RESUMO
BACKGROUND AND PURPOSE: Current pharmacotherapies for Tourette syndrome (TS) are often unsatisfactory and poorly tolerated, underscoring the need for novel treatments. Insufficient striatal acetylcholine has been suggested to contribute to tic ontogeny. Thus, we tested whether activating M1 and/or M4 receptors-the two most abundant muscarinic receptors in the striatum-reduced tic-related behaviours in mouse models of TS. EXPERIMENTAL APPROACH: Studies were conducted using CIN-d and D1CT-7 mice, two TS models characterized by early-life depletion of striatal cholinergic interneurons and cortical neuropotentiation, respectively. First, we tested the effects of systemic and intrastriatal xanomeline, a selective M1/M4 receptor agonist, on tic-like and other TS-related responses. Then, we examined whether xanomeline effects were reduced by either M1 or M4 antagonists or mimicked by the M1/M3 agonist cevimeline or the M4 positive allosteric modulator (PAM) VU0467154. Finally, we measured striatal levels of M1 and M4 receptors and assessed the impact of VU0461754 on the striatal expression of the neural marker activity c-Fos. KEY RESULTS: Systemic and intrastriatal xanomeline reduced TS-related behaviours in CIN-d and D1CT-7 mice. Most effects were blocked by M4, but not M1, receptor antagonists. VU0467154, but not cevimeline, elicited xanomeline-like ameliorative effects in both models. M4, but not M1, receptors were down-regulated in the striatum of CIN-d mice. Additionally, VU0467154 reduced striatal c-Fos levels in these animals. CONCLUSION AND IMPLICATIONS: Activation of striatal M4, but not M1, receptors reduced tic-like manifestations in mouse models, pointing to xanomeline and M4 PAMs as novel putative therapeutic strategies for TS.
Assuntos
Corpo Estriado , Modelos Animais de Doenças , Agonistas Muscarínicos , Receptor Muscarínico M4 , Síndrome de Tourette , Animais , Síndrome de Tourette/metabolismo , Síndrome de Tourette/tratamento farmacológico , Receptor Muscarínico M4/metabolismo , Receptor Muscarínico M4/agonistas , Receptor Muscarínico M4/antagonistas & inibidores , Camundongos , Corpo Estriado/metabolismo , Corpo Estriado/efeitos dos fármacos , Masculino , Agonistas Muscarínicos/farmacologia , Comportamento Animal/efeitos dos fármacos , Piridinas/farmacologia , Tiques/tratamento farmacológico , Tiques/metabolismo , Tiofenos/farmacologia , Receptor Muscarínico M1/metabolismo , Receptor Muscarínico M1/agonistas , Dioxóis/farmacologia , Camundongos Endogâmicos C57BL , TiadiazóisRESUMO
Muscarinic acetylcholine receptors (mAChRs) play a significant role in the pathophysiology of schizophrenia. Although activating mAChRs holds potential in addressing the full range of schizophrenia symptoms, clinical application of many non-selective mAChR agonists in cognitive deficits, positive and negative symptoms is hindered by peripheral side effects (gastrointestinal disturbances and cardiovascular effects) and dosage restrictions. Ligands binding to the allosteric sites of mAChRs, particularly the M1 and M4 subtypes, demonstrate activity in improving cognitive function and amelioration of positive and negative symptoms associated with schizophrenia, enhancing our understanding of schizophrenia. The article aims to critically examine current design concepts and clinical advancements in synthesizing and designing small molecules targeting M1/M4, providing theoretical insights and empirical support for future research in this field.
Assuntos
Antipsicóticos , Receptor Muscarínico M1 , Esquizofrenia , Antipsicóticos/farmacologia , Antipsicóticos/química , Antipsicóticos/uso terapêutico , Estrutura Molecular , Receptor Muscarínico M1/metabolismo , Receptor Muscarínico M1/agonistas , Receptor Muscarínico M1/antagonistas & inibidores , Receptor Muscarínico M4/metabolismo , Receptor Muscarínico M4/antagonistas & inibidores , Esquizofrenia/tratamento farmacológico , Esquizofrenia/metabolismoRESUMO
In this manuscript, we report a series of chiral 6-azaspiro[2.5]octanes and related spirocycles as highly potent and selective antagonists of the muscarinic acetylcholine receptor subtype 4 (mAChR4). Chiral separation and subsequent X-ray crystallographic analysis of early generation analogs revealed the R enantiomer to possess excellent human and rat M4 potency, and further structure-activity relationship (SAR) studies on this chiral scaffold led to the discovery of VU6015241 (compound 19). Compound 19 is characterized by high M4 potency and selectivity across multiple species, excellent aqueous solubility, and moderate brain exposure in rodents after intraperitoneal administration.
Assuntos
Antagonistas Muscarínicos/farmacologia , Receptor Muscarínico M4/antagonistas & inibidores , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Antagonistas Muscarínicos/síntese química , Antagonistas Muscarínicos/química , Receptor Muscarínico M4/metabolismo , Relação Estrutura-AtividadeRESUMO
This Letter details our efforts to develop novel tricyclic M4 PAM scaffolds with improved pharmacological properties. This endeavor involved a "tie-back" strategy to replace the 3-amino-4,6-dimethylthieno[2,3-b]pyridine-2-carboxamide core which lead to the discovery of two novel tricyclic cores: a 7,9-dimethylpyrido[3',2':4,5]thieno[3,2-d]pyrimidine core and 2,4-dimethylthieno[2,3-b:5,4-c']dipyridine core. Both tricyclic cores displayed low nanomolar potency against the human M4 receptor.
Assuntos
Descoberta de Drogas , Pirimidinas/farmacologia , Receptor Muscarínico M4/antagonistas & inibidores , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Pirimidinas/síntese química , Pirimidinas/química , Receptor Muscarínico M4/metabolismo , Relação Estrutura-AtividadeRESUMO
Monoamine oxidases (MAOs) and muscarinic acetylcholine receptors (mAChRs) are considered important therapeutic targets for Parkinson's disease (PD). Lipophilic tanshinones are major phytoconstituents in the dried roots of Salvia miltiorrhiza that have demonstrated neuroprotective effects against dopaminergic neurotoxins and the inhibition of MAO-A. Since MAO-B inhibition is considered an effective therapeutic strategy for PD, we tested the inhibitory activities of three abundant tanshinone congeners against recombinant human MAO (hMAO) isoenzymes through in vitro experiments. In our study, tanshinone I (1) exhibited the highest potency against hMAO-A, followed by tanshinone IIA and cryptotanshinone, with an IC50 less than 10 µM. They also suppressed hMAO-B activity, with an IC50 below 25 µM. Although tanshinones are known to inhibit hMAO-A, their enzyme inhibition mechanism and binding sites have yet to be investigated. Enzyme kinetics and molecular docking studies have revealed the mode of inhibition and interactions of tanshinones during enzyme inhibition. Proteochemometric modeling predicted mAChRs as possible pharmacological targets of 1, and in vitro functional assays confirmed the selective M4 antagonist nature of 1 (56.1% ± 2.40% inhibition of control agonist response at 100 µM). These findings indicate that 1 is a potential therapeutic molecule for managing the motor dysfunction and depression associated with PD.
Assuntos
Abietanos , Inibidores da Monoaminoxidase , Monoaminoxidase , Fenantrenos , Receptor Muscarínico M4 , Salvia miltiorrhiza/química , Abietanos/química , Abietanos/farmacologia , Animais , Células CHO , Cricetulus , Humanos , Monoaminoxidase/química , Monoaminoxidase/genética , Monoaminoxidase/metabolismo , Inibidores da Monoaminoxidase/química , Inibidores da Monoaminoxidase/farmacologia , Fenantrenos/química , Fenantrenos/farmacologia , Receptor Muscarínico M4/antagonistas & inibidores , Receptor Muscarínico M4/química , Receptor Muscarínico M4/genética , Receptor Muscarínico M4/metabolismoRESUMO
Divided attention may be more important than ever to comprehend, given ubiquitous distractors in modern living. In humans, concern has been expressed about the negative impact of distraction in education, the home, and the workplace. While acetylcholine supports divided attention, in part via muscarinic receptors, little is known about the specific muscarinic subtypes that may contribute. We designed a novel, high-response rate test of auditory sustained attention, in which rats complete variable-ratio runs on one of two levers, rather than emitting a single response. By doing this, we can present a secondary visual distractor task during some trials, for which a correct nosepoke response is reinforced with a more palatable food pellet. The nonspecific muscarinic antagonist scopolamine impaired performance, and slowed and reduced lever press activity. We then explored antagonists that preferentially block the M1 and M4 subtypes, because these receptors are potential therapeutic targets for cognitive enhancers. Telenzepine, an M1-preferring antagonist, impaired divided attention performance, but not performance of the attention task without distraction. Telenzepine also had fewer nonspecific effects than scopolamine. In contrast, the M4-preferring antagonist tropicamide had no effects. Analysis of overall behavior also indicated that accuracy in the main attention task decreased as a function of engagement with the distractor task. These results implicate the M1 receptor in divided attention.
Assuntos
Atenção/efeitos dos fármacos , Antagonistas Muscarínicos/farmacologia , Receptor Muscarínico M1/antagonistas & inibidores , Receptor Muscarínico M4/antagonistas & inibidores , Acetilcolina/farmacologia , Animais , Condicionamento Operante , Humanos , Masculino , Comportamento Multitarefa/efeitos dos fármacos , Pirenzepina/análogos & derivados , Pirenzepina/farmacologia , Ratos , Ratos Sprague-Dawley , Receptor Muscarínico M1/metabolismo , Receptor Muscarínico M4/metabolismo , Escopolamina/farmacologia , Tropicamida/farmacologiaRESUMO
BACKGROUND: Previous studies suggest that muscarinic cholinergic receptors might act upon the dopamine release in the mesolimbic system and alter drug-reinforcing values related to drug craving. AIMS: We examined the effects of systemic biperiden administration, a muscarinic cholinergic (M1/M4) receptor antagonist, on ethanol (dose of 2 g/Kg) conditioned place preference (CPP), neuronal activation, dopamine and its metabolites levels in the nucleus accumbens. METHODS: Thirty minutes before the ethanol-induced CPP test, mice received saline or biperiden at doses of 1.0, 5.0, or 10.0 mg/kg. The time spent in each compartment was recorded for 15 min. After the CPP protocol, animals were euthanized, and we investigated the activation of the nucleus accumbens by immunohistochemistry for Fos. We also quantified dopamine, homovanillic acid (HVA), and dihydroxyphenylacetic acid (DOPAC) levels in the nucleus accumbens by high-performance liquid chromatography (HPLC). Additionally, the rotarod was employed to evaluate the effects of biperiden on motor coordination. RESULTS: Biperiden at different doses (1.0, 5.0, and 10.0 mg/kg) blocked the expression of ethanol-induced CPP. These biperiden doses increased the number of Fos-positive cells and the dopamine turnover in the nucleus accumbens. None of the doses affected the motor coordination evaluated by the rotarod. CONCLUSIONS: Our results show that biperiden can modulate the effect of alcohol reward, and its mechanism of action may involve a change in dopamine and cholinergic mesolimbic neurotransmission.
Assuntos
Biperideno/administração & dosagem , Condicionamento Clássico/efeitos dos fármacos , Etanol/administração & dosagem , Antagonistas Muscarínicos/administração & dosagem , Receptor Muscarínico M1/antagonistas & inibidores , Receptor Muscarínico M4/antagonistas & inibidores , Animais , Condicionamento Clássico/fisiologia , Dopamina/metabolismo , Relação Dose-Resposta a Droga , Ácido Homovanílico/metabolismo , Injeções Intraperitoneais , Masculino , Camundongos , Núcleo Accumbens/efeitos dos fármacos , Núcleo Accumbens/metabolismo , Receptor Muscarínico M1/metabolismo , Receptor Muscarínico M4/metabolismoRESUMO
Acetylcholine muscarinic receptors (mAChRs) contribute to both the facilitation and inhibition of levodopa-induced dyskinesia operated by striatal cholinergic interneurons, although the receptor subtypes involved remain elusive. Cholinergic afferents from the midbrain also innervate the substantia nigra reticulata, although the role of nigral mAChRs in levodopa-induced dyskinesia is unknown. Here, we investigate whether striatal and nigral M1 and/or M4 mAChRs modulate dyskinesia and the underlying striato-nigral GABAergic pathway activation in 6-hydroxydopamine hemilesioned rats. Reverse microdialysis allowed to deliver the mAChR antagonists telenzepine (M1 subtype preferring), PD-102807 and tropicamide (M4 subtype preferring), as well as the selective M4 mAChR positive allosteric modulator VU0152100 in striatum or substantia nigra, while levodopa was administered systemically. Dyskinetic movements were monitored along with nigral GABA (and glutamate) and striatal glutamate dialysate levels, taken as neurochemical correlates of striato-nigral pathway and cortico-basal ganglia-thalamo-cortical loop activation. We observed that intrastriatal telenzepine, PD-102807 and tropicamide alleviated dyskinesia and inhibited nigral GABA and striatal glutamate release. This was partially replicated by intrastriatal VU0152100. The M2 subtype preferring antagonist AFDX-116, used to elevate striatal acetylcholine levels, blocked the behavioral and neurochemical effects of PD-102807. Intranigral VU0152100 prevented levodopa-induced dyskinesia and its neurochemical correlates whereas PD-102807 was ineffective. These results suggest that striatal, likely postsynaptic, M1 mAChRs facilitate dyskinesia and striato-nigral pathway activation in vivo. Conversely, striatal M4 mAChRs can both facilitate and inhibit dyskinesia, possibly depending on their localization. Potentiation of striatal and nigral M4 mAChR transmission leads to powerful multilevel inhibition of striato-nigral pathway and attenuation of dyskinesia.
Assuntos
Dopaminérgicos/efeitos adversos , Discinesia Induzida por Medicamentos/metabolismo , Levodopa/efeitos adversos , Neostriado/metabolismo , Receptor Muscarínico M1/metabolismo , Receptor Muscarínico M4/metabolismo , Substância Negra/metabolismo , Regulação Alostérica , Animais , Discinesia Induzida por Medicamentos/etiologia , Discinesia Induzida por Medicamentos/fisiopatologia , Ácido Glutâmico/efeitos dos fármacos , Ácido Glutâmico/metabolismo , Microdiálise , Antagonistas Muscarínicos/farmacologia , Neostriado/efeitos dos fármacos , Vias Neurais , Oxidopamina/toxicidade , Transtornos Parkinsonianos/tratamento farmacológico , Transtornos Parkinsonianos/etiologia , Transtornos Parkinsonianos/metabolismo , Ratos , Receptor Muscarínico M1/antagonistas & inibidores , Receptor Muscarínico M4/antagonistas & inibidores , Substância Negra/efeitos dos fármacos , Simpatolíticos/toxicidade , Ácido gama-Aminobutírico/efeitos dos fármacos , Ácido gama-Aminobutírico/metabolismoRESUMO
Opioids strongly inhibit GABAergic neurons in the rostromedial tegmental nucleus (RMTg) that expresses µ-opioid receptors to induce rewarding and psychomotor effects. M3 and M4 muscarinic receptors are co-localized with µ-opioid receptors at these GABAergic neurons. This study explored whether RMTg M3 and M4 muscarinic receptors are involved in regulating opioid-induced reward and locomotion via a conditioned place preference (CPP) paradigm. Selective muscarinic receptor agonists and antagonists were both singly and combinatorically injected into the RMTg to examine their effects on the acquisition of systemic morphine-induced CPP and locomotor activity. The M3 muscarinic receptor agonist, pilocarpine, inhibited the acquisition of morphine-induced CPP, whereas its antagonist, 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP, 1 µg/side), reversed the inhibitory effect of pilocarpine (30 µg/side). Additionally, 4-DAMP increased locomotor activity while pilocarpine (30 µg/side) partially decreased locomotor activity when combined with morphine. In contrast, the M4 muscarinic receptor agonist, LY2033298 (0.1 and 0.2 µg/side), and antagonist, tropicamide (20 and 40 µM/side), did not affect the acquisition of morphine-induced CPP or locomotor activity. Taken together, our findings suggest that RMTg M3 muscarinic receptors are involved in opioid-induced rewarding and psychomotor effects. Therefore, RMTg M3 muscarinic receptors may represent a promising target for the treatment of opioid addiction.
Assuntos
Condicionamento Psicológico , Receptor Muscarínico M3/metabolismo , Recompensa , Tegmento Mesencefálico/metabolismo , Analgésicos Opioides , Animais , Locomoção/efeitos dos fármacos , Masculino , Morfina , Agonistas Muscarínicos/farmacologia , Antagonistas Muscarínicos/farmacologia , Ratos Wistar , Receptor Muscarínico M3/agonistas , Receptor Muscarínico M3/antagonistas & inibidores , Receptor Muscarínico M4/agonistas , Receptor Muscarínico M4/antagonistas & inibidores , Receptor Muscarínico M4/metabolismoRESUMO
The septo-hippocampal cholinergic system is critical for hippocampal learning and memory. However, a quantitative description of the in vivo firing patterns and physiological function of medial septal (MS) cholinergic neurons is still missing. In this study, we combined optogenetics with multichannel in vivo recording and recorded MS cholinergic neuron firings in freely behaving male mice for 5.5-72 h. We found that their firing activities were highly correlated with hippocampal theta states. MS cholinergic neurons were highly active during theta-dominant epochs, such as active exploration and rapid eye movement sleep, but almost silent during non-theta epochs, such as slow-wave sleep (SWS). Interestingly, optogenetic activation of these MS cholinergic neurons during SWS suppressed CA1 ripple oscillations. This suppression could be rescued by muscarinic M2 or M4 receptor antagonists. These results suggest the following important physiological function of MS cholinergic neurons: maintaining high hippocampal acetylcholine level by persistent firing during theta epochs, consequently suppressing ripples and allowing theta oscillations to dominate.SIGNIFICANCE STATEMENT The major source of acetylcholine in the hippocampus comes from the medial septum. Early experiments found that lesions to the MS result in the disappearance of hippocampal theta oscillation, which leads to speculation that the septo-hippocampal cholinergic projection contributing to theta oscillation. In this article, by long-term recording of MS cholinergic neurons, we found that they show a theta state-related firing pattern. However, optogenetically activating these neurons shows little effect on theta rhythm in the hippocampus. Instead, we found that activating MS cholinergic neurons during slow-wave sleep could suppress hippocampal ripple oscillations. This suppression is mediated by muscarinic M2 and M4 receptors.
Assuntos
Potenciais de Ação/fisiologia , Neurônios Colinérgicos/fisiologia , Hipocampo/fisiologia , Receptor Muscarínico M2/fisiologia , Receptor Muscarínico M4/fisiologia , Ritmo Teta/fisiologia , Potenciais de Ação/efeitos dos fármacos , Animais , Agonistas Colinérgicos/farmacologia , Neurônios Colinérgicos/química , Neurônios Colinérgicos/efeitos dos fármacos , Hipocampo/química , Hipocampo/efeitos dos fármacos , Masculino , Camundongos , Camundongos Transgênicos , Antagonistas Muscarínicos/farmacologia , Optogenética/métodos , Técnicas de Cultura de Órgãos , Receptor Muscarínico M2/agonistas , Receptor Muscarínico M2/antagonistas & inibidores , Receptor Muscarínico M4/agonistas , Receptor Muscarínico M4/antagonistas & inibidores , Receptores Muscarínicos/fisiologia , Ritmo Teta/efeitos dos fármacosRESUMO
The rostromedial tegmental nucleus (RMTg) receives inputs from the laterodorsal tegmental and pedunculopontine tegmental nuclei, the two principle brainstem cholinergic nuclei. We tested the effects of RMTg M3 and M4 muscarinic cholinergic receptor antagonism in a conditioned place preference (CPP) paradigm in mice. RMTg infusions of the M3 muscarinic cholinergic receptor antagonist 1,1-Dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP) do not result in the acquisition of CPP but increase locomotor activation. By contrast, RMTg infusions of the M4 muscarinic cholinergic receptor antagonist Tropicamide result in the acquisition of CPP but do not increase locomotor activation. The rewarding effects of RMTg Tropicamide infusions are dopamine-dependent as systemic pre-treatment with the broad-spectrum dopamine receptor antagonist flupenthixol prevents the acquisition of CPP induced by RMTg Tropicamide infusions. Under conditions of systemic dopamine receptor blockade, RMTg Tropicamide infusions significantly increase locomotor activation. These data provide further support for an important role of endogenous cholinergic input to the RMTg in reward function and suggest that the contributions of RMTg cholinergic input to rewarding and locomotor-activating effects involve differential contributions of RMTg M4 and M3 muscarinic receptors, respectively.
Assuntos
Comportamento Animal/efeitos dos fármacos , Condicionamento Psicológico/efeitos dos fármacos , Antagonistas de Dopamina/farmacologia , Locomoção/efeitos dos fármacos , Antagonistas Muscarínicos/farmacologia , Receptor Muscarínico M3/antagonistas & inibidores , Receptor Muscarínico M4/antagonistas & inibidores , Recompensa , Área Tegmentar Ventral/efeitos dos fármacos , Animais , Antagonistas de Dopamina/administração & dosagem , Flupentixol/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Antagonistas Muscarínicos/administração & dosagem , Piperidinas/farmacologia , Tropicamida/farmacologiaRESUMO
Acetylcholine (ACh) released from cholinergic interneurons acting through nicotinic and muscarinic acetylcholine receptors (mAChRs) in the striatum have been thought to be central for the potent cholinergic regulation of basal ganglia activity and motor behaviors. ACh activation of mAChRs has multiple actions to oppose dopamine (DA) release, signaling, and related motor behaviors and has led to the idea that a delicate balance of DA and mAChR signaling in the striatum is critical for maintaining normal motor function. Consistent with this, mAChR antagonists have efficacy in reducing motor symptoms in diseases where DA release or signaling is diminished, such as in Parkinson's disease and dystonia, but are limited in their utility because of severe adverse effects. Recent breakthroughs in understanding both the anatomical sites of action of ACh and the mAChR subtypes involved in regulating basal ganglia function reveal that the M4 subtype plays a central role in regulating DA signaling and release in the basal ganglia. These findings have raised the possibility that sources of ACh outside of the striatum can regulate motor activity and that M4 activity is a potent regulator of motor dysfunction. We discuss how M4 activity regulates DA release and signaling, the potential sources of ACh that can regulate M4 activity, and the implications of targeting M4 activity for the treatment of the motor symptoms in movement disorders. © 2019 International Parkinson and Movement Disorder Society.
Assuntos
Acetilcolina/metabolismo , Gânglios da Base/metabolismo , Dopamina/metabolismo , Transtornos dos Movimentos/metabolismo , Neostriado/metabolismo , Receptor Muscarínico M4/metabolismo , Neurônios Colinérgicos/metabolismo , Distonia/tratamento farmacológico , Distonia/metabolismo , Ácido Glutâmico/metabolismo , Humanos , Interneurônios/metabolismo , Terapia de Alvo Molecular , Transtornos dos Movimentos/tratamento farmacológico , Antagonistas Muscarínicos/uso terapêutico , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/metabolismo , Receptor Muscarínico M4/antagonistas & inibidores , Receptores Dopaminérgicos/metabolismo , Transmissão SinápticaRESUMO
Standard treatment for Parkinson's disease (PD) is L-DOPA, but with chronic administration the majority of patients develop L-DOPA-induced dyskinesia (LID). Emerging evidence implicates the cholinergic system in PD and LID. Muscarinic acetylcholine receptors (mAChR) are known to modulate movement and of late have been implicated as possible targets for LID. Therefore the current study investigated the role of M1 and M4 mAChRs in LID, on motor performance following L-DOPA treatment, and sought to identify brain sites through which these receptors were acting. We first administered M1R-preferring antagonist trihexyphenidyl (0, 0.1, and 1.0â¯mg/kg, i.p.) or the M4R-preferring antagonist tropicamide (0, 10, and 30â¯mg/kg, i.p.) before L-DOPA, after which LID and motor performance were evaluated. Both compounds worsened and extended the time course of LID, while M1R blockade improved motor performance. We then evaluated the effects of tropicamide and trihexyphenidyl on dyskinesia induced by D1R agonist SKF81297 or D2R agonist quinpirole. Surprisingly, both M1R and M4R antagonists reduced D1R agonist-induced dyskinesia but not D2R agonist-induced dyskinesia, suggesting that mAChR blockade differentially affects MSN firing in the absence of postsynaptic DA. Finally, we evaluated effects of striatum- or PPN-targeted tropicamide microinfusion on LID and motor performance. Despite prior evidence, M4R blockade in either site alone did not affect the severity of LID via local striatal or PPN infusions. Taken together, these data suggest M4R as a promising therapeutic target for reducing LID using more selective compounds.
Assuntos
Discinesia Induzida por Medicamentos/tratamento farmacológico , Antagonistas Muscarínicos/uso terapêutico , Doença de Parkinson Secundária/tratamento farmacológico , Receptor Muscarínico M1/antagonistas & inibidores , Receptor Muscarínico M4/antagonistas & inibidores , Animais , Antiparkinsonianos/efeitos adversos , Antiparkinsonianos/uso terapêutico , Comportamento Animal/efeitos dos fármacos , Corpo Estriado/efeitos dos fármacos , Levodopa/efeitos adversos , Levodopa/uso terapêutico , Masculino , Antagonistas Muscarínicos/farmacologia , Oxidopamina , Ratos , Ratos Sprague-Dawley , Resultado do Tratamento , Triexifenidil/farmacologia , Triexifenidil/uso terapêutico , Tropicamida/farmacologia , Tropicamida/uso terapêuticoRESUMO
This letter describes a focused exercise to explore the role of the ß-amino carboxamide moiety found in all of the first generation M4 PAMs and question if the NH2 group served solely to stabilize an intramolecular hydrogen bond (IMHB) and enforce planarity. To address this issue (and to potentially find a substitute for the ß-amino carboxamide that engendered P-gp and contributed to solubility liabilities), we removed the NH2, generating des-amino congeners and surveyed other functional groups in the ß-position. These modifications led to weak M4 PAMs with poor DMPK properties. Cyclization of the ß-amino carboxamide moiety by virtue of a pyrazole ring re-enforced the IMHB, led to potent (and patented) M4 PAMs, many as potent as the classical bicyclic ß-amino carboxamide analogs, but with significant CYP1A2 inhibition. Overall, this exercise indicated that the ß-amino carboxamide moiety most likely facilitates an IMHB, and is essential for M4 PAM activity within classical bicyclic M4 PAM scaffolds.
Assuntos
Amidas/farmacologia , Receptor Muscarínico M4/antagonistas & inibidores , Regulação Alostérica/efeitos dos fármacos , Amidas/síntese química , Amidas/química , Relação Dose-Resposta a Droga , Humanos , Ligação de Hidrogênio , Ligantes , Estrutura Molecular , Receptor Muscarínico M4/metabolismo , Relação Estrutura-AtividadeRESUMO
Disruptions to motivated behaviour are a highly prevalent and severe symptom in a number of neuropsychiatric and neurodegenerative disorders. Current treatment options for these disorders have little or no effect upon motivational impairments. We assessed the contribution of muscarinic acetylcholine receptors to motivated behaviour in mice, as a novel pharmacological target for motivational impairments. Touchscreen progressive ratio (PR) performance was facilitated by the nonselective muscarinic receptor antagonist scopolamine as well as the more subtype-selective antagonists biperiden (M1) and tropicamide (M4). However, scopolamine and tropicamide also produced increases in non-specific activity levels, whereas biperiden did not. A series of control tests suggests the effects of the mAChR antagonists were sensitive to changes in reward value and not driven by changes in satiety, motor fatigue, appetite or perseveration. Subsequently, a sub-effective dose of biperiden was able to facilitate the effects of amphetamine upon PR performance, suggesting an ability to enhance dopaminergic function. Both biperiden and scopolamine were also able to reverse a haloperidol-induced deficit in PR performance, however only biperiden was able to rescue the deficit in effort-related choice (ERC) performance. Taken together, these data suggest that the M1 mAChR may be a novel target for the pharmacological enhancement of effort exertion and consequent rescue of motivational impairments. Conversely, M4 receptors may inadvertently modulate effort exertion through regulation of general locomotor activity levels.
Assuntos
Antipsicóticos/efeitos adversos , Apatia/efeitos dos fármacos , Comportamento Animal/efeitos dos fármacos , Biperideno/farmacologia , Disfunção Cognitiva/tratamento farmacológico , Motivação/efeitos dos fármacos , Antagonistas Muscarínicos/farmacologia , Desempenho Psicomotor/efeitos dos fármacos , Receptor Muscarínico M1/antagonistas & inibidores , Receptor Muscarínico M4/antagonistas & inibidores , Escopolamina/farmacologia , Tropicamida/farmacologia , Animais , Disfunção Cognitiva/induzido quimicamente , Modelos Animais de Doenças , Haloperidol/farmacologia , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Herein we describe the continued optimization of M4 positive allosteric modulators (PAMs) within the 5-amino-thieno[2,3-c]pyridazine series of compounds. In this letter, we disclose our studies on tertiary amides derived from substituted azetidines. This series provided excellent CNS penetration, which had been challenging to consistently achieve in other amide series. Efforts to mitigate high clearance, aided by metabolic softspot analysis, were unsuccessful and precluded this series from further consideration as a preclinical candidate. In the course of this study, we found that potassium tetrafluoroborate salts could be engaged in a tosyl hydrazone reductive cross coupling reaction, a previously unreported transformation, which expands the synthetic utility of the methodology.
Assuntos
Amidas/química , Azetidinas/química , Receptor Muscarínico M4/metabolismo , Regulação Alostérica , Amidas/metabolismo , Avaliação Pré-Clínica de Medicamentos , Humanos , Ligação Proteica , Piridazinas/síntese química , Piridazinas/química , Piridazinas/metabolismo , Receptor Muscarínico M4/antagonistas & inibidores , Relação Estrutura-AtividadeRESUMO
This Letter details the discovery and subsequent optimization of a novel M4 PAM scaffold based on an 6-fluoro-4-(piperidin-1-yl)quinoline-3-carbonitrile core, which represents a distinct departure from the classical M4 PAM chemotypes. Optimized compounds in this series demonstrated improved M4 PAM potency on both human and rat M4 (4 to 5-fold relative to HTS hit), and displayed attractive physicochemical and DMPK profiles, including good CNS penetration (rat brain:plasma Kp=5.3, Kp,uu=2.4; MDCK-MDR1 (P-gp) ER=1.1).
Assuntos
Sistema Nervoso Central/efeitos dos fármacos , Descoberta de Drogas , Piperidinas/farmacologia , Quinolinas/farmacologia , Receptor Muscarínico M4/antagonistas & inibidores , Animais , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Piperidinas/síntese química , Piperidinas/química , Quinolinas/síntese química , Quinolinas/química , Ratos , Relação Estrutura-AtividadeRESUMO
Tamoxifen is an estrogen modulator that acts to competitively inhibit the binding of endogenous estrogens. It is widely used for treatment of breast cancer; however, analogous with many antineoplastic agents, tamoxifen is associated with numerous adverse effects, most prominently nausea. We have identified several off-target receptors of tamoxifen and 22 of its metabolites that include histamine H1 and H3, and muscarinic M1, M4, and M5 subtypes, and dopamine D2 receptor. We have shown how they are associated with tamoxifen and its metabolites' toxicity through a comprehensive computational analysis of their interaction modes, which were also compared to that of the related endogenous substrates of each receptor. The results were further evaluated using available in vivo and in vitro data. The presented work provides foundational knowledge toward the determination of the precise mechanism of nausea induction, and in particular, interactions of tamoxifen and its metabolites with the receptors involved in that biomolecular pathway. This study can assist in predicting the potential undesired effects of the chemicals with common pharmacophores or similar fragments to that of tamoxifen and its metabolites and serve drug discovery research in developing more effective and tolerable tamoxifen analogues or chemotherapeutic agents.
Assuntos
Tamoxifeno/metabolismo , Tamoxifeno/toxicidade , Sítios de Ligação/efeitos dos fármacos , Receptor alfa de Estrogênio/agonistas , Receptor alfa de Estrogênio/antagonistas & inibidores , Receptor beta de Estrogênio/agonistas , Receptor beta de Estrogênio/antagonistas & inibidores , Humanos , Ligantes , Modelos Moleculares , Receptor Muscarínico M4/antagonistas & inibidores , Receptores de Dopamina D2/agonistas , Relação Estrutura-Atividade , Especificidade por Substrato , Tamoxifeno/químicaRESUMO
This letter describes the synthesis and structure activity relationship (SAR) studies of structurally novel M4 antagonists, based on a 3-(4-aryl/heteroarylsulfonyl)piperazin-1-yl)-6-(piperidin-1-yl)pyridazine core, identified from a high-throughput screening campaign. A multi-dimensional optimization effort enhanced potency at human M4 (hM4 IC50s<200nM), with only moderate species differences noted, and with enantioselective inhibition. Moreover, CNS penetration proved attractive for this series (rat brain:plasma Kp=2.1, Kp,uu=1.1). Despite the absence of the prototypical mAChR antagonist basic or quaternary amine moiety, this series displayed pan-muscarinic antagonist activity across M1-5 (with 9- to 16-fold functional selectivity at best). This series further expands the chemical diversity of mAChR antagonists.
Assuntos
Encéfalo/metabolismo , Antagonistas Muscarínicos/farmacologia , Antagonistas Muscarínicos/farmacocinética , Piridazinas/farmacologia , Piridazinas/farmacocinética , Receptor Muscarínico M4/antagonistas & inibidores , Animais , Encéfalo/efeitos dos fármacos , Células CHO , Cricetulus , Humanos , Antagonistas Muscarínicos/química , Piperazina , Piperazinas/química , Piperazinas/farmacocinética , Piperazinas/farmacologia , Piridazinas/química , Ratos , Receptor Muscarínico M4/metabolismo , Relação Estrutura-AtividadeRESUMO
Striatal cholinergic dysfunction has been suggested to play a critical role in the pathophysiology of dystonia. In the dtsz hamster, a phenotypic model of paroxysmal dystonia, M1 antagonists exerted moderate antidystonic efficacy after acute systemic administration. In the present study, we examined the effects of the M4 preferring antagonist tropicamid and whether long-term systemic or acute intrastriatal injections of the M1 preferring antagonist trihexyphenidyl are more effective in mutant hamsters. Furthermore, M1 and M4 receptors were analyzed by autoradiography and immunohistochemistry. Tropicamide retarded the onset of dystonic attacks, as previously observed after acute systemic administration of trihexyphenidyl. Combined systemic administration of trihexyphenidyl (30mg/kg) and tropicamide (15mg/kg) reduced the severity in acute trials and delayed the onset of dystonia during long-term treatment. In contrast, acute striatal microinjections of trihexyphenidyl, tropicamid or the positive allosteric M4 receptor modulator VU0152100 did not exert significant effects. Receptor analyses revealed changes of M1 receptors in the dorsomedial striatum, suggesting that the cholinergic system is involved in abnormal striatal plasticity in dtsz hamsters, but the pharmacological data argue against a crucial role on the phenotype in this animal model. However, antidystonic effects of tropicamide after systemic administration point to a novel therapeutic potential of M4 preferring anticholinergics for the treatment of dystonia.