scholarly journals Lateral habenula M2 muscarinic receptor control of neuronal activity and cocaine seeking behavior

2021 ◽  
Author(s):  
Clara I.C. Wolfe ◽  
Eun-Kyung Hwang ◽  
Agustin Zapata ◽  
Alexander F Hoffman ◽  
Carl R. Lupica
Keyword(s):  
Acetylcholine Receptors ◽  
Behavioral Control ◽  
Control Point ◽  
Muscarinic Acetylcholine Receptors ◽  
Self Administration ◽  
Cellular Mechanisms ◽  
Lateral Habenula ◽  
Selective Blockade ◽  
Cocaine Seeking

The lateral habenula (LHb) plays a central role in balancing reward and aversion by opposing the contributions of brain reward nuclei. Using a rat cocaine self-administration model, we previously found that LHb inhibition or non-selective blockade of LHb muscarinic acetylcholine receptors (mAChRs) led to persistent cocaine seeking despite its signaled unavailability. As understanding roles for the LHb and cholinergic signaling in behavioral control is important to psychiatric illness and addiction, we examine how mAChRs act on LHb neurons using in vitro electrophysiology. We find that different groups of LHb neurons are depolarized or hyperpolarized by the cholinergic agonist carbachol (CCh), and that CCh could inhibit GABAergic and glutamatergic synaptic inputs to these cells. Presynaptic CCh effects were reversed by the M2 mAChR (M2R) antagonist AFDX-116, but not by pirenzepine, an M1R antagonist. Contemporaneous measurement of CCh effects on synaptic inhibition and excitation in LHb neurons showed a smaller effect on inhibition, suggesting a net shift in synaptic integration toward greater inhibition by mAChRs. Synaptic currents elicited by light-activation of ventral tegmental area (VTA) axons in the LHb, following channelrhodopsin-2 transfection of VTA, were also inhibited by M2Rs, suggesting the VTA as at least one M2R-sensitive LHb afferent. Finally, Go-NoGo cocaine seeking studies showed that blockade of LHb M2Rs, and not M1Rs, triggered continued cocaine seeking. These data identify LHb M2Rs as a potential control point of LHb function that enables withholding responses for cocaine and define cellular mechanisms through which mAChRs modulate LHb activity.

scholarly journals Effects of acute and repeated administration of the selective M4 PAM VU0152099 on cocaine vs. food choice in male rats

2021 ◽  
Author(s):  
Morgane H Thomsen ◽  
Jill R Crittenden ◽  
Craig W. Lindsley ◽  
Ann M. Graybiel
Keyword(s):  
Acetylcholine Receptors ◽  
Repeated Administration ◽  
Muscarinic Acetylcholine Receptors ◽  
Male Rats ◽  
Contrast Effects ◽  
Self Administration ◽  
Cocaine Use ◽  
Dopamine Receptor Antagonists ◽  
Cocaine Seeking ◽  
Term Administration

Ligands that stimulate muscarinic acetylcholine receptors 1 and 4 (M1, M4) have shown promising effects as putative pharmacotherapy for cocaine use disorder in rodent assays. We have previously shown reductions in cocaine effects with acute M4 stimulation, as well as long-lasting, delayed, reductions in cocaine taking and cocaine seeking with combined M1/M4 receptor stimulation or with M1 stimulation alone. M4 stimulation opposes dopaminergic signaling acutely, but direct dopamine receptor antagonists have proved unhelpful in managing cocaine use disorder because they lose efficacy with long-term administration. It is therefore critical to determine whether M4 approaches themselves can remain effective with repeated or chronic dosing. We assessed the effects of repeated administration of the M4 positive allosteric modulator (PAM) VU0152099 in rats trained to choose between intravenous cocaine and a liquid food reinforcer, to obtain quantitative measurement of whether M4 stimulation could produce delayed and lasting reduction in cocaine taking. VU0152099 produced progressively augmenting suppression of cocaine choice and cocaine intake, but produced neither rebound nor lasting effects after treatment ended. To compare and contrast effects of M1 vs. M4 stimulation, we tested whether the M4 PAM VU0152100 suppressed cocaine self-administration in mice lacking CalDAG-GEFI signaling factor, required for M1- mediated suppression of cocaine self-administration. CalDAG-GEFI ablation had no effect on M4- mediated suppression of cocaine self-administration. These findings support the potential usefulness of M4 PAMs as pharmacotherapy to manage cocaine use disorder, alone or in combination with M1-selective ligands, and show that M1 and M4 stimulation modulate cocaine-taking behavior by distinct mechanisms.

scholarly journals Structure and selectivity engineering of the M1 muscarinic receptor toxin complex

Science ◽  
2020 ◽  
Vol 369 (6500) ◽  
pp. 161-167 ◽  
Author(s):  
Shoji Maeda ◽  
Jun Xu ◽  
Francois Marie N. Kadji ◽  
Mary J. Clark ◽  
Jiawei Zhao ◽  
...  
Keyword(s):  
Acetylcholine Receptors ◽  
Muscarinic Acetylcholine Receptors ◽  
Tertiary Structures ◽  
Venom Toxin ◽  
Natural Toxins ◽  
Subtype Specificity ◽  
Snake Venom Toxin ◽  
M1 Muscarinic ◽  
Subtype Selective

Muscarinic toxins (MTs) are natural toxins produced by mamba snakes that primarily bind to muscarinic acetylcholine receptors (MAChRs) and modulate their function. Despite their similar primary and tertiary structures, MTs show distinct binding selectivity toward different MAChRs. The molecular details of how MTs distinguish MAChRs are not well understood. Here, we present the crystal structure of M1AChR in complex with MT7, a subtype-selective anti-M1AChR snake venom toxin. The structure reveals the molecular basis of the extreme subtype specificity of MT7 for M1AChR and the mechanism by which it regulates receptor function. Through in vitro engineering of MT7 finger regions that was guided by the structure, we have converted the selectivity from M1AChR toward M2AChR, suggesting that the three-finger fold is a promising scaffold for developing G protein–coupled receptor modulators.

scholarly journals Presynaptic cholinergic neuromodulation alters the temporal dynamics of short-term depression at parvalbumin-positive basket cell synapses from juvenile CA1 mouse hippocampus

2015 ◽  
Vol 113 (7) ◽  
pp. 2408-2419 ◽  
Author(s):  
J. Josh Lawrence ◽  
Heikki Haario ◽  
Emily F. Stone
Keyword(s):  
Pyramidal Cell ◽  
Acetylcholine Receptors ◽  
Temporal Dynamics ◽  
Hippocampal Slices ◽  
Pyramidal Cells ◽  
Calcium Transient ◽  
Muscarinic Acetylcholine Receptors ◽  
Presynaptic Calcium

Parvalbumin-positive basket cells (PV BCs) of the CA1 hippocampus are active participants in theta (5–12 Hz) and gamma (20–80 Hz) oscillations in vivo. When PV BCs are driven at these frequencies in vitro, inhibitory postsynaptic currents (IPSCs) in synaptically connected CA1 pyramidal cells exhibit paired-pulse depression (PPD) and multiple-pulse depression (MPD). Moreover, PV BCs express presynaptic muscarinic acetylcholine receptors (mAChRs) that may be activated by synaptically released acetylcholine during learning behaviors in vivo. Using acute hippocampal slices from the CA1 hippocampus of juvenile PV-GFP mice, we performed whole cell recordings from synaptically connected PV BC-CA1 pyramidal cell pairs to investigate how bath application of 10 μM muscarine impacts PPD and MPD at CA1 PV BC-pyramidal cell synapses. In accordance with previous studies, PPD and MPD magnitude increased with stimulation frequency. mAChR activation reduced IPSC amplitude and transiently reduced PPD, but MPD was largely maintained. Consistent with a reduction in release probability ( pr), MPD and mAChR activation increased both the coefficient of variation of IPSC amplitudes and the fraction of failures. Using variance-mean analysis, we converted MPD trains to pr functions and developed a kinetic model that optimally fit six distinct pr conditions. The model revealed that vesicular depletion caused MPD and that recovery from depression was dependent on calcium. mAChR activation reduced the presynaptic calcium transient fourfold and initial pr twofold, thereby reducing PPD. However, mAChR activation slowed calcium-dependent recovery from depression during sustained repetitive activity, thereby preserving MPD. Thus the activation of presynaptic mAChRs optimally protects PV BCs from vesicular depletion during short bursts of high-frequency activity.

scholarly journals Regulation of the transient receptor potential channel TRPM3 by phosphoinositides

2015 ◽  
Vol 146 (1) ◽  
pp. 51-63 ◽  
Author(s):  
Balázs I. Tóth ◽  
Maik Konrad ◽  
Debapriya Ghosh ◽  
Florian Mohr ◽  
Christian R. Halaszovich ◽  
...  
Keyword(s):  
Acetylcholine Receptors ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Membrane Receptors ◽  
Muscarinic Acetylcholine Receptors ◽  
Cellular Mechanisms ◽  
Dynamic Regulation ◽  
Transient Receptor ◽  
Phosphatidylinositol Phosphates

The transient receptor potential (TRP) channel TRPM3 is a calcium-permeable cation channel activated by heat and by the neurosteroid pregnenolone sulfate (PregS). TRPM3 is highly expressed in sensory neurons, where it plays a key role in heat sensing and inflammatory hyperalgesia, and in pancreatic β cells, where its activation enhances glucose-induced insulin release. However, despite its functional importance, little is known about the cellular mechanisms that regulate TRPM3 activity. Here, we provide evidence for a dynamic regulation of TRPM3 by membrane phosphatidylinositol phosphates (PIPs). Phosphatidylinositol 4,5-bisphosphate (PI[4,5]P2) and ATP applied to the intracellular side of excised membrane patches promote recovery of TRPM3 from desensitization. The stimulatory effect of cytosolic ATP on TRPM3 reflects activation of phosphatidylinositol kinases (PI-Ks), leading to resynthesis of PIPs in the plasma membrane. Various PIPs directly enhance TRPM3 activity in cell-free inside-out patches, with a potency order PI(3,4,5)P3 > PI(3,5)P2 > PI(4,5)P2 ≈ PI(3,4)P2 >> PI(4)P. Conversely, TRPM3 activity is rapidly and reversibly inhibited by activation of phosphatases that remove the 5-phosphate from PIPs. Finally, we show that recombinant TRPM3, as well as the endogenous TRPM3 in insuloma cells, is rapidly and reversibly inhibited by activation of phospholipase C–coupled muscarinic acetylcholine receptors. Our results reveal basic cellular mechanisms whereby membrane receptors can regulate TRPM3 activity.

scholarly journals Control of Cardiac Function in vivo with a Light-Regulated Drug

2018 ◽  
Author(s):  
Fabio Riefolo ◽  
Carlo Matera ◽  
Aida Garrido-Charles ◽  
Alexandre M. J. Gomila ◽  
Luca Agnetta ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Mammalian Cells ◽  
Acetylcholine Receptors ◽  
Genetic Manipulation ◽  
Muscarinic Acetylcholine Receptors ◽  
Therapeutic Interventions ◽  
Muscarinic Acetylcholine ◽  
First Time

<p>Remote control of physiological functions with light offers the promise of unveiling their complex spatiotemporal dynamics in vivo, and enabling highly focalized therapeutic interventions with reduced systemic toxicity. Optogenetic methods have been implemented in the heart, but the need of genetic manipulation jeopardizes clinical applicability. This study aims at developing, testing and validating the first light-regulated drug with cardiac effects, in order to avoid the requirement of genetic manipulation offered by optogenetic methods. A M2 muscarinic acetylcholine receptors (mAChRs) light-regulated drug (PAI) was designed, synthesized and pharmacologically characterized. The design was based on the orthosteric mAChRs agonist Iperoxo, an allosteric M2 ligand, and a photoswitchable azobenzene linker. PAI can be reversibly photoisomerized between <i>cis</i> and <i>trans</i> configurations under ultraviolet (UV) and visible light, respectively, and it reversibly photoswitches the activity of M2 muscarinic acetylcholine receptors. We have evaluated <i>in vitro</i> photoresponses using a calcium imaging assay in genetically unmodified receptors overexpressed in mammalian cells. Furthermore, using this new chemical tool, we demonstrate for the first time photoregulation of cardiac function <i>in vivo</i> in wildtype frog tadpoles and in rats with a method that does not require genetic manipulation. Such a new approach may enable enhanced spatial and temporal selectivity for cardiovascular drugs.</p>

scholarly journals Novel Analgesic Agents Obtained by Molecular Hybridization of Orthosteric and Allosteric Ligands

2019 ◽  
Author(s):  
Carlo Matera ◽  
Lisa Flammini ◽  
Fabio Riefolo ◽  
Giuseppe Domenichini ◽  
Marco De Amici ◽  
...  
Keyword(s):  
Acetylcholine Receptors ◽  
Functional Characterization ◽  
Unmet Need ◽  
Muscarinic Acetylcholine Receptors ◽  
Molecular Hybridization ◽  
Bioactive Substances ◽  
Pharmacological Agents ◽  
Nociceptive Transmission ◽  
Analgesic Agents

AbstractDespite the high incidence of acute and chronic pain in the general population, the efficacy of currently available medications is unsatisfactory. Insufficient management of pain has a profound impact on the quality of life and can have serious physical, psychological, social, and economic consequences. This unmet need reflects a failure to develop novel classes of analgesic drugs with superior clinical properties and lower risk of abuse. Nevertheless, recent advances in our understanding of the neurobiology of pain are offering new opportunities for developing different therapeutic approaches. Among those, the activation of M2 muscarinic acetylcholine receptors, which play a key role in the cholinergic regulation of the nociceptive transmission, constitutes one of the most promising strategies. We have recently developed a small library of novel pharmacological agents by merging the structures of known orthosteric and allosteric muscarinic ligands through their molecular hybridization, an emerging approach in medicinal chemistry based on the combination of pharmacophoric moieties of different bioactive substances to produce a new compound with improved pharmacological properties. Herein we report the functional characterization of the new ligands in vitro and the assessment of their efficacy as analgesic agents and tolerability in mice. This work provides new insights for the development and optimization of novel muscarinic hybrid compounds for the management of pain.

Temporally distinct mechanisms of use-dependent depression at inhibitory synapses in the rat hippocampus in vitro

1994 ◽  
Vol 72 (1) ◽  
pp. 121-130 ◽  
Author(s):  
N. A. Lambert ◽  
W. A. Wilson
Keyword(s):  
Acetylcholine Receptors ◽  
Interstimulus Interval ◽  
Gabab Receptor ◽  
Muscarinic Acetylcholine Receptors ◽  
Rat Hippocampus ◽  
Inhibitory Neurons ◽  
Inhibitory Synapses ◽  
Gamma Aminobutyric Acid ◽  
Independent Components

1. Gamma-aminobutyric acid-B (GABAB) autoreceptor-dependent and -independent components of paired-pulse depression (PPD) at inhibitory synapses in area CA3 of the rat hippocampus were studied using whole-cell recording techniques. Inhibitory fibers were activated directly in the presence of the ionotropic glutamate receptor antagonists 6,7-dinitroquinoxaline-2,3,dione (20 microM) and D-2-amino-5-phosphonovalerate (20 microM). 2. When pairs of monosynaptic inhibitory postsynaptic currents (eIPSCs) were evoked with an interstimulus interval of 200 ms, the amplitude of the second response (eIPSC2) was depressed when compared with the first (eIPSC1). The GABAB receptor agonist baclofen (10 microM) depressed both responses, but eIPSC1 was depressed more than eIPSC2, resulting in PPD that was comparatively smaller. Addition of the GABAB receptor antagonist CGP 55845A (1 microM) completely reversed depression of eIPSC1 by baclofen and increased the amplitude of eIPSC2 above the control value, such that PPD in the combination of baclofen and CGP 55845A was equivalent to that in baclofen alone. The ratio eIPSC2/eIPSC1 was 0.64 under control conditions, 0.77 in the presence of baclofen, and 0.79 in the presence of baclofen and CGP 55845A. These results demonstrate the existence of two components of PPD at inhibitory synapses, one that depends on activation of GABAB autoreceptors (GABAB receptor-dependent PPD) and one that does not (GABAB receptor-independent PPD). 3. When the number of inhibitory fibers activated was lowered by decreasing the stimulus intensity, eIPSC2/eIPSC1 was 0.76 under control conditions, 0.75 in the presence of baclofen, and 0.76 in the presence of baclofen and CGP 55845A. These results indicate that GABAB receptor-dependent PPD requires activation of several presynaptic inhibitory neurons, whereas GABAB receptor-independent PPD does not. 4. The time-courses of the GABAB-dependent and -independent components of PPD were compared by varying the interstimulus interval in the absence and presence of CGP 55845A. GABAB-dependent PPD was maximal at an interstimulus interval of 100 ms and was undetectable at 1 s. In contrast, GABAB-independent PPD was maximal at 5 ms and 1 s, was slightly less pronounced at intermediate intervals (50–200 ms), and was present at intervals as long as 5 s. 5. GABAB-independent PPD was not blocked by antagonists at opioid receptors (10 microM naloxone) or muscarinic acetylcholine receptors (10 microM atropine). GABAB-independent PPD could not be accounted for by a decrease in driving force because of Cl- redistribution.(ABSTRACT TRUNCATED AT 400 WORDS)

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