Receptor Binding Affinity Research Articles

The antidepressants and sexual dysfunction: a pharmacovigilance-pharmacodynamic study of the FDA adverse event reporting system

ABSTRACT Background Sexual dysfunction (SD) is a commonly occurring yet often underestimated adverse event associated with the use of antidepressants. This study aimed to analyze the reporting of SD associated with the use of antidepressants in comparison with one another, and to explore potential receptor mechanisms based on the real-world data from the Food and Drug Administration Adverse Event Reporting System (FAERS). Methods Disproportionality analysis was conducted based on FAERS reports (2004 Q1 to 2024 Q2) using reporting odds ratios (ROR) and information components (IC) methods. Spearman correlation analysis was performed to explore the relationship between ROR and the related receptor-binding properties. Results In total, 233 significant signals involving 9767 cases were included. The analysis confirmed that selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors exhibited significant signals, consistent with previous research. Additionally, unexpected signals were detected for vortioxetine (ROR = 13.60), suggesting a potential risk despite its low reported incidence rates of SD. Spearman correlation analysis revealed potential effects for the binding affinities of serotonin transporter, 5-HT1B and 5-HT2A receptors on reduced sexual desire. Conclusions The present investigation has detected new and unexpected signals of antidepressant-related SDs. Further research is needed to validate and clarify the observed associations.

Marked neurotropism and potential adaptation of H5N1 clade 2.3.4.4.b virus in naturally infected domestic cats

ABSTRACT In April 2024, ten cats died in a rural South Dakota (SD) residence, showing respiratory and neurological symptoms. Necropsy and laboratory testing of two cats confirmed H5N1 clade 2.3.4.4b infection. The viral genome sequences are closely related to recent SD cattle H5N1 sequences. Cat H5N1 genomes had unique mutations, including T143A in haemagglutinin, known to affect infectivity and immune evasion, and two novel mutations in PA protein (F314L, L342Q) that may affect polymerase activity and virulence, suggesting potential virus adaptation. Dead cats showed systemic infection with lesions and viral antigens in multiple organs. Higher viral RNA and antigen in the brain indicated pronounced neurotropism. Lectin-histochemistry revealed widespread co-expression of sialic acid α-2,6 and α-2,3 receptors, suggesting cats could serve as mixing vessels for reassortment of avian and mammalian influenza viruses. No differences in clade 2.2 or 2.3.4.4b H5 pseudoviruses binding to cat lung/brain tissues indicated the neurotropism is unlikely mediated by receptor binding affinity.

Screened Fv-Antibodies against the Angiotensin-Converting Enzyme 2 (ACE2) Receptor Neutralizing the Infection of SARS-CoV-2.

For the prevention of SARS-CoV-2 infection, four Fv-antibodies with binding affinity for the ACE2 receptor were screened from an Fv-antibody library. The screened Fv-antibodies were expressed as soluble proteins and estimated to have a high binding affinity, comparable to that between SARS-CoV-2 and the ACE2 receptor. The interaction between the Fv-antibodies and the ACE2 receptor was analyzed using docking simulation, and the significant binding affinity of the screened Fv-antibodies was attributed to the homology in amino acid sequence with the ACE2 receptor. The neutralizing activities of the Fv-antibodies were demonstrated using a cell-based infection assay based on four pseudo-virus types with SARS-CoV-2 variant spike proteins (Wild-type D614, Delta B.1.617.2, and Omicron BA.2, and Omicron BA.4/5).

Selective Glycan Presentation in Liquid‐Ordered or ‐Disordered Membrane Phases and its Effect on Lectin Binding

AbstractGlycan‐protein interactions play a key role in various biological processes from fertilization to infections. Many of these interactions take place at the glycocalyx—a heavily glycosylated layer at the cell surface. Despite its significance, studying the glycocalyx remains challenging due to its complex, dynamic, and heterogeneous nature. This study introduces a glycocalyx model allowing for the first time to control spatial organization and heterogeneity of the glycan moieties. Glycan‐mimetics with lipid‐moieties that partition into either liquid‐ordered (Lo, lipid rafts) or liquid‐disordered (Ld) phases of giant unilamellar vesicles (GUVs), which serve as simplified cell membrane models mimicking lipid rafts, are developed. This phase‐specific allocation allows controlled placement of glycan motifs in distinct membrane environments, creating heteromultivalent systems that replicate the natural glycocalyx's complexity. We show that phase localization of glycan mimetics significantly influences recruitment of protein receptors to the membrane. Glycan‐conjugates in the ordered phase demonstrate enhanced lectin binding, supporting the idea that raft‐like domains facilitate stronger receptor interactions. This study provides a platform for systematically investigating spatial and dynamic presentation of glycans in biological systems and presents the first experimental evidence that glycan accumulation in lipid rafts enhances receptor binding affinity, offering deeper insights into the glycocalyx‘s functional mechanisms.

Selective Glycan Presentation in Liquid-Ordered or -Disordered Membrane Phases and its Effect on Lectin Binding.

Glycan-protein interactions play a key role in various biological processes from fertilization to infections. Many of these interactions take place at the glycocalyx-a heavily glycosylated layer at the cell surface. Despite its significance, studying the glycocalyx remains challenging due to its complex, dynamic, and heterogeneous nature. This study introduces a glycocalyx model allowing for the first time to control spatial organization and heterogeneity of the glycan moieties. Glycan-mimetics with lipid-moieties that partition into either liquid-ordered (Lo, lipid rafts) or liquid-disordered (Ld) phases of giant unilamellar vesicles (GUVs), which serve as simplified cell membrane models mimicking lipid rafts, are developed. This phase-specific allocation allows controlled placement of glycan motifs in distinct membrane environments, creating heteromultivalent systems that replicate the natural glycocalyx's complexity. We show that phase localization of glycan mimetics significantly influences recruitment of protein receptors to the membrane. Glycan-conjugates in the ordered phase demonstrate enhanced lectin binding, supporting the idea that raft-like domains facilitate stronger receptor interactions. This study provides a platform for systematically investigating spatial and dynamic presentation of glycans in biological systems and presents the first experimental evidence that glycan accumulation in lipid rafts enhances receptor binding affinity, offering deeper insights into the glycocalyx's functional mechanisms.

Synergistic Antiemetic Effects of Nerolidol on Domperidone, Hyoscine, and Ondansetron: In Vivo and in Silico Investigations on Receptor Binding Affinity.

The present study was designed to measure the potential antiemetic properties of nerolidol (NDL) via in vivo and in silico studies. To induce emesis copper sulfate pentahydrate (CuSO4.5H2O) was administered at a dose of 50 mg/kg (orally) to 2-day-old chicks. The test sample (NDL) was given at two doses of 50 and 100 mg/kg. b.w. orally. Additionally, aprepitant (16 mg/kg), domperidone (6 mg/kg), hyoscine (21 mg/kg), ondansetron (5 mg/kg), and diphenhydramine (10 mg/kg) were given also orally as positive controls. To observe the modulatory effects of the test sample, combination therapies with reference drugs were also administered to three different groups of animals. Molecular docking and visualization of ligand-receptor interaction were performed against several emesis-inducing receptors (5HT3, D2, D3, H1, and M1-M5) using diverse computational tools. Pharmacokinetics and drug-likeness of the selected ligands were also calculated. Findings demonstrated that NDL significantly (p <0.05) dose-dependently lessens the mean number of retches and delays the emetic onset in the chicks. The combined drug therapy with ondansetron exposed better antiemetic activity. In addition, in silico analysis, NDL has greater binding affinity (-7.3 kcal/mol) against M2 and M3 receptors. In conclusion, NDL exerted mild antiemetic activity with synergistic properties through muscarinic receptors.

Immunoinformatics investigation on pathogenic Escherichia coli proteome to develop an epitope-based peptide vaccine candidate.

Escherichia coli (E. coli), a gram-negative bacterium, quickly colonizes in the human gastrointestinal tract after birth and typically sustains a long-term, symbiotic relationship with the host. However, certain virulent strains of E. coli can cause diseases such as urinary tract infections, meningitis, and enteric disorders. The rising antibiotic resistance among these strains has heightened the urgency for an effective vaccine. This study employs immunoinformatics and a reverse vaccinology technique to identify prospective antigens and create an efficient vaccine construct. In this study, we reported the "Attaching and Effacing Protein" a novel outer-membrane protein conserved in all pathogenic E. coli strains, based on proteome screening. We developed an in silico multi-epitope vaccine that includes helper T lymphocyte (HTL), cytotoxic T lymphocyte (CTL), B cell lymphocyte (BCL), and pan HLA DR-binding reactive epitope (PADRE) sequences, along with appropriate linkers and adjuvants. Machine Learning algorithms were used to evaluate antigenicity, solubility, stability, and non-allergenicity of the vaccine construct. Additionally, molecular docking analysis revealed that vaccine construct has a strong predicted binding affinity for human toll-like receptors on the cell surface. In this context, laboratory validations are necessary to demonstrate the effectiveness of the possible vaccine design that showed encouraging findings through computational validation.

Effects of Ficus exasperata on neurotransmission and expression of BDNF, tau, ACHE and BACE in diabetic rats

Diabetes mellitus, a chronic metabolic disorder, has significant global health implications, particularly due to its neurological complications, such as diabetic neuropathy. This condition increases the risk of neurodegenerative diseases by affecting peripheral nerves and cognition. Ficus exasperata, known for its neuroprotective properties, shows promise as a therapeutic option for addressing these complications. This study evaluates the effects of methanol extract of Ficus exasperata (MEFE) on neurotransmission and the expression of Tau, brain-derived neurotrophic factor (BDNF), acetylcholinesterase (ACHE), and Beta-Site Amyloid Precursor Protein Cleaving Enzyme (BACE) in alloxan-induced diabetic Wistar rats. The controlled experimental design involved 20 Wistar rats divided into four groups (n = 5): control, diabetic untreated, diabetes + MEFE (200 mg/kg), and diabetes + insulin (0.3 IU). The methanol extract was prepared using cold maceration, and an aliquot was subjected to gas chromatography-mass spectrometry. Constituents of MEFE were docked with neurologic receptors. Blood glucose levels were measured using the glucose oxidase method, and neurotransmitter levels, antioxidants, oxidative stress markers, and the expression of Tau, BDNF, ACHE, and BACE were assessed using standard procedures and qRT-PCR. Data were analyzed using one-way ANOVA at P < 0.05. Results indicated that MEFE significantly reduced fasting blood glucose levels compared to untreated diabetic rats. In silico docking identified kaur-16-ene, a constituent of MEFE, as having the highest binding affinity for NMDA, TrkB, mAchR and nAchR receptors, indicating its neuroprotective potential. MEFE also enhanced antioxidant enzyme levels (SOD, GPx, catalase) while reducing oxidative stress markers (MDA, 8-OHdG). Gene expression analysis revealed that MEFE modulates the expression of Tau, BDNF, ACHE, and BACE, suggesting its potential to influence neurodegenerative pathways associated with diabetic neuropathy. Ficus exasperata demonstrates significant therapeutic potential in managing diabetic neuropathy and related cognitive impairments by modulating neurotransmission, protein expression, and antioxidant defenses.

Patterns of the within-host evolution of human norovirus in immunocompromised individuals and implications for treatment

Currently, there is no licensed treatment for chronic norovirus infections, but the use of intra-duodenally-delivered immunoglobulins is promising; nevertheless, varying results have limited their wide use. Little is known about the relationship between norovirus genetic diversity and treatment efficacy. We analyzed the norovirus within-host diversity and evolution in a cohort of 20 immunocompromised individuals using next-generation sequencing (NGS) and clone-based sequencing of the capsid (VP1) gene. Representative VP1s were expressed and their glycan receptor binding affinity and antigenicity were evaluated. The P2 domain, within the VP1, accumulated up to 30-fold more non-synonymous mutations than other genomic regions. Intra-host virus populations in these patients tended to evolve into divergent lineages that were often antigenically distinct. Several of these viruses were widely resistant to binding-blocking antibodies in immunoglobulin preparations. Notably, for one patient, a single amino-acid substitution in the P2 domain resulted in an immune-escape phenotype, and it was likely the main contributor to treatment failure. Furthermore, we found evidence for transmission of late-stage viruses between two immunocompromised individuals. The findings demonstrated that within-host noroviruses in chronic infections tend to evolve into antigenically distinct subpopulations. This antigenic evolution was likely caused by the remaining low immunity levels exerted by immunocompromised individuals, possibly undermining antiviral treatment. Our observations provide insights into norovirus (within-host) evolution and treatment. Erasmus MC grant mRACE, the European Union's Horizon 2020 research and innovation program under grant agreement No. 874735 (VEO), and the NWO STEVIN award (Koopmans).

Iterative Catalyst-Controlled Diastereoselective Matteson Homologations Enable the Selective Synthesis of Benzestrol Isomers.

We report the development of an iterative Matteson homologation reaction with catalyst-controlled diastereoselectivity through the design of a new catalyst. This reaction was applied to the selective synthesis of each stereoisomer of benzestrol, a bioactive compound with estrogenic activity featuring three contiguous stereocenters. The different stereoisomers were assayed to determine their binding affinity for the estrogen receptor α (ERα), and the absolute configuration of the compound having uniquely high activity was determined. This research lays a framework for the catalytic synthesis and study of complete stereoisomeric sets of other bioactive molecules and chemical probes containing contiguous stereocenters.

Systematic Review: Comparative Efficacy and Safety of Losartan vs. Candesartan for the Treatment of Hypertension

Hypertension is one of the most significant modifiable risk factors for cardiovascular disease (CVD) and remains a leading cause of morbidity and mortality globally. Effective management of hypertension is essential for preventing comp lications such as stroke, myocardial infarction, and heart failure. Angiotensin II receptor blockers (ARBs) like losartan and candesartan are well-established therapeutic options for blood pressure (BP) control and are widely prescribed due to their favorable side-effect profiles and organ-protective properties. Despite being members of the same drug class, these ARBs differ in their pharmacokinetics, receptor binding affinity, and clinical efficacy. This systematic review aims to provide a detailed comparison of the efficacy and safety of losartan versus candesartan in managing hypertension. We conducted a comprehensive search of the PubMed, Embase, and Cochrane databases, retrieving studies published from 2000 to 2024 that compared the two ARBs directly in hypertensive populations. A total of 25 randomized controlled trials (RCTs) and observational studies, comprising more than 12,000 participants, were included in the analysis. The primary outcomes evaluated were the reduction in systolic and diastolic blood pressure, cardiovascular event prevention, and adverse event profiles. The results suggest that both losartan and candesartan effectively lower BP, but candesartan consistently demonstrated greater reductions in both systolic and diastolic BP compared to losartan. Candesartan also appeared to have superior cardiovascular outcomes, with a lower incidence of major cardiovascular events such as stroke, myocardial infarction, and heart failure hospitalizations. The safety profiles of both drugs were comparable, though losartan was associated with a slightly higher incidence of cough and discontinuation due to adverse events. Overall, candesartan may offer a slight clinical advantage over losartan, particularly in patients requiring more potent or sustained BP control. However, both drugs remain valuable options in the management of hypertension. Further long-term studies are recommended to confirm these findings and to investigate the potential benefits of each drug in specific patient subgroups.

Reverse Vaccinology Integrated with Biophysics Techniques for Designing a Peptide-Based Subunit Vaccine for Bourbon Virus.

Despite the seriousness of the disease carried by ticks, little is known about the Bourbon virus. Only three US states have recorded human cases of Bourbon virus (BRBV) infection; in all cases, a tick bite was connected with the onset of the illness. The Bourbon virus (BRBV) belongs to the Orthomyxoviridae family and Thogotovirus genus, originating in the states of the US, i.e., Kansas, Oklahoma and Missouri. The growing rates of BRBV infections in various parts of the US highlight the necessity for a thorough analysis of the virus's transmission mechanisms, vector types and reservoir hosts. Currently, there are no vaccines or efficient antiviral therapies to stop these infections. It is imperative to produce a vaccination that is both affordable and thermodynamically stable to reduce the likelihood of future pandemics. Various computational techniques and reverse vaccinology methodologies were employed to identify specific B- and T-cell epitopes. After thorough examination, the linker proteins connected the B- and T-cell epitopes, resulting in this painstakingly constructed vaccine candidate. Furthermore, 3D modeling directed the vaccine construct toward molecular docking to determine its binding affinity and interaction with TLR-4. Human beta-defensin was used as an adjuvant and linked to the N-terminus to boost immunogenicity. Furthermore, the C-IMMSIM simulation resulted in high immunogenic activities, with activation of high interferon, interleukins and immunoglobulin. The results of the in silico cloning process for E. coli indicated that the vaccine construct will try its utmost to express itself in the host, with a codon adaptation CAI value of 0.94. A net binding free energy of -677.7 kcal/mol obtained during docking showed that the vaccine has a high binding affinity for immunological receptors. Further validation was achieved via molecular dynamic simulations, inferring the confirmational changes during certain time intervals, but the vaccine remained intact to the binding site for a 100 ns interval. The thermostability determined using an RMSF score predicted certain changes in the mechanistic insights of the loop region with carbon alpha deviations, but no major changes were observed during the simulations. Thus, the results obtained highlight a major concern for researchers to further validate the vaccine's efficacy using in vitro and in vivo approaches.

Cipaglucosidase alfa plus miglustat: linking mechanism of action to clinical outcomes in late-onset Pompe disease.

Enzyme replacement therapy (ERT) is the only approved disease-modifying treatment modality for Pompe disease, a rare, inherited metabolic disorder caused by a deficiency in the acid α-glucosidase (GAA) enzyme that catabolizes lysosomal glycogen. First-generation recombinant human GAA (rhGAA) ERT (alglucosidase alfa) can slow the progressive muscle degeneration characteristic of the disease. Still, most patients experience diminished efficacy over time, possibly because of poor uptake into target tissues. Next-generation ERTs aim to address this problem by increasing bis-phosphorylated high mannose (bis-M6P) N-glycans on rhGAA as these moieties have sufficiently high receptor binding affinity at the resultant low interstitial enzyme concentrations after dosing to drive uptake by the cation-independent mannose 6-phosphate receptor on target cells. However, some approaches introduce bis-M6P onto rhGAA via non-natural linkages that cannot be hydrolyzed by natural human enzymes and thus inhibit the endolysosomal glycan trimming necessary for complete enzyme activation after cell uptake. Furthermore, all rhGAA ERTs face potential inactivation during intravenous delivery (and subsequent non-productive clearance) as GAA is an acid hydrolase that is rapidly denatured in the near-neutral pH of the blood. One new therapy, cipaglucosidase alfa plus miglustat, is hypothesized to address these challenges by combining an enzyme enriched with naturally occurring bis-M6P N-glycans with a small-molecule stabilizer. Here, we investigate this hypothesis by analyzing published and new data related to the mechanism of action of the enzyme and stabilizer molecule. Based on an extensive collection of in vitro, preclinical, and clinical data, we conclude that cipaglucosidase alfa plus miglustat successfully addresses each of these challenges to offer meaningful advantages in terms of pharmacokinetic exposure, target-cell uptake, endolysosomal processing, and clinical benefit.

Hepatotoxicity of antipsychotics: an exploratory pharmacoepidemiologic and pharmacodynamic study integrating FAERS data and in vitro receptor-binding affinities.

Antipsychotic psychopharmacotherapy is associated with the risk of drug-induced liver injury (DILI). However, understanding specific risk factors remains challenging due to limited data. This study investigates the relationship between receptor binding affinities and occupancies of antipsychotics and their associated hepatotoxic risks. A disproportionality analysis with calculation of the Reporting Odds Ratio (ROR) and the Information Component (IC) was conducted using data fromthe FDA Adverse Event Reporting System (FAERS) to identify signals related to the Standardised MedDRA Query "drug-related hepatic disorders", which served as a proxy for drug-induced hepatotoxicity. This was followed by a pharmacoepidemiologic-pharmacodynamic approach to investigate the relationship between the ROR and substance-related receptor binding affinities and occupancy, which was estimated based on in vitro receptor-binding profiles. Significant signals were identified for several antipsychotics, including chlorpromazine, loxapine, olanzapine, and quetiapine, with chlorpromazine and loxapine showing the highest RORs for DILI. Gender-specific analysis revealed a higher frequency of signals in female patients. Statistically significant negative correlations were identified between the ROR for drug-related hepatic disorders and the affinity for serotonin receptor 5-HT1A (r (17) = -0.68, p = 0.0012), while a positive correlation was observed for cholinergic receptors (r (17) = 0.46, p = 0.048). No significant correlations were found related to other receptors or drug properties. Our findings suggest that the serotonin and probably the cholinergic system may play a role in the development of DILI related to antipsychotic medications. The identification of antipsychotics with a higher association with DILI, such as chlorpromazine, underscores the need for careful monitoring in clinical practice. However, our findings need further longitudinal studies to confirm causality. A better understanding of the associations may inform clinical decision-making, particularly in patients with an increased susceptibility to liver damage.

A Small-molecule Antagonist Radiotracer for Positron Emission Tomography Imaging of the Mu Opioid Receptor.

The opioid crisis is a catastrophic health emergency catalyzed by the misuse of opioids that target and activate the mu opioid receptor. Traditional radioligands used to study the mu opioid receptor are often tightly regulated owing to their abuse and respiratory depression potential. In the present study, we sought to design and characterize a library of 24 non-agonist ligands for the mu opioid receptor. Ligands were evaluated for the binding affinity, intrinsic activity, and predicted blood-brain barrier permeability. Several ligands demonstrated single-digit nM binding affinity for the mu opioid receptor while also demonstrating selectivity over the delta and kappa opioid receptors. The antagonist behavior of 1A and 3A at the mu opioid receptor indicate that these ligands would likely not induce opioid-dependent respiratory depression. Therefore, these ligands can enable a safer means to interrogate the endogenous opioid system. Based on binding affinity, selectivity, and potential off-target binding, [ 11 C] 1A was prepared via metallophotoredox of the aryl-bromide functional group to [ 11 C]methyl iodide. The nascent radiotracer demonstrated brain uptake in a rhesus macaque model and accumulation in the caudate and putamen. Naloxone was able to reduce [ 11 C] 1A binding, though the interactions were not as pronounced as naloxone's ability to displace [ 11 C]carfentanil. These results suggest that GSK1521498 and related congeners are amenable to radioligand design and can offer a safer way to query opioid neurobiology.

Chimeras Derived from a P2Y14 Receptor Antagonist and UDP-Sugar Agonists for Potential Treatment of Inflammation.

Tethered glycoconjugates of a naphthalene- and piperidine-containing antagonist of the P2Y14 receptor (PPTN) were synthesized, and their nM receptor binding affinity was determined using a fluorescent tracer in hP2Y14R-expressing whole CHO cells. The rationale for preparing mono- and disaccharide conjugates of the antagonists was to explore the receptor binding site, which we know recognizes a glucose moiety on the native agonist (UDP-glucose), as well as enhance aqueous solubility and pharmacokinetics, including kidney excretion to potentially counteract sterile inflammation. Glycoconjugates with varied linker length, including PEG chains, were compared in hP2Y14R binding, suggesting that an optimal affinity (IC50, nM) in the piperidine series was achieved for triazolyl N-linked glucose conjugates having one (8a, MRS4872, 3.21) or two (7a, MRS4865, 2.40) methylene spacers. In comparison of different carbohydrate conjugates lacking a piperidine moiety but containing triazole spacers, optimal hP2Y14R affinity (IC50, nM) was achieved with N-linked glycosides of fucose 10f (6.19) and lactose 10h (1.88), and C-linked glucose 11a (5.30). Selected compounds were examined in mouse models of conditions known to be ameliorated by P2Y14R antagonists. Two glycoconjugates that lacked a piperidine moiety, N-linked glucose derivative 10a and the isomeric C-linked glucose derivative 11a, were protective in a mouse model of allergic asthma. Piperidine-containing glucose conjugate 7a of intermediate linker length and corresponding glucuronide 7b (MRS4866) protected against neuropathic pain. Thus, glycoconjugation of a known antagonist scaffold has produced less hydrophobic P2Y14R antagonists having substantial in vitro and in vivo activity.

Regulating IL-2 immune signaling function via a core allosteric structural network.

NMR and molecular dynamics simulations revealed distinct conformational dynamics and allosteric networks in computationally re-designed IL-2 superkines compared to wild-type IL-2, despite their similar crystal structures.The superkines S1 and S15 exhibit altered sampling of excited state conformations at an intermediate timescale, with slower conformational exchange rates compared to wild-type IL-2.A rationally designed mutation (L56A) in the S1 superkine's core allosteric network partially reverted its dynamics, receptor binding affinity, and T cell signaling behavior towards that of wild-type IL-2.Our study demonstrates that IL-2 core dynamics play a critical role in receptor binding and signaling function, providing a foundation for engineering more selective IL-2-based immunotherapies.

GABALAGEN Facilitates Pentobarbital-Induced Sleep by Modulating the Serotonergic System in Rats.

Gamma-aminobutyric acid (GABA) is one of the inhibitory neurotransmitters with beneficial effects including sedative properties. However, despite various clinical trials, scientific evidence regarding the impact on sleep of orally ingested GABA, whether natural or synthesized through biological pathways, is not clear. GABALAGEN (GBL) is the product of fermented collagen by Lactobacillus brevis BJ20 (L. brevis BJ20) and Lactobacillus plantarum BJ21 (L. plantarum BJ21), enriched with GABA and characterized by low molecular weight. The aim of this study was to investigate the effect of GBL on sleep improvement via a receptor binding assay in a pentobarbital-induced sleep-related rat model. We utilized a pentobarbital-induced sleep-related rat model to conduct this research. The present study investigated the sedative effects of GBL through electroencephalography (EEG) analysis in the pentobarbital-induced sleep animal model. Exploration of the neural basis of these positive effects involved evaluating orexin in the brain via immunohistochemical methods and 5-HT in the serum using an enzyme-linked immunosorbent assay (ELISA). Furthermore, we conducted a binding assay for 5-HT2C receptors, as these are considered pivotal targets in the mechanism of action for sleep aids. Diazepam (DZP) was used as a positive control to compare the efficacy of GBL. Results: In the binding assay, GBL displayed binding affinity to the 5-HT2C receptor (IC50 value, 5.911 µg/mL). Administration of a low dose of GBL (GBL_L; 100 mg/kg) increased non-rapid eye movement sleep time and decreased wake time based on EEG data in pentobarbital-induced rats. Administration of a high dose of GBL (GBL_H; 250 mg/kg) increased non-rapid eye movement sleep time. Additionally, GBL groups significantly increased concentration of the 5-HT level in the serum. GBL_H decreased orexin expression in the lateral hypothalamus. Conclusion: Overall, the sedative effect of GBL may be linked to the activation of serotonergic systems, as indicated by the heightened affinity of the 5-HT2C receptor binding and elevated levels of 5-HT observed in the serum. This suggests that GBL holds promise as a novel compound for inducing sleep in natural products.

Design, Synthesis, and Preclinical Evaluation of a High-Affinity 18F-Labeled Radioligand for Myocardial Growth Hormone Secretagogue Receptor Before and After Myocardial Infarction.

The peptide hormone ghrelin is produced in cardiomyocytes and acts through the myocardial growth hormone secretagogue receptor (GHSR) to promote cardiomyocyte survival. Administration of ghrelin may have therapeutic effects on post-myocardial infarction (MI) outcomes. Therefore, there is a need to develop molecular imaging probes that can track the dynamics of GHSR in health and disease to better predict the effectiveness of ghrelin-based therapeutics. We designed a high-affinity GHSR ligand labeled with 18F for imaging by PET and characterized its invivo properties in a canine model of MI. Methods: We rationally designed and radiolabeled with 18F a quinazolinone derivative ([18F]LCE470) with subnanomolar binding affinity to GHSR. We determined the sensitivity and invivo and ex vivo specificity of [18F]LCE470 in a canine model of surgically induced MI using PET/MRI, which allowed for anatomic localization of tracer uptake and simultaneous determination of global cardiac function. Uptake of [18F]LCE470 was determined by time-activity curve and SUV analysis in 3 regions of the left ventricle-area of infarct, territory served by the left circumflex coronary artery, and remote myocardium-over a period of 1.5 y. Changes in cardiac perfusion were tracked by [13N]NH3 PET. Results: The receptor binding affinity of LCE470 was measured at 0.33 nM, the highest known receptor binding affinity for a radiolabeled GHSR ligand. In vivo blocking studies in healthy hounds and ex vivo blocking studies in myocardial tissue showed the specificity of [18F]LCE470, and sensitivity was demonstrated by a positive correlation between tracer uptake and GHSR abundance. Post-MI changes in [18F]LCE470 uptake occurred independently of perfusion tracer distributions and changes in global cardiac function. We found that the regional distribution of [18F]LCE470 within the left ventricle diverged significantly within 1 d after MI and remained that way throughout the 1.5-y duration of the study. Conclusion: [18F]LCE470 is a high-affinity PET tracer that can detect changes in the regional distribution of myocardial GHSR after MI. In vivo PET molecular imaging of the global dynamics of GHSR may lead to improved GHSR-based therapeutics in the treatment of post-MI remodeling.

Modulatory Sedative Activity of Abrine on Diazepam in Thiopental Sodium Mediated Sleeping Mice: An In Vivo Approach with Receptor Binding Affinity of GABAergic Transmission

AbstractThe current study aims to assess the effects of abrine (ABR) in thiopental sodium (TS)‐induced sleeping mice and to explore the sedative impacts of the compound by using in vivo and in silico investigations. ABR (5 and 10 mg k−1g, i.p.) and diazepam (DZP) (2 mg k−1g, i.p.) were administered to the experimental animals either single or combined. TS (20 mg k−1g, i.p.) was administered to induce sleep, and latency with sleeping duration was observed for 3 h. The in silico investigation was conducted to predict the role of ABR in the gamma‐aminobutyric acid A (GABAA) receptor in the sleeping process and to evaluate pharmacokinetics and toxicity. Results showed that ABR (10 mg k−1g) significantly (p &lt; 0.05) decreased the latency period (8.20 ± 1.85 min) and enhanced sleep duration (187.8 ± 8.87 min) in comparison with the control group. Additionally, the co‐treatments of ABR and DZP remarkably reduced the latency period (4.40 ± 0.24 min) and increased the sleeping duration (201.40 ± 5.89 min) compared to the single therapy. The molecular docking indicated that ABR has a binding affinity of −7.4 kcal/mol for the GABAA receptor. In conclusion, ABR provides strong sedative and synergistic efficacy on TS‐induced sleeping mice via the GABAergic system.