Novel 5-HT7 receptor antagonists modulate intestinal immune responses and reduce severity of colitis.

Inflammatory bowel disease (IBD) encompasses a number of debilitating chronic gastrointestinal (GI) inflammatory disorders, including Crohn's disease and ulcerative colitis. In both conditions, mucosal inflammation is a key clinical presentation and is associated with altered serotonin (5-hydroxytryptamine; 5-HT) signaling. This altered 5-HT signaling is also found across various animal models of colitis. Of the 14 known receptor subtypes, 5-HT receptor type 7 (5-HT7) is one of the most recently discovered. We previously reported that blocking 5-HT signaling, with either a selective 5-HT7 receptor antagonist (SB-269970) or genetic ablation alleviated intestinal inflammation in murine experimental models of colitis. Here, we developed novel antagonists, namely MC-170073 and MC-230078, which target 5-HT7 receptors with high selectivity. We also investigated the in vivo efficacy of these antagonists in experimental colitis by utilizing dextran sulfate sodium (DSS) and the transfer of CD4+CD45RBhigh T cells to induce intestinal inflammation. Inhibition of 5-HT7 receptor signaling with the antagonists, MC-170073 and MC-230078, ameliorated intestinal inflammation in both acute and chronic colitis models, which was accompanied by lower histopathological damage and diminished levels of pro-inflammatory cytokines in comparison to vehicle-treated controls. Together, the data reveal that the pharmacological inhibition of 5-HT7 receptors by these selective antagonists ameliorates the severity of colitis across various experimental models and may, in the future, serve as a potential treatment option for patients with IBD. In addition, these findings support that 5-HT7 is a viable therapeutic target for IBD.

Retromer Stabilization Improves Cognitive Function and Synaptic Plasticity in a Mouse Model of Down Syndrome.

BACKGROUND: Retromer complex proteins are decreased in postmortem brain tissues from Down syndrome subjects and inversely correlate with the Alzheimer's disease-like neuropathology. However, whether targeting in vivo the retromer system affects cognitive deficits and synaptic function in Down syndrome remains unknown. OBJECTIVE: The aim of the current study was to examine the effects of pharmacological retromer stabilization on cognitive and synaptic functions in a mouse model of Down syndrome. METHODS: Ts65dn mice were administered the pharmacological chaperone, TPT-172, or vehicle from 4 to 9 months of age and then assessed for changes in cognitive function. To assess the effects of TPT-172 on synaptic plasticity, hippocampal slices from Ts65dn mice were incubated in TPT-172 and used for field potential recordings. RESULTS: Chronic TPT-172 treatment improved performance in cognitive function tests, its incubation with hippocampal slices ameliorated synaptic function response. CONCLUSION: Pharmacological stabilization of the retromer complex improves synaptic plasticity and memory in a mouse model of Down syndrome. These results support the therapeutic potential of pharmacological retromer stabilization for individual with Down syndrome.

HIV gp120 impairs nucleus accumbens neuroimmune function and dopamine D3 receptor-mediated inhibition of cocaine seeking in male rats.

Cocaine Use Disorders (CUDs) are associated with an increased risk of human immunodeficiency virus (HIV) infection. Cocaine and the HIV envelope protein gp120 each induce distinct deficits to mesocorticolimbic circuit function and motivated behavior; however, little is known regarding how they interact to dysregulate these functions or how such interactions impact pharmacotherapeutic efficacy. We have previously shown that the selective, weak partial agonist of the dopamine D3 receptor (D3R), MC-25-41, attenuates cocaine-seeking behavior in male rats. Here, we sought to characterize changes in striatal neuroimmune function in gp120-exposed rats across abstinence from operant access to cocaine (0.75 mg/kg, i.v.) or sucrose (45 mg/pellet), and to examine the impact of gp120 exposure on MC-25-41-reduced cocaine seeking. After establishing a history of cocaine or sucrose self-administration, rats received intracerebroventricular gp120 infusions daily the first 5 days of abstinence and were sacrificed either on day 6 or after 21 days of forced abstinence and a cue-induced cocaine seeking test. We demonstrated that MC-25-41 treatment attenuated cue-induced cocaine seeking among control rats but not gp120-exposed rats. Moreover, postmortem analysis of nucleus accumbens (NAc) core neuroimmune function indicated cocaine abstinence- and gp120-induced impairments, and the expression of several immune factors within the NAc core significantly correlated with cocaine-seeking behavior. We conclude that cocaine abstinence dysregulates striatal neuroimmune function and interacts with gp120 to inhibit the effectiveness of a D3R partial agonist in reducing cocaine seeking. These findings highlight the need to consider comorbidities, such as immune status, when evaluating the efficacy of novel pharmacotherapeutics.

Novel druggable mechanism of Parkinson's disease: Potential therapeutics and underlying pathogenesis based on ferroptosis.

Genetics, age, environmental factors, and oxidative stress have all been implicated in the development of Parkinson's disease (PD); however, a complete understanding of its pathology remains elusive. At present, there is no cure for PD, and currently available therapeutics are insufficient to meet patient needs. Ferroptosis, a distinctive iron-dependent cell death mode characterized by lipid peroxidation and oxidative stress, has pathophysiological features similar to those of PD, including iron accumulation, reactive oxygen species-induced oxidative damage, and mitochondrial dysfunction. Ferroptosis has been identified as a specific pathway of neuronal death and is closely related to the pathogenesis of PD. Despite the similarities in the biological targets involved in PD pathogenesis and ferroptosis, the relationship between novel targets in PD and ferroptosis has been neglected in the literature. In this review, the mechanism of ferroptosis is discussed, and the potential therapeutic targets implicated in both PD and ferroptosis are compared. Furthermore, the anti-PD effects of several ferroptosis inhibitors, as well as clinical studies thereof, and the identification of novel lead compounds for the treatment of PD and the inhibition of ferroptosis are reviewed. It is hoped that this review can promote research to further elucidate the relationship between ferroptosis and PD and provide new strategies for the development of novel ferroptosis-targeting PD therapy.

Beneficial Effect of a Small Pharmacologic Chaperone on the Established Alzheimer's Disease Phenotype.

BACKGROUND: The endosomal retromer complex system is a key controller for trafficking of proteins. Downregulation of its recognition core proteins, such as VPS35, is present in Alzheimer's disease (AD) brain, whereas its normalization prevents the development of AD pathology in a transgenic model with amyloid-ß deposits and tau tangles. OBJECTIVE: Assess the effect of targeting VPS35 after the AD pathology and memory impairments have developed. METHODS: Twelve-month-old triple transgenic mice were treated with a small pharmacological chaperone, TPT-172, or vehicle for 14 weeks. At the end of this period, the effect of the drug on their phenotype was evaluated. RESULTS: While control mice had a decline of learning and memory, the group receiving the chaperone did not. Moreover, when compared with controls the treated mice had significantly less amyloid-ß peptides and phosphorylated tau, elevation of post-synaptic protein, and reduction in astrocytes activation. CONCLUSION: Taken together, our findings demonstrate that pharmacologic stabilization of the retromer recognition core is beneficial also after the AD-like pathologic phenotype is established.

5-HT1B receptor agonist enhances breakpoint for cocaine on a progressive ratio (PR) schedule during maintenance of self-administration in female rats but reduces breakpoint for sucrose.

Background: Previous research showed that the 5-HT1B receptor agonist CP94253 enhanced cocaine reinforcement rate during maintenance of daily self-administration (SA), but inhibited reinforcement rate after 21 days of abstinence in male rats. Here we examined whether female rats show similar effects of CP94253 during maintenance as males across estrous cycle phases. Methods: Female rats trained on a fixed ratio 5 (FR5) cocaine reinforcement schedule were tested for the effects of CP94253 (5.6 mg/kg, s.c.) on cocaine reinforcement rate during each phase of the estrous cycle, with access to either low (0.075 and 0.1875) or high (0.375 and 0.75) cocaine doses available for 1 h sequentially in descending dose order. Other female and male rats trained on a progressive ratio (PR) schedule of cocaine or sucrose reinforcement were tested for CP94253 (0, 3.2, 5.6, and 10 mg/kg, s.c.) effects on reinforcement rate in 3-h sessions. CP94253 effects on responding during sucrose cue-reactivity were also examined post-abstinence. Results: Regardless of sex, CP94253 enhanced breakpoints on the PR schedule during maintenance of cocaine SA but attenuated breakpoints for sucrose reinforcement and decreased responding during sucrose cue-reactivity. FR results showed that CP94253 attenuated cocaine reinforcement rate during all estrous cycle phases except metestrus. Conclusions: Overall, we suggest that CP94253 increased incentive motivation for cocaine during maintenance of SA in female and male rats, yet decreased motivation for sucrose. We also suggest that 5-HT1BRs modulate motivation similarly across sexes except when females are in metestrus.

Dysfunction of the retromer complex system contributes to amyloid and tau pathology in a stem cell model of Down syndrome.

Introduction: Retromer complex proteins are decreased in Down syndrome (DS) brains and correlate inversely with brain amyloidosis. However, whether retromer dysfunction contributes to the amyloid beta (Aß) and tau neuropathology of DS remains unknown. Methods: Human trisomic induced Pluripotent Stem Cells (iPSCs) and isogenic controls were differentiated into forebrain neurons, and changes in retromer proteins, tau phosphorylated epitopes, and Aß levels were assessed in euploid and trisomic neurons using western blot and enzyme-linked immunosorbent assay (ELISA). Genetic overexpression and pharmacological retromer stabilization were used to determine the functional role of the retromer complex system in modulating amyloid and tau pathology. Results: Trisomic neurons developed age-dependent retromer core protein deficiency associated with accumulation of Aß peptides and phosphorylated tau isoforms. Enhancing retromer function through overexpression or pharmacological retromer stabilization reduced amyloid and tau pathology in trisomic neurons. However, the effect was greater using a pharmacological approach, suggesting that targeting the complex stability may be more effective in addressing this neuropathology in DS. Discussion: Our results demonstrate that the retromer complex is directly involved in the development of the neuropathologic phenotype in DS, and that pharmacological stabilization of the complex should be considered as a novel therapeutic tool in people with DS.

Selectivity profile comparison for certain γ-butyrolactone and oxazolidinone-based ligands on a sigma 2 receptor over sigma 1: a molecular docking approach.

Sigma receptors (σ1 R and σ2 R) are pharmacologically characterized membrane-bound receptors that bind a wide range of chemical compounds. Alzheimer's disease, traumatic brain injury, schizophrenia, and neuropathic pain have all been associated with abnormal σ2 activity. The σ2 receptor has recently been identified as a potential therapeutic target for inhibiting the formation of amyloid plaques. Numerous laboratories are now investigating the potential of σ2 ligands. Small molecule discovery is the focus of current research, with the goal of using target-based action to treat a variety of illnesses and ailments. Functionalized γ-butyrolactone and oxazolidinone-based ligands, in particular, are pharmacologically important scaffolds in drug discovery research and have been thoroughly examined for σ2 receptor efficacy. The purpose of this study was to evaluate the pharmacophoric features of different σ2 receptor ligands using in silico techniques. This study used a library of 58 compounds having a γ-butyrolactone and oxazolidinone core. To investigate the binding characteristics of the ligands with the σ2 receptor, a 3D homology model was developed. To understand the binding pattern of the γ-butyrolactone and oxazolidinone based ligands, molecular docking studies were performed on both σ1 and σ2 receptors. Furthermore, MM/GBSA binding energy calculations were used to confirm the binding of ligands on the σ2 over σ1 receptor. These in silico findings will aid in the discovery of selective σ2 ligands with good pharmacophoric properties and potency in the future.

Dopamine D3 receptor ligand suppresses the expression of levodopa-induced dyskinesia in nonhuman primate model of parkinson's disease.

Parkinson's disease (PD) is a complex multisystem, chronic and so far incurable disease with significant unmet medical needs. The incidence of PD increases with aging and the expected burden will continue to escalate with our aging population. Since its discovery in the 1961 levodopa has remained the gold standard pharmacotherapy for PD. However, the progressive nature of the neurodegenerative process in and beyond the nigrostriatal system causes a multitude of side effects, including levodopa-induced dyskinesia within 5 years of therapy. Attenuating dyskinesia has been a significant challenge in the clinical management of PD. We report on a small molecule that eliminates the expression of levodopa-induced dyskinesia and significantly improves PD-like symptoms. The lead compound PD13R we discovered is a dopamine D3 receptor partial agonist with high affinity and selectivity, orally active and with desirable drug-like properties. Future studies are aimed at developing this lead compound for treating PD patients with dyskinesia.

Antifungal properties of (2S, 4R)-Ketoconazole sulfonamide analogs.

Invasive candidiasis remains a significant health concern, as it is associated with a high mortality risk. In addition, the risk of infection is significantly elevated in immunocompromised patients such as those with HIV, cancer, or those taking imcmunosuppressive drugs as a result of organ transplantation. The majority of these cases are caused by C. albicans, and C. glabrata is the second most common cause. These infections are typically treated using approved antifungal agents, but the rise of drug-resistant fungi is a serious concern. As part of our on-going effort to identify novel antifungal agents, we have studied the in vitro antifungal properties of a series of sulfonamide analogs of (2S, 4R)-Ketoconazole. Herein we report on the in vitro activity against the key fungal pathogens C. albicans, and C. glabrata.

5-HT1B receptor agonist attenuates cocaine self-administration after protracted abstinence and relapse in rats.

BACKGROUND: The 5-HT1B receptor (5-HT1BR) agonist, CP94253, enhances cocaine intake during maintenance of self-administration (SA) but attenuates intake after 21 days of forced abstinence in male rats. AIMS: We examined whether CP94253 attenuates cocaine intake in female rats after a period of abstinence, and if these attenuating effects persist or revert to enhancing cocaine intake during resumption (i.e. relapse) of daily cocaine SA. METHODS: Male and female rats trained to lever press on a fixed ratio 5 schedule of cocaine reinforcement underwent ⩾21 days of forced abstinence. They were then tested for the effects of CP94253 (5.6 mg/kg, SC) or vehicle on cocaine SA. During the test session, rats had 1-h access to the training dose of cocaine (0.75 mg/kg, IV) followed by 1-h access to a lower cocaine dose (0.075 mg/kg, IV). Rats then resumed cocaine SA for 15 days to mimic relapse and were retested as done previously. Subsequently, rats underwent abstinence again (21-60 days) and were tested for CP94253 effects on locomotion and cue reactivity (i.e. responding for light/tone cues previously paired with cocaine infusions). RESULTS: Regardless of sex, CP94253 decreased cocaine intake after abstinence and during resumption of SA and decreased cue reactivity while having no effect on locomotion. CONCLUSIONS: CP94253 decreases cocaine intake and cocaine seeking in both males and females even after resumption of cocaine SA. These findings suggest that the inhibitory effects of CP94253 observed after abstinence are long-lasting, and therefore, 5-HT1BR agonists may have clinical efficacy as anti-relapse medications for cocaine use disorders.

Factors Governing Selectivity of Dopamine Receptor Binding Compounds for D2R and D3R Subtypes.

Targeting the D3 dopamine receptor (D3R) is a promising pharmacotherapeutic strategy for the treatment of many disorders. The structure of the D3R is similar to the D2 dopamine receptor (D2R), especially in the transmembrane spanning regions that form the orthosteric binding site, making it difficult to identify D3R selective pharmacotherapeutic agents. Here, we examine the molecular basis for the high affinity D3R binding and D3R vs D2R binding selectivity of substituted phenylpiperazine thiopheneamides. We show that removing the thiophenearylamide portion of the ligand consistently decreases the affinity of these ligands at D3R, while not affecting their affinity at the D2R. Our long (>10 µs) molecular dynamics simulations demonstrated that both dopamine receptor subtypes adopt two major conformations that we refer to as closed or open conformations, with D3R sampling the open conformation more frequently than D2R. The binding of ligands with conjoined orthosteric-allosteric binding moieties causes the closed conformation to populate more often in the trajectories. Also, significant differences were observed in the extracellular loops (ECL) of these two receptor subtypes leading to the identification of several residues that contribute differently to the ligand binding for the two receptors that could potentially contribute to ligand binding selectivity. Our observations also suggest that the displacement of ordered water in the binding pocket of D3R contributes to the affinity of the compounds containing an allosteric binding motif. These studies provide a better understanding of how a bitopic mode of engagement can determine ligands that bind selectively to D2 and D3 dopamine receptor subtypes.

Targeting SARS-CoV-2 M3CLpro by HCV NS3/4a Inhibitors: In Silico Modeling and In Vitro Screening.

Currently the entire human population is in the midst of a global pandemic caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome CoronaVirus 2). This highly pathogenic virus has to date caused >71 million infections and >1.6 million deaths in >180 countries. Several vaccines and drugs are being studied as possible treatments or prophylactics of this viral infection. M3CLpro (coronavirus main cysteine protease) is a promising drug target as it has a significant role in viral replication. Here we use the X-ray crystal structure of M3CLpro in complex with boceprevir to study the dynamic changes of the protease upon ligand binding. The binding free energy was calculated for water molecules at different locations of the binding site, and molecular dynamics (MD) simulations were carried out for the M3CLpro/boceprevir complex, to thoroughly understand the chemical environment of the binding site. Several HCV NS3/4a protease inhibitors were tested in vitro against M3CLpro. Specifically, asunaprevir, narlaprevir, paritaprevir, simeprevir, and telaprevir all showed inhibitory effects on M3CLpro. Molecular docking and MD simulations were then performed to investigate the effects of these ligands on M3CLpro and to provide insights into the chemical environment of the ligand binding site. Our findings and observations are offered to help guide the design of possible potent protease inhibitors and aid in coping with the COVID-19 pandemic.