Nicotinic acetylcholine receptors (nAChRs) are widely expressed in the central nervous system and play an important role in the control of neural functions including neuronal activity, transmitter release and synaptic plasticity. Although the common subtypes of nAChRs are abundantly expressed throughout the brain, their expression in different brain regions and by individual neuronal types is not homogeneous or incidental. In recent years, several studies have emerged showing that particular subtypes of nAChRs are expressed by specific neuronal populations in which they have major influence on the activity of local circuits and behavior. It has been demonstrated that even nAChRs expressed by relatively rare neuronal types can induce significant changes in behavior and contribute to pathological processes. Depending on the identity and connectivity of the particular nAChRs-expressing neuronal populations, the activation of nAChRs can have distinct or even opposing effects on local neuronal signaling. In this review, we will summarize the available literature describing the expression of individual nicotinic subunits by different neuronal types in two crucial brain regions, the striatum and the prefrontal cortex. The review will also briefly discuss nicotinic expression in non-neuronal, glial cells, as they cannot be ignored as potential targets of nAChRs-modulating drugs. The final section will discuss options that could allow us to target nAChRs in a neuronal-type-specific manner, not only in the experimental field, but also eventually in clinical practice.

• MeSH
• corpus striatum metabolismus   MeSH
• lidé MeSH
• neurony * metabolismus   MeSH
• nikotinové receptory * metabolismus   MeSH
• prefrontální mozková kůra * metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Motor learning and flexibility allow animals to perform routine actions efficiently while keeping them flexible. A number of paradigms are used to test cognitive flexibility, but not many of them focus specifically on the learning of complex motor sequences and their flexibility. While many tests use operant or touchscreen boxes that offer high throughput and reproducibility, the motor actions themselves are mostly simple presses of a designated lever. To focus more on motor actions during the operant task and to probe the flexibility of these well trained actions, we developed a new operant paradigm for mice, the "timed sequence task." The task requires mice to learn a sequence of lever presses that have to be emitted in precisely defined time limits. After training, the required pressing sequence and/or timing of individual presses is modified to test the ability of mice to alter their previously trained motor actions. We provide a code for the new protocol that can be used and adapted to common types of operant boxes. In addition, we provide a set of scripts that allow automatic extraction and analysis of numerous parameters recorded during each session. We demonstrate that the analysis of multiple performance parameters is necessary for detailed insight into the behavior of animals during the task. We validate our paradigm in an experiment using the valproate model of autism as a model of cognitive inflexibility. We show that the valproate mice show superior performance at specific stages of the task, paradoxically because of their propensity to more stereotypic behavior.

• MeSH
• kyselina valproová * MeSH
• myši MeSH
• operantní podmiňování MeSH
• reprodukovatelnost výsledků MeSH
• učení * MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Acetylcholine is an important modulator of striatal activity, and it is vital to controlling striatal-dependent behaviors, including motor and cognitive functions. Despite this significance, the mechanisms determining how acetylcholine impacts striatal signaling are still not fully understood. In particular, little is known about the role of nAChRs expressed by striatal interneurons. In the present study, we used FISH to determine which neuronal types express the most prevalent beta2 nicotinic subunit in the mouse striatum. Our data support a common view that nAChR expression is mostly restricted to striatal interneurons. Surprisingly though, cholinergic interneurons were identified as a population with the highest expression of beta2 nicotinic subunit. To investigate the functional significance of beta2-containing nAChRs in striatal interneurons, we deleted them by injecting the AAV-Cre vector into the striatum of beta2-flox/flox male mice. The deletion led to alterations in several behavioral domains, namely, to an increased anxiety-like behavior, decrease in sociability ratio, deficit in discrimination learning, and increased amphetamine-induced hyperlocomotion and c-Fos expression in mice with beta2 deletion. Further colocalization analysis showed that the increased c-Fos expression was present in both medium spiny neurons and presumed striatal interneurons. The present study concludes that, despite being relatively rare, beta2-containing nAChRs are primarily expressed in striatal neurons by cholinergic interneurons and play a significant role in behavior.SIGNIFICANCE STATEMENT A large variety of nAChRs are expressed in the striatum, a brain region that is crucial in the control of behavior. The complexity of receptors with different functions is hindering our understanding of mechanisms through which striatal acetylcholine modulates behavior. We focused on the role of a small population of beta2-containing nAChRs. We identified neuronal types expressing these receptors and determined their impact in the control of explorative behavior, anxiety-like behavior, learning, and sensitivity to stimulants. Additional experiments showed that these alterations were associated with an overall increased activity of striatal neurons. Thus, the small population of nicotinic receptors represents an interesting target for a modulation of response to stimulant drugs and other striatal-based behavior.

• MeSH
• acetylcholin metabolismus   MeSH
• cholinergní látky farmakologie   MeSH
• corpus striatum metabolismus   MeSH
• interneurony metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• nikotinové receptory * metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Disruptions in social behaviour are prevalent in many neuropsychiatric disorders such as schizophrenia, bipolar disorder and autism spectrum disorders. However, the underlying neurochemical regulation of social behaviour is still not well understood. The central cholinergic system has been proposed to contribute to the regulation of social behaviour. For instance, decreased global levels of acetylcholine release in the brain leads to decreased social interaction and an impairment of social memory in mice. Nonetheless, it has been difficult to ascertain the specific brain areas where cholinergic signalling influences social preference and social memory. In this study, we investigated the impact of different forebrain cholinergic regions on social behaviour by examining mouse lines that differ in their regional expression level of the vesicular acetylcholine transporter-the protein that regulates acetylcholine secretion. We found that when cholinergic signalling is highly disrupted in the striatum, hippocampus, cortex and amygdala mice have intact social preference but are impaired in social memory, as they cannot remember a familiar conspecific nor recognize a novel one. A similar pattern emerges when acetylcholine release is disrupted mainly in the striatum, cortex, and amygdala; however, the ability to recognize novel conspecifics is retained. In contrast, cholinergic signalling of the striatum and amygdala does not appear to significantly contribute to the modulation of social memory and social preference. Furthermore, we demonstrated that increasing global cholinergic tone does not increase social behaviours. Together, these data suggest that cholinergic transmission from the hippocampus and cortex are important for regulating social memory.

• MeSH
• acetylcholin MeSH
• cholinergní látky MeSH
• hipokampus metabolismus   MeSH
• myši MeSH
• pars basalis telencephali * 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

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

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

The overproduction of β-amyloid (Aβ) fragments in transgenic APPswe/PS1dE9 mice results in formation of amyloid deposits in the cerebral cortex and hippocampus starting around four months of age and leading to cognitive impairment much later. We have previously found an age and transgene-dependent weakening of muscarinic receptor-mediated transmission that was not present in young (6-10-week-old) animals but preceded both amyloid deposits and cognitive deficits. Now we investigated immediate and prolonged in vitro effects of non-aggregated Aβ(1-42) on coupling of individual muscarinic receptor subtypes expressed in CHO (Chinese hamster ovary) cells and their underlying mechanisms. Immediate application of 1 μM Aβ(1-42) had no effect on the binding of the muscarinic antagonist N-methylscopolamine or the agonist carbachol. In contrast, 4-day treatment of CHO cells expressing the M1 muscarinic receptor with 100 nM Aβ(1-42) significantly changed the binding characteristics of the muscarinic agonist carbachol and reduced the extent of the M1 receptor-stimulated breakdown of phosphatidylinositol while it did not demonstrate overt toxic effects. The treatment had no influence on the expression of either G-proteins or muscarinic receptors. In concert, we found no change in the gene expression of muscarinic receptor subtypes and gene or protein expression of the G(s), G(q/11), and G(i/o) G-proteins in the cerebral cortex of young adult APPswe/PS1dE9 mice that demonstrate high concentrations of soluble Aβ(1-42) and impaired muscarinic receptor-mediated G-protein activation. Our results provide strong evidence that the initial injurious effects of Aβ(1-42) on M1 muscarinic receptor-mediated transmissionis is due to compromised coupling of the receptor with G(q/11) G-protein.

• MeSH
• amyloidní beta-protein antagonisté a inhibitory   metabolismus   MeSH
• CHO buňky MeSH
• Cricetulus MeSH
• křečci praví MeSH
• kultivované buňky MeSH
• lidé MeSH
• myši transgenní MeSH
• myši MeSH
• peptidové fragmenty antagonisté a inhibitory   metabolismus   MeSH
• receptor muskarinový M1 metabolismus   MeSH
• receptory spřažené s G-proteiny antagonisté a inhibitory   metabolismus   MeSH
• rozpřahující látky farmakologie   MeSH
• vazba proteinů účinky léků   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Based on the kinetics of interaction between a receptor and G-protein, a myriad of possibilities may result. Two extreme cases are represented by: 1/Collision coupling, where an agonist binds to the free receptor and then the agonist-receptor complex "collides" with the free G-protein. 2/Pre-coupling, where stable receptor/G-protein complexes exist in the absence of agonist. Pre-coupling plays an important role in the kinetics of signal transduction. Odd-numbered muscarinic acetylcholine receptors preferentially couple to G(q/11), while even-numbered receptors prefer coupling to G(i/o). We analyzed the coupling status of the various subtypes of muscarinic receptors with preferential and non-preferential G-proteins. The magnitude of receptor-G-protein coupling was determined by the proportion of receptors existing in the agonist high-affinity binding conformation. Antibodies directed against the C-terminus of the α-subunits of the individual G-proteins were used to interfere with receptor-G-protein coupling. Effects of mutations and expression level on receptor-G-protein coupling were also investigated. Tested agonists displayed biphasic competition curves with the antagonist [(3)H]-N-methylscopolamine. Antibodies directed against the C-terminus of the α-subunits of the preferential G-protein decreased the proportion of high-affinity sites, and mutations at the receptor-G-protein interface abolished agonist high-affinity binding. In contrast, mutations that prevent receptor activation had no effect. Expression level of preferential G-proteins had no effect on pre-coupling to non-preferential G-proteins. Our data show that all subtypes of muscarinic receptors pre-couple with their preferential classes of G-proteins, but only M(1) and M(3) receptors also pre-couple with non-preferential G(i/o) G-proteins. Pre-coupling is not dependent on agonist efficacy nor on receptor activation. The ultimate mode of coupling is therefore dictated by a combination of the receptor subtype and the class of G-protein.

• MeSH
• CHO buňky MeSH
• Cricetulus MeSH
• guanosin 5'-O-(3-thiotrifosfát) metabolismus   MeSH
• karbachol metabolismus   MeSH
• kinetika MeSH
• kompetitivní vazba MeSH
• křečci praví MeSH
• lidé MeSH
• mutace MeSH
• N-methylskopolamin metabolismus   MeSH
• proteiny vázající GTP metabolismus   MeSH
• receptory muskarinové genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• křečci praví MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH