The membrane cholesterol was found to bind and modulate the function of several G-protein coupled receptors including muscarinic acetylcholine receptors. We investigated the binding of 20 steroidal compounds including neurosteroids and steroid hormones to muscarinic receptors. Corticosterone, progesterone and some neurosteroids bound to muscarinic receptors with the affinity of 100 nM or greater. We established a structure-activity relationship for steroid-based allosteric modulators of muscarinic receptors. Further, we show that corticosterone and progesterone allosterically modulate the functional response of muscarinic receptors to acetylcholine at physiologically relevant concentrations. It can play a role in stress control or in pregnancy, conditions where levels of these hormones dramatically oscillate. Allosteric modulation of muscarinic receptors via the cholesterol-binding site represents a new pharmacological approach at diseases associated with altered cholinergic signalling.

• MeSH
• acetylcholin metabolismus   MeSH
• alosterická regulace MeSH
• hormony kůry nadledvin metabolismus   MeSH
• kortikosteron metabolismus   MeSH
• křečci praví MeSH
• kultivované buňky MeSH
• lidé MeSH
• neurosteroidy metabolismus   MeSH
• pohlavní steroidní hormony metabolismus   MeSH
• progesteron metabolismus   MeSH
• receptory muskarinové metabolismus   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Endogenous neurosteroids and their synthetic analogues-neuroactive steroids-have been found to bind to muscarinic acetylcholine receptors and allosterically modulate acetylcholine binding and function. Using radioligand binding experiments we investigated their binding mode. We show that neuroactive steroids bind to two binding sites on muscarinic receptors. Their affinity for the high-affinity binding site is about 100 nM. Their affinity for the low-affinity binding site is about 10 µM. The high-affinity binding occurs at the same site as binding of steroid-based WIN-compounds that is different from the common allosteric binding site for alcuronium or gallamine that is located between the second and third extracellular loop of the receptor. This binding site is also different from the allosteric binding site for the structurally related aminosteroid-based myorelaxants pancuronium and rapacuronium. Membrane cholesterol competes with neurosteroids/neuroactive steroids binding to both high- and low-affinity binding site, indicating that both sites are oriented towards the cell membrane..

• MeSH
• alosterická regulace účinky léků   fyziologie   MeSH
• androstany metabolismus   farmakologie   MeSH
• androsteny metabolismus   farmakologie   MeSH
• benzimidazoly metabolismus   farmakologie   MeSH
• CHO buňky MeSH
• cholesterol metabolismus   MeSH
• Cricetulus MeSH
• křečci praví MeSH
• lidé MeSH
• nervosvalové látky nedepolarizující metabolismus   farmakologie   MeSH
• neurosteroidy metabolismus   MeSH
• receptory muskarinové metabolismus   MeSH
• triethojodid gallaminia metabolismus   farmakologie   MeSH
• vazebná místa účinky léků   fyziologie   MeSH
• vekuronium analogy a deriváty   metabolismus   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Xanomeline (3-(Hexyloxy)-4-(1-methyl-1,2,5,6-tetrahydropyridin-3-yl)-1,2,5-thiadiazole) is a muscarinic agonist that is considered to be functionally selective for the M1/M4 receptor subtypes. Part of xanomeline binding is resistant to washing. Wash-resistant xanomeline activates muscarinic receptors persistently, except for the M5 subtype. Mutation of leucine 6.46 to isoleucine at M1 or M4 receptors abolished persistent activation by wash-resistant xanomeline. Reciprocal mutation of isoleucine 6.46 to leucine at the M5 receptor made it sensitive to activation by wash-resistant xanomeline. Lowering of membrane cholesterol made M1 and M4 mutants and M5 wild type receptors sensitive to activation by wash-resistant xanomeline. Molecular docking revealed a cholesterol binding site in the groove between transmembrane helices 6 and 7. Molecular dynamics showed that interaction of cholesterol with this binding site attenuates receptor activation. We hypothesize that differences in cholesterol binding to this site between muscarinic receptor subtypes may constitute the basis for xanomeline apparent functional selectivity and may have notable therapeutic implications. Differences in receptor-membrane interactions, rather than in agonist-receptor interactions, represent a novel possibility to achieve pharmacological selectivity. Our findings may be applicable to other G protein coupled receptors.

• MeSH
• agonisté muskarinových receptorů farmakokinetika   MeSH
• buněčná membrána účinky léků   metabolismus   MeSH
• CHO buňky cytologie   MeSH
• cholesterol metabolismus   MeSH
• Cricetulus MeSH
• inositolfosfáty metabolismus   MeSH
• magnetická rezonanční spektroskopie MeSH
• molekulární modely MeSH
• průtoková cytometrie MeSH
• pyridiny farmakokinetika   MeSH
• radioligandová zkouška MeSH
• receptory muskarinové genetika   metabolismus   MeSH
• simulace molekulového dockingu MeSH
• thiadiazoly farmakokinetika   MeSH
• tritium farmakokinetika   MeSH
• vápník metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Apolipoprotein E4 (apoE4) is the most prevalent genetic risk factor for Alzheimer's disease. We utilized apoE4-targeted replacement mice (approved by the Tel Aviv University Animal Care Committee) to investigate whether cholinergic dysfunction, which increases during aging and is a hallmark of Alzheimer's disease, is accentuated by apoE4. This revealed that levels of the pre-synaptic cholinergic marker, vesicular acetylcholine transporter in the hippocampus and the corresponding electrically evoked release of acetylcholine, are similar in 4-month-old apoE4 and apolipoprotein E3 (apoE3) mice. Both parameters decrease with age. This decrease is, however, significantly more pronounced in the apoE4 mice. The levels of cholinacetyltransferase (ChAT), acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) were similar in the hippocampus of young apoE4 and apoE3 mice and decreased during aging. For ChAT, this decrease was similar in the apoE4 and apoE3 mice, whereas it was more pronounced in the apoE4 mice, regarding their corresponding AChE and BuChE levels. The level of muscarinic receptors was higher in the apoE4 than in the apoE3 mice at 4 months and increased to similar levels with age. However, the relative representation of the M1 receptor subtype decreased during aging in apoE4 mice. These results demonstrate impairment of the evoked release of acetylcholine in hippocampus by apoE4 in 12-month-old mice but not in 4-month-old mice. The levels of ChAT and the extent of the M2 receptor-mediated autoregulation of ACh release were similar in the adult mice, suggesting that the apoE4-related inhibition of hippocampal ACh release in these mice is not driven by these parameters. Evoked ACh release from hippocampal and cortical slices is similar in 4-month-old apoE4 and apoE3 mice but is specifically and significantly reduced in hippocampus, but not cortex, of 12-month-old apoE4 mice. This effect is accompanied by decreased VAChT levels. These findings show that the hipocampal cholinergic nerve terminals are specifically affected by apoE4 and that this effect is age dependent.

• MeSH
• acetylcholin metabolismus   MeSH
• apolipoprotein E3 genetika   MeSH
• apolipoprotein E4 genetika   metabolismus   MeSH
• cholin-O-acetyltransferasa metabolismus   MeSH
• guanosin 5'-O-(3-thiotrifosfát) farmakologie   MeSH
• hipokampus účinky léků   metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši transgenní MeSH
• myši MeSH
• N-methylskopolamin farmakologie   MeSH
• receptory muskarinové metabolismus   MeSH
• tritium metabolismus   MeSH
• věkové faktory MeSH
• vezikulární transportní proteiny acetylcholinu metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Human-secreted Ly-6/uPAR-related protein-2 (SLURP-2) regulates the growth and differentiation of epithelial cells. Previously, the auto/paracrine activity of SLURP-2 was considered to be mediated via its interaction with the α3β2 subtype of the nicotinic acetylcholine receptors (nAChRs). Here, we describe the structure and pharmacology of a recombinant analogue of SLURP-2. Nuclear magnetic resonance spectroscopy revealed a 'three-finger' fold of SLURP-2 with a conserved β-structural core and three protruding loops. Affinity purification using cortical extracts revealed that SLURP-2 could interact with the α3, α4, α5, α7, β2, and β4 nAChR subunits, revealing its broader pharmacological profile. SLURP-2 inhibits acetylcholine-evoked currents at α4β2 and α3β2-nAChRs (IC50 ~0.17 and >3 μM, respectively) expressed in Xenopus oocytes. In contrast, at α7-nAChRs, SLURP-2 significantly enhances acetylcholine-evoked currents at concentrations <1 μM but induces inhibition at higher concentrations. SLURP-2 allosterically interacts with human M1 and M3 muscarinic acetylcholine receptors (mAChRs) that are overexpressed in CHO cells. SLURP-2 was found to promote the proliferation of human oral keratinocytes via interactions with α3β2-nAChRs, while it inhibited cell growth via α7-nAChRs. SLURP-2/mAChRs interactions are also probably involved in the control of keratinocyte growth. Computer modeling revealed possible SLURP-2 binding to the 'classical' orthosteric agonist/antagonist binding sites at α7 and α3β2-nAChRs.

• MeSH
• alfa7 nikotinové acetylcholinové receptory metabolismus   MeSH
• buněčné linie MeSH
• buňky PC12 MeSH
• CHO buňky MeSH
• Cricetulus MeSH
• dospělí MeSH
• epilepsie temporálního laloku patologie   MeSH
• evokované potenciály fyziologie   MeSH
• GPI-vázané proteiny metabolismus   MeSH
• keratinocyty metabolismus   MeSH
• krysa rodu rattus MeSH
• lidé středního věku MeSH
• lidé MeSH
• nikotinové receptory metabolismus   MeSH
• nukleární magnetická rezonance biomolekulární MeSH
• oocyty metabolismus   MeSH
• počítačová simulace MeSH
• proliferace buněk fyziologie   MeSH
• receptory muskarinové metabolismus   MeSH
• vazba proteinů fyziologie   MeSH
• vazebná místa fyziologie   MeSH
• Xenopus MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• krysa rodu rattus MeSH
• lidé středního věku MeSH
• lidé MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Transgenic APPswe/PS1dE9 mice modeling Alzheimer's disease demonstrate ongoing accumulation of β-amyloid fragments resulting in formation of amyloid plaques that starts at the age of 4-5 months. Buildup of β-amyloid fragments is accompanied by impairment of muscarinic transmission that becomes detectable at this age, well before the appearance of cognitive deficits that manifest around the age of 12 months. We have recently demonstrated that long-term feeding of trangenic mice with specific isocaloric fish oil-based diets improves specific behavioral parameters. Now we report on the influence of short-term feeding (3 weeks) of three isocaloric diets supplemented with Fortasyn (containing fish oil and ingredients supporting membrane renewal), the plant sterol stigmasterol together with fish oil, and stigmasterol alone on markers of cholinergic neurotransmission in the hippocampus of 5-month-old transgenic mice and their wild-type littermates. Transgenic mice fed normal diet demostrated increase in ChAT activity and attenuation of carbachol-stimulated GTP-γ(35)S binding compared to wild-type mice. None of the tested diets compared to control diet influenced the activities of ChAT, AChE, BuChE, muscarinic receptor density or carbachol-stimulated GTP-γ(35)S binding in wild-type mice. In contrast, all experimental diets increased the potency of carbachol in stimulating GTP-γ(35)S binding in trangenic mice to the level found in wild-type animals. Only the Fortasyn diet increased markers of cholinergic synapses in transgenic mice. Our data demonstrate that even short-term feeding of transgenic mice with chow containing specific lipid-based dietary supplements can influence markers of cholinergic synapses and rectify impaired muscarinic signal transduction that develops in transgenic mice.

• MeSH
• Alzheimerova nemoc dietoterapie   patofyziologie   MeSH
• amyloidový prekurzorový protein beta genetika   metabolismus   MeSH
• dietní tuky aplikace a dávkování   MeSH
• hipokampus patofyziologie   MeSH
• kaspasa 8 metabolismus   MeSH
• lidé MeSH
• modely nemocí na zvířatech MeSH
• myši inbrední C3H MeSH
• myši inbrední C57BL MeSH
• myši transgenní MeSH
• nervový přenos fyziologie   MeSH
• presenilin-1 genetika   metabolismus   MeSH
• receptory muskarinové metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Weak toxin from Naja kaouthia (WTX) belongs to the group of nonconventional "three-finger" snake neurotoxins. It irreversibly inhibits nicotinic acetylcholine receptors and allosterically interacts with muscarinic acetylcholine receptors (mAChRs). Using site-directed mutagenesis, NMR spectroscopy, and computer modeling, we investigated the recombinant mutant WTX analogue (rWTX) which, compared with the native toxin, has an additional N-terminal methionine residue. In comparison with the wild-type toxin, rWTX demonstrated an altered pharmacological profile, decreased binding of orthosteric antagonist N-methylscopolamine to human M1- and M2-mAChRs, and increased antagonist binding to M3-mAChR. Positively charged arginine residues located in the flexible loop II were found to be crucial for rWTX interactions with all types of mAChR. Computer modeling suggested that the rWTX loop II protrudes to the M1-mAChR allosteric ligand-binding site blocking the entrance to the orthosteric site. In contrast, toxin interacts with M3-mAChR by loop II without penetration into the allosteric site. Data obtained provide new structural insight into the target-specific allosteric regulation of mAChRs by "three-finger" snake neurotoxins.

• MeSH
• Elapidae MeSH
• inzerční mutageneze MeSH
• jedy hadů čeledi Elapidae chemie   MeSH
• konformace proteinů MeSH
• molekulární sekvence - údaje MeSH
• neurotoxiny chemie   genetika   metabolismus   MeSH
• nukleární magnetická rezonance biomolekulární MeSH
• receptory muskarinové metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

We mutated key amino acids of the human variant of the M1 muscarinic receptor that target ligand binding, receptor activation, and receptor-G protein interaction. We compared the effects of these mutations on the action of two atypical M1 functionally preferring agonists (N-desmethylclozapine and xanomeline) and two classical non-selective orthosteric agonists (carbachol and oxotremorine). Mutations of D105 in the orthosteric binding site and mutation of D99 located out of the orthosteric binding site decreased affinity of all tested agonists that was translated as a decrease in potency in accumulation of inositol phosphates and intracellular calcium mobilization. Mutation of D105 decreased the potency of the atypical agonist xanomeline more than that of the classical agonists carbachol and oxotremorine. Mutation of the residues involved in receptor activation (D71) and coupling to G-proteins (R123) completely abolished the functional responses to both classical and atypical agonists. Our data show that both classical and atypical agonists activate hM1 receptors by the same molecular switch that involves D71 in the second transmembrane helix. The principal difference among the studied agonists is rather in the way they interact with D105 in the orthosteric binding site. Furthermore, our data demonstrate a key role of D105 in xanomeline wash-resistant binding and persistent activation of hM1 by wash-resistant xanomeline.

• MeSH
• agonisté muskarinových receptorů farmakologie   MeSH
• buněčná membrána účinky léků   MeSH
• CHO buňky MeSH
• Cricetulus MeSH
• inositolfosfáty metabolismus   MeSH
• karbachol farmakologie   MeSH
• křečci praví MeSH
• molekulární modely MeSH
• mutace MeSH
• oxotremorin farmakologie   MeSH
• pyridiny farmakologie   MeSH
• receptor muskarinový M1 agonisté   genetika   MeSH
• receptory spřažené s G-proteiny účinky léků   MeSH
• thiadiazoly farmakologie   MeSH
• vápník metabolismus   MeSH
• vazebná místa účinky léků   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Muscarinc receptor-mediated signaling takes part in many physiological functions ranging from complex higher nervous activity to vegetative responses. Specificity of action of the natural muscarinic agonist acetylcholine is effected by action on five muscarinic receptor subtypes with particular tissue and cellular localization, and coupling preference with different G-proteins and their signaling pathways. In addition to physiological roles it is also implicated in pathologic events like promotion of carcinoma cells growth, early pathogenesis of neurodegenerative diseases in the central nervous system like Alzheimer's disease and Parkinson's disease, schizophrenia, intoxications resulting in drug addiction, or overactive bladder in the periphery. All of these disturbances demonstrate involvement of specific muscarinic receptor subtypes and point to the importance to develop selective pharmacotherapeutic interventions. Because of the high homology of the orthosteric binding site of muscarinic receptor subtypes there is virtually no subtype selective agonist that binds to this site. Activation of specific receptor subtypes may be achieved by developing allosteric modulators of acetylcholine binding, since ectopic binding domains on the receptor are less conserved compared to the orthosteric site. Potentiation of the effects of acetylcholine by allosteric modulators would be beneficial in cases where acetylcholine release is reduced due to pathological conditions. When presynaptic function is severely compromised, the utilization of ectopic agonists can be a thinkable solution.

• MeSH
• agonisté muskarinových receptorů terapeutické užití   MeSH
• antagonisté muskarinových receptorů terapeutické užití   MeSH
• lidé MeSH
• nemoci nervového systému farmakoterapie   metabolismus   MeSH
• neurony účinky léků   metabolismus   MeSH
• receptory muskarinové účinky léků   metabolismus   MeSH
• signální transdukce účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Xanomeline is an agonist endowed with functional preference for M1/M4 muscarinic acetylcholine receptors. It also exhibits both reversible and wash-resistant binding to and activation of these receptors. So far the mechanisms of xanomeline selectivity remain unknown. To address this question we employed microfluorometric measurements of intracellular calcium levels and radioligand binding to investigate differences in the short- and long-term effects of xanomeline among muscarinic receptors expressed individually in Chinese hamster ovary cells. 1/One-min exposure of cells to xanomeline markedly increased intracellular calcium at hM1 and hM4, and to a lesser extent at hM2 and hM3 muscarinic receptors for more than 1 hour. 2/Unlike the classic agonists carbachol, oxotremorine, and pilocarpine 10-min exposure to xanomeline did not cause internalization of any receptor subtype. 3/Wash-resistant xanomeline selectively prevented further increase in intracellular calcium by carbachol at hM1 and hM4 receptors. 4/After transient activation xanomeline behaved as a long-term antagonist at hM5 receptors. 5/The antagonist N-methylscopolamine (NMS) reversibly blocked activation of hM1 through hM4 receptors by xanomeline. 6/NMS prevented formation of xanomeline wash-resistant binding and activation at hM2 and hM4 receptors and slowed them at hM1, hM3 and hM5 receptors. Our results show commonalities of xanomeline reversible and wash-resistant binding and short-time activation among the five muscarinic receptor subtypes. However long-term receptor activation takes place in full only at hM1 and hM4 receptors. Moreover xanomeline displays higher efficacy at hM1 and hM4 receptors in primary phasic intracellular calcium release. These findings suggest the existence of particular activation mechanisms specific to these two receptors.

• MeSH
• AMP cyklický metabolismus   MeSH
• buněčná membrána účinky léků   metabolismus   MeSH
• časové faktory MeSH
• CHO buňky MeSH
• Cricetulus MeSH
• extracelulární prostor účinky léků   metabolismus   MeSH
• intracelulární prostor účinky léků   metabolismus   MeSH
• kinetika MeSH
• křečci praví MeSH
• lidé MeSH
• N-methylskopolamin farmakologie   MeSH
• pyridiny farmakologie   MeSH
• receptor muskarinový M1 agonisté   antagonisté a inhibitory   metabolismus   MeSH
• receptor muskarinový M4 agonisté   antagonisté a inhibitory   metabolismus   MeSH
• thiadiazoly farmakologie   MeSH
• vápník metabolismus   MeSH
• vazebná místa účinky léků   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH