Muscarinic Research Articles

Impact of salivary flow inhibition on masticatory behaviours in healthy individuals.

It remains unclear how the salivary flow and the fat content of food affect bolus formation during mastication. We aimed to clarify: (1) how hyposalivation affects jaw-closing and hyoid-elevating muscle activities in bolus formation, and (2) if the effect of hyposalivation on muscle activity depends on the fat content of food. Eighteen healthy male volunteers were instructed to freely ingest four test foods: Plain, Fat without seasoning, Fat with seasoning, and Soft rice crackers. Masseter and suprahyoid electromyographic activities were recorded before and 30 min after the administration of atropine sulfate, a muscarinic receptor antagonist that induces hyposalivation. Hyposalivation extended the masticatory duration significantly in all the test foods except Fat with seasoning. Masticatory cycle time was significantly longer with vs without hyposalivation for the Soft (p = .011). Suprahyoid activity/cycle was significantly greater with vs without hyposalivation (p = .013). Masticatory cycle time was significantly longer at the late stage with vs without hyposalivation for the Soft (p < .001). Suprahyoid activity/cycle was significantly greater at the middle (p = .045) and late stages (p = .002) with vs without hyposalivation for the Soft and greater at the late stage with vs without hyposalivation for the Plain (p = .043). Changes in masticatory cycle time and suprahyoid activity/cycle for these foods had significantly positive relationship (p < .001). Hyposalivation-induced changes in masticatory behaviours resulted from the middle and late stage suprahyoid activity. Fat content and seasoning compensate for salivary flow inhibition.

Ophthalmic effects of Bitis atropos (Berg Adder) envenomation

Objective: Bitis atropos, commonly known as the Berg Adder, is a venomous viperid found in Southern Africa. Envenomation is rare, with reported cases primarily exhibiting cytotoxic, neurotoxic, and myotoxic effects, including severe systemic manifestations and ophthalmologic complications such as ptosis, mydriasis, and loss of accommodation. However, the underlying pathophysiology of these sequelae remains poorly understood. Case: We present the case of a 26-year-old male who suffered severe envenomation by a Berg Adder in the Limpopo Province, South Africa. Within minutes of the bite, the patient experienced hypoesthesia, progressive dyspnea, and loss of consciousness, followed by prolonged intensive care management. Ophthalmic examination revealed bilateral dilated pupils, right ptosis, and impaired accommodation, alongside generalized muscle weakness, anosmia, ageusia, and dysphagia. Despite the absence of antivenom, the patient’s condition showed gradual improvement over a 127-day follow-up period. Notably, the pupils exhibited denervation supersensitivity, similar to Adie’s tonic pupil, and responded well to low-dose pilocarpine. Conclusion: The clinical features observed, particularly the ophthalmoplegic triad, can be attributed to the effects of phospholipase A2 proteins in the venom, which disrupt cholinergic transmission at muscarinic receptors. This case underscores the complexity of Berg Adder envenomation and highlights the variability in recovery timelines for different neuro-ophthalmic effects. This case provides valuable insights into the pathophysiology and management of severe Berg Adder envenomation, emphasizing the role of targeted therapeutic interventions such as pilocarpine in mitigating long-term sequelae.

Synthesis and nootropic activity prediction of some 4-(aminomethyl)-1-benzylpyrrolidin-2-one derivatives structurally related with nebracetam

The aim. Search for new biologically active substances with improved nootropic parameters among analogues of 4-(aminomethyl)-1-benzylpyrrolidine-2-one (Nebracetam). Materials and methods. The required reagents were purified using standard techniques. The elemental analysis was performed on a "Hewlett Packard" automatic analyzer M-180 company. 1H NMR spectra were recorded on Varian Gemini 400 MHz spectrometer in DMSO-d6 as a solvent. LC/MS spectra were recorded with a PE SCIEX API 150EX liquid chromatograph equipped. The Autodock 4.2 software package was used for molecular docking. The active centers of the peptides (PDB ID: 5CXV, 6PV7) was used as the biologycal targets. Results and discussion. Basic and alternative methods (1 and 2) of obtaining were used to synthesise target analogues of 4-(aminomethyl)-1-R-benzylpyrrolidine-2-one. As a result of synthetic studies, an optimized method with an alternative method has been proposed. The advantages include reducing the duration and number of synthesis stages and avoiding the use of sodium azide, a highly toxic and hazardous substance. Molecular docking of the synthesized compounds at well-documented acetylcholine receptor sites indicates that all tested molecules will contribute to the manifestation of nootropic activity to varying degrees through cholinergic neurotransmission mechanisms. This is evidenced by the calculated docking values in relation to the muscarinic target. According to the docking results, it was found that depending on the enantiomeric configuration, the molecules formed stable complexes with the target and had characteristic binding modes both in the orthosteric site and in the extracellular vestibule (site of positive allosteric modulation of mAChR). It indicates the prospects of modifying the "nebracetam scaffold" at the phenyl fragment with halogen substituents. Conclusions. An effective method for synthesising analogues of 4-(aminomethyl)-1-R-benzylpyrrolidin-2-ones has been developed. The molecular docking revealed potential mechanisms of nootropic action of the synthesized derivatives as potential agonists and positive allosteric modulators of the muscarinic receptor

Higher levels of AKT-interacting protein in the frontal pole from people with schizophrenia are limited to a sub-group who have a marked deficit in cortical muscarinic M1 receptors

We are studying the molecular pathology of a sub-group within schizophrenia (∼ 25 %: termed Muscarinic Receptor Deficit subgroup of Schizophrenia (MRDS)) who can be separated because they have very low levels of cortical muscarinic M1 receptors (CHRM1). Based on our transcriptomic data from Brodmann's area ((BA) 9, 10 and 33 (controls, schizophrenia and mood disorders) and the cortex of the CHRM1−/− mouse (a molecular model of aberrant CHRM1 signaling), we predicted levels of AKT interacting protein (AKTIP), but not tubulin alpha 1b (TUBA1B) or AKT serine/threonine kinase 1 (AKT1) and pyruvate dehydrogenase kinase 1 (PDK1) (two AKTIP-functionally associated proteins), would be changed in MRDS. Hence, we used Western blotting to measure AKTIP (BA 10: controls, schizophrenia and mood disorders; BA 9: controls and schizophrenia) plus TUBA1B, AKT1 and PDK1 (BA 10: controls and schizophrenia) proteins. The only significant change with diagnosis was higher levels of AKTIP protein in BA 10 (Cohen's d = 0.73; p = 0.02) in schizophrenia compared to controls due to higher levels of AKTIP only in people with MRDS (Cohen's d = 0.80; p = 0.03). As AKTIP is involved in AKT1 signaling, our data suggests that signaling pathway is particularly disturbed in BA 10 in MRDS.

Effect of Tiotropium on eye findings in the treatment of chronic obstructive pulmonary disease

BackgroundChronic obstructive pulmonary disease (COPD) is a persistent, chronic inflammatory disease of the lungs. Tiotropium, used in the treatment of COPD, is a muscarinic receptor antagonist that provides long-acting bronchodilation. Our study aimed to investigate the effects of Tiotropium on anterior chamber parameters.MethodsThe study was conducted as an observational cross-sectional and prospectively between October 2023 and April 2024. Patients were examined in three groups: Group 1 consisted of untreated COPD patients; Group 2 consisted of healthy volunteers similar age and gender, and Group 3 included COPD patients receiving Tiotropium 18 mcg via HandiHaler. Anterior chamber parameters, intraocular pressure values, and photopic-mesopic pupil diameters were measured at the initial visit for Group 1 and Group 2 patients, and at the third month of treatment for Group 3 patients.ResultsThirty-six patients were included in each group in the study. No significant differences were observed in ocular findings between the patient and control groups. In COPD patients receiving Tiotropium, narrowing of angle parameters, an increase in photopic-mesopic pupil diameters, and intraocular pressure were observed at the third month of treatment.ConclusionThis study is the first research that investigate the effects of Tiotropium on anterior chamber parameters, pupil diameters, and intraocular pressure in COPD treatment. In conclusion, patients with COPD receiving Tiotropium therapy for three months showed narrowing in angle parameters, an increase in intraocular pressure, and photopic-mesopic pupil diameter; however, no patients developed drug-induced acute angle closure glaucoma.Trial registrationAn independent ethics committee approved the study (Giresun EAH KEAK 2023/180 and 9.10.2023/02) which was performed in accordance with the Declaration of Helsinki, Guidelines for Good Clinical Practice. The study was conducted as prospectively, observational case–control. The Clinical Trial Number obtained for the study is NCT06525051 and was taken on 2024–07-29.

Chemoarchitectural signatures of subcortical shape alterations in generalized epilepsy

Genetic generalized epilepsies (GGE) exhibit widespread morphometric alterations in the subcortical structures. Subcortical structures are essential for understanding GGE pathophysiology, but their fine-grained morphological diversity has yet to be comprehensively investigated. Furthermore, the relationships between macroscale morphological disturbances and microscale molecular chemoarchitectures are unclear. High-resolution structural images were acquired from patients with GGE (n = 97) and sex- and age-matched healthy controls (HCs, n = 184). Individual measurements of surface shape features (thickness and surface area) of seven bilateral subcortical structures were quantified. The patients and HCs were then compared vertex-wise, and shape anomalies were co-located with brain neurotransmitter profiles. We found widespread morphological alterations in GGE and prominent disruptions in the thalamus, putamen, and hippocampus. Shape area dilations were observed in the bilateral ventral, medial, and right dorsal thalamus, as well as the bilateral lateral putamen. We found that the shape area deviation pattern was spatially correlated with the norepinephrine transporter and nicotinic acetylcholine (Ach) receptor (α4β2) profiles, but a distinct association was seen in the muscarinic Ach receptor (M1). The findings provided a comprehensive picture of subcortical morphological disruptions in GGE, and further characterized the associated molecular mechanisms. This information may increase our understanding of the pathophysiology of GGE.

Muscarinic and nicotinic receptors stimulation by vagus nerve stimulation ameliorates trastuzumab-induced cardiotoxicity via reducing programmed cell death in rats

Despite its efficacy in human epidermal growth factor receptor 2 positive cancer treatment, trastuzumab-induced cardiotoxicity (TIC) has become a growing concern. Due to the lack of cardiomyocyte regeneration and proliferation in adult heart, cell death significantly contributes to cardiovascular diseases. Cardiac autonomic modulation by vagus nerve stimulation (VNS) has shown cardioprotective effects in several heart disease models, while the effects of VNS and its underlying mechanisms against TIC have not been found. Forty adult male Wistar rats were divided into 5 groups: (i) control without VNS (CSham) group, (ii) trastuzumab (4 mg/kg/day, i.p.) without VNS (TSham) group, (iii) trastuzumab + VNS (TVNS) group, (iv) trastuzumab + VNS + mAChR blocker (atropine; 1 mg/kg/day, ip, TVNS + Atro) group, and (v) trastuzumab + VNS + nAChR blocker (mecamylamine; 7.5 mg/kg/day, ip, TVNS + Mec) group. Our results showed that trastuzumab induced cardiac dysfunction by increasing autonomic dysfunction, mitochondrial dysfunction/dynamics imbalance, and cardiomyocyte death including apoptosis, autophagic deficiency, pyroptosis, and ferroptosis, which were notably alleviated by VNS. However, mAChR and nAChR blockers significantly inhibited the beneficial effects of VNS on cardiac autonomic dysfunction, mitochondrial dysfunction, cardiomyocyte apoptosis, pyroptosis, and ferroptosis. Only nAChR could counteract the protective effects of VNS on cardiac mitochondrial dynamics imbalance and autophagy insufficiency. Therefore, VNS prevented TIC by rebalancing autonomic activity, ameliorating mitochondrial dysfunction and cardiomyocyte death through mAChR and nAChR activation. The current study provides a novel perspective elucidating the potential treatment of VNS, thus also offering other pharmacological therapeutic promises in TIC patients.

Role of pterygopalatine ganglion in regulating isoflurane-induced cerebral hyper-perfusion.

Cerebral perfusion is functionally regulated by neural mechanisms in addition to the systemic hemodynamic variation, vascular reactivity and cerebral metabolism. Although anesthesia is generally esteemed to suppress the overall brain neural activity and metabolism, a few inhalation anesthetics, such as isoflurane, can increase cerebral perfusion, thus heightening the risks of higher intracranial pressure, bleeding, and brain edema during surgery. With the aid of laser speckle contrast imaging, we observed a transient yet limited effect of cerebral perfusion enhancement in mice from awake to anesthetized conditions with different concentration of isoflurane. Retrograde and antegrade tracing revealed a higher proportion of parasympathetic control more than sympathetic innervation for the blood vessels. Surprisingly, isoflurane directly activated pterygopalatine ganglion (PPG) explants and induced FOS expression in the cholinergic neurons. Chemogenetic activation of cholinergic PPG neurons reduced isoflurane-related cerebral perfusion. On the contrary, ablation of the cholinergic PPG neurons resulted in further enhancement of cerebral perfusion induced by isoflurane. While blocking muscarinic cholinergic receptors resulted in the overall reduction upon isoflurane stimulation, the blockage of nicotinic cholinergic receptors enhanced the isoflurane-induced cerebral perfusion only when PPG neurons exist. Collectively, these results suggest that PPG play important roles in regulating cerebral perfusion under isoflurane inhalation.

Mouse Exploratory Behaviour in the Open Field with and without NAT-1 EEG Device: Effects of MK801 and Scopolamine.

One aspect of reproducibility in preclinical research that is frequently overlooked is the physical condition in which physiological, pharmacological, or behavioural recordings are conducted. In this study, the physical conditions of mice were altered through the attachments of wireless electrophysiological recording devices (Neural Activity Tracker-1, NAT-1). NAT-1 devices are miniaturised multichannel devices with onboard memory for direct high-resolution recording of brain activity for >48 h. Such devices may limit the mobility of animals and affect their behavioural performance due to the added weight (total weight of approximately 3.4 g). The mice were additionally treated with saline (control), N-methyl-D-aspartate (NMDA) receptor antagonist MK801 (0.85 mg/kg), or the muscarinic acetylcholine receptor blocker scopolamine (0.65 mg/kg) to allow exploration of the effect of NAT-1 attachments in pharmacologically treated mice. We found only minimal differences in behavioural outcomes with NAT-1 attachments in standard parameters of locomotor activity widely reported for the open field test between the drug treatments. Hypoactivity was globally observed as a consistent outcome in the MK801-treated mice and hyperactivity in scopolamine groups regardless of NAT-1 attachments. These data collectively confirm the reproducibility for combined behavioural, pharmacological, and physiological endpoints even in the presence of lightweight wireless data loggers. The NAT-1 therefore constitutes a pertinent tool for investigating brain activity in, e.g., drug discovery and models of neuropsychiatric and/or neurodegenerative diseases with minimal effects on pharmacological and behavioural outcomes.

The plasma membrane inner leaflet PI(4,5)P2 is essential for the activation of proton-activated chloride channels

Proton-activated chloride (PAC) channels, ubiquitously expressed in tissues, regulate intracellular Cl- levels and cell death following acidosis. However, molecular mechanisms and signaling pathways involved in PAC channel modulation are largely unknown. Herein, we determine that phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] of the plasma membrane inner leaflet is essential for the proton activation of PAC channels. PI(4,5)P2 depletion by activating phosphatidylinositol 5-phosphatases or Gq protein-coupled muscarinic receptors substantially inhibits human PAC currents. In excised inside-out patches, PI(4,5)P2 application to the cytoplasmic side increases the currents. Structural simulation reveals that the putative PI(4,5)P2-binding site is localized within the cytosol in resting state but shifts to the cell membrane’s inner surface in an activated state and interacts with inner leaflet PI(4,5)P2. Alanine neutralization of basic residues near the membrane-cytosol interface of the transmembrane helice 2 significantly attenuates PAC currents. Overall, our study uncovers a modulatory mechanism of PAC channel through inner membrane PI(4,5)P2.

A golden age of muscarinic acetylcholine receptor modulation in neurological diseases.

Over the past 40 years, the muscarinic acetylcholine receptor family, particularly the M1-receptor and M4-receptor subtypes, have emerged as validated targets for the symptomatic treatment of neurological diseases such as schizophrenia and Alzheimer disease. However, despite considerable effort and investment, no drugs have yet gained clinical approval. This is largely attributable to cholinergic adverse effects that have halted the majority of programmes and resulted in a waning of interest in these G-protein-coupled receptor targets. Recently, this trend has been reversed. Driven by advances in structure-based drug design and an appreciation of the optimal pharmacological properties necessary to deliver clinical efficacy while minimizing adverse effects, a new generation of M1-receptor and M4-receptor orthosteric agonists and positive allosteric modulators are now entering the clinic. These agents offer the prospect of novel therapeutic solutions for 'hard to treat' neurological diseases, heralding a new era of muscarinic drug discovery.

Sericin-induced hypophagia mediates via M1 muscarinic, NMDA glutamate and glycine receptors in neonatal chicken

This study aimed to determine interaction between muscarinic, NMDA glutamate and glycine receptors on sericin-induced hypophagia in neonatal chicken. This study included 6 experiments with 4 groups in each with 11 repeats for each group. In experiment 1, chicken received ICV injection of the saline, sericin (0.5 n m o l), Telenzepine (M 1 muscarinic receptor antagonist, 125 n m o l), and in group 4 co-injection of the sericin and Telenzepine were applied. In experiments 2-6, chicken received ICV injections of the AF-DX116 (M 2 muscarinic receptor antagonist, 125 n m o l), 4-DAMP (M3 muscarinic receptor antagonist, 125 n m o l), PD102807 (M 4 muscarinic receptor antagonist, 125 nmol), MK-801 (NMDA glutamate receptor antagonist, 15 n m o l), and Strychnine (glycine receptor antagonist, 100 nmol) instead of telenzepine. Then the cumulative food intake was measured at 30, 60 and 120 minutes after the injection. According to the results, ICV injection of the sericin (0.5 n m o l) significantly decreased cumulative food intake comparison to control chicken (P &lt; 0 . 0 5). Co-injection of the telenzepine + sericin significantly decreased sericin induced hypophagia (P &lt; 0.05). Co-injection of the MK - 801 + sericin decreased hypophagic effects of the sericin comparison to control chicken (P &lt; 0. 0 5). Co-injection of the strychnine + sericin decreased hypophagic effects of the sericin comparison to control chicken (P &lt; 0. 05). These findings suggested, sericin-induced hypophagia mediates via M1 muscarinic, NMDA glutamate and glycine receptors in neonatal chicken.

Human epithelial protein SLURP-2 as a prototype of drugs for wound healing

Wound healing is a complex process based on the regulation of proliferation and migration of epithelial cells. Chronic wounds are characterized by increased proliferation and lack of migration of epidermal cells. The secreted human protein SLURP-2 regulates the growth and differentiation of epithelial cells. It has previously been shown that the targets of SLURP-2 are various types of nicotinic acetylcholine receptors (nAChRs), as well as muscarinic acetylcholine receptors involved in the regulation of epithelial cell homeostasis. In this work, we found that the previously demonstrated acceleration of keratinocyte migration under the incubation with SLURP-2 is due to its interaction with α7 type nAChR. Using alanine scanning mutagenesis, we showed that the R20A mutation of the SLURP-2 molecule increases the inhibitory activity of SLURP-2 towards α7-nAChR and leads to an even greater stimulation of Het-1A keratinocyte migration, while, in contrast to SLURP-2, does not stimulate, but suppresses the proliferation of Het-1A cells. At the same time, other SLURP-2 mutations simultaneously lead to inhibition of α7-nAChR, proliferation and migration of keratinocytes. Thus, new information was obtained about the localization of regions of the SLURP-2 molecule, the replacement of which can lead to a targeted change in the biological activity of SLURP-2. Further research into the possibility of regulating the activity of SLURP-2 and the creation of targeted drugs based on it may be useful for the development of new drugs that stimulate wound healing.

Therapeutic Potential of 1-(2-Chlorophenyl)-6,7-dimethoxy-3-methyl-3,4-dihydroisoquinoline.

The synthesized compound 1-(2-chlorophenyl) 6-7-dimethoxy-3-methyl-3,4-dihydroisoquinoline (DIQ) was investigated as a biological agent. Its potential to affect muscle contractility was predicted through in silico PASS analysis. Based on the in silico analysis, its capabilities were experimentally investigated. The study aimed to investigate the effects of DIQ on the ex vivo spontaneous contractile activity (CA) of smooth muscle (SM) tissue. DIQ was observed to reduce the strength of Ca2+-dependent contractions in SM preparations (SMP), possibly by increasing cytosolic Ca2+ levels through the activation of a voltage-gated L-type Ca2+ channel. DIQ potently affected calcium currents by modulating the function of muscarinic acetylcholine receptors (mAChRs) and 5-hydroxytryptamine (5-HT) receptors at a concentration of 50 μM. Immunohistochemical tests showed a 47% reduction in 5-HT2A and 5-HT2B receptor activity in SM cells and neurons in the myenteric plexus (MP), further confirming the effects of DIQ. Furthermore, a significant inhibition of neuronal activity was observed when the compound was co-administered with 5-HT to SM tissues. The conducted experiments confirm the ability of the isoquinoline analog to act as a physiologically active molecule to control muscle contractility and related physiological processes.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of a Muscarinic M3 Receptor-Positive Allosteric Modulator ASP8302 Following Single and Multiple Ascending Oral Doses in Healthy Volunteers.

ASP8302 is an orally administered positive allosteric modulator of the muscarinic M3 receptor. Two Phase 1 studies were conducted, a first-in-human study in Europe and a Japanese phase 1 study. Both were randomized, participant- and investigator-blinded, placebo-controlled, single and multiple ascending oral doses, parallel group, clinical studies in healthy volunteers. Both studies evaluated safety and pharmacokinetics and also included salivary secretion and pupil diameter as pharmacodynamic assessments. There were no deaths, serious adverse events, or treatment-emergent adverse events reported leading to study discontinuation. There were no clinically relevant findings in any of the laboratory, vital signs, electrocardiogram assessments, or photosensitivity testing following multiple administration of up to 150 mg or up to 140 mg once daily for 14 days in the European first-in-human and Japanese Phase 1 study, respectively. The pharmacokinetics of ASP8302 were approximately linear over the dose range studied. There was no evidence of drug accumulation upon repeated dosing. In both studies, ASP8302 showed a dose-dependent pharmacodynamic effect on saliva production at doses from 100 mg onward, which was maintained during repeated dosing. No effect was observed on pupil diameter. These data supported progression of ASP8302 into Phase 2 clinical trials for further clinical development.

Development of VU6036864: A Triazolopyridine-Based High-Quality Antagonist Tool Compound of the M5 Muscarinic Acetylcholine Receptor.

While the muscarinic acetylcholine receptor mAChR subtype 5 (M5) has been studied over decades, recent findings suggest that more in-depth research is required to elucidate a thorough understanding of its physiological function related to neurological and psychiatric disorders. Our efforts to identify potent, selective, and pharmaceutically favorable next-generation M5 antagonist tool compounds have led to the discovery of a novel triazolopyridine-based series. In particular, VU6036864 (45) showed exquisite potency (human M5 IC50 = 20 nM), good subtype selectivity (>500 fold selectivity against human M1-4), desirable brain exposure (Kp = 0.68, Kp,uu = 0.65), and high oral bioavailability (%F > 100%). VU6036864 (45) and its close analogues will support further studies of M5 as advanced antagonist tool compounds and play an important role in the emerging biology of M5.

Abstract Mo131: Time-Restricted Feeding Normalizes Dim Light at Night-Induced Disruption of Cardiovascular Rhythms in Mice

Background: Light input to the suprachiasmatic nucleus entrains circadian rhythms in physiology and behavior to the day-night cycle. Exposure to light at night in people is associated with cardiometabolic disease. Pre-clinical studies show that artificial light at night, including at very low levels, disrupts day-night rhythms in activity, feeding behavior, heart rate, and blood pressure dipping. Hypothesis: Dim light at night (dLAN) disrupts day-night rhythms in feeding behavior to blunt day-night rhythms in autonomic input to the heart and blood pressure dipping. Methods: Mice (n=5-6/sex) in thermoneutral housing were implanted with telemetry probes to record heart rate, blood pressure, and core body temperature. Autonomic input to the heart was assessed by measuring heart rate and subtracting the temperature-dependent changes in the heart rate after pharmacological inhibition of muscarinic and β-adrenergic receptor activation. Mice were housed in 12 h light: 12 h dark cycles (LD, 200 lux: 0 lux) with ad libitum access to food (LD-ALF), subjected to 12 h light: 12 h dLAN cycles (dLAN-ALF; 200 lux: 5 lux) for two weeks, and then feeding was time-restricted (not calorically restricted) to the dLAN cycle (dLAN-RF). Data were extracted from Ponemah and Clocklab, and statistical analysis was done using GraphPad PRISM software. Results: Compared to LD-ALF mice, dLAN-ALF mice showed reduced amplitudes in day-night activity, feeding, heart rate, and blood pressure rhythms, with males more affected than females (p&lt;0.001). dLAN-ALF male and female mice had decreased amplitudes in the day-night rhythms in autonomic input to the heart. In addition, dLAN-ALF male mice had less blood pressure dipping. dLAN-RF normalized autonomic input to the heart and heart rate in male and female mice (p&lt;0.05, p&lt;0.01, respectively). dLAN-RF also improved blood pressure dipping in male mice (p&lt;0.001). dLAN-RF did not normalize activity rhythms. Conclusion: dLAN disrupts day-night rhythms in activity, feeding, heart rate, and blood pressure dipping in mice, with males being more impacted. Time-restricted feeding to the dLAN cycle normalizes autonomic input to the heart and blood pressure dipping. These data suggest that time-restricted feeding counteracts the light-at-night-induced circadian disruption of cardiovascular function.

Acetylcholine regulates the melanogenesis of retinal pigment epithelia cells via a cAMP-dependent pathway: A non-neuronal function of cholinergic system in retina

The turnover rate of melanogenesis in retinal pigment epithelium (RPE) and its molecular signaling remain unclear. This study aimed to investigate the role of cholinergic signaling in the process of melanogenesis of cultured RPE cells. Here, a human retinal pigment epithelia cell line, ARPE-19 cell, was used to study the process of melanogenesis. The mRNA and protein expressions of cholinergic molecules, e.g., acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and melanogenic molecules i.e., tyrosinase (TYR), microphthalmia-associated transcription factor (MITF), and melanin pigment were measured during melanogenesis of cultured ARPE-19 cells. Forskolin (a cAMP inducing agent), acetylcholine (ACh) and bethanechol (Bch; a muscarinic AChR agonist) were used to induce melanogenesis in the cultures. Muscarinic acetylcholine receptor (mAChR) antagonists were employed to identify the receptor subtype. During melanogenesis of ARPE-19 cells, the mRNA and protein expressions of cholinergic molecules, e.g., AChE and BChE, were increased along with melanogenic molecules, i.e., TYR, MITF and melanin pigment. Forskolin, ACh, and Bch induced an upregulation of melanogenesis in cultured ARPE-19 cultures: the induction was parallel to an increase of AChE expression. The Bch-induced enzymatic activities and mRNA levels of AChE and TYR were fully blocked by the treatments of gallamine (a M2 specific antagonist), tropicamide (a M4 specific antagonist) and atropine (non-specific antagonist for mAChRs). Cholinergic signaling via M2/M4 mAChRs regulates melanogenesis in cultured ARPE-19 cells through a cAMP-dependent pathway. This study provides insights into the regulation of RPE cell melanogenesis via a non-neuronal function of cholinergic system.

Pharmacological potential of 4-dimethylamino chalcone against acute and neuropathic pain in mice.

This work investigated the acute antinociceptive effect of a synthetic chalcone, 4-dimethylamino chalcone (DMAC), as well as its effects on vincristine-induced peripheral neuropathy (VIPN) in mice. The inhibitory activity of myeloperoxidase was assessed by measuring HOCl formation. Formalin and hot plate tests were used to study the acute antinociceptive effect of DMAC. VIPN was induced through the administration of vincristine sulphate (0.1 mg/kg, i.p., 14 days). Then, DMSO, DMAC (10 or 30 mg/kg; i.p.), or pregabalin (10 mg/kg, i.p.) were administered for 14 consecutive days. Thermal hyperalgesia and mechanical allodynia were evaluated before and after VIPN induction and on days 1, 3, 7, and 14 of treatment. Neurodegeneration and neuroinflammation were assessed through immunohistochemistry for NF200, iNOS, and arginase-1 within the sciatic nerve. DMAC inhibited myeloperoxidase activity in vitro and presented an acute antinociceptive effect in both formalin and hot plate tests, with the involvement of muscarinic and opioid receptors. Treatment with 30 mg/kg of DMAC significantly attenuated thermal hyperalgesia and mechanical allodynia and prevented macrophage proinflammatory polarisation in VIPN mice. Our results show that DMAC, acting through different mechanisms, effectively attenuates VIPN.

Neuroprotective effect of long-term resistance physical exercise against memory damage elicited by a lipopolysaccharide-induced neuroinflammation model in malerats.

Resistance exercise training (RET) is considered an excellent tool for preventing diseases with an inflammatory background. Its neuroprotective, antioxidant, and anti-inflammatory properties are responsible for positively modulating cholinergic and oxidative systems, promoting neurogenesis, and improving memory. However, the mechanisms behind these actions are largely unknown. In order to investigate the pathways related to these effects of exercise, we conducted a 12-week long-term exercise training protocol and used lipopolysaccharide (LPS) to induce damage to the cortex and hippocampus of male Wistar rats. The cholinergic system, oxidative stress, and histochemical parameters were analyzed in the cerebral cortex and hippocampus, and memory tests were also performed. It was observed that LPS: (1) caused memory loss in the novel object recognition (NOR) test; (2) increased the activity of acetylcholinesterase (AChE) and Iba1 protein density; (3) reduced the protein density of brain-derived neurotrophic factor (BDNF) and muscarinic acetylcholine receptor M1 (CHRM1); (4) elevated the levels of lipid peroxidation (TBARS) and reactive species (RS); and (5) caused inflammatory damage to the dentate gyrus. RET, on the other hand, was able to prevent all alterations induced by LPS, as well as increase per se the protein density of the alpha-7 nicotinic acetylcholine receptor (nAChRα7) and Nestin, and the levels of protein thiols (T-SH). Overall, our study elucidates some mechanisms that support resistance physical exercise as a valuable approach against LPS-induced neuroinflammation and memory loss.