaptic transmission found in the caudal region. Accordingly, GABAA receptors of rostral region show larger sensitivity to GABA and PTX. These results suggest the presence of different types of GABAA receptors in each region that result in a different regional levels of endogenous GABA inhibition. Finally, we discuss a possible correlation of these different levels of GABA modulation and the function of the target organs innervated by rostral and caudal ganglionic neurons.

Abstract: Memory extinction is referred to as a learning process in which a conditioned response (CR) progressively reduces over time as an animal learns to uncouple a response from a stimulus. Extinction occurs when the rat is placed into a context without shock after training. Docosahexaenoic acid (DHA, C22:6, n-3) is implicated in memory formation in mammalian brains. In a two-way active shuttle-avoidance apparatus, we examined whether DHA affects the extinction memory and the expression of brain cognition-related proteins, including gastrin-releasing peptide receptor (GRPR), brain-derived neurotrophic factor receptor (BDNFR) tyrosine kinase receptor B (TrKB), and N-methyl-d-aspartate receptor (NMDAR) subunits NR2A and NR2B. Also, the protein levels of GRP, BDNF, postsynaptic density protein-95 (PSD-95), and vesicular acetylcholine transporter (VAChT), and the antioxidative potentials, in terms of lipid peroxide (LPO) and reactive oxygen species (ROS), were examined in the hippocampus. During the acquisition phase, the rats received a conditioned stimulus (CS-tone) paired with an unconditioned stimulus (UCS foot shock) for three consecutive days (Sessions S1, S2, and S3, each consisting of 30-trials) after 12 weeks of oral administration of DHA. After a three-day interval, the rats were re-subjected to two extinction sessions (S4, S5), each comprising 30 trials of CS alone. During the acquisition training in S1, the shock-related avoidance frequency (acquisition memory) was significantly higher in the DHA-administered rats compared with the control rats. The avoidance frequency, however, decreased with successive acquisition trainings in sessions S2 and S3. When the rats were subjected to the extinction sessions after a break for consolidation, the conditioned response (CR) was also significantly higher in the DHA-administered rats. Interestingly, the freezing responses (frequency and time) also significantly decreased in the DHA-administered rats, thus suggesting that a higher coping capacity was present during fear stress in the DHA-administered rats. DHA treatments increased the mRNA levels of GRPR, BDNF receptor TrKB, and NMDAR subunit NR2B. DHA also increased the protein levels of GRP, BDNF, PSD-95, and VAChT, and the antioxidative potentials in the hippocampus. These results suggest the usefulness of DHA for treating stress disorders.

The mouse gastro-intestinal and biliary tract mucosal epithelia harbor choline acetyltransferase (ChAT)-positive brush cells with taste cell-like traits. With the aid of two transgenic mouse lines that express green fluorescent protein (EGFP) under the control of the ChAT promoter (EGFPChAT) and by using in situ hybridization and immunohistochemistry we found that EGFPChAT cells were clustered in the epithelium lining the gastric groove. EGFPChAT cells were numerous in the gall bladder and bile duct, and found scattered as solitary cells along the small and large intestine. While all EGFPChAT cells were also ChAT-positive, expression of the high-affinity choline transporter (ChT1) was never detected. Except for the proximal colon, EGFPChAT cells also lacked detectable expression of the vesicular acetylcholine transporter (VAChT). EGFPChAT cells were found to be separate from enteroendocrine cells, however they were all immunoreactive for cytokeratin 18 (CK18), transient receptor potential melastatin-like subtype 5 channel (TRPM5), and for cyclooxygenases 1 (COX1) and 2 (COX2). The ex vivo stimulation of colonic EGFPChAT cells with the bitter substance denatonium resulted in a strong increase in intracellular calcium, while in other epithelial cells such an increase was significantly weaker and also timely delayed. Subsequent stimulation with cycloheximide was ineffective in both cell populations. Given their chemical coding and chemosensory properties, EGFPChAT brush cells thus may have integrative functions and participate in induction of protective reflexes and inflammatory events by utilizing ACh and prostaglandins for paracrine signaling.

The cholinergic anti-inflammatory pathway controls the inflammatory response and nonreflexive consciousness through bidirectional communication between the brain and immune system. Moreover, brain acetylcholinesterase activity may have a role in regulating the vagus nerve in this pathway. Thus, we analyzed the role of acetylcholine (ACh) in the inflammatory response 15 days after induction of sepsis by cecal ligation and puncture (CLP). Balb/c mice were pretreated with or without donepezil (5 mg/kg/day, orally) 7 days before CLP, and mice homozygous for vesicular ACh transporter (VAChT) knockdown (KD) were subjected to CLP. All animals were sacrificed 15 days after CLP, and the plasma, spleen, and hippocampus were collected. Characterization of splenic lymphocytes and cytokine levels in the plasma, spleen, and hippocampus was determined. Our results showed a splenomegaly in group CLP. The numbers of cytotoxic T cells, helper T cells, regulatory T cells, B cells, and Th17 cells differed between mice subjected to CLP and to sham operation in both untreated and donepezil-treated groups. In VAChT-KD mice, CLP resulted in decreased cytotoxic and helper T cells and increased in Th17 cells compared with the sham. Additionally, in VAChT-KD mice, the levels of pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α, were increased following CLP. Thus, we concluded that ACh affected the inflammatory response at 15 days after CLP since stimulation of cholinergic transmission increased the proliferation of lymphocytes, including regulatory T cells, in association with a lower inflammatory profile and VAChT-KD decreased the number of lymphocytes and increased inflammation. [ABSTRACT FROM AUTHOR]

Background: Cholinergic dysfunction occurs during aging and in a variety of diseases, including amyotrophic lateral sclerosis (ALS). However, it remains unknown whether changes in cholinergic transmission contributes to age- and disease-related degeneration of the motor system. Here we investigated the effect of moderately increasing levels of synaptic acetylcholine (ACh) on the neuromuscular junction (NMJ), muscle fibers, and motor neurons during development and aging and in a mouse model for amyotrophic lateral sclerosis (ALS). Methods: Chat-ChR2-EYFP (VAChTHyp ) mice containing multiple copies of the vesicular acetylcholine transporter (VAChT), mutant superoxide dismutase 1 (SOD1G93A ), and Chat-IRES-Cre and tdTomato transgenic mice were used in this study. NMJs, muscle fibers, and α-motor neurons’ somata and their axons were examined using a light microscope. Transcripts for select genes in muscles and spinal cords were assessed using real-time quantitative PCR. Motor function tests were carried out using an inverted wire mesh and a rotarod. Electrophysiological recordings were collected to examine miniature endplate potentials (MEPP) in muscles. Results: We show that VAChT is elevated in the spinal cord and at NMJs of VAChTHyp mice. We also show that the amplitude of MEPPs is significantly higher in VAChTHyp muscles, indicating that more ACh is loaded into synaptic vesicles and released into the synaptic cleft at NMJs of VAChTHyp mice compared to control mice. While the development of NMJs was not affected in VAChTHyp mice, NMJs prematurely acquired age-related structural alterations in adult VAChTHyp mice. These structural changes at NMJs were accompanied by motor deficits in VAChTHyp mice. However, cellular features of muscle fibers and levels of molecules with critical functions at the NMJ and in muscle fibers were largely unchanged in VAChTHyp mice. In the SOD1G93A mouse model for ALS, increasing synaptic ACh accelerated degeneration of NMJs caused motor deficits and resulted in premature death specifically in male mice. Conclusions: The data presented in this manuscript demonstrate that increasing levels of ACh at the synaptic cleft promote degeneration of adult NMJs, contributing to age- and disease-related motor deficits. We thus propose that maintaining normal cholinergic signaling in muscles will slow degeneration of NMJs and attenuate loss of motor function caused by aging and neuromuscular diseases. [ABSTRACT FROM AUTHOR]

Substantial evidence implicates Acetylcholine (ACh) in the acquisition of object memories. While most research has focused on the role of the cholinergic basal forebrain and its cortical targets, there are additional cholinergic networks that may contribute to object recognition. The striatum contains an independent cholinergic network comprised of interneurons. In the current study, we investigated the role of this cholinergic signalling in object recognition using mice deficient for Vesicular Acetylcholine Transporter (VAChT) within interneurons of the striatum. We tested whether these striatal VAChT D2−Cre−flox/flox mice would display normal short-term (5 or 15 min retention delay) and long-term (3 h retention delay) object recognition memory. In a home cage object recognition task, male and female VAChT D2−Cre−flox/flox mice were impaired selectively with a 15 min retention delay. When tested on an object location task, VAChT D2−Cre−flox/flox mice displayed intact spatial memory. Finally, when object recognition was tested in a Y-shaped apparatus, designed to minimize the influence of spatial and contextual cues, only females displayed impaired recognition with a 5 min retention delay, but when males were challenged with a 15 min retention delay, they were also impaired; neither males nor females were impaired with the 3 h delay. The pattern of results suggests that striatal cholinergic transmission plays a role in the short-term memory for object features, but not spatial location. [ABSTRACT FROM AUTHOR]

The presence of lead (Pb) in fetal brain may affect brain development-related proteins. We studied whether gestational/lactational Pb-exposure affects oxidative stress, proinflammatory response, apoptosis and levels of brain development/cognition-related proteins, including presynaptic synaptosome-associated protein-25 (SNAP-25), postsynaptic density protein-95 (PSD-95), brain-derived neurotropic factor (BDNF), tyrosine receptor-kinase protein B (TrkB) and vesicular acetylcholine transporter (VAChT) in the offspring. Female Wistar rats were randomly divided into control and Pb-exposed mother groups. The Pb-exposed rats received 0.1% (w/v) Pb acetate via drinking water during pregnancy and lactation. Milk and mammary glands were collected from lactating mothers to measure milk/mammary gland levels of lipid peroxide (LPO), as indicator of oxidative stress and proinflammatory TNF-α. Afterwards, the pups were sacrificed to determine brain levels of Pb, LPO, TNF-α, cytochrome C, SNAP-25, PSD-95, BDNF, TrkB and VAChT. The levels of LPO and TNF-α increased in the milk/mammary glands of the Pb-exposed mothers, concurrently with increases in the levels of Pb, LPO, TNF-α and cytochrome C and decreases in the levels of SNAP-25, PSD-95, BDNF, TrkB and VAChT in the brains of their offspring. Our results demonstrate that Pb-exposure during development reduces the brain levels of PSD-95 and SNAP-25 (synaptogenesis-markers), with concomitant upsurges of oxidative stress, TNF-α and apoptosis in the offspring. Furthermore, BDNF-TrkB proteins that comprehend memory-related brain cognitions and/or VAChT that comprises cholinergic-neuromotor activities might be impaired by Pb-exposure. These findings provide evidence of toxic effects of Pb on brain development, at least, partially by decreasing the levels of PSD-95, SNAP-25 and other cognition-related proteins. [ABSTRACT FROM AUTHOR]

ABSTRACT Motor function in mammalian species depends on the maturation of spinal circuits formed by a large variety of interneurons that regulate motoneuron firing and motor output. Interneuron activity is in turn modulated by the organization of their synaptic inputs, but the principles governing the development of specific synaptic architectures unique to each premotor interneuron are unknown. For example, Renshaw cells receive, at least in the neonate, convergent inputs from sensory afferents (likely Ia) and motor axons, raising the question of whether they interact during Renshaw cell development. In other well-studied neurons, such as Purkinje cells, heterosynaptic competition between inputs from different sources shapes synaptic organization. To examine the possibility that sensory afferents modulate synaptic maturation on developing Renshaw cells, we used three animal models in which afferent inputs in the ventral horn are dramatically reduced ( ER81 −/− knockout), weakened ( Egr3 −/− knockout), or strengthened ( mlcNT3 +/− transgenic). We demonstrate that increasing the strength of sensory inputs on Renshaw cells prevents their deselection and reduces motor axon synaptic density, and, in contrast, absent or diminished sensory afferent inputs correlate with increased densities of motor axons synapses. No effects were observed on other glutamatergic inputs. We conclude that the early strength of Ia synapses influences their maintenance or weakening during later development and that heterosynaptic influences from sensory synapses during early development regulates the density and organization of motor inputs on mature Renshaw cells. J. Comp. Neurol. 524:1892-1919, 2016. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Cholinergic vulnerability, characterized by loss of acetylcholine (ACh), is one of the hallmarks of Alzheimer's disease (AD). Previous work has suggested that decreasedAChactivity inADmaycontribute to pathological changes through global alterations in alternative splicing. This occurs, at least partially, via the regulation of the expression of a critical protein family in RNA processing, heterogeneous nuclear ribonucleoprotein (hnRNP) A/B proteins. These proteins regulate several steps of RNA metabolism, including alternative splicing, RNA trafficking, miRNA export, and gene expression, providing multilevel surveillance in RNA functions. To investigate the mechanism by which cholinergic tone regulates hnRNPA2/B1 expression, we used a combination of genetic mouse models and in vivo and in vitro techniques. Decreasing cholinergic tone reduced levels of hnRNPA2/B1, whereas increasing cholinergic signaling in vivo increased expression of hnRNPA2/B1. This effect was not due to decreased hnRNPA2/B1mRNAexpression, increased aggregation, or degradation of the protein, but rather to decreased mRNA translation by nonsense-mediated decay regulation of translation. Cell culture and knockout mice experiments demonstrated that M1 muscarinic signaling is critical for cholinergic control of hnRNPA2/B1 protein levels. Our experiments suggest an intricate regulation of hnRNPA2/B1 levels by cholinergic activity that interferes with alternative splicing in targeted neurons mimicking deficits found in AD. [ABSTRACT FROM AUTHOR]

Chronic cerebral ischemia (CCI) is associated with cognitive decline in aging, vascular dementia and Alzheimer’s disease. Substantial evidence has shown that chronic cerebral ischemia may cause cognitive impairment, but the underlying neurobiological mechanism is poorly understood so far. In the present study, we used a rat model of chronic cerebral ischemia by permanent bilateral common carotid artery occlusion (BCCAO) to investigate the alterations of glutamatergic and central cholinergic dysfunction, and their causal relationship with the cognitive deficits induced by chronic cerebral ischemia. We found that BCCAO rats exhibited spatial learning and memory impairments dysfunction 3 month after BCCAO. Meanwhile, vGluT levels as well as glutamatergic and central cholinergic positive neurons in the hippocampus CA1-3 field significantly decreased. The protection of glutamergic and cholinergic neurons or regulating glutamate and central cholinergic levels in hippocampal subregion may have beneficial effects on cognitive impairments associated with the possible mechanism in CCI-induced vascular dementia. [ABSTRACT FROM AUTHOR]

Sympathetic neurons have the capability to segregate their neurotransmitters (NTs) and co-transmitters to separate varicosities of single axons; furthermore, in culture, these neurons can even segregate classical transmitters. In vivo sympathetic neurons employ acetylcholine (ACh) and other classical NTs such as gamma aminobutyric acid (GABA). Herein, we explore whether these neurons in vivo segregate these classical NTs in the superior cervical ganglia of the rat. We determined the topographical distribution of GABAergic varicosities, somatic GABAA receptor, as well as the regional distribution of the segregation of ACh and GABA. We evaluated possible regional differences in efficacy of ganglionic synaptic transmission, in the sensitivity of GABAA receptor to GABA and to the competitive antagonist picrotoxin (PTX). We found that sympathetic preganglionic neurons in vivo do segregate ACh and GABA. GABAergic varicosities and GABAA receptor expression showed a rostro-caudal gradient along ganglia; in contrast, segregation exhibited a caudo-rostral gradient. These uneven regional distributions in expression of GABA, GABAA receptors, and level of segregation correlate with stronger synaptic transmission found in the caudal region. Accordingly, GABAA receptors of rostral region showed larger sensitivity to GABA and PTX. These results suggest the presence of different types of GABAA receptors in each region that result in a different regional levels of endogenous GABA inhibition. Finally, we discuss a possible correlation of these different levels of GABA modulation and the function of the target organs innervated by rostral and caudal ganglionic neurons. [ABSTRACT FROM AUTHOR]

Autonomic dysfunction is a characteristic of cardiac disease and decreased vagal activity is observed in heart failure. Rodent cardiomyocytes produce de novo ACh, which is critical in maintaining cardiac homeostasis. We report that this nonneuronal cholinergic system is also found in human cardiomyocytes, which expressed choline acetyltransferase (ChAT) and the vesicular acetylcholine transporter (VAChT). Furthermore, VAChT expression was increased 3- and 1.5-fold at the mRNA and protein level, respectively, in ventricular tissue from patients with heart failure, suggesting increased ACh secretion in disease. We used mice with genetic deletion of cardiomyocyte-specific VAChT or ChAT and mice overexpressing VAChT to test the functional significance of cholinergic signaling. Mice deficient for VAChT displayed an 8% decrease in fractional shortening and 13% decrease in ejection fraction compared with angiotensin II (Ang II)-treated control animals, suggesting enhanced ventricular dysfunction and pathologic remodeling in response to Ang II. Similar results were observed in ChAT-deficient mice. Conversely, no decline in ventricular function was observed in Ang II-treated VAChT overexpressors. Furthermore, the fibrotic area was significantly greater (P < 0.05) in Ang II-treated VAChT-deficient mice (3.61 ± 0.64%) compared with wild-type animals (2.24 ± 0.11%). In contrast, VAChT overexpressing mice did not display an increase in collagen deposition. Our results provide new insight into cholinergic regulation of cardiac function, suggesting that a compensatory increase in cardiomyocyte VAChT levels may help offset cardiac remodeling in heart failure. [ABSTRACT FROM AUTHOR]

ABSTRACT Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that primarily targets the motor system. Although much is known about the effects of ALS on motor neurons and glial cells, little is known about its effect on proprioceptive sensory neurons. This study examines proprioceptive sensory neurons in mice harboring mutations associated with ALS, in SOD1G93A and TDP43A315T transgenic mice. In both transgenic lines, we found fewer proprioceptive sensory neurons containing fluorescently tagged cholera toxin in their soma five days after injecting this retrograde tracer into the tibialis anterior muscle. We asked whether this is due to neuronal loss or selective degeneration of peripheral nerve endings. We found no difference in the total number and size of proprioceptive sensory neuron soma between symptomatic SOD1G93A and control mice. However, analysis of proprioceptive nerve endings in muscles revealed early and significant alterations at Ia/II proprioceptive nerve endings in muscle spindles before the symptomatic phase of the disease. Although these changes occur alongside those at α-motor axons in SOD1G93A mice, Ia/II sensory nerve endings degenerate in the absence of obvious alterations in α-motor axons in TDP43A315T transgenic mice. We next asked whether proprioceptive nerve endings are similarly affected in the spinal cord and found that nerve endings terminating on α-motor neurons are affected during the symptomatic phase and after peripheral nerve endings begin to degenerate. Overall, we show that Ia/II proprioceptive sensory neurons are affected by ALS-causing mutations, with pathological changes starting at their peripheral nerve endings. J. Comp. Neurol. 523:2477-2494, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]