Search results for "choline"
showing 10 items of 1138 documents
Lipid carbonyl groups terminate the hydrogen bond network of membrane-bound water.
2015
We present a combined experimental sum-frequency generation (SFG) spectroscopy and ab initio molecular dynamics simulations study to clarify the structure and orientation of water at zwitterionic phosphatidylcholine (PC) lipid and amine N-oxide (AO) surfactant monolayers. Simulated O-H stretch SFG spectra of water show good agreement with the experimental data. The SFG response at the PC interface exhibits positive peaks, whereas both negative and positive bands are present for the similar zwitterionic AO interface. The positive peaks at the water/PC interface are attributed to water interacting with the lipid carbonyl groups, which act as efficient hydrogen bond acceptors. This allows the …
Expression of Muscarinic Receptor Types in the Primate Ovary and Evidence for Nonneuronal Acetylcholine Synthesis1
2001
The presence of muscarinic receptors (MR) in the ovary of different species has been recognized, but the identity of these receptors as well as ovarian sources of their natural ligand, acetylcholine (ACh), have not been determined. Because luteinized human granulosa cells (GC) in culture express functional MR, we have determined whether the group of the related MR subtypes, M1R, M3R, and M5R, are present in vivo in human and rhesus monkey ovaries. To this end, ribonucleic acids (RNAs) of different human and monkey ovaries as well as RNAs from human GC and monkey oocytes were reverse transcribed and subjected to PCR amplification, followed by sequencing of the amplified complementary DNAs. R…
Comparison of Two Schizophyllum commune Strains in Production of Acetylcholinesterase Inhibitors and Antioxidants from Submerged Cultivation
2021
In recent years, fungi have been recognized as producers of acetylcholinesterase (AChE) inhibitors, agents important for the prevention of Alzheimer’s disease (AD). This study aimed to examine the AChE inhibitory, the antioxidative and antibacterial activity of two different Schizophyllum commune strains that originated from Serbia (SRB) and Italy (IT). Submerged cultivation of grown mycelia (M) and fermentation broth (F) of ethanol (EtOH) and polysaccharide (PSH) extracts lasted for 7, 14, 21 and 28 days. For AChE activity Ellman method was performed, while for antioxidative activity, sevendifferent assays were conducted: DPPH, ABTS, FRAP, SOA, OH, NO together with total phenolic content. …
KA-672 inhibits rat brain acetylcholinesterase in vitro but not in vivo.
1999
Abstract KA-672, a lipophilic benzopyranone derivative which is currently under development as a cognitive enhancer and antidementia drug, has previously been shown to have facilitatory effects on learning and memory in rats at doses of 0.1–1 mg/kg. We now report that KA-672 inhibited the activity of acetylcholinesterase (AChE), measured in vitro in rat brain cortical homogenate, with an IC 50 value of 0.36 μ M indicating that KA-672 may improve cognitive functions as a consequence of AChE inhibition. However, when we employed the microdialysis procedure to monitor acetylcholine (ACh) release from rat hippocampus, no effect of KA-672 (0.1–10 mg/kg) was found, indicating a lack of inhibition…
Dual modulation of striatal acetylcholine release by hyperforin, a constituent of St. John's wort.
2002
Extracts of the medicinal plant St. John's wort (Hypericum perforatum) are widely used for the treatment of mild to moderate depression. Hyperforin, a constituent of St. John's wort, is known to inhibit the sodium-dependent uptake of catecholamines and amino acids into synaptic nerve endings, probably by interference with mechanisms controlling the synaptic sodium concentration. Because de novo synthesis of acetylcholine (ACh) is dependent on sodium-dependent high-affinity choline uptake, we studied the effect of hyperforin on choline (Ch) uptake in vitro and on striatal ACh release in vivo using microdialysis. In rat brain synaptosomes, hyperforin inhibited high-affinity choline uptake wit…
Stimulation of hippocampal acetylcholine release by hyperforin, a constituent of St. John’s Wort
2004
Abstract Extracts of the medicinal plant St. John’s Wort ( Hypericum perforatum ) are widely used in the therapy of affective disorders and have been reported to exert antidepressant, anxiolytic, and cognitive effects in experimental and clinical studies. We here report that hyperforin, the major active constituent of the extract, increases the release of acetylcholine from rat hippocampus in vivo as determined by microdialysis. Hippocampal acetylcholine levels were increased by 50–100% following the systemic administration of pure hyperforin at doses of 1 and 10 mg/kg. The effect was almost completely suppressed by local perfusion with calcium-free buffer or with tetrodotoxin (1 μM). We co…
Mitochondrial oxidative stress and nitrate tolerance – comparison of nitroglycerin and pentaerithrityl tetranitrate in Mn-SOD+/- mice
2006
Abstract Background Chronic therapy with nitroglycerin (GTN) results in a rapid development of nitrate tolerance which is associated with an increased production of reactive oxygen species (ROS). According to recent studies, mitochondrial ROS formation and oxidative inactivation of the organic nitrate bioactivating enzyme mitochondrial aldehyde dehydrogenase (ALDH-2) play an important role for the development of nitrate and cross-tolerance. Methods Tolerance was induced by infusion of wild type (WT) and heterozygous manganese superoxide dismutase mice (Mn-SOD+/-) with ethanolic solution of GTN (12.5 μg/min/kg for 4 d). For comparison, the tolerance-free pentaerithrityl tetranitrate (PETN, 1…
Effect of cholesterol on the physical properties of pulmonary surfactant films: Atomic force measurements study
2006
International audience; Atomic force measurements were performed on supported pulmonary surfactant (PS) films to address the effect of cholesterol on the physical properties of lung surfactant films. We recently found that cholesterol in excess of a physiological proportion abolishes surfactant function, and is the reason that surfactant fails to lower the surface tension upon compression. In this study, we investigated how the loss of mechanical stability observed earlier is related to the local mechanical properties of the film by local force measurements. The presence of 20% of cholesterol in bovine lipid extract surfactant (BLES) resulted in a decrease of the observed adhesive interacti…
Pores Formed by Baxα5 Relax to a Smaller Size and Keep at Equilibrium
2010
AbstractPores made by amphipathic cationic peptides (e.g., antimicrobials and fragments of pore-forming proteins) are typically studied by examining the kinetics of vesicle leakage after peptide addition or obtaining structural measurements in reconstituted peptide-lipid systems. In the first case, the pores have been considered transient phenomena that allow the relaxation of the peptide-membrane system. In the second, they correspond to equilibrium structures at minimum free energy. Here we reconcile both approaches by investigating the pore activity of the α5 fragment from the proapoptotic protein Bax (Baxα5) before and after equilibrium of peptide/vesicle complexes. Quenching assays on …
A Structural Model of the Human α7 Nicotinic Receptor in an Open Conformation
2015
International audience; Nicotinic acetylcholine receptors (nAchRs) are ligand-gated ion channels that regulate chemical transmission at the neuromuscular junction. Structural information is available at low resolution from open and closed forms of an eukaryotic receptor, and at high resolution from other members of the same structural family, two prokaryotic orthologs and an eukary- otic GluCl channel. Structures of human channels however are still lacking. Homology modeling and Molecular Dynamics simulations are valuable tools to predict structures of unknown proteins, however, for the case of human nAchRs, they have been unsuccessful in providing a stable open structure so far. This is du…